01444nas a2200169 4500008004100000245007800041210006900119260004000188300001400228520083000242100002601072700002001098700002401118700001801142700002101160856009301181 2025 eng d00aAntarctic mosaic: Mixing methods and metaphors in the McMurdo Dry Valleys0 aAntarctic mosaic Mixing methods and metaphors in the McMurdo Dry aCambridge, UKbOpen Book Publishers a355 - 3763 a

Different methods use different metaphors, and the way we write can reflect our underlying philosophical assumptions, positionalities, and values. To mix methods, it follows, is also in a very tangible sense to mix metaphors. In this chapter, we use the metaphor of a mosaic, as well as several others, to help us reflect on our experiences of working together on a decade-long historical research project about the McMurdo Dry Valleys Long Term Ecological Research site in East Antarctica. We describe our process of ‘going with the flow’, using whichever methods we thought might help produce insights. We also describe the challenges and benefits of collaboratively writing together and offer several practical takeaways that may be useful for others conducting interdisciplinary mixed-methods research.

1 aChignell, Stephen, M.1 aHowkins, Adrian1 aFountain, Andrew, G1 aLave, Rebecca1 aLane, Stuart, N. uhttps://www.openbookpublishers.com/books/10.11647/obp.0418/chapters/10.11647/obp.0418.1802706nas a2200481 4500008004100000245003700041210003700078260001200115520135400127100002401481700002001505700002801525700002001553700002001573700002201593700002501615700001601640700001901656700002001675700002601695700001901721700002001740700002601760700002901786700001901815700002401834700001801858700002401876700002401900700002801924700002401952700001101976700001901987700003402006700002702040700001602067700002402083700001402107700001302121700001602134700001902150856005502169 2025 eng d00aAtmospheric rivers in Antarctica0 aAtmospheric rivers in Antarctica c02/20253 a

Antarctic atmospheric rivers (ARs) are a form of extreme weather that transport heat and moisture from the Southern Hemisphere subtropics and/or mid-latitudes to the Antarctic continent. Present-day AR events generally have a positive influence on the Antarctic ice-sheet mass balance by producing heavy snowfall, yet they also cause melt of sea ice and coastal ice sheet areas, as well as ice shelf destabilization. In this Review, we explore the atmospheric dynamics and impacts of Antarctic ARs over their life cycle to better understand their net contributions to ice-sheet mass balance. ARs occur in high-amplitude pressure couplets, and those strong enough to reach the Antarctic are often formed within Rossby waves initiated by tropical convection. Antarctic ARs are rare events (~3 days per year per location) but have been responsible for 50–70% of extreme snowfall events in East Antarctica since the 1980s. However, they can also trigger extensive surface melting events, such as the final ice shelf collapse of Larsen A in 1995 and Larsen B in 2002. Climate change will likely cause stronger ARs as anthropogenic warming increases atmospheric water vapour. Future research must determine how these climate change impacts will alter the relationship among Antarctic ARs, net ice-sheet mass balance and future sea-level rise.

1 aWille, Jonathan, D.1 aFavier, Vincent1 aGorodetskaya, Irina, V.1 aAgosta, Cécile1 aBaiman, Rebecca1 aBarrett, John, E.1 aBarthelemy, Léonard1 aBoza, Burcu1 aBozkurt, Deniz1 aCasado, Mathieu1 aChyhareva, Anastasiia1 aClem, Kyle, R.1 aCodron, Francis1 aDatta, Rajashree, Tri1 aDurán-Alarcón, Claudio1 aFrancis, Diana1 aHoffman, Andrew, O.1 aKolbe, Marlen1 aKrakovska, Svitlana1 aLinscott, Gabrielle1 aMaclennan, Michelle, L.1 aMattingly, Kyle, S.1 aMu, Ye1 aPohl, Benjamin1 aSantos, Christophe, Leroy-Dos1 aShields, Christine, A.1 aToker, Emir1 aWinters, Andrew, C.1 aYin, Ziqi1 aZou, Xun1 aZhang, Chen1 aZhang, Zhenhai uhttps://www.nature.com/articles/s43017-024-00638-702348nas a2200217 4500008004100000245023200041210006900273260001200342300001200354490000700366520154300373653001501916653002001931653000801951653002001959653001401979653002101993100002102014700002402035856007102059 2025 eng d00aChemical signatures of microbial life in an ecological end-member: Shifting hydroclimate and sediment fluxes influence DOM biogeochemistry in Lake Fryxell, a permanently ice-covered lake in the McMurdo Dry Valleys of Antarctica0 aChemical signatures of microbial life in an ecological endmember c04/2025 a24786780 v573 a

The ice-covered lakes in the McMurdo Dry Valleys (MDV) of Antarctica provide end-member ecosystems for understanding the production of dissolved organic matter (DOM) in aquatic ecosystems in the absence of vegetation on the landscape and under resource and nutrient constraints. Given these constraints, DOM in MDV lakes is derived solely from microbial phototrophs and heterotrophic bacteria, contrasting with the dominant terrestrial sources in temperate regions. Previous research developed fluorometric approaches for characterizing DOM, including in MDV lakes. In this study we leveraged these approaches along with contemporary molecular-based techniques to elucidate changes in DOM composition across the depth profile for Lake Fryxell in the MDV. The results showed that the presence of organic molecules containing sulfur increased at depth where anoxic conditions prevailed. To evaluate the influences of climate-induced rising lake levels and multiple flood events in the MDV, we compared recent and historical samples. The results indicated a remarkable consistency in source-related fluorescence metrics over time, whereas a twofold decrease in sulfur content of the fulvic acid fraction was observed in samples from above and below the oxycline. Biogeochemical processes associated with the influx of iron oxide–rich sediments during flood events may have contributed to this change, and similar processes may stimulate biogeochemical cycling and remineralization in temperate lakes during seasonal transitions.

10aAntarctica10abiogeochemistry10aDOM10alake metabolism10alimnology10anutrient cycling1 aRue, Garrett, P.1 aMcKnight, Diane, M. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2025.247867802735nas a2200325 4500008004100000022001400041245008600055210006900141260001200210490000700222520179000229653001502019653001302034653001002047653002202057653001002079100002602089700002402115700002502139700002102164700001802185700002502203700002102228700002202249700001902271700002402290700002102314700001702335856005702352 2025 eng d a0722-406000aA comprehensive survey of soil microbial diversity across the Antarctic continent0 acomprehensive survey of soil microbial diversity across the Anta c02/20250 v483 a

Antarctic soils are unique from those found nearly anywhere else on Earth yet can still harbor a broad diversity of microorganisms able to tolerate the challenging conditions typical of the continent. For these reasons, microbiologists have been drawn to Antarctica for decades. However, our understanding of which microbes thrive in Antarctic soils and how they to do so remains limited. To help resolve these knowledge gaps, we analyzed a collection of 200 archived Antarctic soils—from Livingston Island on the Antarctic Peninsula to Cape Hallett in northern Victoria Land. We analyzed the prokaryotic and fungal communities in these soils using both cultivation-independent marker gene sequencing and cultivation-dependent approaches (microbial isolation), paired with extensive soil geochemical analyses. Our cultivation-independent analyses indicate that colder, saltier, and drier soils harbor less diverse communities of bacteria and fungi, distinct from those found in soils with less challenging conditions. We also built a culture collection from a subset of these soils that encompasses more than 50 bacterial and fungal genera, including cold-tolerant organisms, such as <i>Cryobacterium</i> and <i>Cryomyces</i>. By directly comparing the diversity of our cultured isolates against our cultivation-independent data, we show that many of the more abundant Antarctic taxa are not readily cultivated and highlight bacterial and fungal taxa that should be the focus of future cultivation efforts. Together, we hope that our collection of isolates, the comprehensive data compiled from the cultivation-independent analyses, and our geochemical analyses will serve as a community resource to accelerate the study of Antarctic soil microbes.

10aAntarctica10abacteria10afungi10amicrobial ecology10asoils1 aDragone, Nicholas, B.1 aChildress, Mary, K.1 aVanderburgh, Caihong1 aWillmore, Rachel1 aHogg, Ian, D.1 aSancho, Leopoldo, G.1 aLee, Charles, K.1 aBarrett, John, E.1 aQuandt, Alisha1 aLeMonte, Joshua, J.1 aAdams, Byron, J.1 aFierer, Noah uhttps://link.springer.com/10.1007/s00300-025-03372-y02680nas a2200337 4500008004100000022001400041245015000055210006900205260001200274300000700286490000700293520167400300653001401974653001701988653000902005653001402014653002702028653001502055100002002070700001802090700001902108700002102127700002402148700001702172700002302189700001902212700001502231700001602246700001502262856006502277 2025 eng d a0722-406000aInference from eDNA-based field distributions vs laboratory analysis of isolated strains: Physiological performance of non-marine Antarctic biota0 aInference from eDNAbased field distributions vs laboratory analy c03/2025 a360 v483 a

Environmental DNA (eDNA) is frequently used to infer distributions of microorganisms in Antarctica. Their distributions relative to environmental variables are, in turn, sometimes used to infer their physiological range (and a relationship between the two is generally assumed for conservation purposes). We sought to determine whether ecological inferences based on distributions accurately reflect tolerances of the organisms concerned, using 249 legacy non-marine samples from a latitudinal gradient between 72 and 86°S, Antarctica. A cyanobacterium, a heterotrophic bacterium, two eukaryotic algae, two fungi, and a moss were isolated into culture, and their field distributions inferred using eDNA analysis of the samples above. Tolerances of each organism with respect to environmental predictors were then inferred from the eDNA distribution and metadata using Generalised Additive Models. We then measured growth of the cultured isolates in response to a set of these predictors. Laboratory responses were then compared to inferences from the eDNA/metadata. Predictions from eDNA/metadata agreed with the results of physiological laboratory experiments for strains that were detected at high taxonomic resolution in the field samples. However, errors were never completely eliminated, and direct contradictions occurred when strains were represented at lower taxonomic resolution in the field data. We found that accurate ecological inference from eDNA studies would be best achieved via maximising both taxonomic resolution (through marker choice/read length) and ecological signal (through careful sampling design and rigorous metadata collection).

10aAntarctic10adistribution10aeDNA10ainference10amicrobial biodiversity10aphysiology1 aNovis, Phil, M.1 aMonks, Adrian1 aHunt, John, E.1 aAdams, Byron, J.1 aDhami, Manpreet, K.1 aKim, Ji, Hee1 aMitchell, Caroline1 aMorgan, Fraser1 aHawes, Ian1 aAislabie, J1 aBroady, P. uhttps://link.springer.com/article/10.1007/s00300-025-03356-y02348nas a2200217 4500008004100000022001400041245012100055210006900176260001200245520149200257653001101749653001801760653002201778653001501800653001301815653001701828100002101845700002301866700002201889856021901911 2025 eng d a0954-102000aMicrobial mat activity and soil biogeochemistry across variable phosphorus availability in Taylor Valley, Antarctica0 aMicrobial mat activity and soil biogeochemistry across variable  c05/20253 a

Primary production is fundamental to ecosystems, and in many extreme environments production is facilitated by microbial mats. Microbial mats are complex assemblages of photo- and heterotrophic microorganisms colonizing sediment and soil surfaces. These communities are the dominant producers of the McMurdo Dry Valleys, Antarctica, where they occupy lentic and lotic environments as well as intermittently wet soils. While the influence of microbial mats on stream nutrient dynamics and lake organic matter cycling is well documented, the influence of microbial mats on underlying soil is less well understood, particularly the effects of microbial mat nitrogen and carbon fixation. Taylor Valley soils occur across variable levels of inorganic phosphorus availability, with the Ross Sea drift containing four times that of the Taylor drifts, providing opportunities to examine how soil geochemistry influences microbial mats and the ecological functions they regulate. We found that inorganic phosphorus availability is positively correlated with microbial mat biomass, pigment concentration and nitrogen fixation potential. Additionally, our results demonstrate that dense microbial mats influence the ecological functioning of underlying soils by enriching organic carbon and total nitrogen stocks (two times higher). This work contributes to ongoing questions regarding the sources of energy fuelling soil food webs and the regional carbon balance in the McMurdo Dry Valleys.

10acarbon10acyanobacteria10anitrogen fixation10aphosphorus10apigments10asoil ecology1 aPower, Sarah, N.1 aOsburn, Ernest, D.1 aBarrett, John, E. uhttps://www.cambridge.org/core/journals/antarctic-science/article/microbial-mat-activity-and-soil-biogeochemistry-across-variable-phosphorus-availability-in-taylor-valley-antarctica/0655E2F09B8D6961618B8F396BA692F202426nas a2200241 4500008004100000022001400041245010000055210006900155260001200224490000800236520166500244653001501909653001701924653002901941653002401970653002201994653001902016100002202035700002202057700001502079700002102094856006902115 2025 eng d a2169-895300aMorphology and distribution of bubble-supported microbial mats from ice-covered Antarctic lakes0 aMorphology and distribution of bubblesupported microbial mats fr c03/20250 v1303 a

Gas bubbles directly influence the macromorphology of benthic microbial mats resulting in preservable biosedimentary structures. This study characterizes the morphology and distribution of microbial mats growing in gas-supersaturated, perennially ice-covered lakes Fryxell, Joyce, and Hoare of the McMurdo Dry Valleys of Antarctica. Photosynthetic benthic mats within the gas-supersaturated zone trap oxygen-rich bubbles and become buoyant, tearing off the bottom as “liftoff mats.” These liftoff mats form a succession of morphologies starting with bubble-induced deformation of flat mats into tent, ridge, and finger liftoff mat. With progressive deformation, mats tear, forming sheet liftoff, while multiple cycles of deformation and tearing transform sheet into strip liftoff. Some mats detach from the substrate and float to the underside of the ice. The depth range of the liftoff zone has varied over time at each lake. Downslope expansion of bubble formation brings previously bubble-free, deep-water pinnacle mats into the liftoff zone. When the liftoff zone shallows, liftoff mats at the deeper end deflate and can become scaffolding for additional mat growth. The superposition and relative orientation of liftoff and pinnacle mats can be used to track the maximum depth of the liftoff zone and changes in gas saturation state in these lakes through time. Our results demonstrate that gas bubbles, even when they are transitory, can exert a significant impact on the morphology of microbial mats at larger scales. This provides a way to identify similar structures and gas supersaturated environments in the biosedimentary record.

10aAntarctica10abiosediments10abubble-driven morphology10agas-supersaturation10aice-covered lakes10amicrobial mats1 aJuarez-Rivera, M.1 aMackey, Tyler, J.1 aHawes, Ian1 aSumner, Dawn, Y. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024JG00851603241nas a2200505 4500008004100000022001400041245010400055210006900159260001200228300001800240490000700258520177600265653001502041653001302056653001402069653001302083653001902096100002202115700001802137700001602155700002402171700002302195700002302218700001502241700002202256700001802278700002202296700002302318700002402341700002202365700001902387700002302406700001302429700002302442700002102465700002702486700002402513700002302537700001402560700002602574700002002600700003102620700001502651856006902666 2025 eng d a0043-139700aOne-hundred fundamental, open questions to integrate methodological approaches in lake ice research0 aOnehundred fundamental open questions to integrate methodologica c05/2025 ae2024WR0390420 v613 a

The rate of technological innovation within aquatic sciences outpaces the collective ability of individual scientists within the field to make appropriate use of those technologies. The process of in situ lake sampling remains the primary choice to comprehensively understand an aquatic ecosystem at local scales; however, the impact of climate change on lakes necessitates the rapid advancement of understanding and the incorporation of lakes on both landscape and global scales. Three fields driving innovation within winter limnology that we address here are autonomous real-time in situ monitoring, remote sensing, and modeling. The recent progress in low-power in situ sensing and data telemetry allows continuous tracing of under-ice processes in selected lakes as well as the development of global lake observational networks. Remote sensing offers consistent monitoring of numerous systems, allowing limnologists to ask certain questions across large scales. Models are advancing and historically come in different types (process-based or statistical data-driven), with the recent technological advancements and integration of machine learning and hybrid process-based/statistical models. Lake ice modeling enhances our understanding of lake dynamics and allows for projections under future climate warming scenarios. To encourage the merging of technological innovation within limnological research of the less-studied winter period, we have accumulated both essential details on the history and uses of contemporary sampling, remote sensing, and modeling techniques. We crafted 100 questions in the field of winter limnology that aim to facilitate the cross-pollination of intensive and extensive modes of study to broaden knowledge of the winter period.

10acryosphere10alake ice10alimnology10amodeling10aremote sensing1 aCulpepper, Joshua1 aSharma, Sapna1 aGunn, Grant1 aMagee, Madeline, R.1 aMeyer, Michael, F.1 aAnderson, Eric, J.1 aArp, Chris1 aCooley, Sarah, W.1 aDolan, Wayana1 aDugan, Hilary, A.1 aDuguay, Claude, R.1 aJones, Benjamin, M.1 aKirillin, Georgiy1 aLadwig, Robert1 aLeppäranta, Matti1 aLong, Di1 aMagnuson, John, J.1 aPavelsky, Tamlin1 aPiccolroaz, Sebastiano1 aRobertson, Dale, M.1 aSteele, Bethel, G.1 aTom, Manu1 aWeyhenmeyer, Gesa, A.1 aWoolway, Iestyn1 aXenopoulos, Marguerite, A.1 aYang, Xiao uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024WR03904202394nas a2200301 4500008004100000022001400041245012200055210006900177260001200246300001100258490000800269520142600277653001501703653002401718653001901742653001901761653003401780653002301814100002801837700002001865700002501885700002401910700002201934700002101956700001901977700002101996856007502017 2025 eng d a0012-965800aRemote sensing for species distribution models: An illustration from a sentinel taxon of the world's driest ecosystem0 aRemote sensing for species distribution models An illustration f c02/2025 ae700350 v1063 a

In situ observed data are commonly used as species occurrence response variables in species distribution models. However, the use of remotely observed data from high-resolution multispectral remote-sensing images as a source of presence/absence data for species distribution models remains under-developed. Here, we describe an ensemble species distribution model of black microbial mats (Nostoc spp.) using presence/absence points derived from the unmixing of 4-m resolution WorldView-2 and WorldView-3 images in the Lake Fryxell basin region of Taylor Valley, Antarctica. Environmental and topographical characteristics such as soil moisture, snow, elevation, slope, and aspect were used as predictor variables in our models. We demonstrate that we can build and run ensemble species distribution models using both dependent and independent variables derived from remote-sensing data to generate spatially explicit habitat suitability maps. Snow and soil moisture were found to be the most important variables accounting for about 80% of the variation in the distribution of black mats throughout the Fryxell basin. This study highlights the potential contribution of high-resolution remote-sensing to species distribution modeling and informs new studies incorporating remotely derived species occurrences in species distribution models, especially in remote areas where access to in situ data is often limited.

10aAntarctica10aMcMurdo Dry Valleys10amicrobial mats10aremote sensing10aspecies distribution modeling10aspecies occurrence1 aThapa‐Magar, Khum, B.1 aSokol, Eric, R.1 aGooseff, Michael, N.1 aSalvatore, Mark, R.1 aBarrett, John, E.1 aLevy, Joseph, S.1 aKnightly, Paul1 aPower, Sarah, N. uhttps://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecy.7003502254nas a2200217 4500008004100000245009400041210006900135260001200204300000600216490000700222520158800229653002601817653002401843653001901867653002401886653001801910100002301928700002101951700002201972856004201994 2025 eng d00aRethinking the lake history of Taylor Valley, Antarctica during the Ross Sea I glaciation0 aRethinking the lake history of Taylor Valley Antarctica during t c01/2025 a90 v153 a

The Ross Sea I glaciation, marked by the northward advance of the Ross Ice Sheet (RIS) in the Ross Sea, east Antarctica, corresponds with the last major expansion of the West Antarctic Ice Sheet during the last glacial period. During its advance, the RIS was grounded along the southern Victoria Land coast, completely blocking the mouths of several of the McMurdo Dry Valleys (MDVs). Several authors have proposed that very large paleolakes, proglacial to the RIS, existed in many of the MDVs. Studies of these large paleolakes have been key in the interpretation of the regional landscape, climate, hydrology, and glacier and ice sheet movements. By far the most studied of these large paleolakes is Glacial Lake Washburn (GLW) in Taylor Valley. Here, we present a comprehensive review of literature related to GLW, focusing on the waters supplying the paleolake, signatures of the paleolake itself, and signatures of past glacial movements that controlled the spatial extent of GLW. We find that while a valley-wide proglacial lake likely did exist in Taylor Valley during the early stages of the Ross Sea I glaciation, during later stages two isolated lakes occupied the eastern and western sections of the valley, confined by an expansion of local alpine glaciers. Lake levels above ~140 m asl were confined to western Taylor Valley, and major lake level changes were likely driven by RIS movements, with climate variables playing a more minor role. These results may have major implications for our understanding of the MDVs and the RIS during the Ross Sea I glaciation.

10aGlacial Lake Washburn10aMcMurdo Dry Valleys10aRoss Ice Sheet10aRoss Sea glaciation10aTaylor Valley1 aStone, Michael, S.1 aDoran, Peter, T.1 aMyers, Krista, F. uhttps://www.mdpi.com/2076-3263/15/1/902267nas a2200265 4500008004100000022001400041245008300055210006900138260001200207490000700219520143800226653002201664653002001686653002401706653002401730653002301754100002501777700002101802700002301823700001701846700002101863700002401884700002201908856007101930 2025 eng d a1523-043000aSoil biota sensitivity to hydroclimate variability in a polar desert ecosystem0 aSoil biota sensitivity to hydroclimate variability in a polar de c05/20250 v573 a

An anomalous warm weather event in the Antarctic McMurdo Dry Valleys on 18 March 2022 created an opportunity to characterize soil biota communities most sensitive to freeze–thaw stress. This event caused unseasonal melt within Taylor Valley, activating stream water and microbial mats around Canada Stream. Liquid water availability in this polar desert is a driver of soil biota distribution and activity. Because climate change impacts hydrological regimes, we aimed to determine the effect on soil communities. We sampled soils identified from this event that experienced thaw, nearby hyper-arid areas, and wetted areas that did not experience thaw to compare soil bacterial and invertebrate communities. Areas that exhibited evidence of freeze–thaw supported the highest live and dead nematode counts and were composed of soil taxa from hyper-arid landscapes and wetted areas. They received water inputs from snowpacks, hyporheic water, or glacial melt, contributing to community differences associated with organic matter and salinity gradients. Inundated soils had higher organic matter and lower conductivity (p < .02) and hosted the most diverse microbial and invertebrate communities on average. Our findings suggest that as liquid water becomes more available under predicted climate change, soil communities adapted to the hyper-arid landscape will shift toward diverse, wetted soil communities.

10aclimate variation10aextreme weather10aMcMurdo Dry Valleys10amicrobial community10asoil invertebrates1 aSnyder, Meredith, D.1 aAdams, Byron, J.1 aBorgmeier, Abigail1 aJorna, Jesse1 aPower, Sarah, N.1 aSalvatore, Mark, R.1 aBarrett, John, E. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2025.248528304374nas a2200193 4500008004100000245011900041210006900160260005800229490000900287520367400296653002603970653002403996653002904020653001604049653001904065100002704084700002204111856004704133 2025 eng d00aThe temporal and spatial dynamics of surface sediment on the permanently frozen lakes of Taylor Valley, Antarctica0 atemporal and spatial dynamics of surface sediment on the permane aMadison, WIbUniversity of Wisconsin-Madisonc05/20250 vM.S.3 a

The McMurdo Dry Valleys are the largest unglaciated region of Antarctica and are home to some of the only perennially frozen lakes in the world. The ice covers of the Taylor Valley lakes are subject to decadal-length fluctuations in thickness, largely ranging between three and five meters thick. It has been hypothesized that the changes in ice cover thickness are due to a combination of climate factors and lake ice surface characteristics, but as of yet there have been no studies focusing on interannual dynamics of lake ice albedo by leveraging remote sensing datasets. Landsat 8 imagery was manipulated using spectral mixture analysis to find the abundance of sediment cover across three different Taylor Valley lakes from 2016-2024 during the sunlit period of the year. Peak sediment coverage was not synchronous across years, with Lake Hoare peaking the earliest in 2021, followed by East Lake Bonney and Lake Fryxell in 2023. West Lake Bonney had no apparent peak, although concentrations have declined since 2021. Overall sediment abundance values across all lakes ranged from near 0% to over 75%, though each lake has a different level of sediment coverage. Lake Fryxell and Lake Hoare had the highest mean sediment concentrations, followed by East Lake Bonney, then West Lake Bonney. The relationship between ice thickness and sediment coverage was strongest at Lake Fryxell, followed by East Lake Bonney. Lake Hoare and West Lake Bonney appear to have weaker links between ice thickness and surface sediment, likely driven by differences in overall sediment cover and shading from the surrounding landscape. Ice surface albedo is a historically understudied component of ice physical structure and thermal mechanics and should be more closely considered in future studies predicting ice thickness in the McMurdo Dry Valleys, especially in cases to predict total ice loss. Permanently frozen lakes exhibit unique ice dynamics compared to seasonally freezing lakes, due to their consistent lake ice, where previous years ice conditions have a large effect on ice into the future. The McMurdo Dry Valleys (MDVs), a large unglaciated region in Antarctica, contain many of the few permanently frozen lakes that exist globally. Albedo is a critical factor influencing lake ice mass balance and may strongly govern lake ice thickness. Changes in surface albedo on MDVs lakes occur as a result of aeolian sediment deposition from the surrounding bare soil landscape or physical changes in ice quality throughout the summer, like ice whitening. To investigate the importance of surface characteristics of Taylor Valley lake ice, a one-dimensional thermal diffusion model was developed using in situ meteorological data and a satellite derived ice albedo estimates to simulate ice thickness on East Lake Bonney, Antarctica. Ice thickness was modeled from late 2016 through 2024 using a novel ice albedo dataset, derived from Landsat 8 imagery using linear spectral mixture analysis. Estimated albedo values ranged from 0.5-0.85, covering years when sediment cover was very heavy to very low. Modeled ice thickness was strongly correlated with measured thicknesses. For the period of the year where manual ice thickness measurements are made, modeled ice thicknesses ranged between 2.92-4.16 m, where measured values for that same time span ranged between 3.06-4.19 m. When either increasing or decreasing albedo by 5-10%, mean ice thicknesses diverged by up to 0.8 m. Ice thicknesses are strongly influenced by surface sediment concentrations, and the contribution of a tailored albedo dataset was a valuable input that has historically been over-simplified.

10aaeolian geomorphology10aMcMurdo Dry Valleys10apermanently frozen lakes10apolar lakes10aremote sensing1 aDougherty, Charles, E.1 aDugan, Hilary, A. uhttp://digital.library.wisc.edu/1793/9519402224nas a2200277 4500008004100000022001400041245011700055210006900172260001200241490000700253520135300260653003401613653001601647653001801663653002401681653002101705653001301726653002601739100002401765700002601789700002401815700002101839700001701860700001901877856005001896 2025 eng d a2210-634000aThree new Pseudogymnoascus species (Pseudeurotiaceae, Thelebolales) described from Antarctic soils0 aThree new Pseudogymnoascus species iPseudeurotiaceaei iThelebola c03/20250 v163 a

The genus Pseudogymnoascus includes several species frequently isolated from extreme environments worldwide, including cold environments such as Antarctica. This study describes three new species of PseudogymnoascusP. russus sp. nov., P. irelandiae sp. nov., and P. ramosus sp. nov.—isolated from Antarctic soils. These species represent the first Pseudogymnoascus taxa to be formally described from Antarctic soil samples, expanding our understanding of fungal biodiversity in this extreme environment. Microscopic descriptions of asexual structures from living cultures, along with measurements of cultural characteristics and growth on various media types at different temperatures, identify three distinct new species. In addition, phylogenetic analyses based on five gene regions (ITS, LSU, MCM7, RPB2, TEF1) and whole-genome proteomes place these new species within three distinct previously described clades: P. irelandiae in clade K, P. ramosus in clade Q, and P. russus in clade B. These results provide further evidence of the extensive undescribed diversity of Pseudogymnoascus in high-latitude soils. This study contributes to the growing body of knowledge on Antarctic mycology and the broader ecology of psychrophilic and psychrotolerant fungi.

10aAntarctic microbial diversity10anew species10aphylogenetics10apsychrophilic fungi10apsychrotolerance10ataxonomy10awhole genome assembly1 aChildress, Mary, K.1 aDragone, Nicholas, B.1 aYoung, Benjamin, D.1 aAdams, Byron, J.1 aFierer, Noah1 aQuandt, Alisha uhttps://imafungus.pensoft.net/article/142219/02022nas a2200217 4500008004100000022001400041245004800055210004800103260001200151300000900163520139500172653001501567653001501582653001901597653002401616653001701640653001501657100001801672700002101690856009301711 2025 eng d a0954-102000aWinter warming of McMurdo Dry Valleys soils0 aWinter warming of McMurdo Dry Valleys soils c01/2025 a1-183 a

Continuous permafrost is present across the McMurdo Dry Valleys of southern Victoria Land, Antarctica. While summer active-layer thaw is common in the low-elevation portions of the Dry Valleys, active layers have not significantly thickened over time. However, in some locations, coastal Antarctic permafrost has begun to warm. Here, based on soil and meteorological measurements from 1993 to 2023, we show that wintertime soil temperatures have increased across multiple sites in the Dry Valleys, at rates exceeding the pace of summer soil warming. Linear warming trends over time are significant (P < 0.05) at six of seven soil monitoring sites. Winter warming is strongly correlated with increased numbers of down-valley wind events (Foehn/katabatics), but it may also be driven by increased incident longwave radiation at some stations (although winter longwave increase is not significant over time). While down-valley wind events increase winter warming, when down-valley wind events are excluded from the record, winter soil warming remains persistent and significant, suggesting that Antarctic soils are experiencing less cold winters over time in response to regional warming. Together, these observations suggest that some Antarctic permafrost may be approaching a transition to discontinuous permafrost in some regions as winter freezing intensity is reduced over time.

10aAntarctica10aFoehn wind10akatabatic wind10aMcMurdo Dry Valleys10amicroclimate10apermafrost1 aFowler, Gavin1 aLevy, Joseph, S. uhttps://www.cambridge.org/core/product/identifier/S0954102024000488/type/journal_article02098nas a2200181 4500008004100000022001400041245014900055210006900204260001200273490000700285520143900292100002101731700002201752700002501774700002001799700002601819856007101845 2024 eng d a1523-043000aAn analysis of McMurdo Dry Valleys’ lotic habitats within Antarctica’s protected area network and addressing gaps in biodiversity protection0 aanalysis of McMurdo Dry Valleys lotic habitats within Antarctica c08/20240 v563 a

The McMurdo Dry Valleys (MDV), Antarctica’s largest ice-free region, hosts unique terrestrial ecosystems, with biodiversity concentrated in the aquatic environments and surrounding soils. Despite being a scientific hub, the creation of the MDV Antarctic Specially Managed Area (ASMA) made significant steps toward protecting the environment from degradation from human usage. However, with sustained human presence within the MDV, increasing human activity across Antarctica, and aquatic ecosystems subject to environmental change, the effectiveness of current protections for biodiversity conservation requires evaluation. This study employs spatial analysis of MDV protected areas, streams, lakes, research camps, and tourist sites to assess the robustness of current protections, identify underprotected areas, and outline steps for future protection. Within the MDV ASMA, five smaller Antarctic Specially Protected Areas (ASPAs) exist. Only two ASPAs contain streams, and only one with a full hydrologic catchment. With roughly 6% of the lotic habitat area protected by ASPAs, the MDV fall short of global goals for freshwater protection. Past successful management of the MDV shows the effectiveness of collaboration and early action, and amongst calls for ASPA network expansion and restructuring, the MDV has the opportunity to be at the forefront again and increase the protection of Antarctic aquatic ecosystems.

1 aWright, Anna, T.1 aBrooks, Cassandra1 aGooseff, Michael, N.1 aHowkins, Adrian1 aChignell, Stephen, M. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2024.237517602343nas a2200217 4500008004100000245011300041210006900154260001200223490000700235520161700242653001501859653001301874653001401887653001701901653001001918100002401928700002901952700001601981700003301997856009502030 2024 eng d00aAntarctic lake viromes reveal potential virus associated influences on nutrient cycling in ice-covered lakes0 aAntarctic lake viromes reveal potential virus associated influen c09/20240 v153 a

The McMurdo Dry Valleys (MDVs) of Antarctica are a mosaic of extreme habitats which are dominated by microbial life. The MDVs include glacial melt holes, streams, lakes, and soils, which are interconnected through the transfer of energy and flux of inorganic and organic material via wind and hydrology. For the first time, we provide new data on the viral community structure and function in the MDVs through metagenomics of the planktonic and benthic mat communities of Lakes Bonney and Fryxell. Viral taxonomic diversity was compared across lakes and ecological function was investigated by characterizing auxiliary metabolic genes (AMGs) and predicting viral hosts. Our data suggest that viral communities differed between the lakes and among sites: these differences were connected to microbial host communities. AMGs were associated with the potential augmentation of multiple biogeochemical processes in host, most notably with phosphorus acquisition, organic nitrogen acquisition, sulfur oxidation, and photosynthesis. Viral genome abundances containing AMGs differed between the lakes and microbial mats, indicating site specialization. Using procrustes analysis, we also identified significant coupling between viral and bacterial communities (p = 0.001). Finally, host predictions indicate viral host preference among the assembled viromes. Collectively, our data show that: (i) viruses are uniquely distributed through the McMurdo Dry Valley lakes, (ii) their AMGs can contribute to overcoming host nutrient limitation and, (iii) viral and bacterial MDV communities are tightly coupled.

10aAntarctica10abacteria10alimnology10ametagenomics10avirus1 aRobinson, David, M.1 aMorgan-Kiss, Rachael, M.1 aWang, Zhong1 aTakacs-Vesbach, Cristina, D. uhttps://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1422941/full03078nas a2200241 4500008004100000022001300041245011000054210006900164260001200233300001100245490000800256520229200264653002502556653002602581653002802607653002502635653002702660653001802687100001302705700002502718700002102743856007202764 2024 eng d a0929139300aAn Antarctic worm and its soil ecosystem: A review of an emerging research program in ecological genomics0 aAntarctic worm and its soil ecosystem A review of an emerging re c01/2024 a1051100 v1933 a

Relationships between the evolution of species and their ecosystems can be difficult to accurately assess due to the high number of confounding biological variables (e.g., biotic interactions among community members and the resulting complex relationships between genetic pathways and organism phenotypes). Thus, progress in ecological genomics by making inferences about fundamental ecological patterns and processes is hampered by high biodiversity and subsequent complex biotic interactions. Study systems that are naturally low in biological and ecological complexity, and strongly structured by abiotic drivers, can serve as models for bridging the gap between controlled mesocosm experiments and natural ecosystems. The terrestrial ecosystems of the Antarctic dry valleys have low biodiversity and constrained ecological complexity, primarily because ecological communities are so strongly shaped by physical, rather than biological, factors. The harsh constraints of the physical environment on organismal evolution and the structure of ecological communities make this an optimal natural system for disentangling the influence of specific environmental parameters on genotype/phenotype and gene by environment interactions. This work reviews the biology, evolution, and ecology of an emerging model organism, the free-living nematode Plectus murrayi, in a model ecosystem, the McMurdo Dry Valleys (MDVs) of Antarctica. In the MDVs, habitat suitability, including nutrient availability, has been shown to drive organismal (nematode) life history evolution, including growth and reproduction, primarily by way of changes in the expression of developmental genes. Changes in growth rates and reproductive schedules are accomplished primarily through alterations of nuclear rRNA gene copy number. The predicted and observed responses to natural experiments have been replicated in the laboratory, providing a synthesis of field observations and experimental evolution. Studying such natural model systems as this could fill several persistent knowledge gaps in our understanding of how genetic variation, genomic architecture, and gene regulation drive the genotype-phenotype paradigm, and the consequent effects of these drivers on ecosystem structure and functioning.

10aecological amplitude10aecological succession10aelemental stoichiometry10aextreme environments10alife history evolution10amodel systems1 aXue, Xia1 aThompson, Andrew, R.1 aAdams, Byron, J. uhttps://www.sciencedirect.com/science/article/pii/S092913932300308602859nas a2200181 4500008004100000245009200041210006900133260001200202300001400214490000700228520227800235100002002513700002502533700002402558700002102582700002002603856005402623 2024 eng d00aThe application and modification of WRF-Hydro/Glacier to a cold-based Antarctic glacier0 aapplication and modification of WRFHydroGlacier to a coldbased A c02/2024 a459 - 4780 v283 a

The McMurdo Dry Valleys (MDV) are home to a unique microbial ecosystem that is dependent on the availability of freshwater. This is a polar desert and freshwater originates almost entirely from surface and near-surface melt of the cold-based glaciers. Understanding the future evolution of these environments requires the simulation of the full chain of physical processes from net radiative forcing, surface energy balance, melt, runoff and transport of meltwater in stream channels from the glaciers to the terminal lakes where the microbial community resides. To establish a new framework to do this, we present the first application of WRF-Hydro/Glacier in the MDV, which as a fully distributed hydrological model has the capability to resolve the streams from the glaciers to the bare land that surround them. Given that meltwater generation in the MDV is almost entirely dependent on small changes in the energy balance of the glaciers, the aim of this study is to optimize the multi-layer snowpack scheme that is embedded in WRF-Hydro/Glacier to ensure that the feedbacks between albedo, snowfall and melt are fully resolved. To achieve this, WRF-Hydro/Glacier is implemented at a point scale using automatic weather station data on Commonwealth Glacier to physically model the onset, duration and end of melt over a 7-month period (1 August 2021 to 28 February 2022). To resolve the limited energetics controlling melt, it was necessary to (1) limit the percolation of meltwater through the ice layers in the multi-layer snowpack scheme and (2) optimize the parameters controlling the albedo of both snow and ice over the melt season based on observed spectral signatures of albedo. These modifications enabled the variability of broadband albedo over the melt season to be accurately simulated and ensured that modelled surface and near-surface temperatures, surface height change and runoff were fully resolved. By establishing a new framework that couples a detailed snowpack model to a fully distributed hydrological model, this work provides a stepping stone to model the spatial and temporal variability of melt and streamflow in the future, which will enable some of the unknown questions about the hydrological connectivity of the MDV to be answered.

1 aPletzer, Tamara1 aConway, Jonathan, P.1 aCullen, Nicolas, J.1 aEidhammer, Trude1 aKaturji, Marwan uhttps://hess.copernicus.org/articles/28/459/2024/02145nas a2200409 4500008004100000245007300041210006900114260001200183490000700195520089800202653005701100653003001157653002601187653001701213653002401230653002001254653001001274100002001284700002101304700001701325700002201342700001801364700002101382700001601403700002101419700001501440700001801455700002301473700001801496700002601514700002201540700002301562700002201585700002501607700001901632856008401651 2024 eng d00aBiogeographic survey of soil bacterial communities across Antarctica0 aBiogeographic survey of soil bacterial communities across Antarc c01/20240 v123 a

Antarctica and its unique biodiversity are increasingly at risk from the effects of global climate change and other human influences. A significant recent element underpinning strategies for Antarctic conservation has been the development of a system of Antarctic Conservation Biogeographic Regions (ACBRs). The datasets supporting this classification are, however, dominated by eukaryotic taxa, with contributions from the bacterial domain restricted to Actinomycetota and Cyanobacteriota. Nevertheless, the ice-free areas of the Antarctic continent and the sub-Antarctic islands are dominated in terms of diversity by bacteria. Our study aims to generate a comprehensive phylogenetic dataset of Antarctic bacteria with wide geographical coverage on the continent and sub-Antarctic islands, to investigate whether bacterial diversity and distribution is reflected in the current ACBRs.

10aAntarctic Conservation Biogeographic Regions (ACBRs)10aAntarctic soil microbiome10abioclimatic variables10abiogeography10amicrobial diversity10aregionalization10asoils1 aVarliero, Gilda1 aLebre, Pedro, H.1 aAdams, Byron1 aChown, Steven, L.1 aConvey, Peter1 aDennis, Paul, G.1 aFan, Dandan1 aFerrari, Belinda1 aFrey, Beat1 aHogg, Ian, D.1 aHopkins, David, W.1 aKong, Weidong1 aMakhalanyane, Thulani1 aMatcher, Gwynneth1 aNewsham, Kevin, K.1 aStevens, Mark, I.1 aWeigh, Katherine, V.1 aCowan, Don, A. uhttps://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-023-01719-301254nas a2200145 4500008004100000245010600041210006900147260001200216300001600228490000700244520075400251100002601005700002501031856005201056 2024 eng d00aBrief communication: Significant biases in ERA5 output for the McMurdo Dry Valleys region, Antarctica0 aBrief communication Significant biases in ERA5 output for the Mc c03/2024 a1207 - 12130 v183 a

The ERA5 climate reanalysis dataset plays an important role in applications such as monitoring and modeling climate system changes in polar regions, so the calibration of the reanalysis to ground observations is of great relevance. Here, we compare the 2 m air temperature time series of the ERA5 reanalysis and the near-surface bias-corrected reanalysis to the near-ground air temperature measured at 17 automatic weather stations (AWSs) in the McMurdo Dry Valleys, Antarctica. We find that the reanalysis data have biases that change with the season of the year and do not clearly correlate with elevation. Our results show that future work should rely on secondary observations to calibrate when using the ERA5 reanalysis in polar regions.

1 aGarza-Girón, Ricardo1 aTulaczyk, Slawek, M. uhttps://tc.copernicus.org/articles/18/1207/202402191nas a2200241 4500008004100000022001400041245008000055210006900135260001200204300001400216490000700230520147500237653001801712653001901730653001301749653001301762653002901775653001401804100002501818700002501843700002401868856005701892 2024 eng d a1531-107400aDetectability of surface biosignatures for directly imaged rocky exoplanets0 aDetectability of surface biosignatures for directly imaged rocky c03/2024 a283 - 2990 v243 a

Modeling the detection of life has never been more opportune. With next-generation space telescopes, such as the currently developing Habitable Worlds Observatory (HWO) concept, we will begin to characterize rocky exoplanets potentially similar to Earth. However, few realistic planetary spectra containing surface biosignatures have been paired with direct imaging telescope instrument models. Therefore, we use a HWO instrument noise model to assess the detection of surface biosignatures affiliated with oxygenic, anoxygenic, and nonphotosynthetic extremophiles. We pair the HWO telescope model to a one-dimensional radiative transfer model to estimate the required exposure times necessary for detecting each biosignature on planets with global microbial coverage and varying atmospheric water vapor concentrations. For modeled planets with 0–50% cloud coverage, we determine pigments and the red edge could be detected within 1000 hr (100 hr) at distances within 15 pc (11 pc). However, tighter telescope inner working angles (2.5 λ/D) would allow surface biosignature detection at further distances. Anoxygenic photosynthetic biosignatures could also be more easily detectable than nonphotosynthetic pigments and the photosynthetic red edge when compared against a false positive iron oxide slope. Future life detection missions should evaluate the influence of false positives on the detection of multiple surface biosignatures.

10aextremophiles10afalse positive10apigments10ared edge10areflectance spectroscopy10atelescope1 aBorges, Schuyler, R.1 aJones, Gabrielle, G.1 aRobinson, Tyler, D. uhttps://www.liebertpub.com/doi/10.1089/ast.2023.009902147nas a2200205 4500008004100000245009900041210006900140260005900209300000800268490000900276520148500285653001501770653001601785653001401801653001801815653001701833100002201850700002101872856004801893 2024 eng d00aDevelopment of a laboratory simulation for freeze-thaw of aeolian sediments in glacial systems0 aDevelopment of a laboratory simulation for freezethaw of aeolian aBoulder, CO, USAbUniversity of Colorado Boulderc2024 a2610 vM.A.3 a

Glacial systems are vital for supplying trace metals, nutrients, and weathering products to downstream ecosystems. While subglacial and proglacial weathering pathways are highly studied, supraglacial weathering processes receive less attention. Aeolian sediments on glaciers can lower albedo, generating meltwater; this water can refreeze around sediment grains during cloudy periods or when the sun is obstructed, resulting in a freeze-thaw process. For solute generation in the most upstream source in glacial-proglacial environments, it's unclear whether chemical or physical weathering dominates nutrient release. This study presents a methodology to simulate freeze-thaw processes in a controlled laboratory setting to understand the importance of freeze-thaw in nutrient mobilization. Analysis of sediments from Antarctica's McMurdo Dry Valleys showed significant differences in the concentrations of ion, nutrient, and trace metal between initial wetting and subsequent freeze-thaw cycles. For example, phosphorus concentrations consistently increased with each cycle, indicating that freeze-thaw is an important mobilization mechanism for this nutrient. Silicon increased from cycle 1-30 but decreased at cycle 60 and iron concentrations were initially higher but decreased during subsequent cycles. This research highlights the importance of freeze-thaw processes in understanding glacial weathering dynamics and nutrient release for downstream ecosystems.

10aAntarctica10afreeze-thaw10anutrients10aTaylor Valley10atrace metals1 aMondragon, Denise1 aDiaz, Melisa, A. uhttps://www.proquest.com/docview/306679220202991nas a2200229 4500008004100000245018700041210006900228260001200297490000700309520217100316653001802487653001102505653001602516653001402532653001802546653001102564100002102575700002202596700002402618700002402642856009502666 2024 eng d00aDrifting along: Using diatoms to track the contribution of microbial mats to particulate organic matter transport in a glacial meltwater stream in the McMurdo Dry Valleys, Antarctica0 aDrifting along Using diatoms to track the contribution of microb c05/20240 v153 a

Flow pulses mobilize particulate organic matter (POM) in streams from the surrounding landscape and streambed. This POM serves as a source of energy and nutrients, as well as a means for organismal dispersal, to downstream communities. In the barren terrestrial landscape of the McMurdo Dry Valleys (MDV) of Antarctica, benthic microbial mats occupying different in-stream habitat types are the dominant POM source in the many glacier-fed streams. Many of these streams experience daily flow peaks that mobilize POM, and diatoms recovered from underlying stream sediments suggest that mat-derived diatoms in the POM are retained there through hyporheic exchange. Yet, ‘how much’ and ‘when’ different in-stream habitat types contribute to POM diatom assemblages is unknown. To quantify the contribution of different in-stream habitat types to POM diatom assemblages, we collected time-integrated POM samples over four diel experiments, which spanned a gradient of flow conditions over three summers. Diatoms from POM samples were identified, quantified, and compared with dominant habitat types (i.e., benthic ‘orange’ mats, marginal ‘black’ mats, and bare sediments). Like bulk POM, diatom cell concentrations followed a clockwise hysteresis pattern with stream discharge over the daily flow cycles, indicating supply limitation. Diatom community analyses showed that different habitat types harbor distinct diatom communities, and mixing models revealed that a substantial proportion of POM diatoms originated from bare sediments during baseflow conditions. Meanwhile, orange and black mats contribute diatoms to POM primarily during daily flow peaks when both cell concentrations and discharge are highest, making mats the most important contributors to POM diatom assemblages at high flows. These observations may help explain the presence of mat-derived diatoms in hyporheic sediments. Our results thus indicate a varying importance of different in-stream habitats to POM generation and export on daily to seasonal timescales, with implications for biogeochemical cycling and the local diatom metacommunity.

10acyanobacteria10adiatom10aflow regime10ahydrology10amicrobial mat10aNostoc1 aStanish, Lee, F.1 aKohler, Tyler, J.1 aDarling, Joshua, P.1 aMcKnight, Diane, M. uhttps://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1352666/full02546nas a2200241 4500008004100000022001400041245007500055210006900130260001200199490000700211520184500218653001302063653001102076653001202087653002402099653001902123653001702142100002102159700002402180700002402204700002202228856005402250 2024 eng d a2045-775800aHabitat suitability of biocrust communities in a cold desert ecosystem0 aHabitat suitability of biocrust communities in a cold desert eco c07/20240 v143 a

Drylands are unique among terrestrial ecosystems in that they have a significant proportion of primary production facilitated by non-vascular plants such as colonial cyanobacteria, moss, and lichens, i.e., biocrusts, which occur on and in the surface soil. Biocrusts inhabit all continents, including Antarctica, an increasingly dynamic continent on the precipice of change. Here, we describe in-situ field surveying and sampling, remote sensing, and modeling approaches to assess the habitat suitability of biocrusts in the Lake Fryxell basin of Taylor Valley, Antarctica, which is the main site of the McMurdo Dry Valleys Long-Term Ecological Research Program. Soils suitable for the development of biocrusts are typically wetter, less alkaline, and less saline compared to unvegetated soils. Using random forest models, we show that gravimetric water content, electrical conductivity, and snow frequency are the top predictors of biocrust presence and biomass. Areas most suitable for the growth of dense biocrusts are soils associated with seasonal snow patches. Using geospatial data to extrapolate our habitat suitability model to the whole basin predicts that biocrusts are present in 2.7 × 105 m2 and contain 11–72 Mg of aboveground carbon, based on the 90% probability of occurrence. Our study illustrates the synergistic effect of combining field and remote sensing data for understanding the distribution and biomass of biocrusts, a foundational community in the carbon balance of this region. Extreme weather events and changing climate conditions in this region, especially those influencing snow accumulation and persistence, could have significant effects on the future distribution and abundance of biocrusts and therefore soil organic carbon storage in the McMurdo Dry Valleys.

10abiocrust10acarbon10adryland10ahabitat suitability10aremote sensing10asoil ecology1 aPower, Sarah, N.1 aThomas, Valerie, A.1 aSalvatore, Mark, R.1 aBarrett, John, E. uhttps://onlinelibrary.wiley.com/toc/20457758/14/702764nas a2200253 4500008004100000022001400041245011400055210006900169260001200238300001100250490000700261520197300268653001502241653002102256653002702277653002202304653001502326653001302341100002102354700002502375700002402400700002402424856006202448 2024 eng d a0885-608700aThe hydrologic and geochemical contributions from snow to streamflow in the McMurdo Dry Valleys of Antarctica0 ahydrologic and geochemical contributions from snow to streamflow c06/2024 ae151950 v383 a

The glacial meltwater streams in the McMurdo Dry Valleys (MDVs), Antarctica only flow during the austral summer and contain abundant algal mats which grow at the onset of flow. Their relative abundance in stream channels of this polar desert make the streams biogeochemical hot spots. The MDVs receive minimal precipitation as snow, which is redistributed by wind and deposited in distinct locations, some of which become persistent snow patches each year. Previous studies identified that MDV streamflow comes from a combination of glacier ice and snow, although snow was assumed to contribute little to the overall water budget. This study uses a combination of satellite imagery, terrain analysis, and field measurements to determine where snow patches accumulate and persist across MDV watersheds, and to quantify the potential hydrologic and biogeochemical contributions of snow patches to streams. Watersheds near the coast have the highest snow-covered area and longest snow persistence. Many of these snow patches accumulate within the stream channels, which results in the potential to contribute to streamflow. During the summer of 2021–2022, stream channel snow patches had the potential to contribute anywhere between <1% and 90% of the total annual discharge in Lake Fryxell Basin streams, and may increase with different hydrometeorological conditions. On average the potential inputs from snow patches to streamflow was between 12% and 25% of the annual discharge during the 2021–2022 season, as determined by snow area and SWE. Snow patches in the majority of the watersheds had higher nitrogen and phosphorous concentrations than stream water, and six streams contained snow with higher N:P ratios than the average N:P in the stream water. This suggests that if such patches melt early in the summer, these nutrient and water inputs could occur at the right time and stoichiometry to be crucial for early season algal mat growth.

10aAntarctica10aephemeral stream10apolar desert hydrology10arunoff generation10asnow patch10asnowmelt1 aWright, Anna, T.1 aGooseff, Michael, N.1 aBergstrom, Anna, J.1 aWelch, Kathleen, A. uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.1519503243nas a2200193 4500008004100000245010700041210006900148260005600217300000800273490001000281520253500291653001502826653001702841653001302858653001702871653001802888100002502906856011802931 2024 eng d00aIn situ and remote biosignatures from microbial mats in ephemeral streams of Fryxell Basin, Antarctica0 aIn situ and remote biosignatures from microbial mats in ephemera aFlagstaff, AZbNorthern Arizona Universityc08/2024 a3400 vPh.D.3 a

Transient water-limited environments are understood to have hosted microbial communities early in Earth’s history, and thus, may have been important ecosystems for life in ancient fluvial systems on Mars and water-limited environments on rocky Earth-like exoplanets. Similar environmental systems exist on Earth today, acting as meaningful analogs to study the preservation and detection of life in these environments. Particularly useful analogs are the McMurdo Dry Valleys of Antarctica, given their cold temperatures, aridity, elevated UV radiation exposure, and predominantly microbial ecosystem. Basins in these valleys contain ephemeral glacial meltwater streams, which contain a diversity of microbial communities that are only active when the streams are flowing ten weeks of the summer. These microbial communities were studied to examine how their in situ and remote biosignatures could inform the detection of similar life on Mars and rocky exoplanets. Specifically, these organisms were found in association with carbonate rock coatings, morphologically resembling modern and ancient stromatolites from rivers, ponds, lakes, and hot springs. Microorganisms from these communities were preserved within and influenced the formation of these coatings, becoming an additional Antarctic analog to ancient stromatolites. The presence of these carbonate coatings in an ephemeral stream suggests that processes in transient fluvial environments on Mars could have also generated coatings, which could have preserved biosignatures. We also identified pigments within these microbial communities and correlated the pigments to community composition. We determined how the reflectance spectra of these communities were influenced by their pigments, demonstrating the capability of distinguishing microbial mat community composition in visible and near-infrared spectroscopy. The results of our study indicate that pigment spectral absorptions can act as remote biosignatures which we then applied to modeling the detection of similar life on the surfaces of cold and rocky Earth-like exoplanets. The detection times of Antarctic microbial mat remote biosignatures were compared with those of anoxygenic photosynthetic and nonphotosynthetic microorganisms, accounting for false positives, to determine which biosignatures were most detectable. The results from this work demonstrate the ability of the future space-based telescope, Habitable Worlds Observatory, to detect surface life on rocky Earth-like exoplanets.

10aAntarctica10aastrobiology10apigments10aspectroscopy10astromatolites1 aBorges, Schuyler, R. uhttps://www.proquest.com/dissertations-theses/em-situ-remote-biosignatures-microbial-mats/docview/3094642420/se-201464nas a2200181 4500008004100000022001400041245014100055210006900196260001200265520082200277653002101099653002001120653002301140653001801163653001001181100002901191856006201220 2024 eng d a0028-646X00aLong days and long nights: An integrative study reveals survival strategies of an Antarctic diatom during the cold and dark polar winter0 aLong days and long nights An integrative study reveals survival  c01/20243 a

The vast majority of photosynthetic organisms on Earth have evolved under a circadian cycle, with many cellular processes being regulated by the predictable patterns of day and night. Polar algal species living in Arctic and Antarctic aquatic habitats are faced with bizarre light environments of continuous light during the short summer months and 24-h darkness during the winter, that is one long day transitioning into one long, cold night. It is well known that polar phytoplankton survive the winter and return in the summer to form blooms. In an article recently published in New Phytologist, Joli et al. (2023, doi: 10.1111/nph.19387) use an integrative approach to dissect how an Antarctic marine diatom not only survives the long, dark polar winter, but also recovers rapidly upon the onset of summer.

10aaquatic habitats10acircadian cycle10alight environments10aphytoplankton10apolar1 aMorgan-Kiss, Rachael, M. uhttps://nph.onlinelibrary.wiley.com/doi/10.1111/nph.1953602587nas a2200313 4500008004100000022001400041245012700055210006900182260001200251300001100263520145800274653001701732653001401749653000801763653001901771653001501790100002301805700001801828700001501846700002401861700002501885700003301910700002901943700001701972700002201989700002102011700002102032856022002053 2024 eng d a0954-102000aMcMurdo Dry Valley lake edge ‘moats’: The ecological intersection between terrestrial and aquatic polar desert habitat0 aMcMurdo Dry Valley lake edge moats The ecological intersection b c04/2024 a1 - 173 a

Aquatic ecosystems - lakes, ponds and streams - are hotspots of biodiversity in the cold and arid environment of Continental Antarctica. Environmental change is expected to increasingly alter Antarctic aquatic ecosystems and modify the physical characteristics and interactions within the habitats that they support. Here, we describe physical and biological features of the peripheral ‘moat’ of a closed-basin Antarctic lake. These moats mediate connectivity amongst streams, lake and soils. We highlight the cyclical moat transition from a frozen winter state to an active open-water summer system, through refreeze as winter returns. Summer melting begins at the lakebed, initially creating an ice-constrained lens of liquid water in November, which swiftly progresses upwards, creating open water in December. Conversely, freezing progresses slowly from the water surface downwards, with water at 1 m bottom depth remaining liquid until May. Moats support productive, diverse benthic communities that are taxonomically distinct from those under the adjacent permanent lake ice. We show how ion ratios suggest that summer exchange occurs amongst moats, streams, soils and sub-ice lake water, perhaps facilitated by within-moat density-driven convection. Moats occupy a small but dynamic area of lake habitat, are disproportionately affected by recent lake-level rises and may thus be particularly vulnerable to hydrological change.

10aconnectivity10aecosystem10aice10amicrobial mats10atransition1 aStone, Michael, S.1 aDevlin, Shawn1 aHawes, Ian1 aWelch, Kathleen, A.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D.1 aMorgan-Kiss, Rachael, M.1 aAdams, Byron1 aBarrett, John, E.1 aPriscu, John, C.1 aDoran, Peter, T. uhttps://www.cambridge.org/core/journals/antarctic-science/article/mcmurdo-dry-valley-lake-edge-moats-the-ecological-intersection-between-terrestrial-and-aquatic-polar-desert-habitats/31D94DD51E651603482A3AE6E8A52A5701966nas a2200253 4500008004100000022001400041245010100055210006900156260001200225490000700237520119400244653001701438653001301455653002401468653000901492653000901501653002101510100002301531700002401554700002201578700002001600700002101620856007101641 2024 eng d a1523-043000aMeasuring and modelling functional moat area in perennially ice-covered Lake Fryxell, Antarctica0 aMeasuring and modelling functional moat area in perennially icec c10/20240 v563 a

The perennially ice-covered lakes of the McMurdo Dry Valleys (MDVs), Antarctica, are an important reservoir of liquid water in an arid and largely frozen environment. During the austral summer, the margins of these ice covers melt, forming a “moat” of liquid water and thin ice, allowing exchange between lake waters and the atmosphere to occur and serving as an interface between lake, soil, and stream ecosystems. The size of these moats varies from year to year. Here, we have established the first published record of moat area changes at MDVs’ Lake Fryxell through time using manual traces of the moat as observed via satellite imagery. We have also tested a semi-automated approach for measuring moat area and found that it consistently underestimated the manual record, which we suspect may be due to the lower spatial resolution of images used in this versus the manual approach. Finally, we developed a predictive model based on readily available climate data, allowing moat area to be predicted beyond the limits of the satellite-based records. We found that functional moat area varies annually, potentially influencing ecosystem processes in the moats.

10aLake Fryxell10alake ice10aMcMurdo Dry Valleys10amoat10aNDWI10apredictive model1 aStone, Michael, S.1 aSalvatore, Mark, R.1 aDugan, Hilary, A.1 aMyers, Madeline1 aDoran, Peter, T. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2024.240662602619nas a2200205 4500008004100000245006000041210006000101260006000161300000800221490001000229520198900239653001302228653002702241653001302268653001702281653001002298100002402308700003302332856004802365 2024 eng d00aMetagenomic analysis of Antarctic microbial communities0 aMetagenomic analysis of Antarctic microbial communities aAlbuquerque, NM, USAbUniversity of New Mexicoc06/2024 a1360 vPh.D.3 a

The research presented in this dissertation focuses on microbial roles in biogeochemical cycling in Antarctic aquatic environments. The major objective of my research was to examine the impact of biotic and abiotic pressures on nutrient cycling in microbially dominated systems. I used three perennially ice covered lakes in the McMurdo Dry Valleys (MDVs) along with subglacial lakes Whillans and Mercer as natural case studies. The MDVs are located in Victoria Land, East Antarctica and have been studied since 1993 as part of the McMurdo Long Term Ecological Research Project. Viruses in the MDVs were shown to be seasonally abundant and have high infection rates. My work built upon this previous research by showing that viruses are also diverse and potentially re-direct host metabolism through auxiliary metabolic genes (AMGs). Subglacial lake Whillans and Mercer lie underneath 800 and 1100 meters of ice respectively beneath the West Antarctic Ice Sheet. Previous studies in subglacial lakes Whillans have shown an active prokaryotic community. Through viral-like particle counts, microscopy, and metagenomics, we established the presence and potential metabolic influence of viruses in both Whillans and Mercer. In MDV lakes have an extensive high-throughput DNA dataset studying microbial communities through the 16S rRNA gene. We used metagenomic sequencing within two MCM lakes at multiple depths to build upon these previous datasets by annotating metagenomically assembled genomes for functional characteristics. This project highlights the lakes' vertical redox gradient, showing that dominant taxa, nutrient cycling genes, and metabolic potentials change down the water column. The MDVs serve as a biological indicator for climate change in continental Antarctica and functional changes serve as important indicators of climate change. Taken together, this dissertation shows the importance of multi-kingdom microbial function under oligotrophic conditions.

10abacteria10abiogeochemical cycling10afunction10ametagenomics10avirus1 aRobinson, David, M.1 aTakacs-Vesbach, Cristina, D. uhttps://www.proquest.com/docview/311991058502270nas a2200229 4500008004100000245011800041210006900159260001200228300000900240490000700249520153800256653002501794653002501819653001701844653002201861653002001883100001801903700002301921700002101944700002901965856004601994 2024 eng d00aPermanent stress adaptation and unexpected high light tolerance in the shade-adapted Chlamydomonas priscui0 aPermanent stress adaptation and unexpected high light tolerance  c08/2024 a22540 v133 a

The Antarctic photopsychrophile, Chlamydomonas priscui UWO241, is adapted to extreme environmental conditions, including permanent low temperatures, high salt, and shade. During long-term exposure to this extreme habitat, UWO241 appears to have lost several short-term mechanisms in favor of constitutive protection against environmental stress. This study investigated the physiological and growth responses of UWO241 to high-light conditions, evaluating the impacts of long-term acclimation to high light, low temperature, and high salinity on its ability to manage short-term photoinhibition. We found that UWO241 significantly increased its growth rate and photosynthetic activity at growth irradiances far exceeding native light conditions. Furthermore, UWO241 exhibited robust protection against short-term photoinhibition, particularly in photosystem I. Lastly, pre-acclimation to high light or low temperatures, but not high salinity, enhanced photoinhibition tolerance. These findings extend our understanding of stress tolerance in extremophilic algae. In the past 2 decades, climate change-related increasing glacial stream flow has perturbed long-term stable conditions, which has been associated with lake level rise, the thinning of ice covers, and the expansion of ice-free perimeters, leading to perturbations in light and salinity conditions. Our findings have implications for phytoplankton survival and the response to change scenarios in the light-limited environment of Antarctic ice-covered lakes.

10aCyclic electron flow10aenvironmental change10aextremophile10aphoto-acclimation10aphotoinhibition1 aPopson, Devon1 aD’Silva, Susanna1 aWheeless, Kaylie1 aMorgan-Kiss, Rachael, M. uhttps://www.mdpi.com/2223-7747/13/16/225403255nas a2200277 4500008004100000022001300041245011100054210006900165260001200234300001100246520240400257653001502661653001302676653001102689653002902700653000902729653001702738100002102755700002402776700002002800700002102820700002502841700001702866700002202883856007202905 2024 eng d a2666017200aRemotely characterizing photosynthetic biocrust in snowpack-fed microhabitats of Taylor Valley, Antarctica0 aRemotely characterizing photosynthetic biocrust in snowpackfed m c02/2024 a1001203 a

Microbial communities are the primary drivers of carbon cycling in the McMurdo Dry Valleys of Antarctica. Dense microbial mats, consisting mainly of photosynthetic cyanobacteria, occupy aquatic areas associated with streams and lakes. Other microbial communities also occur at lower densities as patchy surface biological soil crusts (hereafter, biocrusts) across the terrestrial landscape. Multispectral satellite data have been used to model microbial mat abundance in high-density areas like stream and lake margins, but no previous studies have investigated the lower detection limits of biocrusts. Here, we describe remote sensing and field-based survey and sampling approaches to study the detectability and distribution of biocrusts in the McMurdo Dry Valleys. Using a combination of multi- and hyperspectral tools and spectral linear unmixing, we modeled the abundances of biocrust in eastern Taylor Valley. Our spectral approaches can detect low masses of biocrust material in laboratory microcosms down to biocrust concentrations of 1% by mass. These techniques also distinguish the spectra of biocrust from both surface rock and mineral signatures from orbit. We found that biocrusts are present throughout the soils of eastern Taylor Valley and are associated with diverse underlying soil communities. The densest biocrust communities identified in this study had total organic carbon 5x greater than the content of typical arid soils. The most productive biocrusts were located downslope of melting snowpacks in unique soil ecosystems that are distinct from the surrounding arid landscape. There are similarities between the snowpack and stream sediment communities (high diversity of soil invertebrates) as well as their ecosystem properties (e.g., persistence of liquid water, high transfer of available nutrients, lower salinity from flushing) compared to the typical arid terrestrial ecosystem of the dry valleys. Our approach extends the capability of orbital remote sensing of photosynthetic communities out of the aquatic margins and into the drier soils which comprise most of this landscape. This interdisciplinary work is critical for measuring and monitoring terrestrial carbon stocks and predicting future ecosystem dynamics in this currently water-limited but increasingly dynamic Antarctic landscape, which is particularly climate-sensitive and difficult to access.

10aAntarctica10abiocrust10acarbon10areflectance spectroscopy10asnow10asoil ecology1 aPower, Sarah, N.1 aSalvatore, Mark, R.1 aSokol, Eric, R.1 aStanish, Lee, F.1 aBorges, Schuyler, R.1 aAdams, Byron1 aBarrett, John, E. uhttps://www.sciencedirect.com/science/article/pii/S266601722400004X02186nas a2200313 4500008004100000022001400041245009000055210006900145260001200214300001800226490000700244520123000251653002201481653002401503653002001527653001701547653001501564100002201579700002101601700002101622700002201643700002201665700002401687700002101711700002501732700002101757700002501778856006901803 2024 eng d a2328-427700aResponse of a terrestrial polar ecosystem to the March 2022 Antarctic weather anomaly0 aResponse of a terrestrial polar ecosystem to the March 2022 Anta c08/2024 ae2023EF0043060 v123 a

Record high temperatures were documented in the McMurdo Dry Valleys, Antarctica, on 18 March 2022, exceeding average temperatures for that day by nearly 30°C. Satellite imagery and stream gage measurements indicate that surface wetting coincided with this warming more than 2 months after peak summer thaw and likely exceeded thresholds for rehydration and activation of resident organisms that typically survive the cold and dry conditions of the polar fall in a freeze-dried state. This weather event is notable in both the timing and magnitude of the warming and wetting when temperatures exceeded 0°C at a time when biological communities and streams have typically entered a persistent frozen state. Such events may be a harbinger of future climate conditions characterized by warmer temperatures and greater thaw in this region of Antarctica, which could influence the distribution, activity, and abundance of sentinel taxa. Here we describe the ecosystem responses to this weather anomaly reporting on meteorological and hydrological measurements across the region and on later biological observations from Canada Stream, one of the most diverse and productive ecosystems within the McMurdo Dry Valleys.

10aatmospheric river10aclimate variability10aextreme weather10apolar desert10asoil biota1 aBarrett, John, E.1 aAdams, Byron, J.1 aDoran, Peter, T.1 aDugan, Hilary, A.1 aMyers, Krista, F.1 aSalvatore, Mark, R.1 aPower, Sarah, N.1 aSnyder, Meredith, D.1 aWright, Anna, T.1 aGooseff, Michael, N. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023EF00430602559nas a2200301 4500008004100000245008000041210006900121260001200190300001200202490000700214520166000221653001501881653001601896653002901912653001801941653001201959100002901971700001802000700002202018700002002040700002202060700001202082700001602094700002602110700002102136700003302157856006702190 2024 eng d00aSentinel protist taxa of the McMurdo Dry Valley lakes, Antarctica: A review0 aSentinel protist taxa of the McMurdo Dry Valley lakes Antarctica c03/2024 a13234720 v123 a

High-latitude meromictic lakes such as those in the Antarctic McMurdo Dry Valleys (MDV) harbor aquatic ecosystems dominated by the microbial loop. Within this habitat, which is limited year-round by light and nutrients, protists, or single celled eukaryotes, play outsized roles in the food web as the dominant primary producers and the apex predators. Thus, the MDV lake ecosystem represents an ideal system to study the role of sentinel protist taxa in carbon and nutrient cycling. The perennially ice-covered lakes are part of the McMurdo Long Term Ecological Research (McM LTER; mcmlter.org) established in 1993. In this review we will highlight the diversity and trophic roles of the MDV lake protist community and compare environmental factors driving spatiotemporal patterns in key protist taxa in two lakes within the McM LTER, Lakes Bonney and Fryxell. We will then discuss lessons learned from manipulated experiments on the impact of current and future climate-driven environmental change on sensitive protist taxa. Last, we will integrate knowledge gained from 25 years of lab-controlled experiments on key photosynthetic protists to extend our understanding of the function of these extremophiles within the MDV aquatic food webs. Our research group has studied the distribution and function of the MDV microbial community for nearly two decades, training the next generation of scientists to tackle future problems of these globally significant microbes. This review article will also highlight early career scientists who have contributed to this body of work and represent the future of scientific understanding in the Anthropocene.

10aAntarctica10aDisturbance10aMcMurdo Dry Valley lakes10aphytoplankton10aprotist1 aMorgan-Kiss, Rachael, M.1 aPopson, Devon1 aPereira, Rochelle1 aDolhi-Binder, J1 aTeufel, Amber, G.1 aLi, Wei1 aKalra, Isha1 aSherwell, Shasten, S.1 aReynebeau, Emily1 aTakacs-Vesbach, Cristina, D. uhttps://www.frontiersin.org/articles/10.3389/fevo.2024.132347202601nas a2200241 4500008004100000022001400041245005900055210005400114260001200168520187700180653001302057653001902070653001702089653001502106653003102121100001702152700002102169700002602190700002302216700003302239700001702272856007002289 2024 eng d a0030-129900aThe underground network: Facilitation in soil bacteria0 aunderground network Facilitation in soil bacteria c06/20243 a

Our understanding of the fundamental role that soil bacteria play in the structure and functioning of Earth's ecosystems is ever expanding, but insight into the nature of interactions within these bacterial communities remains rudimentary. Bacterial facilitation may enhance the establishment, growth, and succession of eukaryotic biota, elevating the complexity and diversity of the entire soil community and thereby modulating multiple ecosystem functions. Global climate change often alters soil bacterial community composition, which, in turn, impacts other dependent biota. However, the impact of climate change on facilitation within bacterial communities remains poorly understood even though it may have important cascading consequences for entire ecosystems. The wealth of metagenomic data currently being generated gives community ecologists the ability to investigate bacterial facilitation in the natural world and how it affects ecological systems responses to climate change. Here, we review current evidence demonstrating the importance of facilitation in promoting emergent properties such as community diversity, ecosystem functioning, and resilience to climate change in soil bacterial communities. We show that a synthesis is currently missing between the abundant data, newly developed models and a coherent ecological framework that addresses these emergent properties. We highlight that including phylogenetic information, the physicochemical environment, and species-specific ecologies can improve our ability to infer interactions in natural soil communities. Following these recommendations, studies on bacterial facilitation will be an important piece of the puzzle to understand the consequences of global change on ecological communities and a model to advance our understanding of facilitation in complex communities more generally.

10abacteria10aclimate change10afacilitation10aresilience10astress-gradient hypothesis1 aJorna, Jesse1 aAdams, Byron, J.1 aAanderud, Zachary, T.1 aFrandsen, Paul, B.1 aTakacs-Vesbach, Cristina, D.1 aKéfi, Sonia uhttps://nsojournals.onlinelibrary.wiley.com/doi/10.1111/oik.1029901497nas a2200169 4500008004100000022001400041245012500055210006900180260001200249300001400261490000700275520092800282100001901210700001601229700002001245856006201265 2023 eng d a1084-545300aBetter together? The values, obstacles, opportunities, and prospects for collaborative research in environmental history0 aBetter together The values obstacles opportunities and prospects c04/2023 a269 - 2990 v283 a

Environmental historians have long argued for the value of collaborative research, many have called for more of it, and some have experimented with new forms of teamwork. Yet data gathered from three prominent journals—Environmental History, Environment and History, and the Journal of Historical Geography—show that, over the fifteen-year period from 2006 through 2020, coauthorship on published research remained remarkably rare, with no discernible trend over time. Why do environmental historians still collaborate so infrequently on published research? What are the causes and consequences of this failure to work together? And how can we help better fulfill long-standing calls in our field for a more collaborative research culture? This essay answers these questions, and it offers practical remedies for fostering a culture of greater collaboration in environmental history.

1 aAlagona, Peter1 aCarey, Mark1 aHowkins, Adrian uhttps://www.journals.uchicago.edu/doi/full/10.1086/72378402499nas a2200277 4500008004100000245009500041210006900136260001200205300000800217490000700225520169100232653001001923653002701933653001801960653002501978653001502003100002302018700002202041700001802063700002202081700001902103700001702122700002002139700001802159856004402177 2023 eng d00aBiogeography and genetic diversity of terrestrial mites in the Ross Sea region, Antarctica0 aBiogeography and genetic diversity of terrestrial mites in the R c03/2023 a6060 v143 a

Free-living terrestrial mites (Acari) have persisted through numerous glacial cycles in Antarctica. Very little is known, however, of their genetic diversity and distribution, particularly within the Ross Sea region. To redress this gap, we sampled mites throughout the Ross Sea region, East Antarctica, including Victoria Land and the Queen Maud Mountains (QMM), covering a latitudinal range of 72–85 °S, as well as Lauft Island near Mt. Siple (73 °S) in West Antarctica and Macquarie Island (54 °S) in the sub-Antarctic. We assessed genetic diversity using mitochondrial cytochrome c oxidase subunit I gene sequences (COI-5P DNA barcode region), and also morphologically identified voucher specimens. We obtained 130 sequences representing four genera: Nanorchestes (n = 30 sequences), Stereotydeus (n = 46), Coccorhagidia (n = 18) and Eupodes (n = 36). Tree-based analyses (maximum likelihood) revealed 13 genetic clusters, representing as many as 23 putative species indicated by barcode index numbers (BINs) from the Barcode of Life Datasystems (BOLD) database. We found evidence for geographically-isolated cryptic species, e.g., within Stereotydeus belli and S. punctatus, as well as unique genetic groups occurring in sympatry (e.g., Nanorchestes spp. in QMM). Collectively, these data confirm high genetic divergence as a consequence of geographic isolation over evolutionary timescales. From a conservation perspective, additional targeted sampling of understudied areas in the Ross Sea region should be prioritised, as further diversity is likely to be found in these short-range endemic mites.

10aAcari10aAntarctic conservation10aDNA barcoding10ageographic isolation10aspeciation1 aCollins, Gemma, E.1 aYoung, Monica, R.1 aConvey, Peter1 aChown, Steven, L.1 aCary, Craig, S1 aAdams, Byron1 aWall, Diana, H.1 aHogg, Ian, D. uhttps://www.mdpi.com/2073-4425/14/3/60602505nas a2200325 4500008004100000022001400041245012700055210006900182260001200251300001800263490000800281520146500289653001701754653003701771653002401808653002401832100002701856700002101883700002301904700002201927700002201949700002501971700002001996700002202016700002202038700002202060700002202082700001402104856006102118 2023 eng d a2169-900300aCauses and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica0 aCauses and characteristics of electrical resistivity variability c02/2023 ae2022JF0066960 v1283 a

Airborne electromagnetic surveys collected in December 2011 and November 2018 and three soil sampling transects were used to analyze the spatial heterogeneity of shallow (<4 m) soil properties in lower Taylor Valley (TV), East Antarctica. Soil resistivities from 2011 to 2018 ranged from ∼33 Ωm to ∼3,500 Ωm with 200 Ωm assigned as an upper boundary for brine-saturated sediments. Elevations below ∼50 m above sea level (masl) typically exhibit the lowest resistivities with resistivity increasing at high elevations on steeper slopes. Soil water content was empirically estimated from electrical resistivities using Archie's Law and range from ∼<1% to ∼68% by volume. An increase in silt- and clay-sized particles at low elevations increases soil porosity but decreases hydraulic conductivity, promoting greater residence times of soil water at low elevations near Lake Fryxell. Soil resistivity variability between 2011 and 2018 shows soils at different stages of soil freeze-thaw cycles, which are caused predominantly by solar warming of soils as opposed to air temperature. This study furthers the understanding of the hydrogeologic structure of the shallow subsurface in TV and identifies locations of soils that are potentially prone to greater rates of thaw and resulting ecosystem homogenization of soil properties from projected increases in hydrological connectivity across the region over the coming decades.

10aactive layer10aairborne electromagnetic surveys10aMcMurdo Dry Valleys10apermafrost dynamics1 aGutterman, William, S.1 aDoran, Peter, T.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aMyers, Krista, F.1 aTulaczyk, Slawek, M.1 aFoley, Neil, T.1 aMikucki, Jill, A.1 aDugan, Hilary, A.1 aGrombacher, Denys1 aBording, Thue, S.1 aAuken, E. uhttps://onlinelibrary.wiley.com/doi/10.1029/2022JF00669601795nas a2200205 4500008004100000022001400041245009300055210006900148260001200217520099200229653002501221653001901246653002401265100002101289700002901310700002201339700001701361700001701378856019401395 2023 eng d a0260-305500aChange at 85 degrees south: Shackleton Glacier region proglacial lakes from 1960 to 20200 aChange at 85 degrees south Shackleton Glacier region proglacial  c05/20233 a

Over the last two decades, anomalous warming events have been observed in coastal Antarctic regions. While these events have been documented in the Ross Sea sector, the Antarctic interior is believed to have been buffered from warming. In this work, we present data from lakes located near Mt. Heekin and Thanksgiving Valley (~85° S) along the Shackleton Glacier, which are believed to be the southern-most Antarctic dry valley lakes. In 2018, the lakes were characterized, repeat satellite images were examined, and lake water chemistry was measured. Our analysis shows that lake areas recently increased, and the water-soluble ion chemistry indicates a flushing of salts from periglacial soils, likely from increased glacial melt as illustrated by water isotope data. Our results show that high southern latitude ice-free areas have likely been affected by warm pulses over the past 60 years and these pulses may be quasi-synchronous throughout the Transantarctic Mountains.

10aAntarctic glaciology10aclimate change10ameltwater chemistry1 aDiaz, Melisa, A.1 aGardner, Christopher, B.1 aElliot, David, H.1 aAdams, Byron1 aLyons, Berry uhttps://www.cambridge.org/core/journals/annals-of-glaciology/article/change-at-85-degrees-south-shackleton-glacier-region-proglacial-lakes-from-1960-to-2020/565D96AD7AE72BD22C49CCB772867AC402923nas a2200181 4500008004100000245015400041210006900195260004800264300000700312490000900319520225400328653002202582653001502604653002902619100002002648700002502668856004802693 2023 eng d00aCharacterizing velocity gradients in the McMurdo Dry Valleys with high-resolution optical imagery, feature-tracking methods, and in situ observations0 aCharacterizing velocity gradients in the McMurdo Dry Valleys wit aBoulder, CObUniversity of Colorado Boulder a430 vM.S.3 a

In the water-limited McMurdo Dry Valleys – the largest ice-free region of Antarctica – glaciers are the only significant source of meltwater to ephemeral streams and ecosystems. Understanding changes to the flow of these glaciers, along with characterizing how they are growing or shrinking, can elucidate how these physical controls on the region’s hydrology and ecology are responding to changing environmental conditions. Because in situ observations are difficult to collect and discrete by nature, various computer vision techniques are increasingly used to track glacier surface velocities from satellite optical and radar datasets. The most common of these techniques is image cross-correlation in the form of template matching or particle image velocimetry (PIV). Although exact methods vary, generally, cross-correlation works by co-registering temporally offset image pairs using similarity in pixel values resulting from distinctive surface features, such as crevasses, large sastrugi and snow dunes. When surface features are well-resolved with respect to an image pair’s spatial resolution, and well-preserved relative to its temporal resolution, velocity estimates can have sub-pixel precision. However, when glaciers lack meaningful surface texture – a common occurrence for the low-gradient, frozen-bed glaciers of the McMurdo Dry Valleys – cross correlation performs poorly. Using high-resolution (sub-meter per pixel) imagery can help derive texture from minor cracks and small erratics on otherwise smooth, uncrevassed surfaces, but additional adaptations are needed to improve cross correlation performance. These include additional filtering and histogram stretching steps, along with informed search area windows. Velocity estimates derived from this workflow are shown to be comparable to recorded ranges, in situ measurements, and manual feature tracking, but provide a much higher spatial and temporal resolution dataset. Alongside contemporaneous analyses of glacier mass balance, terminal thickness and surface roughness, these glacier velocity data help characterize how glaciers are dynamically evolving in response to environmental conditions in the Dry Valleys.

10across correlation10acryosphere10aglacier surface velocity1 aVanderwilt, Mia1 aGooseff, Michael, N. uhttps://www.proquest.com/docview/291637751903072nas a2200253 4500008004100000022001400041245011200055210006900167260001200236490000700248520227400255653001902529653001702548653002102565653002002586653001902606653001502625100002202640700002402662700002502686700002402711700002602735856005702761 2023 eng d a2161-954900aDifferentiating physical and biological storage of nitrogen along an intermittent Antarctic stream corridor0 aDifferentiating physical and biological storage of nitrogen alon c09/20230 v423 a

In many temperate streams, biological uptake of N acts to attenuate the transport of excess N from allochthonous anthropogenic imports. Relatively few studies have determined how this N uptake relates to the magnitude of physical vs. biological N storage in the stream corridor, especially for intermittent systems where allochthonous N imports are often low and N transport may only occur during brief periods of streamflow. Glacial meltwater streams in the McMurdo Dry Valleys of Antarctica provide an excellent setting to quantify autochthonous N cycling and storage processes supported by abundant algal mats and well-connected hyporheic zones. We combined historic point-scale sediment and periphyton sample datasets with remote sensing-based modeling of periphyton coverage to estimate how much N was stored in periphyton biomass and the hyporheic zone of a 5-km long McMurdo Dry Valley stream corridor (>100,000 m2). We contextualized these N storage calculations by estimating the magnitude of annual N imports to and exports from the stream corridor based on >2 decades of streamflow and surface water data, source glacier ice cores and meltwater data, and past studies of local aeolian deposition and biological N fixation rates. We found that in this highly oligotrophic system, stream corridor-scale N storage was ~1000x that of total annual N import or export fluxes. More than 90% of this temporarily stored N was autochthonous organic matter in the shallow (<10 cm) hyporheic zone, which acts as a reservoir that sustains N availability in the water column. Despite its location in a polar desert devoid of higher-order vegetation, area-normalized N storage (~40 g N/m2) was greater than that reported for streams at lower latitudes (~1–22 g N/m2). We also demonstrated that NH4+ sorption to stream sediment may be an important physicochemical N storage mechanism that responds to short-term fluctuations in streamflow and governs the mobility of inorganic N. Altogether, this research illustrates the importance of quantifying N storage within stream corridors when evaluating the significance of internal cycling and physical retention processes that modulate N availability.

10ahyporheic zone10aMcMurdo LTER10anitrogen cycling10anutrient budget10aorganic matter10aperiphyton1 aSingley, Joel, G.1 aSalvatore, Mark, R.1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aHinckley, Eve-Lyn, S. uhttps://www.journals.uchicago.edu/doi/10.1086/72567602567nas a2200337 4500008004100000245010300041210006900144260001200213300000900225490000700234520158600241653001601827653001201843653001401855653001901869653001801888100002401906700002201930700002401952700002001976700002101996700002102017700002502038700002102063700002102084700001902105700002102124700001702145700002102162856004602183 2023 eng d00aThe distribution of surface soil moisture over space and time in eastern Taylor Valley, Antarctica0 adistribution of surface soil moisture over space and time in eas c06/2023 a31700 v153 a

Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2–10% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 ± 0.5% gravimetric water content (GWC) across its non-fluvial landscape with ~23% of the landscape experiencing an average GWC > 2% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.

10aDry valleys10aecology10ahydrology10aremote sensing10asoil moisture1 aSalvatore, Mark, R.1 aBarrett, John, E.1 aFackrell, Laura, E.1 aSokol, Eric, R.1 aLevy, Joseph, S.1 aKuentz, Lily, C.1 aGooseff, Michael, N.1 aAdams, Byron, J.1 aPower, Sarah, N.1 aKnightly, Paul1 aMatul, Haley, M.1 aSzutu, Brian1 aDoran, Peter, T. uhttps://www.mdpi.com/2072-4292/15/12/317002076nas a2200313 4500008004100000245008700041210006900128260001200197300001100209490000800220520114900228653002801377653002701405653002401432653002401456653001301480653000901493100001301502700002501515700001601540700002201556700001701578700001801595700001601613700002401629700002001653700001701673856007201690 2023 eng d00aEcological stoichiometry drives the evolution of soil nematode life history traits0 aEcological stoichiometry drives the evolution of soil nematode l c02/2023 a1088910 v1773 a

Ecological stoichiometry is a useful theoretical framework for understanding the sources and controls on nutrient availability that structure the composition and diversity of biotic communities. One such relationship is that organismal development rate is positively linked to cellular Phosphorus (P). We hypothesized that P availability, relative to other nutrients, e.g., nitrogen and carbon, would drive the evolution of traits associated with organismal growth and development. We examined the effects of P availability both in situ and in vitro, on free-living soil nematodes. We found that P-deficient environments produce predictable changes in the ecology and evolution of important life history traits. Our results identify altered rRNA gene copy number and subsequent changes in gene expression and protein synthesis as mechanisms by which P-deficiency influences these traits. These findings have important implications for explaining soil ecological and evolutionary patterns across multiple levels of organization, including the structure and functioning of organisms, populations, communities, and ecosystems.

10aelemental stoichiometry10agrowth rate hypothesis10alife history theory10amolecular evolution10anematoda10arRNA1 aXue, Xia1 aAdhikari, Bishwo, N.1 aBall, Becky1 aBarrett, John, E.1 aMiao, Jinxin1 aPerkes, Ammon1 aMartin, Mac1 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron uhttps://www.sciencedirect.com/science/article/pii/S003807172200348000724nas a2200229 4500008004100000022001400041245005500055210005100110260001200161300000800173490000700181653001200188653001200200653001600212653001600228653001200244100002100256700002200277700002700299700002000326856014800346 2023 eng d a0954-102000aExtreme cold (-69.1°C) in the McMurdo Dry Valleys0 aExtreme cold 691°C in the McMurdo Dry Valleys c03/2023 a1-40 v3010aclimate10aextreme10ameteorology10atemperature10aweather1 aDoran, Peter, T.1 aMyers, Krista, F.1 aMcKay, Christopher, P.1 aBromwich, David uhttps://www.cambridge.org/core/journals/antarctic-science/article/extreme-cold-691c-in-the-mcmurdo-dry-valleys/3516874750E5EF96365A26E8D49CA4EC02098nas a2200265 4500008004100000022001400041245010400055210006900159260001200228300001200240490000800252520131200260653001601572653001501588653001801603653002501621653002101646653001301667653002201680100001601702700001401718700001401732700002901746856005701775 2023 eng d a0166-859500aHigh salt-induced PSI-supercomplex is associated with high CEF and attenuation of state transitions0 aHigh saltinduced PSIsupercomplex is associated with high CEF and c09/2023 a65 - 840 v1573 a

While PSI-driven cyclic electron flow (CEF) and assembly of thylakoid supercomplexes have been described in model organisms like Chlamydomonas reinhardtii, open questions remain regarding their contributions to survival under long-term stress. The Antarctic halophyte, C. priscuii UWO241 (UWO241), possesses constitutive high CEF rates and a stable PSI-supercomplex as a consequence of adaptation to permanent low temperatures and high salinity. To understand whether CEF represents a broader acclimation strategy to short- and long-term stress, we compared high salt acclimation between the halotolerant UWO241, the salt-sensitive model, C. reinhardtii, and a moderately halotolerant Antarctic green alga, C. sp. ICE-MDV (ICE-MDV). CEF was activated under high salt and associated with increased non-photochemical quenching in all three Chlamydomonas species. Furthermore, high salt-acclimated cells of either strain formed a PSI-supercomplex, while state transition capacity was attenuated. How the CEF-associated PSI-supercomplex interferes with state transition response is not yet known. We present a model for interaction between PSI-supercomplex formation, state transitions, and the important role of CEF for survival during long-term exposure to high salt.

10aacclimation10aAntarctica10aChlamydomonas10aCyclic electron flow10aPSI-supercomplex10asalinity10astate transitions1 aKalra, Isha1 aWang, Xin1 aZhang, Ru1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/10.1007/s11120-023-01032-y02591nas a2200229 4500008004100000245013200041210006900173260001200242300000600254490000600260520183600266100002102102700002402123700001802147700001602165700002202181700002402203700003302227700002402260700002202284856005502306 2023 eng d00aImpact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica0 aImpact of meltwater flow intensity on the spatiotemporal heterog c01/2023 a30 v33 a

The meltwater streams of the McMurdo Dry Valleys are hot spots of biological diversity in the climate-sensitive polar desert landscape. Microbial mats, largely comprised of cyanobacteria, dominate the streams which flow for a brief window of time (~10 weeks) over the austral summer. These communities, critical to nutrient and carbon cycling, display previously uncharacterized patterns of rapid destabilization and recovery upon exposure to variable and physiologically detrimental conditions. Here, we characterize changes in biodiversity, transcriptional responses and activity of microbial mats in response to hydrological disturbance over spatiotemporal gradients. While diverse metabolic strategies persist between marginal mats and main channel mats, data collected from 4 time points during the austral summer revealed a homogenization of the mat communities during the mid-season peak meltwater flow, directly influencing the biogeochemical roles of this stream ecosystem. Gene expression pattern analyses identified strong functional sensitivities of nitrogen-fixing marginal mats to changes in hydrological activities. Stress response markers detailed the environmental challenges of each microhabitat and the molecular mechanisms underpinning survival in a polar desert ecosystem at the forefront of climate change. At mid and end points in the flow cycle, mobile genetic elements were upregulated across all mat types indicating high degrees of genome evolvability and transcriptional synchronies. Additionally, we identified novel antifreeze activity in the stream microbial mats indicating the presence of ice-binding proteins (IBPs). Cumulatively, these data provide a new view of active intra-stream diversity, biotic interactions and alterations in ecosystem function over a high-flow hydrological regime.

1 aZoumplis, Angela1 aKolody, Bethany, C.1 aKaul, Drishti1 aZheng, Hong1 aVenepally, Pratap1 aMcKnight, Diane, M.1 aTakacs-Vesbach, Cristina, D.1 aDeVries, Arthur, L.1 aAllen, Andrew, E. uhttps://www.nature.com/articles/s43705-022-00202-802739nas a2200217 4500008004100000245016100041210006900202260003400271490000900305520201700314653001102331653002402342653001802366653001302384653001502397653001702412653000902429100002202438700002202460856003902482 2023 eng d00aInfluence of landscape-variation in geochemistry on taxonomic and functional composition of microbial mat communities in the McMurdo Dry Valleys, Antarctica0 aInfluence of landscapevariation in geochemistry on taxonomic and aBlacksburg, VAbVirginia Tech0 vM.S.3 a

Microbial communities play critical roles in biogeochemical cycles of aquatic and terrestrial ecosystems, but studies of soil microbial communities have been limited by the diversity and complexity found in most ecosystems. Here we report on work investigating the functional diversity of microbial mat and underlying soil communities in the McMurdo Dry Valleys of Antarctica across a gradient of phosphorus availability on glacial tills of distinct age and mineral composition in Taylor Valley, Antarctica. Microbial mat and soil DNA were extracted and sequenced on an Illumina NextSeq500 in a 150 bp paired end format. Raw sequences were uploaded to the MG-RAST server for processing and annotation. Community taxonomic and functional annotation were determined using the RefSeq and SEED Subsystem databases, respectively. The results revealed significant variation in microbial mat community taxonomic composition between the two tills, strongly associated with visual assessment of mat morphology, e.g., "black" and "orange" mats, and soil N:P ratios. The underlying soil microbial communities did not exhibit significant differences in diversity between the two tills, but community composition varied significantly across gradients of soil chemistry, particularly extractable-phosphate content even within tills. The relative abundance of biogeochemistry-relevant pathways determined from the SEED database varied amongst soil microbial communities between the two tills. For example, microbial mat communities exhibited significant variation in the relative abundance of key nitrogen and phosphorus metabolism associated genes strongly associated with the underlying soil N:P. These results suggest that spatial variation in geochemistry influences the distribution and activity of microbial mats, but that the microbial mats themselves also exert a significant homogenizing effect on the underlying soil communities and some of the key biogeochemical processes they facilitate.

10acarbon10amicrobial community10amicrobial mat10anitrogen10aphosphorus10apolar desert10asoil1 aRisteca, Paul, J.1 aBarrett, John, E. uhttp://hdl.handle.net/10919/11538402814nas a2200373 4500008004100000022001400041245010900055210006900164260001200233520170200245653002001947653001001967653001101977653001201988653001102000653001102011100002502022700001902047700001902066700001702085700002102102700002302123700002402146700002502170700002402195700002602219700002102245700002202266700002202288700002102310700001802331700002202349856006902371 2023 eng d a0886-623600aLong-term changes in concentration and yield of riverine dissolved silicon from the poles to the tropics0 aLongterm changes in concentration and yield of riverine dissolve c08/20233 a

Riverine exports of silicon (Si) influence global carbon cycling through the growth of marine diatoms, which account for ∼25% of global primary production. Climate change will likely alter river Si exports in biome-specific ways due to interacting shifts in chemical weathering rates, hydrologic connectivity, and metabolic processes in aquatic and terrestrial systems. Nonetheless, factors driving long-term changes in Si exports remain unexplored at local, regional, and global scales. We evaluated how concentrations and yields of dissolved Si (DSi) changed over the last several decades of rapid climate warming using long-term datasets from 60 rivers and streams spanning the globe (e.g., Antarctic, tropical, temperate, boreal, alpine, Arctic systems). We show that widespread changes in river DSi concentration and yield have occurred, with the most substantial shifts occurring in alpine and polar regions. The magnitude and direction of trends varied within and among biomes, were most strongly associated with differences in land cover, and were often independent of changes in river discharge. These findings indicate that there are likely diverse mechanisms driving change in river Si biogeochemistry that span the land-water interface, which may include glacial melt, changes in terrestrial vegetation, and river productivity. Finally, trends were often stronger in months outside of the growing season, particularly in temperate and boreal systems, demonstrating a potentially important role of shifting seasonality for the flux of Si from rivers. Our results have implications for the timing and magnitude of silica processing in rivers and its delivery to global oceans.

10abiogeochemistry10ariver10asilica10asilicon10astream10atrends1 aJankowski, Kathi, Jo1 aJohnson, Keira1 aSethna, Lienne1 aJulian, Paul1 aWymore, Adam, S.1 aShogren, Arial, J.1 aThomas, Patrick, K.1 aSullivan, Pamela, L.1 aMcKnight, Diane, M.1 aMcDowell, William, H.1 aHeindel, Ruth, C1 aJones, Jeremy, B.1 aWollheim, Wilfred1 aAbbott, Benjamin1 aDeegan, Linda1 aCarey, Joanna, C. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GB00767801851nas a2200229 4500008004100000022001400041245013100055210006900186260001200255300001400267490000600281520108300287100002201370700001801392700002501410700002201435700001801457700002701475700002101502700002501523856007301548 2023 eng d a2378-224200aMacroSheds: A synthesis of long-term biogeochemical, hydroclimatic, and geospatial data from small watershed ecosystem studies0 aMacroSheds A synthesis of longterm biogeochemical hydroclimatic  c06/2023 a419 - 4520 v83 a

The US Federal Government supports hundreds of watershed monitoring efforts from which solute fluxes can be calculated. Although instrumentation and methods vary between studies, the data collected and their motivating questions are remarkably similar. Nevertheless, little effort toward their compilation has previously been made. The MacroSheds project has developed a future-friendly system for harmonizing daily time series of streamflow, precipitation, and solute chemistry from 169+ watersheds, and supplementing each with watershed attributes. Here, we describe the breadth of MacroSheds data, and detail the steps involved in rendering each data product. We provide recommendations for usage and discuss when other datasets might be more suitable. The MacroSheds dataset is an unprecedented resource for watershed science, and for hydrology, as a small-watershed supplement to existing collections of streamflow predictors, like CAMELS and GAGES-II. The MacroSheds platform includes a web dashboard for visualization and an R package for data access and analysis.

1 aVlah, Michael, J.1 aRhea, Spencer1 aBernhardt, Emily, S.1 aSlaughter, Weston1 aGubbins, Nick1 aDelVecchia, Amanda, G.1 aThellman, Audrey1 aRoss, Matthew, R. V. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lol2.1032502348nas a2200253 4500008004100000022001400041245009900055210006900154260001200223300001100235520137700246653002501623653001901648653002401667653003201691653001701723100002601740700002401766700002501790700002501815700003201840700002001872856020201892 2023 eng d a0022-143000aMeteorological drivers of melt at two nearby glaciers in the McMurdo Dry Valleys of Antarctica0 aMeteorological drivers of melt at two nearby glaciers in the McM c12/2023 a1 - 133 a

We study the meteorological drivers of melt at two glaciers in Taylor Valley, Antarctica, using 22 years of weather station observations and surface energy fluxes. The glaciers are located only 30 km apart, but have different local climates; Taylor Glacier is generally drier and windier than Commonwealth Glacier, which receives more snowfall due to its proximity to the coast. Commonwealth Glacier shows more inter-annual melt variability, explained by variable albedo due to summer snowfall events. A significant increase in surface melt at Commonwealth Glacier is associated with a decrease in summer minimum albedo. Inter-annual variability in melt at both glaciers is linked to degree-days above freezing during föhn events, occurring more frequently at Taylor Glacier. At Taylor Glacier melt occurs most often with positive air temperatures, but föhn conditions also favour sublimation, which cools the surface and prevents melt for the majority of the positive air temperatures. At Commonwealth Glacier, most of the melt instead occurs with sub-zero air temperatures, driven by strong solar radiative heating. Future melt at Taylor Glacier will likely be more sensitive to changes in föhn events, while Commonwealth Glacier will be impacted more by changes in near coastal weather, where moisture inputs can drive cloud cover, snowfall and change albedo.

10aAntarctic glaciology10aenergy balance10aglacier meteorology10aice/atmosphere interactions10amelt-surface1 aHofsteenge, Marte, G.1 aCullen, Nicolas, J.1 aConway, Jonathan, P.1 aReijmer, Carleen, H.1 avan den Broeke, Michiel, R.1 aKaturji, Marwan uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/meteorological-drivers-of-melt-at-two-nearby-glaciers-in-the-mcmurdo-dry-valleys-of-antarctica/2B8ED17DEC26AB5F0905BC4C7ACA02FA02238nas a2200205 4500008004100000245004700041210004700088260004800135490001000183520164300193653001501836653002901851653002201880653001901902653001001921653001001931100002601941700001701967856004801984 2023 eng d00aMicrobial life in challenging environments0 aMicrobial life in challenging environments aBoulder, CObUniversity of Colorado Boulder0 vPh.D.3 a

Microorganisms are nearly ubiquitous on Earth, but the identity and function of microbial communities are inherently dependent on the properties of the specific environment in question. Here, I have studied soils around the world to answer questions about how the functional attributes of microorganisms allow them to respond to challenging environmental conditions. First, I explore how microbial communities in soils change across environmental gradients in Antarctica. I show that microbes in Antarctic surface soils are most restricted by low temperatures, low water availability, and high concentrations of salt. Microbial communities near the polar plateau, the most challenging environment, are dominated by Actinobacteria and Chloroflexi, and are enriched in genes associated with the oxidation of hydrogen gas as an energy source. Second, I show that the earliest microbial colonizers of a newly-formed volcanic island in the Kingdom of Tonga are chemolithotrophs that appear to have come from nearby geothermal systems. While many of these microbes utilize sulfur as an energy source, the most abundant organisms have genes that indicate they can oxidize trace gases including carbon monoxide and hydrogen. Finally, I show that organisms associated with carbon limited subsurface soils tend to have smaller genomes, grow more slowly, and have more gene pathways associated with metabolism and the storage of carbon. Taken together, these studies shed light on microbial survival in challenging soil environments and show the varied ways in which microbial communities interact with and are affected by their surroundings.

10aAntarctica10aenvironmental conditions10amicrobial ecology10amicroorganisms10asoils10atonga1 aDragone, Nicholas, B.1 aFierer, Noah uhttps://www.proquest.com/docview/281473420902541nas a2200241 4500008004100000245010600041210006900147260001200216520180200228653001202030653000602042653001802048653001902066653001302085653001902098653000602117653002202123100002202145700002202167700002102189700002402210856006502234 2023 eng d00aNitrogen fixation facilitates stream microbial mat biomass across the McMurdo Dry Valleys, Antarctica0 aNitrogen fixation facilitates stream microbial mat biomass acros c07/20233 a

Nitrogen (N) fixation is a fundamental mechanism by which N enters streams. Yet, because of modern N saturation, it is difficult to study the importance of N-fixation to stream nutrient budgets. Here, we utilized relatively simple and pristine McMurdo Dry Valley streams to investigate the role of N-fixing Nostoc abundance, streamwater dissolved inorganic N (DIN) concentration, and distance from the source glacier in regulating the elemental and isotopic composition of three microbial mat types (black, orange, and green) at the landscape scale. We found Nostoc-based black mats were the most enriched in δ15N, and δ15N signatures of mats increased where Nostoc was abundant, but did not surpass the atmospheric standard (δ15N ≈ 0‰). Furthermore, green and orange mat δ15N signatures became more depleted with increasing DIN, indicating that mats utilize glacial meltwater-sourced N when available. The distance from the source glacier explained limited variability in mat δ15N across sites, indicating the influence of individual stream characteristics on N spiraling. To further explore longitudinal N spiraling processes generating observed δ15Ν patterns, we developed a simple steady-state mathematical model. Analysis of plausible scenarios with this model confirmed that streams both have the capacity to remove allochthonous DIN over the plausible range of inputs, and that internal N sources are required to account for δ15N signatures and observed DIN concentrations at stream outlets. Collectively, these data and modeling results demonstrate that N-fixation exerts substantial influence within and across these streams, and is presumably dependent upon interconnected organic matter reserves, mineralization rates, and geomorphology.

10abiofilm10aC10acyanobacteria10ahyporheic zone10aMCM LTER10amineralization10aN10aP biogeochemistry1 aKohler, Tyler, J.1 aSingley, Joel, G.1 aWlostowski, Adam1 aMcKnight, Diane, M. uhttps://link.springer.com/article/10.1007/s10533-023-01069-002063nas a2200277 4500008004100000245013600041210006900177260001200246300001300258490000600271520117000277100002601447700002601473700002601499700001601525700002101541700002701562700001901589700001901608700002501627700001501652700002101667700002201688700002001710856005501730 2023 eng d00aPostglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes0 aPostglacial adaptations enabled colonization and quasiclonal dis c02/2023 aeadc93920 v93 a

Ammonia-oxidizing archaea (AOA) play a key role in the aquatic nitrogen cycle. Their genetic diversity is viewed as the outcome of evolutionary processes that shaped ancestral transition from terrestrial to marine habitats. However, current genome-wide insights into AOA evolution rarely consider brackish and freshwater representatives or provide their divergence timeline in lacustrine systems. An unbiased global assessment of lacustrine AOA diversity is critical for understanding their origins, dispersal mechanisms, and ecosystem roles. Here, we leveraged continental-scale metagenomics to document that AOA species diversity in freshwater systems is remarkably low compared to marine environments. We show that the uncultured freshwater AOA, “Candidatus Nitrosopumilus limneticus,” is ubiquitous and genotypically static in various large European lakes where it evolved 13 million years ago. We find that extensive proteome remodeling was a key innovation for freshwater colonization of AOA. These findings reveal the genetic diversity and adaptive mechanisms of a keystone species that has survived clonally in lakes for millennia.

1 aNgugi, David, Kamanda1 aSalcher, Michaela, M.1 aAndrei, Adrian-Stefan1 aGhai, Rohit1 aKlotz, Franziska1 aChiriac, Maria-Cecilia1 aIonescu, Danny1 aBüsing, Petra1 aGrossart, Hans-Peter1 aXing, Peng1 aPriscu, John, C.1 aAlymkulov, Salmor1 aPester, Michael uhttps://www.science.org/doi/10.1126/sciadv.adc939201387nas a2200157 4500008004100000022001400041245006900055210006900124260001200193300001600205490000700221520088600228100002701114700002101141856006701162 2023 eng d a0024-359000aSediment oxygen consumption in Antarctic subglacial environments0 aSediment oxygen consumption in Antarctic subglacial environments c07/2023 a1557 - 15660 v683 a

Oxygen consumption in aquatic sediments is an indicator of overall biological activity of the ecosystem. As such, rates of sedimentary oxygen utilization are well documented for much of the open oceans and freshwater lakes. However, there are few direct measurements of sedimentary oxygen consumption from Antarctic subglacial aquatic sediments. We report the first microsensor oxygen profiles and derived sedimentary oxygen consumption rates from beneath the Ross Ice Shelf and a subglacial lake beneath the West Antarctic Ice Sheet. Rates of oxygen consumption in these two environments are relatively low, but comparable to those reported from ice-free polar oceans and oligotrophic Arctic lakes. Our study demonstrates the presence of oxygen within Antarctic subglacial aquatic sediments and its importance for oxygen-consuming microorganisms living in these ecosystems.

1 aMichaud, Alexander, B.1 aPriscu, John, C. uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lno.1236602845nas a2200121 4500008004100000245008700041210006900128260005700197490000900254520237900263100002302642856005802665 2023 eng d00aSnow distribution and influence in Taylor Valley, Antarctica, using remote sensing0 aSnow distribution and influence in Taylor Valley Antarctica usin aBaton Rouge, LAbLouisiana State Universityc04/20230 vM.S.3 a

The McMurdo Dry Valleys is the largest ice-free area in Antarctica, but seasonal snow covers the valley floors sporadically throughout the year. In this study, a model to estimate areal snow coverage from satellite imagery was created. An area-volume model was created to estimate the amount of snow water equivalent (SWE) from the snow area extracted from the imagery. Snow cover influences the total albedo, the hydrologic budget, and the soil moisture and soil temperature in Taylor Valley (TV). Quantifying snow precipitation in TV is challenging because snow redistributes with winds, sublimates, or melts within a short period. Previous estimates found the amount of snow precipitation in TV is small, less than 100 mm/a. (SWE); even so, snow cover may influence processes in the valley. To better understand the controls and feedbacks of snow cover in the valley, a long-term record of spatially distributed abundance is required. This research creates a long-term record of snow cover data in TV using satellite images. The area of snowpacks was calculated by creating a classification scheme based on the brightness of panchromatic images. During the 2021-2022 field season, 250 m x 250 m sampling quadrats were surveyed to approximate how area and volume relate to SWE. Volumetric SWE was calculated by measuring in situ the length, width, depth, and density of each snowpack in the quadrat. There is a strong relationship between the area and the volume of the snowpacks (R2=0.942, P=0.182). With this information, estimates of the SWE can be made from the area calculated from satellite imagery. The average snow area for the entire extent of TV in late winter/early summer (September-December) from 2004 to 2022 is 65.26 km2, the average SWE is 0.0310 km3, and the average SWE depth is 75.72 mm. The amount of areal snow coverage is important when calculating the energy balance of TV, as well as understanding the availability of soil moisture to the soil ecosystem year-to-year. The available SWE can also influence seasonal surface and subsurface hydrology. While most precipitated snow in TV will sublimate or be redistributed by the wind, it is important to quantify how much snow has accumulated each season, especially with a warming climate, which could drastically influence snow accumulation and dynamics in TV.

1 aMcNulty, Katherine uhttps://digitalcommons.lsu.edu/gradschool_theses/574902170nas a2200145 4500008004100000022001400041245013800055210006900193260001200262520161600274100002401890700002401914700002501938856006101963 2023 eng d a2169-900300aSpatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica0 aSpatial patterns of major ions and their relationship to sedimen c03/20243 a

Glaciers form the headwaters of many watersheds and, in arid polar environments, can provide the vast majority of water to downstream systems. Headwater watersheds are critically important for setting the chemistry for downstream systems, yet we know comparatively little about the patterns and processes that generate the geochemical signature of meltwater on glacier surfaces. Here, we focus on glaciers in the McMurdo Dry Valleys of Antarctica, the largest ice-free area on the continent, characterized by alpine glaciers flowing into broad, rocky valleys. We examine patterns from the coast inland, accumulation to ablation zones, laterally across individual glaciers, and through the zone of meltwater generation. We directly compare solute to sediment concentrations, a major source of dissolved solutes. Our findings agree with previous work that the overall meltwater chemistry of a given glacier is a product local sediment sources and of regional wind patterns: foehn winds moving from the ice sheet to the coast and on-shore sea breezes. Further, these patterns hold across an individual glacier. Finally, we find that the ice chemistry and sediment profiles reflect freeze-thaw and melt processes that occur at depth. This indicates that the transport and weathering of sediment in the ice profile likely has a strong influence on supra- and proglacial stream chemistry. This new understanding strengthens connections between physical and geochemical processes in cold-based polar glacier environments and helps us better understand the processes driving landscape and ecosystem connectivity.

1 aBergstrom, Anna, J.1 aWelch, Kathleen, A.1 aGooseff, Michael, N. uhttps://onlinelibrary.wiley.com/doi/10.1029/2022JF00698002259nas a2200289 4500008004100000245009100041210006900132260001200201490000600213520140100219653002301620653001601643653001401659653001001673653001801683100002401701700001701725700002101742700002601763700002601789700001701815700001701832700001801849700002001867700001801887856006401905 2023 eng d00aStrong dispersal limitation of microbial communities at Shackleton Glacier, Antarctica0 aStrong dispersal limitation of microbial communities at Shacklet c01/20230 v83 a

Microbial communities can be structured by both deterministic and stochastic processes, but the relative importance of these processes remains unknown. The ambiguity partly arises from an inability to disentangle soil microbial processes from confounding factors, such as aboveground plant communities or anthropogenic disturbance. In this study, we characterized the relative contributions of determinism and stochasticity to assembly processes of soil bacterial communities across a large environmental gradient of undisturbed Antarctic soils. We hypothesized that harsh soils would impose a strong environmental selection on microbial communities, whereas communities in benign soils would be structured largely by dispersal. Contrary to our expectations, dispersal was the dominant assembly mechanism across the entire soil environmental gradient, including benign environments. The microbial community composition reflects slowly changing soil conditions and dispersal limitation of isolated sites. Thus, stochastic processes, as opposed to deterministic, are primary drivers of soil ecosystem assembly across space at our study site. This is especially surprising given the strong environmental constraints on soil microorganisms in one of the harshest environments on the planet, suggesting that dispersal could be a driving force in microbial community assembly in soils worldwide.

10acommunity assembly10adeterminism10adispersal10aniche10astochasticity1 aLemoine, Nathan, P.1 aAdams, Byron1 aDiaz, Melisa, A.1 aDragone, Nicholas, B.1 aFranco, André, L. C.1 aFierer, Noah1 aLyons, Berry1 aHogg, Ian, D.1 aWall, Diana, H.1 aLurgi, Miguel uhttps://journals.asm.org/doi/full/10.1128/msystems.01254-2202770nas a2200241 4500008004100000245007200041210006900113260001200182300000800194490000700202520208300209653001502292653001902307653001902326653001302345653002202358653002102380100002902401700002002430700001302450700002102463856004402484 2023 eng d00aTemperature response of metabolic activity of an Antarctic nematode0 aTemperature response of metabolic activity of an Antarctic nemat c01/2023 a1090 v123 a

Because of climate change, the McMurdo Dry Valleys of Antarctica (MCM) have experienced an increase in the frequency and magnitude of summer pulse warming and surface ice and snow melting events. In response to these environmental changes, some nematode species in the MCM have experienced steady population declines over the last three decades, but Plectus murrayi, a mesophilic nematode species, has responded with a steady increase in range and abundance. To determine how P. murrayi responds to increasing temperatures, we measured metabolic heat and CO2 production rates and calculated O2 consumption rates as a function of temperature at 5 °C intervals from 5 to 50 °C. Heat, CO2 production, and O2 consumption rates increase approximately exponentially up to 40 °C, a temperature never experienced in their polar habitat. Metabolic rates decline rapidly above 40 °C and are irreversibly lost at 50 °C due to thermal stress and mortality. Caenorhabditis elegans, a much more widespread nematode that is found in more temperate environments reaches peak metabolic heat rate at just 27 °C, above which it experiences high mortality due to thermal stress. At temperatures from 10 to 40 °C, P. murrayi produces about 6 times more CO2 than the O2 it consumes, a respiratory quotient indicative of either acetogenesis or de novo lipogenesis. No potential acetogenic microbes were identified in the P. murrayi microbiome, suggesting that P. murrayi is producing increased CO2 as a byproduct of de novo lipogenesis. This phenomenon, in conjunction with increased summer temperatures in their polar habitat, will likely lead to increased demand for carbon and subsequent increases in CO2 production, population abundance, and range expansion. If such changes are not concomitant with increased carbon inputs, we predict the MCM soil ecosystems will experience dramatic declines in functional and taxonomic diversity.

10aAntarctica10acarbon cycling10aclimate change10anematode10arespiration rates10asoil temperature1 aRobinson, Colin, Michael1 aHansen, Lee, D.1 aXue, Xia1 aAdams, Byron, J. uhttps://www.mdpi.com/2079-7737/12/1/10901137nas a2200193 4500008004100000245005600041210005300097260001200150300001100162490000700173520056500180100002100745700001800766700001400784700002300798700002900821700002600850856006700876 2022 eng d00aAn Antarctic alga that can survive the extreme cold0 aAntarctic alga that can survive the extreme cold c05/2022 a7408380 v103 a

Microscopic algae are tougher than you might think. Some can even survive the extreme cold. In this article, we describe one of the coolest algae of all, the Antarctic green alga called Chlamydomonas sp. UWO241. This one-celled super-organism lives deep in the frigid waters of a remote and permanently ice-covered lake in Antarctica. How does this little alga thrive in such a barren and unwelcoming place? Well, dive into this article to learn how studying the genome of UWO241 is helping scientists better understand this amazingly hardy alga.

1 aSmith, David, R.1 aLeung, Arthur1 aZhang, Xi1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M.1 aHüner, Norman, P. A. uhttps://kids.frontiersin.org/articles/10.3389/frym.2022.74083802039nas a2200169 4500008004100000245013000041210007100171260001200242520142300254100002601677700001601703700001201719700002401731700002101755700002901776856006401805 2022 eng d00aAntarctic lake phytoplankton and bacteria from near‐surface waters exhibit high sensitivity to climate‐driven disturbance0 aAntarctic lake phytoplankton and bacteria from near‐surface wate c07/20223 a

The McMurdo Dry Valleys (MDVs), Antarctica, represent a cold, desert ecosystem poised on the threshold of melting and freezing water. The MDVs have experienced dramatic signs of climatic change, most notably a warm austral summer in 2001–2002 that caused widespread flooding, partial ice cover loss and lake level rise. To understand the impact of these climatic disturbances on lake microbial communities, we simulated lake level rise and ice-cover loss by transplanting dialysis-bagged communities from selected depths to other locations in the water column or to an open water perimeter moat. Bacteria and eukaryote communities residing in the surface waters (5 m) exhibited shifts in community composition when exposed to either disturbance, while microbial communities from below the surface were largely unaffected by the transplant. We also observed an accumulation of labile dissolved organic carbon in the transplanted surface communities. In addition, there were taxa-specific sensitivities: cryptophytes and Actinobacteria were highly sensitive particularly to the moat transplant, while chlorophytes and several bacterial taxa increased in relative abundance or were unaffected. Our results reveal that future climate-driven disturbances will likely undermine the stability and productivity of MDV lake phytoplankton and bacterial communities in the surface waters of this extreme environment.

1 aSherwell, Shasten, S.1 aKalra, Isha1 aLi, Wei1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttps://onlinelibrary.wiley.com/doi/10.1111/1462-2920.1611302206nas a2200229 4500008004100000022001400041245015000055210006900205260001200274300001400286490000700300520141400307653001801721653001501739653001801754100002101772700001601793700001901809700002901828700002601857856009301883 2022 eng d a0954-102000aAntibiotic resistance genes and taxa analysis from mat and planktonic microbiomes of Antarctic perennial ice-covered Lake Fryxell and Lake Bonney0 aAntibiotic resistance genes and taxa analysis from mat and plank c12/2022 a408 - 4220 v343 a

The perennial ice-covered lakes of the Antarctic McMurdo Dry Valleys harbour oligotrophic microbial communities that are separated geographically from other aquatic systems. Their microbiomes include planktonic microbes as well as lift-off mat communities that emerge from the ice. We used the ShortBRED protein family profiler to quantify the antibiotic resistance genes (ARGs) from metagenomes of lift-off mats emerging from ice and from filtered water samples of Lake Fryxell and Lake Bonney. The overall proportion of ARG hits was similar to that found in temperate-zone rural ponds with moderate human inputs. Specific ARGs showed distinct distributions for the two lakes and for mat vs planktonic sources. Metagenomic taxa distributions showed that mat phototrophs consisted mainly of cyanobacteria or Betaproteobacteria, whereas the water column phototrophs were mainly protists. An enrichment culture of the Betaproteobacterium Rhodoferax antarcticus from a Lake Fryxell mat sample showed an unusual mat-forming phenotype not previously reported for this species. Its genome showed no ARGs associated with Betaproteobacteria but had ARGs consistent with a minor Pseudomonas component. The Antarctic lake mats and water showed specific ARGs distinctive to the mat and water sources, but overall ARG levels were similar to those of temperate water bodies with moderate human inputs.

10amicrobial mat10aRhodoferax10aTaylor Valley1 aTallada, Sheetal1 aHall, Grant1 aBarich, Daniel1 aMorgan-Kiss, Rachael, M.1 aSlonczewski, Joan, L. uhttps://www.cambridge.org/core/product/identifier/S0954102022000360/type/journal_article01629nas a2200217 4500008004100000022001400041245007400055210006900129260001200198300001200210490000600222520097000228100002101198700002201219700002401241700001901265700002101284700002101305700001701326856006801343 2022 eng d a2378-224200aBarotropic seiches in a perennially ice-covered lake, East Antarctica0 aBarotropic seiches in a perennially icecovered lake East Antarct c02/2022 a26 - 330 v73 a

Water movement in ice-covered lakes is known to be driven by wind, sediment heat flux, solar radiation, saline density flows, and advective stream discharge. In large ice-covered lakes, wind-induced oscillations have been found to play a major role in horizontal flows. Here, we report recurrent, wind-driven, barotropic seiches in a small lake with a thick (4 m) permanent ice-cover. Between 2010 and 2016, we recorded 10.5- to 13-min oscillations of the hydrostatic water level in Lake Hoare, McMurdo Dry Valleys, East Antarctica, using pressure transducers moored to the lake bottom and suspended from the ice cover. Theoretical calculations showed a barotropic seiche should have a period of 12.6 min. Barotropic seiches were most frequent during high wind events (> 5 m s-1) in winter months (February–November). The period increased during summer months (December–January) when fast ice thinned and melted along the shoreline.

1 aCastendyk, Devin1 aDugan, Hilary, A.1 aGallagher, Hugh, A.1 aPujara, Nimish1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.1022602771nas a2200325 4500008004100000022001400041245013500055210006900190260001200259300001000271490000700281520179400288653001302082653001302095653001002108653001302118653002002131653001702151653001702168653003102185100002602216700001902242700002002261700002102281700001802302700002202320700002102342700002402363856005802387 2022 eng d a0022-364600aBlowin’ in the wind: Dispersal, structure, and metacommunity dynamics of aeolian diatoms in the McMurdo Sound region, Antarctica0 aBlowin in the wind Dispersal structure and metacommunity dynamic c02/2022 a36-540 v583 a

Diatom metacommunities are structured by environmental, historical, and spatial factors that are often attributed to organism dispersal. In the McMurdo Sound region (MSR) of Antarctica, wind connects aquatic habitats through delivery of inorganic and organic matter. We evaluated the dispersal of diatoms in aeolian material and its relation to the regional diatom metacommunity using light microscopy and 18S rRNA high-throughput sequencing. The concentration of diatoms ranged from 0 to 8.76 * 106 valves · g-1 dry aeolian material. Up to 15% of whole cells contained visible protoplasm, indicating that up to 3.43 * 104 potentially viable individuals could be dispersed in a year to a single 2 cm2 site. Diatom DNA and RNA was detected at each site, reinforcing the likelihood that we observed dispersal of viable diatoms. Of the 50 known morphospecies in the MSR, 72% were identified from aeolian material using microscopy. Aeolian community composition varied primarily by site. Meanwhile, each aeolian community was comprised of morphospecies found in aquatic communities from the same lake basin. These results suggest that aeolian diatom dispersal in the MSR is spatially structured, is predominantly local, and connects local aquatic habitats via a shared species pool. Nonetheless, aeolian community structure was distinct from that of aquatic communities, indicating that intrahabitat dispersal and environmental filtering also underlie diatom metacommunity dynamics. The present study confirms that a large number of diatoms are passively dispersed by wind across a landscape characterized by aeolian processes, integrating the regional flora and contributing to metacommunity structure and landscape connectivity.

10a18S rRNA10aairborne10aalgae10aassembly10aBacillariophyta10abiogeography10aconnectivity10ahigh-throughput sequencing1 aSchulte, Nicholas, O.1 aKhan, Alia, L.1 aSmith, Emma, W.1 aZoumplis, Angela1 aKaul, Drishti1 aAllen, Andrew, E.1 aAdams, Byron, J.1 aMcKnight, Diane, M. uhttps://onlinelibrary.wiley.com/doi/10.1111/jpy.1322302136nas a2200205 4500008004100000245007300041210007100114260001200185520148400197653001901681653001901700653002301719653001701742653002601759653002301785653002001808100002701828700001701855856005801872 2022 eng d00aCommunity assembly in the wake of glacial retreat: A meta‐analysis0 aCommunity assembly in the wake of glacial retreat A meta‐analysi c09/20223 a

Antarctic biodiversity faces an unknown future with a changing climate. Most terrestrial biota is restricted to limited patches of ice-free land in a sea of ice, where they are adapted to the continent's extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species' distributions, physiology, abundance, and survivorship will be affected as their habitats transform. Here we use current knowledge to propose hypotheses that ice-free area expansion (i) will increase habitat availability, though the quality of habitat will vary; (ii) will increase structural connectivity, although not necessarily increase opportunities for species establishment; (iii) combined with milder climates will increase likelihood of non-native species establishment, but may also lengthen activity windows for all species; and (iv) will benefit some species and not others, possibly resulting in increased homogeneity of biodiversity. We anticipate considerable spatial, temporal, and taxonomic variation in species responses, and a heightened need for interdisciplinary research to understand the factors associated with ecosystem resilience under future scenarios. Such research will help identify at-risk species or vulnerable localities and is crucial for informing environmental management and policymaking into the future.

10achronosequence10aclimate change10acommunity assembly10adeglaciation10aecological succession10aglacial forefields10asoil ecosystems1 aPothula, Satyendra, K.1 aAdams, Byron uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1642702219nas a2200349 4500008004100000022001400041245012300055210006900178260001200247520113200259653000901391653001901400653001601419653001201435653000901447653001301456100002001469700002501489700001601514700002501530700002101555700001701576700002501593700002501618700002101643700002501664700002601689700002201715700002301737700001801760856009101778 2022 eng d a0006-356800aCross-site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network0 aCrosssite comparisons of dryland ecosystem response to climate c c08/20223 a

Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.

10aANPP10aclimate change10aDisturbance10adrought10aLTER10awildfire1 aHudson, Amy, R.1 aPeters, Debra, P. C.1 aBlair, J.M.1 aChilders, Daniel, L.1 aDoran, Peter, T.1 aGeil, Kerrie1 aGooseff, Michael, N.1 aGross, Katherine, L.1 aHaddad, Nick, M.1 aPastore, Melissa, A.1 aRudgers, Jennifer, A.1 aSala, Osvaldo, E.1 aSeabloom, Eric, W.1 aShaver, Gaius uhttps://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biab134/665484002454nas a2200277 4500008004100000245020000041210006900241260001200310300001400322490000800336520152000344653001501864653001401879653002501893653001801918653001701936653000801953100002401961700001601985700002102001700001902022700001802041700002302059700002902082856006502111 2022 eng d00aCyclic electron flow (CEF) and ascorbate pathway activity provide constitutive photoprotection for the photopsychrophile, Chlamydomonas sp. UWO 241 (renamed Chlamydomonas priscuii)0 aCyclic electron flow CEF and ascorbate pathway activity provide  c03/2022 a235 - 2500 v1513 a

Under environmental stress, plants and algae employ a variety of strategies to protect the photosynthetic apparatus and maintain photostasis. To date, most studies on stress acclimation have focused on model organisms which possess limited to no tolerance to stressful extremes. We studied the ability of the Antarctic alga Chlamydomonas sp. UWO 241 (UWO 241) to acclimate to low temperature, high salinity or high light. UWO 241 maintained robust growth and photosynthetic activity at levels of temperature (2 °C) and salinity (700 mM NaCl) which were nonpermissive for a mesophilic sister species, Chlamydomonas raudensis SAG 49.72 (SAG 49.72). Acclimation in the mesophile involved classic mechanisms, including downregulation of light harvesting and shifts in excitation energy between photosystem I and II. In contrast, UWO 241 exhibited high rates of PSI-driven cyclic electron flow (CEF) and a larger capacity for nonphotochemical quenching (NPQ). Furthermore, UWO 241 exhibited constitutively high activity of two key ascorbate cycle enzymes, ascorbate peroxidase and glutathione reductase and maintained a large ascorbate pool. These results matched the ability of the psychrophile to maintain low ROS under short-term photoinhibition conditions. We conclude that tight control over photostasis and ROS levels are essential for photosynthetic life to flourish in a native habitat of permanent photooxidative stress. We propose to rename this organism Chlamydomonas priscuii.

10aAntarctica10aascorbate10aCyclic electron flow10aPhotosystem I10aPsychrophile10aROS1 aStahl-Rommel, Sarah1 aKalra, Isha1 aD'Silva, Susanna1 aHahn, Mark, M.1 aPopson, Devon1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/article/10.1007/s11120-021-00877-502474nas a2200229 4500008004100000245007500041210006900116260001200185300001800197490000800215520178800223653001502011653001602026653002802042653000802070653002202078653000902100100002502109700002502134700002402159856006102183 2022 eng d00aDissolved organic carbon chemostasis in Antarctic polar desert streams0 aDissolved organic carbon chemostasis in Antarctic polar desert s c07/2022 ae2021JG0066490 v1273 a

Dissolved organic carbon (DOC) is a key variable impacting stream biogeochemical processes. The relationship between DOC concentration (C) and stream discharge (q) can elucidate spatial and temporal DOC source dynamics in watersheds. In the ephemeral glacial meltwater streams of the McMurdo Dry Valleys (MDV), Antarctica, the C-q relationship has been applied to dissolved inorganic nitrogen and weathering solutes including silica, which all exhibit chemostatic C-q behavior; but DOC-q dynamics have not been studied. DOC concentrations here are low compared to temperate streams, in the range of 0.1-2 mg C l-1, and their chemical signal clearly indicates derivation from microbial biomass (benthic mats and hyporheic biofilm). To investigate whether the DOC generation rate from these autochthonous organic matter pools was sufficient to maintain chemostasis for DOC, despite these streams' large diel and interannual fluctuations in discharge, we fit the long-term DOC-q data to a power law and an advection-reaction model. Model outputs and coefficients of variation characterize the DOC-q relationship as chemostatic for several MDV streams. We propose a conceptual model in which hyporheic carbon storage, hyporheic exchange rates, and net DOC generation rates are key interacting components that enable chemostatic DOC-q behavior in MDV streams. This model clarifies the role of autochthonous carbon stores in maintaining DOC chemostasis and may be useful for examining these relationships in temperate systems, which typically have larger sources of bioavailable autochthonous organic carbon than MDV streams but where this autochthonous signal could be masked by a stronger allochthonous contribution.

10aAntarctica10achemostasis10aconcentration-discharge10aDOC10aephemeral streams10aLTER1 aTorrens, Christa, L.1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttps://onlinelibrary.wiley.com/doi/10.1029/2021JG00664900974nas a2200217 4500008004100000245004900041210004200090260001200132490000700144520034200151653001500493653001700508653001300525653002500538653001000563653001400573100001300587700002100600700002200621856011300643 2022 eng d00aA draft mitogenome of Plectus murrayi0 adraft mitogenome of iPlectus murrayii c02/20220 v543 a

Plectus murrayi is a free-living microbivorous nematode endemic to Antarctic soils. Our draft assembly of its mitogenome was 15,656 bp long, containing 12 protein-coding, eight transfer RNA (tRNA), and two ribosomal RNA (rRNA) genes. Mitophylogenomic analyses extend our understanding of mitochondrial evolution in Nematoda

10aAntarctica10agenome decay10agenomics10amitochondrial genome10aMitoZ10aphylogeny1 aXue, Xia1 aAdams, Byron, J.1 aDilman, Adler, R. uhttps://www.sciendo.com/article/10.2478/jofnem-2022-0035https://www.sciendo.com/pdf/10.2478/jofnem-2022-003502399nas a2200217 4500008004100000245008500041210006900126260005400195490000700249520171000256653001501966653001701981653002401998653001402022653002402036653001002060653002402070100002502094700002102119856004102140 2022 eng d00aEffect of climate history on the genetic structure of an Antarctic soil nematode0 aEffect of climate history on the genetic structure of an Antarct aProvo, UT, USAbBrigham Young Universityc12/20220 vMS3 a

Historical climate disturbances such as glacial cycling and fluctuating stream, lake, and sea levels strongly influence the distribution and evolutionary trajectories of Antarctic terrestrial species. Antarctic invertebrates, with limited long-range mobility, including the ubiquitous sentinel nematode species Scottnema lindsayae, are especially sensitive to climate disturbances. We tested hypotheses associated with the historical geographic and population genetic structure of this species as it occurs across the McMurdo Dry Valleys (MDVs) of Antarctica. In order to reconstruct the influence of climate disturbance and ecological conditions on this species, partial mitochondrial COI gene sequences were sequenced and analyzed from individual S. lindsayae collected from sites across the MDVs reflecting a opposing gradients of climate disturbance during the Last Glacial Maximum (LGM). We found that populations were strongly geomorphic barriers with distinct haplotypes associated with valleys except among valleys that experienced glacial advance and retreat during the LGM. One monophyletic clade corresponds with valley systems that were undisturbed during the LGM indicating putative refugia areas. A second monophyletic clade corresponds to recent dispersal and expansion of evolutionarily younger populations into valleys that were strongly reworked by glacial activity during the LGM. Our work shows that contemporary populations of these animals are strongly structured by prior climate history. Such findings can be useful for interpreting long-term monitoring of demographic shifts of soil organisms in response to changing climate trends in the McMurdo Dry Valleys.

10aAntarctica10abiogeography10aclimate disturbance10aevolution10aMcMurdo Dry Valleys10apolar10apopulation genetics1 aJackson, Abigail, C.1 aAdams, Byron, J. uhttp://hdl.lib.byu.edu/1877/etd1262202367nas a2200289 4500008004100000245011400041210006900155260001200224300001400236490000600250520147700256653001501733653002201748653002201770653001001792100002601802700002401828700002701852700002101879700001801900700001701918700002001935700001701955700001701972700002401989856006402013 2022 eng d00aElevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils0 aElevational constraints on the composition and genomic attribute c01/2022 ae01330-210 v73 a

The inland soils found on the Antarctic continent represent one of the more challenging environments for microbial life on Earth. Nevertheless, Antarctic soils harbor unique bacterial and archaeal (prokaryotic) communities able to cope with extremely cold and dry conditions. These communities are not homogeneous, and the taxonomic composition and functional capabilities (genomic attributes) of these communities across environmental gradients remain largely undetermined. We analyzed the prokaryotic communities in soil samples collected from across the Shackleton Glacier region of Antarctica by coupling quantitative PCR, marker gene amplicon sequencing, and shotgun metagenomic sequencing. We found that elevation was the dominant factor explaining differences in the structures of the soil prokaryotic communities, with the drier and saltier soils found at higher elevations harboring less diverse communities and unique assemblages of cooccurring taxa. The higher-elevation soil communities also had lower maximum potential growth rates (as inferred from metagenome-based estimates of codon usage bias) and an overrepresentation of genes associated with trace gas metabolism. Together, these results highlight the utility of assessing community shifts across pronounced environmental gradients to improve our understanding of the microbial diversity found in Antarctic soils and the strategies used by soil microbes to persist at the limits of habitability.

10aAntarctica10amicrobial ecology10asoil microbiology10asoils1 aDragone, Nicholas, B.1 aHenley, Jessica, B.1 aHolland-Moritz, Hannah1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aWall, Diana, H.1 aAdams, Byron1 aFierer, Noah1 aMackelprang, Rachel uhttps://journals.asm.org/doi/full/10.1128/msystems.01330-2102236nas a2200241 4500008004100000245006500041210006400106260001200170300000900182490000700191520155500198653001501753653002401768653001801792653002601810653001201836653002201848100002501870700001701895700001501912700002101927856004601948 2022 eng d00aGlacial legacies: Microbial communities of Antarctic refugia0 aGlacial legacies Microbial communities of Antarctic refugia c10/2022 a14400 v113 a

In the cold deserts of the McMurdo Dry Valleys (MDV) the suitability of soil for microbial life is determined by both contemporary processes and legacy effects. Climatic changes and accompanying glacial activity have caused local extinctions and lasting geochemical changes to parts of these soil ecosystems over several million years, while areas of refugia may have escaped these disturbances and existed under relatively stable conditions. This study describes the impact of historical glacial and lacustrine disturbance events on microbial communities across the MDV to investigate how this divergent disturbance history influenced the structuring of microbial communities across this otherwise very stable ecosystem. Soil bacterial communities from 17 sites representing either putative refugia or sites disturbed during the Last Glacial Maximum (LGM) (22–17 kya) were characterized using 16 S metabarcoding. Regardless of geographic distance, several putative refugia sites at elevations above 600 m displayed highly similar microbial communities. At a regional scale, community composition was found to be influenced by elevation and geographic proximity more so than soil geochemical properties. These results suggest that despite the extreme conditions, diverse microbial communities exist in these putative refugia that have presumably remained undisturbed at least through the LGM. We suggest that similarities in microbial communities can be interpreted as evidence for historical climate legacies on an ecosystem-wide scale.

10aAntarctica10aMcMurdo Dry Valleys10ametabarcoding10amicrobial communities10arefugia10asoil biodiversity1 aJackson, Abigail, C.1 aJorna, Jesse1 aChaston, J1 aAdams, Byron, J. uhttps://www.mdpi.com/2079-7737/11/10/144002315nas a2200265 4500008004100000245009400041210006900135260001200204520148400216653001501700653001701715653002601732653001901758653001701777653001301794653002301807100002101830700002601851700002201877700002401899700002301923700002001946700002501966856005801991 2022 eng d00aIslands in the ice: Potential impacts of habitat transformation on Antarctic biodiversity0 aIslands in the ice Potential impacts of habitat transformation o c07/20223 a

Antarctic biodiversity faces an unknown future with a changing climate. Most terrestrial biota is restricted to limited patches of ice-free land in a sea of ice, where they are adapted to the continent's extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species' distributions, physiology, abundance, and survivorship will be affected as their habitats transform. Here we use current knowledge to propose hypotheses that ice-free area expansion (i) will increase habitat availability, though the quality of habitat will vary; (ii) will increase structural connectivity, although not necessarily increase opportunities for species establishment; (iii) combined with milder climates will increase likelihood of non-native species establishment, but may also lengthen activity windows for all species; and (iv) will benefit some species and not others, possibly resulting in increased homogeneity of biodiversity. We anticipate considerable spatial, temporal, and taxonomic variation in species responses, and a heightened need for interdisciplinary research to understand the factors associated with ecosystem resilience under future scenarios. Such research will help identify at-risk species or vulnerable localities and is crucial for informing environmental management and policymaking into the future.

10aAntarctica10abiodiversity10abiotic homogenization10aclimate change10aconnectivity10aice-free10anon-native species1 aLee, Jasmine, R.1 aWaterman, Melinda, J.1 aShaw, Justine, D.1 aBergstrom, Dana, M.1 aLynch, Heather, J.1 aWall, Diana, H.1 aRobinson, Sharon, A. uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1633102435nas a2200277 4500008004100000245011000041210006900151260001200220300000700232490000700239520155100246653001501797653002601812653002401838653001301862653003001875100001901905700002401924700002101948700002401969700002101993700002302014700002202037700003302059856006502092 2022 eng d00aLimits to the three domains of life: Lessons from community assembly along an Antarctic salinity gradient0 aLimits to the three domains of life Lessons from community assem c04/2022 a150 v263 a

Extremophiles exist among all three domains of life; however, physiological mechanisms for surviving harsh environmental conditions differ among Bacteria, Archaea and Eukarya. Consequently, we expect that domain-specific variation of diversity and community assembly patterns exist along environmental gradients in extreme environments. We investigated inter-domain community compositional differences along a high-elevation salinity gradient in the McMurdo Dry Valleys, Antarctica. Conductivity for 24 soil samples collected along the gradient ranged widely from 50 to 8355 µS cm-1. Taxonomic richness varied among domains, with a total of 359 bacterial, 2 archaeal, 56 fungal, and 69 non-fungal eukaryotic operational taxonomic units (OTUs). Richness for bacteria, archaea, fungi, and non-fungal eukaryotes declined with increasing conductivity (all P < 0.05). Principal coordinate ordination analysis (PCoA) revealed significant (ANOSIM R = 0.97) groupings of low/high salinity bacterial OTUs, while OTUs from other domains were not significantly clustered. Bacterial beta diversity was unimodally distributed along the gradient and had a nested structure driven by species losses, whereas in fungi and non-fungal eukaryotes beta diversity declined monotonically without strong evidence of nestedness. Thus, while increased salinity acts as a stressor in all domains, the mechanisms driving community assembly along the gradient differ substantially between the domains.

10aAntarctica10ainter-domain response10aMcMurdo Dry Valleys10asalinity10aspecies richness patterns1 aJiang, Xiaoben1 aVan Horn, David, J.1 aOkie, Jordan, G.1 aBuelow, Heather, N.1 aSchwartz, Egbert1 aColman, Daniel, R.1 aFeeser, Kelli, L.1 aTakacs-Vesbach, Cristina, D. uhttps://link.springer.com/article/10.1007/s00792-022-01262-303274nas a2200313 4500008004100000245011700041210006900158260001200227300001100239490000700250520227300257653001502530653002502545653001802570653002702588653002802615653002302643653001902666100002202685700002802707700002302735700002302758700002502781700002202806700002202828700001502850700002302865856007202888 2022 eng d00aLipid biomarkers from microbial mats on the McMurdo Ice Shelf, Antarctica: Signatures for life in the cryosphere0 aLipid biomarkers from microbial mats on the McMurdo Ice Shelf An c06/2022 a9036210 v133 a

Persistent cold temperatures, a paucity of nutrients, freeze-thaw cycles, and the strongly seasonal light regime make Antarctica one of Earth’s least hospitable surface environments for complex life. Cyanobacteria, however, are well-adapted to such conditions and are often the dominant primary producers in Antarctic inland water environments. In particular, the network of meltwater ponds on the ‘dirty ice’ of the McMurdo Ice Shelf is an ecosystem with extensive cyanobacteria-dominated microbial mat accumulations. This study investigated intact polar lipids (IPLs), heterocyte glycolipids (HGs), and bacteriohopanepolyols (BHPs) in combination with 16S and 18S rRNA gene diversity in microbial mats of twelve ponds in this unique polar ecosystem. To constrain the effects of nutrient availability, temperature and freeze-thaw cycles on the lipid membrane composition, lipids were compared to stromatolite-forming cyanobacterial mats from ice-covered lakes in the McMurdo Dry Valleys as well as from (sub)tropical regions and hot springs. The 16S rRNA gene compositions of the McMurdo Ice Shelf mats confirm the dominance of Cyanobacteria and Proteobacteria while the 18S rRNA gene composition indicates the presence of Ochrophyta, Chlorophyta, Ciliophora, and other microfauna. IPL analyses revealed a predominantly bacterial community in the meltwater ponds, with archaeal lipids being barely detectable. IPLs are dominated by glycolipids and phospholipids, followed by aminolipids. The high abundance of sugar-bound lipids accords with a predominance of cyanobacterial primary producers. The phosphate-limited samples from the (sub)tropical, hot spring, and Lake Vanda sites revealed a higher abundance of aminolipids compared to those of the nitrogen-limited meltwater ponds, affirming the direct affects that N and P availability have on IPL compositions. The high abundance of polyunsaturated IPLs in the Antarctic microbial mats suggests that these lipids provide an important mechanism to maintain membrane fluidity in cold environments. High abundances of HG keto-ols and HG keto-diols, produced by heterocytous cyanobacteria, further support these findings and reveal a unique distribution compared to those from warmer climates.

10aAntarctica10abacteriohopanepolyol10acyanobacteria10aheterocyte glycolipids10ahomeoviscous adaptation10aintact polar lipid10amicrobial mats1 aEvans, Thomas, W.1 aKalambokidis, Maria, J.1 aJungblut, Anne, D.1 aMillar, Jasmin, L.1 aBauersachs, Thorsten1 aGrotheer, Hendrik1 aMackey, Tyler, J.1 aHawes, Ian1 aSummons, Roger, E. uhttps://www.frontiersin.org/articles/10.3389/fmicb.2022.903621/full01993nas a2200253 4500008004100000022001400041245010200055210006900157260001200226300001100238490000700249520122000256653001501476653000901491653002401500653002201524653001701546653002301563100002501586700002401611700002101635700002101656856006201677 2022 eng d a0885-608700aLong-term stream hydrology and meteorology of a polar desert, the McMurdo Dry Valleys, Antarctica0 aLongterm stream hydrology and meteorology of a polar desert the  c06/2022 ae146230 v363 a

The McMurdo Dry Valleys (MDVs; 77.50°S, 162.25°E) make up the largest ice-free region of Antarctica at 3500 km2. Their position near the coast of the Ross Sea provides for a milder climate than much of the rest of the continent. Alpine and piedmont glaciers in the MDVs melt during the austral summer providing water to down gradient streams and terminal lakes on valley floors. There are currently 14 meteorological stations and 17 stream gauges operating across the MDVs, some with continuous records that go back to 1969. This relatively high density of monitoring stations reflects the fact that glaciers of different sizes and elevation ranges are the main source of water to streams. Thus, each glacier represents a different watershed. The bulk of these records start in the late 1980s/early 1990s. These data collection activities directly support research endeavors of the McMurdo Dry Valleys Long Term Ecological Research project, as well as a host of other science groups working in the MDVs. As such, both real time data and archived data from these sites is available through the online database interface of the project (https://mcmlter.org).

10aAntarctica10aLTER10aMcMurdo Dry Valleys10ameltwater streams10apolar desert10aresearch catchment1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aDoran, Peter, T.1 aFountain, Andrew uhttps://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.1462302431nas a2200277 4500008004100000022001300041245008500054210006900139260001200208300001100220490000800231520163400239653001501873653001301888653001401901653001901915653001901934653001901953100001401972700001201986700002501998700002102023700001702044700001602061856007602077 2022 eng d a0048969700aOrganic matter distribution in the icy environments of Taylor Valley, Antarctica0 aOrganic matter distribution in the icy environments of Taylor Va c10/2022 a1566390 v8413 a

Glaciers can accumulate and release organic matter affecting the structure and function of associated terrestrial and aquatic ecosystems. We analyzed 18 ice cores collected from six locations in Taylor Valley (McMurdo Dry Valleys), Antarctica to determine the spatial abundance and quality of organic matter, and the spatial distribution of bacterial density and community structure from the terminus of the Taylor Glacier to the coast (McMurdo Sound). Our results showed that dissolved and particulate organic carbon (DOC and POC) concentrations in the ice core samples increased from the Taylor Glacier to McMurdo Sound, a pattern also shown by bacterial cell density. Fluorescence Excitation Emission Matrices Spectroscopy (EEMs) and multivariate parallel factor (PARAFAC) modeling identified one humic-like (C1) and one protein-like (C2) component in ice cores whose fluorescent intensities all increased from the Polar Plateau to the coast. The fluorescence index showed that the bioavailability of dissolved organic matter (DOM) also decreased from the Polar Plateau to the coast. Partial least squares path modeling analysis revealed that bacterial abundance was the main positive biotic factor influencing both the quantity and quality of organic matter. Marine aerosol influenced the spatial distribution of DOC more than katabatic winds in the ice cores. Certain bacterial taxa showed significant correlations with DOC and POC concentrations. Collectively, our results show the tight connectivity among organic matter spatial distribution, bacterial abundance and meteorology in the McMurdo Dry Valley ecosystem.

10aAntarctica10abacteria10aice cores10akatabatic wind10amarine aerosol10aorganic matter1 aGuo, Bixi1 aLi, Wei1 aSantibáñez, Pamela1 aPriscu, John, C.1 aLiu, Yongqin1 aLiu, Keshao uhttps://www.sciencedirect.com/science/article/abs/pii/S004896972203736602675nas a2200241 4500008004100000245018700041210006900228260001200297300000900309490000700318520179100325653003202116653002602148653002302174653003502197653001902232653002802251100002602279700002002305700002002325700002402345856006402369 2022 eng d00aPatterns of interdisciplinary collaboration resemble biogeochemical relationships in the McMurdo Dry Valleys, Antarctica: A historical social network analysis of science, 1907–20160 aPatterns of interdisciplinary collaboration resemble biogeochemi c04/2022 a80370 v413 a

Co-authorship networks can provide key insights into the production of scientific knowledge. This is particularly interesting in Antarctica, where most human activity relates to scientific research. Bibliometric studies of Antarctic science have provided a useful understanding of international and interdisciplinary collaboration, yet most research has focused on broad-scale analyses over recent time periods. Here, we take advantage of a ‘Goldilocks’ opportunity in the McMurdo Dry Valleys, an internationally important region of Antarctica and the largest ice-free region on the continent. The McMurdo Dry Valleys have attracted continuous and diverse scientific activity since 1958. It is a geographically confined region with limited access, making it possible to evaluate the influence of specific events and individuals. We trace the history of environmental science in this region using bibliometrics and social network analysis. Our results show a marked shift in focus from the geosciences to the biosciences, which mirrors wider trends in the history of science. Collaboration among individuals and academic disciplines increased through time, and the most productive scientists in the network are also the most interdisciplinary. Patterns of collaboration among disciplines resemble the biogeochemical relationships among respective landscape features, raising interesting questions about the role of the material environment in the development of scientific networks in the region, and the dynamic interaction with socio-cultural and political factors. Our focused, historical approach adds nuance to broad-scale bibliometric studies and could be applied to understanding the dynamics of scientific research in other regions of Antarctica and elsewhere.

10acritical physical geography10aenvironmental history10ahistory of science10ascience and technology studies10ascientometrics10avisual network analysis1 aChignell, Stephen, M.1 aHowkins, Adrian1 aGullett, Poppie1 aFountain, Andrew, G uhttps://polarresearch.net/index.php/polar/article/view/803703572nas a2200301 4500008004100000245010000041210006900141260001200210300001100222490000800233520264300241653002302884653001002907653002002917653002202937653002602959653001902985653001603004100002603020700002103046700002303067700001403090700002603104700002303130700001603153700002903169856007203198 2022 eng d00aPhotosynthetic adaptation to polar life: Energy balance, photoprotection and genetic redundancy0 aPhotosynthetic adaptation to polar life Energy balance photoprot c01/2022 a1535570 v2683 a

The persistent low temperature that characterize polar habitats combined with the requirement for light for all photoautotrophs creates a conundrum. The absorption of too much light at low temperature can cause an energy imbalance that decreases photosynthetic performance that has a negative impact on growth and can affect long-term survival. The goal of this review is to survey the mechanism(s) by which polar photoautotrophs maintain cellular energy balance, that is, photostasis to overcome the potential for cellular energy imbalance in their low temperature environments. Photopsychrophiles are photosynthetic organisms that are obligately adapted to low temperature (0-15 °C) but usually die at higher temperatures (≥20 °C). In contrast, photopsychrotolerant species can usually tolerate and survive a broad range of temperatures (5-40 °C). First, we summarize the basic concepts of excess excitation energy, energy balance, photoprotection and photostasis and their importance to survival in polar habitats. Second, we compare the photoprotective mechanisms that underlie photostasis and survival in aquatic cyanobacteria and green algae as well as terrestrial Antarctic and Arctic plants. We show that polar photopsychrophilic and photopsychrotolerant organisms attain energy balance at low temperature either through a regulated reduction in the efficiency of light absorption or through enhanced capacity to consume photosynthetic electrons by the induction of O2 as an alternative electron acceptor. Finally, we compare the published genomes of three photopsychrophilic and one photopsychrotolerant alga with five mesophilic green algae including the model green alga, Chlamydomonas reinhardtii. We relate our genomic analyses to photoprotective mechanisms that contribute to the potential attainment of photostasis. Finally, we discuss how the observed genomic redundancy in photopsychrophilic genomes may confer energy balance, photoprotection and resilience to their harsh polar environment. Primary production in aquatic, Antarctic and Arctic environments is dependent on diverse algal and cyanobacterial communities. Although mosses and lichens dominate the Antarctic terrestrial landscape, only two extant angiosperms exist in the Antarctic. The identification of a single ‘molecular key’ to unravel adaptation of photopsychrophily and photopsychrotolerance remains elusive. Since these photoautotrophs represent excellent biomarkers to assess the impact of global warming on polar ecosystems, increased study of these polar photoautotrophs remains essential.

10agenomic redundancy10alight10aphotoprotection10aphotopsychrophily10aphotopsychrotolerance10aPhotosynthesis10atemperature1 aHüner, Norman, P. A.1 aSmith, David, R.1 aCvetkovska, Marina1 aZhang, Xi1 aIvanov, Alexander, G.1 aSzyszka-Mroz, Beth1 aKalra, Isha1 aMorgan-Kiss, Rachael, M. uhttps://www.sciencedirect.com/science/article/pii/S017616172100196602944nas a2200301 4500008004100000022001400041245009600055210007100151260001200222490000700234520204100241653001702282653001902299653002002318653001402338653002302352653002302375100002602398700001702424700002102441700002402462700002602486700001702512700001702529700001802546700002002564856005802584 2022 eng d a1354-101300aResponse of Antarctic soil fauna to climate‐driven changes since the Last Glacial Maximum0 aResponse of Antarctic soil fauna to climate‐driven changes since c01/20220 v283 a

Understanding how terrestrial biotic communities have responded to glacial recession since the Last Glacial Maximum (LGM) can inform present and future responses of biota to climate change. In Antarctica, the Transantarctic Mountains (TAM) have experienced massive environmental changes associated with glacial retreat since the LGM, yet we have few clues as to how its soil invertebrate-dominated animal communities have responded. Here, we surveyed soil invertebrate fauna from above and below proposed LGM elevations along transects located at 12 features across the Shackleton Glacier region. Our transects captured gradients of surface ages possibly up to 4.5 million years and the soils have been free from human disturbance for their entire history. Our data support the hypothesis that soils exposed during the LGM are now less suitable habitats for invertebrates than those that have been exposed by deglaciation following the LGM. Our results show that faunal abundance, community composition, and diversity were all strongly affected by climate-driven changes since the LGM. Soils more recently exposed by glacial recession (as indicated by distances from present ice surfaces) had higher faunal abundances and species richness than older exposed soils. Higher abundances of the dominant nematode Scottnema were found in older exposed soils, while Eudorylaimus, Plectus, tardigrades, and rotifers preferentially occurred in more recently exposed soils. Approximately 30% of the soils from which invertebrates could be extracted had only Scottnema, and these single-taxon communities occurred more frequently in soils exposed for longer periods of time. Our structural equation modeling of abiotic drivers highlighted soil salinity as a key mediator of Scottnema responses to soil exposure age. These changes in soil habitat suitability and biotic communities since the LGM indicate that Antarctic terrestrial biodiversity throughout the TAM will be highly altered by climate warming.

10abiodiversity10aclimate change10aglacial retreat10anematodes10aShackleton Glacier10asoil invertebrates1 aFranco, André, L. C.1 aAdams, Byron1 aDiaz, Melisa, A.1 aLemoine, Nathan, P.1 aDragone, Nicholas, B.1 aFierer, Noah1 aLyons, Berry1 aHogg, Ian, D.1 aWall, Diana, H. uhttps://onlinelibrary.wiley.com/doi/10.1111/gcb.1594002569nas a2200373 4500008004100000245008100041210006900122260004300191520135400234100001701588700001801605700002201623700002101645700002001666700003001686700002101716700002401737700002301761700001801784700002101802700002301823700002201846700002001868700002301888700002401911700001601935700002301951700002401974700002101998700001902019700001802038700002002056856011902076 2022 eng d00aTen scientific messages on risks and opportunities for life in the Antarctic0 aTen scientific messages on risks and opportunities for life in t bAntarctic Environments Portalc02/20223 a

Initiated by the SCAR scientific research programme “Antarctic Thresholds – Ecosystem Resilience and Adaptation” (AnT-ERA, 2013-2021), 26 experts synthesized knowledge on impacts and risks of climate-change on biological processes and ecosystem functions in the Antarctic. The ten main scientific messages that emerged addressed (1) accelerating marine and terrestrial biogeochemical cycles, (2) response to ocean acidification, (3) ecological changes in climate change hot spots, (4) unexpected dynamism of marine seafloor communities, (5) biodiversity shifts, (6) low temperature limitation of protein synthesis, (7) life intrinsically linked to changing sea ice conditions, (8) pollution, (9) genetically distinct terrestrial populations under threat, and (10) newly discovered habitats. Two-thirds of the literature included in this synthesis was published between 2010 and 2020 and only one-third was published earlier. The fast mounting, recent decadal evidence indicates various Antarctic biological communities now experience climate stress, or will experience such stress in the coming decades. The responses of organisms, ecosystem functions and services to environmental changes are complex and varied. Key knowledge gaps remain and need addressing to adequately assess future prospects for life in the Antarctic.

1 aGutt, Julian1 aIsla, Enrique1 aXavier, José, C.1 aAdams, Byron, J.1 aAhn, In‐Young1 aCheng, C.‐H., Christina1 aColesie, Claudia1 aCummings, Vonda, J.1 aGriffiths, Huw, J.1 aHogg, Ian, D.1 aMcIntyre, Trevor1 aMeiners, Klaus, M.1 aPearce, David, A.1 aPeck, Lloyd, S.1 aPiepenburg, Dieter1 aReisinger, Ryan, R.1 aSaba, Grace1 aSchloss, Irene, R.1 aSignori, Camila, N.1 aSmith, Craig, R.1 aVacchi, Marino1 aVerde, Cinzia1 aWall, Diana, H. uhttps://environments.aq/publications/ten-scientific-messages-on-risks-and-opportunities-for-life-in-the-antarctic/02575nas a2200397 4500008004100000022001400041245006100055210005700116260001200173490000800185520139000193100002701583700002801610700001701638700002401655700003001679700001901709700002201728700002101750700002301771700002201794700002501816700002001841700002201861700002101883700002201904700003101926700002201957700002301979700002202002700002402024700002102048700002202069700003302091856005302124 2022 eng d a0027-842400aThe time is right for an Antarctic biorepository network0 atime is right for an Antarctic biorepository network c12/20220 v1193 a

Antarctica is a central driver of the Earth’s climate and health. The Southern Ocean surrounding Antarctica serves as a major sink for anthropogenic CO2 and heat, and the loss of Antarctic ice sheets contributes significantly to sea level rise and will continue to do so as the loss of ice sheets accelerates, with sufficient water stores to raise sea levels by 58 m. Antarctica's marine environment is home to a number of iconic species, and the terrestrial realm harbors a remarkable oasis for life, much of which has yet to be discovered. Distinctive oceanographic features of the Southern Ocean—including the Antarctic Circumpolar Current, the Antarctic Polar Front, and exceptional depths surrounding the continent—coupled with chronically cold temperatures have fostered the evolution of a vast number of uniquely coldadapted species, many of which are found nowhere else on the Earth. The Antarctic marine biota, for example, displays the highest level of species endemism on the Earth. However, warming, ocean acidification, pollution, and commercial exploitation threaten the integrity of Antarctic ecosystems. Understanding changes in the biota and its capacities for adaptation is imperative for establishing effective policies for mitigating the impacts of climate change and sustaining the Antarctic ecosystems that are vital to global health.

1 aO’Brien, Kristin, M.1 aCrockett, Elizabeth, L.1 aAdams, Byron1 aAmsler, Charles, D.1 aAppiah-Madson, Hannah, J.1 aCollins, Allen1 aDesvignes, Thomas1 aDetrich, William1 aDistel, Daniel, L.1 aEppley, Sarah, M.1 aFrable, Benjamin, W.1 aFranz, Nico, M.1 aGrim, Jeffrey, M.1 aKocot, Kevin, M.1 aMahon, Andrew, R.1 aMayfield-Meyer, Teresa, J.1 aMikucki, Jill, A.1 aMoser, William, E.1 aSchmull, Michaela1 aSeid, Charlotte, A.1 aSmith, Craig, R.1 aTodgham, Anne, E.1 aWatkins-Colwell, Gregory, J. uhttps://www.pnas.org/doi/10.1073/pnas.221280011902175nas a2200229 4500008004100000022001400041245022200055210006900277260001200346300001400358490000700372520135100379653001501730653001601745653001901761653001601780653001201796100002101808700002101829700002401850856007101874 2022 eng d a1523-043000aTiming and duration of ephemeral Antarctic water tracks and wetlands using high temporal–resolution satellite imagery, high spatial–resolution satellite imagery, and ground-based sensors in the McMurdo Dry Valleys0 aTiming and duration of ephemeral Antarctic water tracks and wetl c12/2022 a538 - 5610 v543 a

Antarctic water tracks and ephemeral wetlands are a primary location for biogeochemical soil processes driving cold desert soil formation. Though the spatial extent of water tracks and wetted soils has been mapped in the McMurdo Dry Valleys (MDV) on the basis of mapping darkened pixels in high-resolution commercial satellite imagery, the timescale over which water tracks and wetlands form and the duration of these biogeochemically active environments remain unknown. Here, we determine the start date and end dates and the duration of wetted soils at ten sites located across the MDV using a combination of in situ soil sensors and two complementary remote imaging platforms (Planet and WorldView) to understand the hydroclimatic processes that drive water track and wetland formation. Our remote sensing employs a terrain correction workflow that removes the contribution of differential direct illumination and small-scale shadowing on pixel brightness, reducing false positives (soils identified as wetted when in fact they are shadowed or darkened as a consequence of high phase angle). Our findings extend the water track and wetland hydroperiod by over a month, showing darkening occurring from November to March, suggesting hydrological contributions from ground ice thaw, snowmelt, and salt deliquescence and soil brine growth.

10aAntarctica10ahydroperiod10aremote sensing10awater track10awetland1 aKuentz, Lily, C.1 aLevy, Joseph, S.1 aSalvatore, Mark, R. uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2022.212385801961nas a2200217 4500008004100000245010100041210006900142260001200211300001200223490000700235520124400242653003001486653001101516653002401527653001501551653002101566100002001587700002101607700002201628856009301650 2022 eng d00aValley-floor snowfall in Taylor Valley, Antarctica, from 1995 to 2017: Spring, summer and autumn0 aValleyfloor snowfall in Taylor Valley Antarctica from 1995 to 20 c08/2022 a325-3350 v343 a

We present an analysis of the 20 year snowfall dataset in Taylor Valley and the results of a new snow cover monitoring study. Snowfall has been measured at four sites in Taylor Valley from 1995 to 2017. We focus on valley-floor snowfall when wind does not exceed 5 m s-1, and we exclude winter from our analysis due to poor data quality. Snowfall averaged 11 mm water equivalent (w.e.) from 1995 to 2017 across all stations and ranged from 1 to 58 mm w.e. Standard deviations ranged from 3 to 17 mm w.e., highlighting the strong interannual variability of snowfall in Taylor Valley. During spring and autumn there is a spatial gradient in snowfall such that the coast received twice as much snowfall as more central and inland stations. We identified a changepoint in 2007 from increasing snowfall (3 mm w.e. yr-1) to decreasing snowfall (1 mm w.e. yr-1), which coincides with a shift from decreasing temperature to no detectable temperature trend. Daily camera imagery from 2007 to 2017 augments the snowfall measurements. The camera imagery revealed a near tripling of the average number of days with snow cover from 37 days between 2006 and 2012 to 106 days with snow cover between 2012 and 2017.

10aautomated weather station10acamera10aMcMurdo Dry Valleys10asnow cover10asnow persistence1 aMyers, Madeline1 aDoran, Peter, T.1 aMyers, Krista, F. uhttps://www.cambridge.org/core/product/identifier/S0954102022000256/type/journal_article02273nas a2200205 4500008004100000022001400041245012200055210006900177260001200246490000800258520159800266653001401864653001901878653002201897653001901919100002001938700002701958700002101985856006102006 2022 eng d a2169-900300aWintertime brine discharge at the surface of a cold polar glacier and the unexpected absence of associated seismicity0 aWintertime brine discharge at the surface of a cold polar glacie c03/20220 v1273 a

A subglacial groundwater system beneath Taylor Glacier, Antarctica, discharges hypersaline, iron-rich brine episodically at the glacier surface to create Blood Falls. However, the triggering mechanism for these brine release events is not yet understood. Identifying which fracture processes are observed seismically can help us better characterize the hydrological system at Taylor Glacier, and more generally, provide us with a broader understanding of englacial hydrologic activity in cold glaciers. We document wintertime brine discharge using time-lapse photography. Subfreezing air temperatures during the brine discharge indicate that surface melt-induced hydrofracture is an unlikely trigger for brine release. Further, we analyze local seismic data to test a hypothesis that fracturing generates elevated surface wave energy preceding and/or coinciding with brine release events. Our results show no discernible elevated Rayleigh wave activity prior to or during Blood Falls brine release. Instead, we find a pattern of seismic events dominated by a seasonal signal, with more Rayleigh events occurring in the summer than the winter from the Blood Falls source area. We calculate that the volumetric opening of cracks that would generate Rayleigh waves at our detection limits are of similar size to myriad cracks in glacier ice, lake ice, and frozen sediment in the terminus area. We therefore propose that any fracturing coincident with brine release activity likely consists of a series of smaller opening events that are masked by other seismicity in the local environment.

10acrevasses10acryoseismology10aglacier hydrology10aRayleigh waves1 aCarr, Chris, G.1 aCarmichael, Joshua, D.1 aPettit, Erin, C. uhttps://onlinelibrary.wiley.com/doi/10.1029/2021JF00632503115nas a2200517 4500008004100000245008300041210006900124260001200193520161800205653001501823653002101838653002601859653001901885653001301904653001701917653002401934653002301958653001701981653001201998100001702010700001802027700002202045700002102067700002002088700003002108700002102138700002402159700002102183700002302204700001502227700001802242700002102260700002302281700002202304700002002326700002302346700002402369700001602393700002302409700002402432700002102456700001902477700001802496700002002514856006302534 2021 eng d00aAntarctic ecosystems in transition – life between stresses and opportunities0 aAntarctic ecosystems in transition life between stresses and opp c06/20213 a

Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder‐relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) ocean acidification, (iii) climate change hotspots, (iv) unexpected dynamism in seabed‐dwelling populations, (v) spatial range shifts, (vi) adaptation and thermal resilience, (vii) sea ice related biological fluctuations, (viii) pollution, (ix) endangered terrestrial endemism and (x) the discovery of unknown habitats. Most Antarctic biotas are exposed to multiple stresses and considered vulnerable to environmental change due to narrow tolerance ranges, rapid change, projected circumpolar impacts, low potential for timely genetic adaptation, and migration barriers. Important ecosystem functions, such as primary production and energy transfer between trophic levels, have already changed, and biodiversity patterns have shifted. A confidence assessment of the degree of ‘scientific understanding’ revealed an intermediate level for most of the more detailed sub‐messages, indicating that process‐oriented research has been successful in the past decade. Additional efforts are necessary, however, to achieve the level of robustness in scientific knowledge that is required to inform protection measures of the unique Antarctic terrestrial and marine ecosystems, and their contributions to global biodiversity and ecosystem services.

10aadaptation10abenthic dynamism10abiogeochemical cycles10aclimate change10ainvasion10anew habitats10aocean acidification10aPrimary production10arange shifts10asea ice1 aGutt, Julian1 aIsla, Enrique1 aXavier, José, C.1 aAdams, Byron, J.1 aAhn, In‐Young1 aCheng, C.‐H., Christina1 aColesie, Claudia1 aCummings, Vonda, J.1 adi Prisco, Guido1 aGriffiths, Huw, J.1 aHawes, Ian1 aHogg, Ian, D.1 aMcIntyre, Trevor1 aMeiners, Klaus, M.1 aPearce, David, A.1 aPeck, Lloyd, S.1 aPiepenburg, Dieter1 aReisinger, Ryan, R.1 aSaba, Grace1 aSchloss, Irene, R.1 aSignori, Camila, N.1 aSmith, Craig, R.1 aVacchi, Marino1 aVerde, Cinzia1 aWall, Diana, H. uhttps://onlinelibrary.wiley.com/doi/full/10.1111/brv.1267902600nas a2200217 4500008004100000245010600041210006900147260001200216490000700228520191500235653001502150653001802165653001602183653002202199653001702221100002202238700001702260700002102277700001702298856006702315 2021 eng d00aAntarctic water tracks: Microbial community responses to variation in soil moisture, pH, and salinity0 aAntarctic water tracks Microbial community responses to variatio c01/20210 v123 a

Ice-free soils in the McMurdo Dry Valleys select for taxa able to cope with challenging environmental conditions, including extreme chemical water activity gradients, freeze-thaw cycling, desiccation, and solar radiation regimes. The low biotic complexity of Dry Valley soils makes them well suited to investigate environmental and spatial influences on bacterial community structure. Water tracks are annually wetted habitats in the cold-arid soils of Antarctica that form briefly each summer with moisture sourced from snow melt, ground ice thaw, and atmospheric deposition via deliquescence and vapor flow into brines. Compared to neighboring arid soils, water tracks are highly saline and relatively moist habitats. They represent a considerable area (∼5–10 km2) of the Dry Valley terrestrial ecosystem, an area that is expected to increase with ongoing climate change. The goal of this study was to determine how variation in the environmental conditions of water tracks influences the composition and diversity of microbial communities. We found significant differences in microbial community composition between on- and off-water track samples, and across two distinct locations. Of the tested environmental variables, soil salinity was the best predictor of community composition, with members of the Bacteroidetes phylum being relatively more abundant at higher salinities and the Actinobacteria phylum showing the opposite pattern. There was also a significant, inverse relationship between salinity and bacterial diversity. Our results suggest water track formation significantly alters dry soil microbial communities, likely influencing subsequent ecosystem functioning. We highlight how Dry Valley water tracks could be a useful model system for understanding the potential habitability of transiently wetted environments found on the surface of Mars.

10aAntarctica10aextremophiles10aMars analog10amicrobial ecology10awater tracks1 aGeorge, Scott, F.1 aFierer, Noah1 aLevy, Joseph, S.1 aAdams, Byron uhttps://www.frontiersin.org/articles/10.3389/fmicb.2021.61673000482nas a2200133 4500008004100000022001400041245011100055210006900166260001200235300001400247490000700261100001500268856006500283 2021 eng d a0006-356800aAntarctica during the Pandemic: Scaled-back field season prioritizes infrastructure, precious climate data0 aAntarctica during the Pandemic Scaledback field season prioritiz c05/2021 a434 - 4400 v711 aMayer, Amy uhttps://academic.oup.com/bioscience/article/71/5/434/618880002179nas a2200121 4500008004100000245012700041210006900168260005300237490000900290520167300299100002701972856005801999 2021 eng d00aCauses and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica0 aCauses and characteristics of electrical resistivity variability aBaton RougebLouisiana State Universityc07/20210 vM.S.3 a

The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are characterized as a polar desert environment. Soils in the region are typically very dry (<1% soil water by weight) and remain frozen for most of the year. Increases in air temperature and incoming solar radiation during the austral summer generate meltwater from glaciers, ground ice, and snow patches supplying moisture to soils and altering the physical and chemical makeup of the subsurface. Previous studies have utilized airborne electromagnetic surveys (AEM) to analyze groundwater systems in the deep subsurface but have not yet examined soil moisture in the shallow (<4 m) subsurface. Here, I used electrical resistivity data from two AEM surveys (2011 and 2018) and soil geochemical data from three transects to characterize the spatial heterogeneity of soil properties in the near-subsurface of lower Taylor Valley. Soil resistivities from 2011 and 2018 range from 33.2 Ωm to 3535 Ωm with low elevations of <100 meters above sea level (masl) typically displaying the lowest resistivities and high elevations displaying greater resistivities. Liquid brine fractions were empirically estimated from electrical resistivity values using Archie’s Law and range from 0.3% to 68.2% for soils with resistivities <200 Ωm. Additionally, soil transect data show greater percentages of fine-grained sediments (<63 µm) exist at elevations <100 masl where soil resistivities begin decreasing. Resistivity variability in the subsurface is ultimately controlled by the site history, local and regional climate, soil salinity, soil moisture, soil lithology.

1 aGutterman, William, S. uhttps://digitalcommons.lsu.edu/gradschool_theses/541102885nas a2200241 4500008004100000245006300041210006200104260004100166300001200207520209300219653003102312653003602343653002402379653001902403653002402422100001602446700001702462700002302479700001702502700002402519700002502543856007502568 2021 eng d00aChemical weathering in the McMurdo Dry Valleys, Antarctica0 aChemical weathering in the McMurdo Dry Valleys Antarctica aHoboken, NJbJohn Wiley & Sons, Inc. a205-2163 a

While chemical weathering has not always been considered an active process in the McMurdo Dry Valleys (MDV), Antarctica, long‐term geochemical and hydrological investigations have provided an overall better understanding of chemical weathering in this polar desert environment. Liquid water on the landscape is limited to stream channels as well as shallow subsurface melt features, as there is no overland flow. Stream total suspended sediment loads are low, with the sources of sediment from stream channels, aeolian input, and/or from the surfaces of glaciers. MDV soils contain high concentrations of soluble salts with little clay material, but since absent of water, these soils are a minimal location of chemical weathering. Hyporheic zones exchange water during streamflow, and these areas control the stream geochemistry over various temporal scales. Hyporheic zones promote rapid aluminosilicate weathering by moving dilute glacial meltwater into intimate contact with sediment surfaces. Rapid weathering of the aluminosilicates in the streambed and hyporheic zones is the most plausible explanation for chemostasis observed in these streams, indicating that little to no catchment processes are necessary to explain the observed chemostasis in the MDV. Shallow subsurface waters with distinct geochemical signatures have much higher dissolved Si concentrations than the stream waters and indicate that they are responsible for enhanced aluminosilicate weathering in this polar desert environment. The dissolution of CaCO3 is also a major process in the hyporheic zones as generally the streams are unsaturated with respect to calcite. Cation‐exchange reactions are also important in the evolution from Na‐Cl brines to Ca‐Cl brines within the soil column, while authigenic CaCO3 can both dissolve and precipitate depending on the condition of the system. Recently, stream channel landscapes are changing due to the melting of buried ice, creating thermokarst and water track features, resulting in a sediment and solute influx to the stream.

10aaluminosilicate weathering10aCaCO3 dissolution/precipitation10achemical weathering10ahyporheic zone10aMcMurdo Dry Valleys1 aHunt, Allen1 aEgli, Markus1 aFaybishenko, Boris1 aLyons, Berry1 aLeslie, Deborah, L.1 aGooseff, Michael, N. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119563952.ch1104166nas a2200565 4500008004100000022001400041245007900055210006900134260001200203300001100215490000700226520245300233653001802686653002702704653001902731653001902750653001202769653001202781653001502793653008902808653002002897100002302917700002502940700002602965700002702991700002103018700002503039700001703064700002203081700002903103700002603132700002403158700002603182700002403208700002103232700001603253700002703269700002403296700002303320700002203343700002403365700002303389700001503412700002203427700002103449700002203470700002603492700002403518856005803542 2021 eng d a2150-892500aConnectivity: Insights from the U.S. Long Term Ecological Research Network0 aConnectivity Insights from the US Long Term Ecological Research  c05/2021 ae034320 v123 a

Ecosystems across the United States are changing in complex and surprising ways. Ongoing demand for critical ecosystem services requires an understanding of the populations and communities in these ecosystems in the future. This paper represents a synthesis effort of the U.S. National Science Foundation-funded Long-Term Ecological Research (LTER) network addressing the core research area of “populations and communities.” The objective of this effort was to show the importance of long-term data collection and experiments for addressing the hardest questions in scientific ecology that have significant implications for environmental policy and management. Each LTER site developed at least one compelling case study about what their site could look like in 50–100 yr as human and environmental drivers influencing specific ecosystems change. As the case studies were prepared, five themes emerged, and the studies were grouped into papers in this LTER Futures Special Feature addressing state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the “connectivity” theme and has examples from the Phoenix (urban), Niwot Ridge (alpine tundra), McMurdo Dry Valleys (polar desert), Plum Island (coastal), Santa Barbara Coastal (coastal), and Jornada (arid grassland and shrubland) sites. Connectivity has multiple dimensions, ranging from multi-scalar interactions in space to complex interactions over time that govern the transport of materials and the distribution and movement of organisms. The case studies presented here range widely, showing how land-use legacies interact with climate to alter the structure and function of arid ecosystems and flows of resources and organisms in Antarctic polar desert, alpine, urban, and coastal marine ecosystems. Long-term ecological research demonstrates that connectivity can, in some circumstances, sustain valuable ecosystem functions, such as the persistence of foundation species and their associated biodiversity or, it can be an agent of state change, as when it increases wind and water erosion. Increased connectivity due to warming can also lead to species range expansions or contractions and the introduction of undesirable species. Continued long-term studies are essential for addressing the complexities of connectivity. The diversity of ecosystems within the LTER network is a strong platform for these studies.

10aalpine tundra10aAntarctic polar desert10aarid grassland10aarid shrubland10acoastal10aestuary10asalt marsh10aSpecial Feature: Forecasting Earth’s Ecosystems with Long-Term Ecological Research10aurban ecosystem1 aIwaniec, David, M.1 aGooseff, Michael, N.1 aSuding, Katharine, N.1 aJohnson, David, Samuel1 aReed, Daniel, C.1 aPeters, Debra, P. C.1 aAdams, Byron1 aBarrett, John, E.1 aBestelmeyer, Brandon, T.1 aCastorani, Max, C. N.1 aCook, Elizabeth, M.1 aDavidson, Melissa, J.1 aGroffman, Peter, M.1 aHanan, Niall, P.1 aHuenneke, L1 aJohnson, Pieter, T. J.1 aMcKnight, Diane, M.1 aMiller, Robert, J.1 aOkin, Gregory, S.1 aPreston, Daniel, L.1 aRassweiler, Andrew1 aRay, Chris1 aSala, Osvaldo, E.1 aSchooley, Robert1 aSeastedt, Timothy1 aSpasojevic, Marko, J.1 aVivoni, Enrique, R. uhttps://onlinelibrary.wiley.com/doi/10.1002/ecs2.343201995nas a2200205 4500008004100000245012000041210006900161260004800230490000900278520132200287653001501609653001101624653001801635653001201653653001501665653001301680100002401693700002401717856004801741 2021 eng d00aControls on microbial mat coverage and diatom species turnover in Antarctic desert streams: A transplant experiment0 aControls on microbial mat coverage and diatom species turnover i aBoulder, CObUniversity of Colorado Boulder0 vM.S.3 a

This thesis evaluates how polar desert streams regulate benthic microbial mat coverage, chlorophyll-a biomass, and diatom species composition. Microbial mats growing on rocks (eplithon) and on sandy substrate (epipelon) were reciprocally transplanted among four glaciers meltwater streams and monitored through time. The selected study streams were Green Creek, Bowles Creek, Delta Stream, Von Guerard Stream in the Lake Fryxell Basin in the McMurdo Dry Valleys, Antarctica. These streams vary in length, streamflow intermittency, and diatom community composition of microbial mats. Results demonstrate that streams strongly control mat biomass (coverage and chlorophyll-a) differently for epilithon and epipelon. However, diatom species composition did not vary between these growth habitats but instead varied by stream, suggesting adaptive niche separation related to environmental conditions. Diatom species composition of transplants in Green Creek became dissimilar from their initial stream communities suggesting downstream dispersal and within stream connectivity regulates community assembly. This experiment confirms that environmental characteristics and intra-stream dispersal processes exert strong control over maintaining microbial mat coverage, biomass accrual, and diatom species composition.

10aAntarctica10adiatom10amicrobial mat10astreams10atransplant10aturnover1 aDarling, Joshua, P.1 aMcKnight, Diane, M. uhttps://www.proquest.com/docview/263459098202111nas a2200205 4500008004100000245010700041210006900148260001200217300001600229490000700245520142400252100002401676700002201700700002501722700002101747700002101768700002001789700002501809856007101834 2021 eng d00aCounting carbon: Quantifying biomass in the McMurdo Dry Valleys through orbital and field observations0 aCounting carbon Quantifying biomass in the McMurdo Dry Valleys t c10/2021 a8597 - 86230 v423 a

We use correlative field studies and high-resolution multispectral remote sensing data from the WorldView-2 instrument to estimate the abundance of photosynthetically active biomass (photoautotrophs consisting primarily of microbial mats and mosses) in Canada Stream in Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica. In situ field investigations were performed to (1) acquire ground validation targets for atmospherically correcting satellite imagery, (2) derive spectra of “pure” geologic and biological endmembers, (3) estimate photoautotroph cover from remote sensing data, and (4) convert these coverage estimates to biomass using data collected in the field. Our results suggest that, on the morning of 12 December 2018, the Canada Stream system contained more than 3,800 kg of photosynthetically active carbon. Extrapolating our unmixing results to the entirety of the Fryxell basin of Taylor Valley, Antarctica, we model the presence of more than 750,000 kg of photosynthetically active carbon across the landscape and carbon fixation rates roughly equivalent to five hectares of tropical rainforest. The ability to spatially and temporally quantify the amount of photosynthetically active biomass using remote sensing data in the MDV of Antarctica is a revolutionary development that will help elucidate the ecological drivers and environmental responses in this cold desert landscape.

1 aSalvatore, Mark, R.1 aBarrett, John, E.1 aBorges, Schuyler, R.1 aPower, Sarah, N.1 aStanish, Lee, F.1 aSokol, Eric, R.1 aGooseff, Michael, N. uhttps://www.tandfonline.com/doi/full/10.1080/01431161.2021.198155902080nas a2200361 4500008004100000245006800041210006800109260001200177300000900189490000700198520108000205653001501285653001701300653001201317653001301329653001501342653000901357100001901366700002401385700001801409700002101427700002501448700002501473700002201498700002001520700001901540700001701559700002601576700001601602700001801618710002301636856005901659 2021 eng d00aDiatoms define a novel freshwater biogeography of the Antarctic0 aDiatoms define a novel freshwater biogeography of the Antarctic c01/2021 a1-130 v443 a

Terrestrial biota in the Antarctic are more globally distinct and highly structured biogeographically than previously believed, but information on biogeographic patterns and endemism in freshwater communities is largely lacking. We studied biogeographic patterns of Antarctic freshwater diatoms based on the analysis of species occurrences in a dataset of 439 lakes spread across the Antarctic realm. Highly distinct diatom floras, both in terms of composition and richness, characterize Continental Antarctica, Maritime Antarctica and the sub-Antarctic islands, with marked biogeographic provincialism in each region. A total of 44% of all species is estimated to be endemic to the Antarctic, and most of them are confined to a single biogeographic region. The level of endemism significantly increases with increasing latitude and geographic isolation. Our results have implications for conservation planning, and suggest that successful dispersal of freshwater diatoms to and within the Antarctic is limited, fostering the evolution of highly endemic diatom floras.

10aAntarctica10abiogeography10adiatoms10aendemism10afreshwater10alake1 aVerleyen, Elie1 aVan de Vijver, Bart1 aTytgat, Bjorn1 aPinseel, Eveline1 aHodgson, Dominic, A.1 aKopalová, Kateřina1 aChown, Steven, L.1 aVan Ranst, Eric1 aImura, Satoshi1 aKudoh, Sakae1 aVan Nieuwenhuyze, Wim1 aSabbe, Koen1 aVyverman, Wim1 aANTDIAT consortium uhttps://onlinelibrary.wiley.com/doi/10.1111/ecog.0537402809nas a2200337 4500008004100000245012000041210006900161260001200230300001800242490000800260520168500268653002201953653002001975653004901995653001902044653001202063653004302075653001902118653002402137653002102161653003102182100002102213700002402234700002202258700002402280700002402304700002502328700002402353700002502377856006902402 2021 eng d00aDiatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica0 aDiatoms in hyporheic sediments trace organic matter retention an c02/2021 ae2020JG0060970 v1263 a

In low‐nutrient streams in cold and arid ecosystems, the spiraling of autochthonous particulate organic matter (POM) may provide important nutrient subsidies downstream. Because of its lability and the spatial heterogeneity of processing in hyporheic sediments, the downstream transport and fate of autochthonous POM can be difficult to trace. In Antarctic McMurdo Dry Valley (MDV) streams, any POM retained in the hyporheic zone is expected to be derived from surface microbial mats that contain diatoms with long‐lasting silica frustules. We tested whether diatom frustules can be used to trace the retention of autochthonous POM in the hyporheic zone and whether certain geomorphic locations promote this process. The accumulation of diatom frustules in hyporheic sediments, measured as biogenic silica, was correlated with loss‐on‐ignition organic matter and sorbed ammonium, suggesting that diatoms can be used to identify locations where POM has been retained and processed over long timescales, regardless of whether the POM remains intact. In addition, by modeling the upstream sources of hyporheic diatom assemblages, we found that POM was predominantly derived from N‐fixing microbial mats of the genus Nostoc. In terms of spatial variability, we conclude that the hyporheic sediments adjacent to the stream channel that are regularly inundated by daily flood pulses are where the most POM has been retained over long timescales. Autochthonous POM is retained in hyporheic zones of low‐nutrient streams beyond the MDVs, and we suggest that biogenic silica and diatom composition can be used to identify locations where this transfer is most prevalent.

10abenthic processes10abiogenic silica10abiogeochemical cycles processes and modeling10acarbon cycling10adiatoms10agroundwater/surface water interactions10ahyporheic zone10aMcMurdo Dry Valleys10anitrogen cycling10aparticulate organic matter1 aHeindel, Ruth, C1 aDarling, Joshua, P.1 aSingley, Joel, G.1 aBergstrom, Anna, J.1 aMcKnight, Diane, M.1 aLukkari, Braeden, M.1 aWelch, Kathleen, A.1 aGooseff, Michael, N. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG00609701659nas a2200193 4500008004100000022001300041245008600054210006900140260001200209300001100221490000700232520104000239100001401279700002301293700002901316700002601345700002201371856007201393 2021 eng d a2589004200aDraft genome sequence of the Antarctic green alga Chlamydomonas sp. UWO2410 aDraft genome sequence of the Antarctic green alga IChlamydomonas c2021-02 a1020840 v243 a

Antarctica is home to an assortment of psychrophilic algae, which have evolved various survival strategies for coping with their frigid environments. Here, we explore Antarctic psychrophily by examining the ∼212 Mb draft nuclear genome of the green alga Chlamydomonas sp. UWO241, which resides within the water column of a perennially ice-covered, hypersaline lake. Like certain other Antarctic algae, UWO241 encodes a large number (≥37) of ice-binding proteins, putatively originating from horizontal gene transfer. Even more striking, UWO241 harbors hundreds of highly similar duplicated genes involved in diverse cellular processes, some of which we argue are aiding its survival in the Antarctic via gene dosage. Gene and partial gene duplication appear to be an ongoing phenomenon within UWO241, one which might be mediated by retrotransposons. Ultimately, we consider how such a process could be associated with adaptation to extreme environments but explore potential non-adaptive hypotheses as well.

1 aZhang, Xi1 aCvetkovska, Marina1 aMorgan-Kiss, Rachael, M.1 aHüner, Norman, P. A.1 aSmith, David, Roy uhttps://www.sciencedirect.com/science/article/pii/S258900422100052302093nas a2200205 4500008004100000022001400041245013400055210006900189260001200258300000900270520139200279653001801671653001401689653001701703653002101720653001301741653001901754100002101773856009301794 2021 eng d a0954-102000aEpisodic basin-scale soil moisture anomalies associated with high relative humidity events in the McMurdo Dry Valleys, Antarctica0 aEpisodic basinscale soil moisture anomalies associated with high c08/2021 a1-153 a

Outside of hydrologically wetted active layer soils and humidity-sensitive soil brines, low soil moisture is a limiting factor controlling biogeochemical processes in the McMurdo Dry Valleys. But anecdotal field observations suggest that episodic wetting and darkening of surface soils in the absence of snowmelt occurs during high humidity conditions. Here, I analyse long-term meteorological station data to determine whether soil-darkening episodes are present in the instrumental record and whether they are, in fact, correlated with relative humidity. A strong linear correlation is found between relative humidity and soil reflectance at the Lake Bonney long-term autonomous weather station. Soil reflectance is found to decrease annually by a median of 27.7% in response to high humidity conditions. This magnitude of darkening is consistent with soil moisture rising from typical background values of < 0.5 wt.% to 2–3 wt.%, suggesting that regional atmospheric processes may result in widespread soil moisture generation in otherwise dry surface soils. Temperature and relative humidity conditions under which darkening is observed occur for hundreds of hours per year, but are dominated by episodes occurring between midnight and 07h00 local time, suggesting that wetting events may be common, but are not widely observed during typical diel science operations.

10adeliquescence10ahydrology10amicroclimate10amicrometeorology10apedology10aremote sensing1 aLevy, Joseph, S. uhttps://www.cambridge.org/core/product/identifier/S0954102021000341/type/journal_article02506nas a2200289 4500008004100000022001400041245006300055210006300118260001200181490000800193520169900201653001501900653001701915653001301932653001801945653001001963653001001973100002601983700002102009700001802030700001702048700002002065700002002085700002102105700001702126856007302143 2021 eng d a2169-895300aExploring the boundaries of microbial habitability in soil0 aExploring the boundaries of microbial habitability in soil c06/20210 v1263 a

Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84–85°S, 174–177°W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils—results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results suggest that microbial life is severely restricted in the coldest, driest, and saltiest Antarctic soils. Constant exposure to these conditions for thousands of years has limited microbial communities so that their presence and activity is below detectable limits using a variety of standard methods. Such soils are unlikely to be unique to the studied region with this work supporting previous hypotheses that microbial habitability is constrained by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that limit microbial life in terrestrial surface soils.

10aAntarctica10aastrobiology10abacteria10aextremophiles10afungi10asoils1 aDragone, Nicholas, B.1 aDiaz, Melisa, A.1 aHogg, Ian, D.1 aLyons, Berry1 aJackson, Andrew1 aWall, Diana, H.1 aAdams, Byron, J.1 aFierer, Noah uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00605201860nas a2200205 4500008004100000022001400041245015300055210006900208260001200277520112000289100002201409700002001431700002001451700002501471700001701496700002401513700002501537700002401562856006801586 2021 eng d a2378-224200aFrom the Heroic Age to today: What diatoms from Shackleton's Nimrod expedition can tell us about the ecological trajectory of Antarctic ponds0 aFrom the Heroic Age to today What diatoms from Shackletons iNimr c07/20213 a

Biological invasion and environmental change pose major threats to ecosystems. While long-term ecological change is commonly evaluated through sediment cores in lakes, it is generally not feasible for smaller ponds, and spatial resolution is limited. Here, we analyze pond diatom communities collected during Shackleton's Nimrod expedition at Cape Royds, Antarctica, to compare with the same waterbodies a century later. We find historical samples to be almost identical to modern counterparts, and provide no evidence of exotic introductions despite increasing human activity. However, a shift occurred in the pond nearest Shackleton's hut, Pony Lake, which was dominated by Luticola muticopsis a century ago, and was replaced by Craspedostauros laevissimus. Both are endemic species previously and currently present at Cape Royds, and we hypothesize that a shift in conductivity accompanying changing precipitation patterns may be responsible. Collectively, these results provide important data for assessing human and climate impacts among Antarctic lacustrine habitats.

1 aKohler, Tyler, J.1 aHowkins, Adrian1 aSokol, Eric, R.1 aKopalová, Kateřina1 aCox, Aneliya1 aDarling, Joshua, P.1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttps://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.1020002256nas a2200217 4500008004100000245008600041210006900127260001200196520154900208653001401757653002401771653002001795653001701815653002001832100001301852700001901865700002201884700002201906700001701928856009301945 2021 eng d00aGenome analysis of Plectus murrayi, a nematode from continental Antarctica0 aGenome analysis of IPlectus murrayiI a nematode from continental c01/20213 a

Plectus murrayi is one of the most common and locally abundant invertebrates of continental Antarctic ecosystems. Because it is readily cultured on artificial medium in the laboratory and highly tolerant to an extremely harsh environment, Plectus murrayi is emerging as a model organism for understanding the evolutionary origin and maintenance of adaptive responses to multiple environmental stressors, including freezing and desiccation. The de novo assembled genome of Plectus murrayi contains 225.741 million base pairs and a total of 14,689 predicted genes. Compared to Caenorhabditis elegans, the architectural components of Plectus murrayi are characterized by a lower number of protein-coding genes, fewer transposable elements, but more exons, than closely related taxa from less harsh environments. We compared the transcriptomes of lab-reared Plectus murrayi with wild-caught Plectus murrayi and found genes involved in growth and cellular processing were up-regulated in lab-cultured Plectus murrayi, while a few genes associated with cellular metabolism and freeze tolerance were expressed at relatively lower levels. Preliminary comparative genomic and transcriptomic analyses suggest that the observed constraints on P. murrayi genome architecture and functional gene expression, including genome decay and intron retention, may be an adaptive response to persisting in a biotically simplified, yet consistently physically harsh environment.

10agene loss10agenome architecture10agenome assembly10agenome decay10aPlectus murrayi1 aXue, Xia1 aSuvorov, Anton1 aFujimoto, Stanley1 aDilman, Adler, R.1 aAdams, Byron uhttps://academic.oup.com/g3journal/advance-article/doi/10.1093/g3journal/jkaa045/604418902615nas a2200229 4500008004100000245011400041210006900155260001200224300001600236490000700252520188900259100002102148700002902169700002102198700002002219700002102239700002002260700001802280700001702298700001702315856005302332 2021 eng d00aGeochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica0 aGeochemical zones and environmental gradients for soils from the c03/2021 a1629 - 16440 v183 a

Previous studies have established links between biodiversity and soil geochemistry in the McMurdo Dry Valleys, Antarctica, where environmental gradients are important determinants of soil biodiversity. However, these gradients are not well established in the central Transantarctic Mountains, which are thought to represent some of the least hospitable Antarctic soils. We analyzed 220 samples from 11 ice-free areas along the Shackleton Glacier (~85°S), a major outlet glacier of the East Antarctic Ice Sheet. We established three zones of distinct geochemical gradients near the head of the glacier (upper), its central part (middle), and at the mouth (lower). The upper zone had the highest water-soluble salt concentrations with total salt concentrations exceeding 80 000 µg g-1, while the lower zone had the lowest water-soluble N:P ratios, suggesting that, in addition to other parameters (such as proximity to water and/or ice), the lower zone likely represents the most favorable ecological habitats. Given the strong dependence of geochemistry on geographic parameters, we developed multiple linear regression and random forest models to predict soil geochemical trends given latitude, longitude, elevation, distance from the coast, distance from the glacier, and soil moisture (variables which can be inferred from remote measurements). Confidence in our random forest model predictions was moderately high with R2 values for total water-soluble salts, water-soluble N:P, ClO4-, and ClO3- of 0.81, 0.88, 0.78, and 0.74, respectively. These modeling results can be used to predict geochemical gradients and estimate salt concentrations for other Transantarctic Mountain soils, information that can ultimately be used to better predict distributions of soil biota in this remote region.

1 aDiaz, Melisa, A.1 aGardner, Christopher, B.1 aWelch, Susan, A.1 aJackson, Andrew1 aAdams, Byron, J.1 aWall, Diana, H.1 aHogg, Ian, D.1 aFierer, Noah1 aLyons, Berry uhttps://bg.copernicus.org/articles/18/1629/2021/02603nas a2200181 4500008004100000245007200041210006900113260001200182300001200194490000800206520196600214100002402180700002402204700001702228700002402245700002402269856012802293 2021 eng d00aGeochemistry of contrasting stream types, Taylor Valley, Antarctica0 aGeochemistry of contrasting stream types Taylor Valley Antarctic c01/2021 a425-4480 v1333 a

The McMurdo Dry Valley region is the largest ice-free area of Antarctica. Ephemeral streams flow here during the austral summer, transporting glacial meltwater to perennially ice-covered, closed basin lakes. The chemistry of 24 Taylor Valley streams was examined over the two-decade period of monitoring from 1993 to 2014, and the geochemical behavior of two streams of contrasting physical and biological character was monitored across the seven weeks of the 2010–2011 flow season. Four species dominate stream solute budgets: HCO3, Ca2+, Na+, and Cl, with SO42–, Mg2+, and K+ present in significantly lesser proportions. All streams contain dissolved silica at low concentrations. Across Taylor Valley, streams are characterized by their consistent anionic geochemical fingerprint of HCO3 > Cl > SO4, but there is a split in cation composition between 14 streams with Ca > Na > Mg > K and 10 streams with Na > Ca > Mg > K.


Andersen Creek is a first-order proglacial stream representative of the 13 short streams that flow <1.5 km from source to gage. Von Guerard is representative of 11 long streams 2–7 km in length characterized by extensive hyporheic zones. Both streams exhibit a strong daily cycle for solute load, temperature, dissolved oxygen, and pH, which vary in proportion to discharge. A well-expressed diurnal co-variation of pH with dissolved oxygen is observed for both streams that reflects different types of biological control. The relative consistency of Von Guerard composition over the summer flow season reflects chemostatic regulation, where water in transient storage introduced during times of high streamflow has an extended opportunity for water-sediment interaction, silicate mineral dissolution, and pore-water exchange.

1 aHarmon, Russell, S.1 aLeslie, Deborah, L.1 aLyons, Berry1 aWelch, Kathleen, A.1 aMcKnight, Diane, M. uhttps://pubs.geoscienceworld.org/gsa/gsabulletin/article/133/1-2/425/587799/Geochemistry-of-contrasting-stream-types-Taylor01774nas a2200229 4500008004100000245011600041210006900157260001200226520104400238653001601282653001801298653001401316653001801330653002401348653001601372653001501388100001801403700001901421700002501440700002101465856005801486 2021 eng d00aHow long do population level field experiments need to be? Utilising data from the 40‐year‐old LTER network0 aHow long do population level field experiments need to be Utilis c02/20213 a

We utilise the wealth of data accessible through the 40‐year‐old Long‐Term Ecological Research (LTER) network to ask if aspects of the study environment or taxa alter the duration of research necessary to detect consistent results. To do this, we use a moving‐window algorithm. We limit our analysis to long‐term (> 10 year) press experiments recording organismal abundance. We find that studies conducted in dynamic abiotic environments need longer periods of study to reach consistent results, as compared to those conducted in more moderated environments. Studies of plants were more often characterised by spurious results than those on animals. Nearly half of the studies we investigated required 10 years or longer to become consistent, where all significant trends agreed in direction, and four studies (of 100) required longer than 20 years. Here, we champion the importance of long‐term data and bolster the value of multi‐decadal experiments in understanding, explaining and predicting long‐term trends.

10adata mining10aisothermality10along-term10amoving window10apopulation dynamics10atime series10atrajectory1 aCusser, Sarah1 aHelms, Jackson1 aBahlai, Christie, A.1 aHaddad, Nick, M. uhttps://onlinelibrary.wiley.com/doi/10.1111/ele.1371002835nas a2200217 4500008004100000245010200041210006900143260005400212490000900266520215600275653001502431653001002446653001602456653001502472653001402487653001202501653000902513100002202522700002502544856004802569 2021 eng d00aHydrologic response to foehn winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica0 aHydrologic response to foehn winds in the McMurdo Dry Valleys So aBoulder, CObUniversity of Colorado Boulderc20200 vM.S.3 a

In the McMurdo Dry Valleys (MDVs), foehn winds are a principal vector of landscape connectivity that facilitate movement of materials between glaciers, streams, soils, lakes and other parts of the ecosystem. While previous publications show that turbulent, warm and dry foehn winds indirectly relate to an increase in lake level rise via an increase in degree days above freezing (DDAF), the direct quantified impact of foehn winds to streamflow and lake level rise remains unclear. The MDVs are the largest ice-free region of Antarctica, which experience minimal precipitation. Valley bottoms contain permanently ice-covered closed basin lakes filled with meltwater from outlet glaciers via stream channels. In Taylor Valley, several meteorological stations and lake monitoring stations record average measurements of weather conditions and lake conditions on 15 to 20-minute intervals. In this thesis, the meteorological definition of foehn winds is refined and hydrologic response to foehn winds is evaluated. During the austral summer streamflow season (November - February), foehn winds are predicted to increase meltwater generation and closed-basin lake level rise. Past publications have shown that foehn wind events contribute to lake ice sublimation year-round, whereas melt does not typically occur in nonsummer months. Analysis of non-summer lake ice ablation utilizing recent lake stage and ablation data is also explored herein. Although a significant correlation was not found, summer foehn winds appear to promote above average daily lake level rise given sufficient air temperatures. Daily average lake level rise is greater for longer periods (i.e., 4-day average daily rise > 3-day average daily rise, etc.) indicating that there is at least a 4-day post-foehn impact on lake level rise during the summer. Lake ice ablation in non-summer months is shown to have a significant relationship with increasing foehn wind occurrence and wind-run. Because foehn winds are expected to increase with global warming, these hydrologic relationships aid in predicting the future of the McMurdo Dry Valley ecosystem in a warming world.

10aAntarctica10afoehn10afoehn winds10ahydrologic10akatabatic10aMcMurdo10awind1 aBeane, Samuel, J.1 aGooseff, Michael, N. uhttps://www.proquest.com/docview/248812693701609nas a2200157 4500008004100000022001400041245012700055210007100182260001200253520103400265100002401299700002501323700002401348700002101372856005801393 2021 eng d a0885-608700aLong‐term shifts in feedbacks among glacier surface change, melt generation, and runoff, McMurdo Dry Valleys, Antarctica0 aLong‐term shifts in feedbacks among glacier surface change melt  c07/20213 a

Glaciers of the McMurdo Dry Valleys (MDVs) Antarctica are the main source of streamflow in this polar desert. Because summer air temperatures hover near 0°C small changes in the energy balance strongly affect meltwater generation. Here we demonstrate that increased surface roughness, which alters the turbulent transfer of energy between the ice surface and atmosphere, yields a detectable increase in meltwater runoff. At low elevations on the glaciers, basin-like topography became significantly rougher over 13 years between repeat lidar surveys, yielding greater melt. In contrast, the smoother ice at higher elevation exhibited no detectable change in roughness. We pose a conceptual model of the cycle of glacier surface change as a result of climate forcing whereby glacier surfaces transition from being dominated by sublimation to becoming increasingly melt-dominated, which is reversible under prolonged cool periods. This research advances our understanding of warm season effects on polar glaciers.

1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aFountain, Andrew, G1 aHoffman, Matthew uhttps://onlinelibrary.wiley.com/doi/10.1002/hyp.1429202981nas a2200253 4500008004100000022001400041245011200055210006900167260001200236300001400248490000700262520216600269653002102435653002602456653002602482100002802508700002202536700002202558700002102580700002202601700001802623700001502641856007102656 2021 eng d a1523-043000aThe magnitude and climate sensitivity of isotopic fractionation from ablation of Antarctic Dry Valley lakes0 amagnitude and climate sensitivity of isotopic fractionation from c12/2021 a352 - 3710 v533 a

There has been extensive research on the effects of evaporation on the isotopic ratio of lacustrine and marine water bodies; however, there are limited data on how ablation or sublimation from lake or sea ice influences the isotopic ratio of the residual water body. This is a challenging problem because there remains uncertainty on the magnitude of fractionation during sublimation and because ablation can involve mixed-phase processes associated with simultaneous sublimation, melting, evaporation, and refreezing. This uncertainty limits the ability to draw quantitative inferences on changing hydrological budgets from stable isotope records in arctic, Antarctic, and alpine lakes. Here, we use in situ measurements of the isotopic ratio of water vapor along with the gradient diffusion method to constrain the isotopic ratio of the ablating ice from two lakes in the McMurdo Dry Valleys, Antarctica. We find that during austral summer, the isotopic fractionation of ablation was insignificant during periods of boundary layer instability that are typical during midday when latent heat is highest. This implies that the loss of mass during these periods did not yield any isotopic enrichment to the residual lake mass. However, fractionation increased after midday when the boundary layer stabilized and the latent heat flux was small. This diurnal pattern was mirrored on synoptic timescales, when following warm and stable conditions latent heat flux was low and dominated by higher fractionation for a few days. We hypothesize that the shifting from negligible to large isotopic fractionation reflects the development and subsequent exhaustion of liquid water on the surface. The results illustrate the complex and nonlinear controls on isotopic fractionation from icy lakes, which implies that the isotopic enrichment from ablation could vary significantly over timescales relevant for changing lake volumes. Future work using water isotope fluxes for longer periods of time and over additional perennial and seasonal ice-covered lake systems is critical for developing models of the isotopic mass balance of arctic and Antarctic lake systems.

10aDry Valley lakes10aisotope fractionation10astable water isotopes1 aBellagamba, Anthony, W.1 aBerkelhammer, Max1 aWinslow, Luke, A.1 aDoran, Peter, T.1 aMyers, Krista, F.1 aDevlin, Shawn1 aHawes, Ian uhttps://www.tandfonline.com/doi/full/10.1080/15230430.2021.200189901707nam a2200205 4500008004100000020001800041245013400059210006900193260001300262520102300275653001501298653001701313653001201330653001201342653001801354653000901372100002401381700002101405856007501426 2021 eng d a978012820245600aThe McMurdo Dry Valleys of Antarctica: A geological, environmental, and ecological analog to the Martian surface and near surface0 aMcMurdo Dry Valleys of Antarctica A geological environmental and bElsevier3 a

The surface of Mars is universally thought to have experienced widespread cold and dry environmental conditions for at least the last half of its geologic history, with more modern studies suggesting relatively cold and dry conditions early in its geologic history as well. However, the paucity of liquid water and mean annual temperatures well below the freezing point of water do not necessarily mean a complete cessation of all water-related geologic activity at the Martian surface. Over the past several decades, investigations in the McMurdo Dry Valleys (MDV) of Antarctica have revealed a dynamic geological, environmental, and ecological system resulting from locally optimized conditions operating over repeated, albeit brief, intervals during summer months. In this chapter, we compare the hyper-arid and hypo-thermal environments of the MDV and the modern Martian surface and discuss three unique enigmas that demonstrate how the Antarctic is a valuable analog to better understand processes on Mars.

10aAntarctica10aastrobiology10aclimate10ageology10ageomorphology10aMars1 aSalvatore, Mark, R.1 aLevy, Joseph, S. uhttps://www.sciencedirect.com/science/article/pii/B978012820245600011202329nas a2200193 4500008004100000022001400041245010500055210006900160260001200229300001200241490000700253520164000260100002301900700002601923700001901949700002201968700002601990856011902016 2021 eng d a1527-140400aMeta-analysis of Cryogenian through modern quartz microtextures reveals sediment transport histories0 aMetaanalysis of Cryogenian through modern quartz microtextures r c09/2021 a929-9440 v913 a

Quantitative analysis of quartz microtextures by means of scanning electron microscopy (SEM) can reveal the transport histories of modern and ancient sediments. However, because workers identify and count microtextures differently, it is difficult to directly compare quantitative microtextural data analyzed by different workers. As a result, the defining microtextures of certain transport modes and their probabilities of occurrence are not well constrained. We used principal-component analysis (PCA) to directly compare modern and ancient aeolian, fluvial, and glacial samples from the literature with nine new samples from active aeolian and glacial environments. Our results demonstrate that PCA can group microtextural samples by transport mode and differentiate between aeolian transport and fluvial and glacial transport across studies. The PCA ordination indicates that aeolian samples are distinct from fluvial and glacial samples, which are in turn difficult to disambiguate from each other. Ancient and modern sediments are also shown to have quantitatively similar microtextural relationships. Therefore, PCA may be a useful tool to constrain the ambiguous transport histories of some ancient sediment grains. As a case study, we analyzed two samples with ambiguous transport histories from the Cryogenian Bråvika Member (Svalbard). Integrating PCA with field observations, we find evidence that the Bråvika Member facies investigated here includes aeolian deposition and may be analogous to syn-glacial Marinoan aeolian units including the Bakoye Formation in Mali and the Whyalla Sandstone in South Australia.

1 aReahl, Jocelyn, N.1 aCantine, Marjorie, D.1 aWilcots, Julia1 aMackey, Tyler, J.1 aBergmann, Kristin, D. uhttps://pubs.geoscienceworld.org/jsedres/article/91/9/929/607764/Meta-analysis-of-Cryogenian-through-modern-quartz02224nas a2200229 4500008004100000245016400041210006900205260001200274300000800286490000700294520144700301100002401748700002301772700002201795700001501817700002101832700002201853700002201875700003201897700002101929856004401950 2021 eng d00aMetabolic capacity of the Antarctic cyanobacterium Phormidium pseudopriestleyi that sustains oxygenic photosynthesis in the presence of hydrogen sulfide0 aMetabolic capacity of the Antarctic cyanobacterium IPhormidium p c03/2021 a4260 v123 a

Sulfide inhibits oxygenic photosynthesis by blocking electron transfer between H2O and the oxygen-evolving complex in the D1 protein of Photosystem II. The ability of cyanobacteria to counter this effect has implications for understanding the productivity of benthic microbial mats in sulfidic environments throughout Earth history. In Lake Fryxell, Antarctica, the benthic, filamentous cyanobacterium Phormidium pseudopriestleyi creates a 1–2 mm thick layer of 50 µmol L−1 O2 in otherwise sulfidic water, demonstrating that it sustains oxygenic photosynthesis in the presence of sulfide. A metagenome-assembled genome of P. pseudopriestleyi indicates a genetic capacity for oxygenic photosynthesis, including multiple copies of psbA (encoding the D1 protein of Photosystem II), and anoxygenic photosynthesis with a copy of sqr (encoding the sulfide quinone reductase protein that oxidizes sulfide). The genomic content of P. pseudopriestleyi is consistent with sulfide tolerance mechanisms including increasing psbA expression or directly oxidizing sulfide with sulfide quinone reductase. However, the ability of the organism to reduce Photosystem I via sulfide quinone reductase while Photosystem II is sulfide-inhibited, thereby performing anoxygenic photosynthesis in the presence of sulfide, has yet to be demonstrated. 

1 aLumian, Jessica, E.1 aJungblut, Anne, D.1 aDillon, Megan, L.1 aHawes, Ian1 aDoran, Peter, T.1 aMackey, Tyler, J.1 aDick, Gregory, J.1 aGrettenberger, Christen, L.1 aSumner, Dawn, Y. uhttps://www.mdpi.com/2073-4425/12/3/42602579nas a2200397 4500008004100000022001300041245012700054210006900181260001200250300001100262490000600273520134500279653003401624653002501658653003101683653002701714653001801741653001401759100002201773700002401795700002201819700002301841700002301864700001401887700001901901700001601920700002101936700002701957700002601984700001602010700002402026700001602050700002102066700002202087856007202109 2021 eng d a2666900500aPatterns and trends of organic matter processing and transport: Insights from the US Long-term Ecological Research Network0 aPatterns and trends of organic matter processing and transport I c12/2021 a1000250 v23 a

Organic matter (OM) dynamics determine how much carbon is stored in ecosystems, a service that modulates climate. We synthesized research from across the US Long-Term Ecological Research (LTER) Network to assemble a conceptual model of OM dynamics that is consistent with inter-disciplinary perspectives and emphasizes vulnerability of OM pools to disturbance. Guided by this conceptual model, we identified unanticipated patterns and long-term trends in processing and transport of OM emerging from terrestrial, freshwater, wetland, and marine ecosystems. Cross-ecosystem synthesis combined with a survey of researchers revealed several themes: 1) strong effects of climate change on OM dynamics, 2) surprising patterns in OM storage and dynamics resulting from coupling with nutrients, 3) characteristic and often complex legacies of land use and disturbance, 4) a significant role of OM transport that is often overlooked in terrestrial ecosystems, and 5) prospects for reducing uncertainty in forecasting OM dynamics by incorporating the chemical composition of OM. Cross-fertilization of perspectives and approaches across LTER sites and other research networks can stimulate the comprehensive understanding required to support large-scale characterizations of OM budgets and the role of ecosystems in regulating global climate.

10acoupled biogeochemical cycles10across-site synthesis10aorganic matter composition10aorganic matter storage10astabilization10atransport1 aHarms, Tamara, K.1 aGroffman, Peter, M.1 aAluwihare, Lihini1 aCraft, Christopher1 aWieder, William, R1 aHobbie, S1 aBaer, Sara, G.1 aBlair, J.M.1 aFrey, Serita, D.1 aRemucal, Christina, K.1 aRudgers, Jennifer, A.1 aCollins, SL1 aKominoski, John, S.1 aBall, Becky1 aPriscu, John, C.1 aBarrett, John, E. uhttps://www.sciencedirect.com/science/article/pii/S266690052100025302380nas a2200253 4500008004100000245012200041210006900163260001200232300000900244490000600253520157500259653001501834653002701849653002401876653001901900653001601919653001901935653002701954100002501981700002902006700002602035700002102061856004402082 2021 eng d00aPhagotrophic protists and their associates: Evidence for preferential grazing in an abiotically driven soil ecosystem0 aPhagotrophic protists and their associates Evidence for preferen c08/2021 a15550 v93 a

The complex relationship between ecosystem function and soil food web structure is governed by species interactions, many of which remain unmapped. Phagotrophic protists structure soil food webs by grazing the microbiome, yet their involvement in intraguild competition, susceptibility to predator diversity, and grazing preferences are only vaguely known. These species-dependent interactions are contextualized by adjacent biotic and abiotic processes, and thus obfuscated by typically high soil biodiversity. Such questions may be investigated in the McMurdo Dry Valleys (MDV) of Antarctica because the physical environment strongly filters biodiversity and simplifies the influence of abiotic factors. To detect the potential interactions in the MDV, we analyzed the co-occurrence among shotgun metagenome sequences for associations suggestive of intraguild competition, predation, and preferential grazing. In order to control for confounding abiotic drivers, we tested co-occurrence patterns against various climatic and edaphic factors. Non-random co-occurrence between phagotrophic protists and other soil fauna was biotically driven, but we found no support for competition or predation. However, protists predominately associated with Proteobacteria and avoided Actinobacteria, suggesting grazing preferences were modulated by bacterial cell-wall structure and growth rate. Our study provides a critical starting-point for mapping protist interactions in native soils and highlights key trends for future targeted molecular and culture-based approaches.

10aAntarctica10aco-occurrence networks10aMcMurdo Dry Valleys10aRhogostoma sp.10aSandona sp.10asoil food webs10avariation partitioning1 aThompson, Andrew, R.1 aRoth-Monzón, Andrea, J.1 aAanderud, Zachary, T.1 aAdams, Byron, J. uhttps://www.mdpi.com/2076-2607/9/8/155502687nas a2200205 4500008004100000022001400041245013600055210006900191260001200260300001400272490000700286520195800293653004302251653002302294653002102317653003102338653002202369100002502391856006502416 2021 eng d a0722-406000aPhagotrophic protists (protozoa) in Antarctic terrestrial ecosystems: Diversity, distribution, ecology, and best research practices0 aPhagotrophic protists protozoa in Antarctic terrestrial ecosyste c08/2021 a1467-14840 v443 a

Phagotrophic protists (formerly protozoa) are a highly diverse, polyphyletic grouping of generally unicellular, heterotrophic eukaryotes that are key regulators of the soil microbiome. The biodiversity and ecology of soil phagotrophic protists are still largely uncharacterized, especially in the Antarctic, which possesses some of the harshest terrestrial environments known and potentially many physiologically unique and scientifically interesting species. Antarctic soil systems are also highly limited in terms of moisture, temperature, and carbon, and the resulting reduced biological complexity can facilitate fine-tuned investigation of the drivers and functioning of microbial communities. To facilitate and encourage future research into protist biodiversity and ecology, especially in context of the broader functioning of Antarctic terrestrial communities, I review the biodiversity, distribution, and ecology of Antarctic soil phagotrophic protists. Biodiversity appears to be highly structured by region and taxonomic group, with the Antarctic Peninsula having the highest taxonomic diversity and ciliates (Ciliophora) being the most diverse taxonomic group. However, richness estimates are likely skewed by disproportionate sampling (over half of the studies are from the peninsula), habitat type bias (predominately moss-associated soils), investigator bias (toward ciliates and the testate amoeba morphogroup), and methodological approach (toward cultivation and morphological identification). To remedy these biases, a standardized methodology using both morphological and molecular identification and increased emphasis on microflagellate and naked amoeba morphogroups is needed. Additionally, future research should transition away from biodiversity survey studies to dedicated ecological studies that emphasize the function, ecophysiology, endemicity, dispersal, and impact of abiotic drivers beyond moisture and temperature.

10aabiotic drivers of protist communities10aAntarctic protozoa10aCorythion dubium10aphagotrophic soil protists10aprotist diversity1 aThompson, Andrew, R. uhttps://link.springer.com/article/10.1007/s00300-021-02896-301817nas a2200169 4500008004100000245017100041210006900212260001200281300001300293490000700306520116600313100002601479700002001505700002001525700002401545856007801569 2021 eng d00aResearch sites get closer to field camps over time: Informing environmental management through a geospatial analysis of science in the McMurdo Dry Valleys, Antarctica0 aResearch sites get closer to field camps over time Informing env c11/2021 ae02579500 v163 a

As in many parts of the world, the management of environmental science research in Antarctica relies on cost-benefit analysis of negative environmental impact versus positive scientific gain. Several studies have examined the environmental impact of Antarctic field camps, but very little work looks at how the placement of these camps influences scientific research. In this study, we integrate bibliometrics, geospatial analysis, and historical research to understand the relationship between field camp placement and scientific production in the McMurdo Dry Valleys of East Antarctica. Our analysis of the scientific corpus from 1907–2016 shows that, on average, research sites have become less dispersed and closer to field camps over time. Scientific output does not necessarily correspond to the number of field camps, and constructing a field camp does not always lead to a subsequent increase in research in the local area. Our results underscore the need to consider the complex historical and spatial relationships between field camps and research sites in environmental management decision-making in Antarctica and other protected areas.

1 aChignell, Stephen, M.1 aMyers, Madeline1 aHowkins, Adrian1 aFountain, Andrew, G uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.025795003475nas a2200217 4500008004100000245017000041210006900211260003900280300000800319490000800327520273200335653001603067653000803083653001703091653001903108653002003127653001703147100001603164700002903180856004803209 2021 eng d00aRole of cyclic electron flow (CEF) and photosystem I (PSI) supercomplex formation during acclimation to long-term salinity stress in green algae: A comparative study0 aRole of cyclic electron flow CEF and photosystem I PSI supercomp aOxford, OHbMiami Universityc2021 a2360 vPhD3 aPhotosynthesis is one of the most important processes on Earth by which organisms convert solar energy into usable forms of energy. Linear electron flow (LEF) and cyclic electron flow (CEF) constitute two major pathways in photosynthesis. While LEF leads to production of both ATP and NADPH, CEF only produces ATP that helps balance the ATP:NADPH ratio required for carbon fixation. CEF also plays a major role during acclimation to several environmental stressors. However, the regulation and mechanism by which CEF operates is still not clearly understood. Recent studies have shown that formation of a protein supercomplex with PSI appears to be essential for induction of CEF in several model organisms. However, both supercomplex formation and CEF induction have been mainly studied under short-term, transitory stress conditions. In addition, the role and mechanism by which organisms may rely on CEF to survive in their natural habitat and acclimate to stress over a long period of time has not been considered. In this study we compared how three photosynthetic organisms (one model alga, Chlamydomonas reinhardtii; two extremophiles, C. sp. UWO241 and C. sp. ICE-MDV) utilize CEF to cope with their natural environment and adapt to steady-state environmental stress. To that end, the objectives of this thesis were i) to elucidate the role of CEF in long-term salinity acclimation ii) to understand the downstream changes associated with increased CEF, and iii) to identify whether PSI-supercomplexes are associated with increased CEF during salinity acclimation. We hypothesized that a stable PSI-supercomplex is required for high CEF, which in turn supports strong carbon fixation capacity for production of downstream metabolic products important for long-term acclimation to salinity stress. We showed for the first time, that increased CEF in UWO241 leads to excess ATP production and rewiring of downstream metabolism under high salinity. Next, we showed that a laboratory evolved salinity-tolerant strain of model C. reinhardtii uses constitutive upregulation of CEF to deal with salinity stress, which is in-turn associated with increased non-photochemical quenching and rewired carbon metabolism. Last, we show that CEF is involved in salinity acclimation in all three Chlamydomonas species, regardless of their salinity tolerance. We also show that PSI-supercomplexes are associated with increased CEF in these species. Characterization of high-salt supercomplex of C. reinhardtii revealed that it shares many similarities with the extensively described state 2 supercomplex, and that supercomplex composition might be species dependent rather than stress dependent.10aacclimation10aCEF10aextremophile10aPhotosynthesis10asalinity stress10asupercomplex1 aKalra, Isha1 aMorgan-Kiss, Rachael, M. uhttps://www.proquest.com/docview/257256058502603nas a2200217 4500008004100000022001400041245012400055210006900179260001200248520186200260653001502122653002702137653001902164653002102183653001502204100002202219700002502241700002402266700002602290856006902316 2021 eng d a2169-895300aThe role of hyporheic connectivity in determining nitrogen availability: Insights from an intermittent Antarctic stream0 arole of hyporheic connectivity in determining nitrogen availabil c04/20223 a

Due to widespread manipulation of nitrogen (N), much research has focused on processes controlling the fate of anthropogenic N in streams. Yet, in a variety of oligotrophic systems, N fixed by periphyton is a significant driver of ecosystem metabolism. Due to difficulties partitioning allochthonous and autochthonous sources, there is limited information regarding how the latter is processed. Autochthonous N may be particularly important in alpine, arid, or polar environments. We test the hypothesis that the availability of remineralized autochthonous N is controlled by connectivity between the hyporheic zone and main channel due to the contrasting biogeochemical functions of benthic autotrophs (including N‐fixing Nostoc) and hyporheic heterotrophs in an intermittent Antarctic stream. There, we collected surface water and hyporheic water concurrently at 4‐6 hour intervals over a 32.5‐hr period during one flow season and opportunistically throughout a second. Hyporheic water had 7 to 30 times greater nitrate‐N concentrations relative to surface water across all flow conditions. In contrast, ammonium concentrations were generally lower, although similar among locations. Additionally, nitrate in hyporheic water was positively correlated with silica, an indicator of hyporheic residence time. A laboratory assay confirmed prior inferences that hyporheic microbial communities possess the functional potential to perform nitrification. Together, these findings suggest that remineralized autochthonous N accumulates in the hyporheic zone even as streamflow varies and likely subsidizes stream N availability—which supports prior inferences from N stable isotope data at this site. These results highlight the importance of hyporheic connectivity in controlling autochthonous N cycling and availability in streams.

10aAntarctica10aautochthonous nitrogen10ahyporheic zone10anitrogen cycling10astreamflow1 aSingley, Joel, G.1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aHinckley, Eve-Lyn, S. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JG00630903417nas a2200193 4500008004100000245006200041210006200103260006200165490000800227520280000235653001503035653001903050653002103069653001203090100002203102700002603124700002503150856004803175 2021 eng d00aStream corridor connectivity controls on nitrogen cycling0 aStream corridor connectivity controls on nitrogen cycling aBoulder, CO, USAbUniversity of Colorado Boulderc05/20210 vPhD3 a

As water flows downstream, it is transported to and from environments that surround the visible stream. Along with surface water, these laterally and vertically connected environments comprise the stream corridor. Stream corridor connectivity influences many ecosystem services, including retention of excess nutrients. The subsurface area where stream water and groundwater mixes—the hyporheic zone—represents one of the most biogeochemically active parts of stream corridors.

The goal of my research is to advance understanding of how connectivity between different parts of a stream corridor controls the availability and retention of nitrogen (N), a nutrient that can limit primary productivity (low-N) and negatively impact water quality (excess N). First, I developed and applied a new machine learning method to objectively characterize the extent and variability of hyporheic exchange in terms of statistically unique functional zones using geophysical data. In applying this method to a benchmark dataset, I found that hyporheic extent does not scale uniformly with streamflow and that changes in the heterogeneity of connectivity differ over small (<10 m) distances. Next, I leveraged the relative simplicity of ephemeral streams of the McMurdo Dry Valleys (MDVs), Antarctica, to isolate stream corridor processes that influence the fate of N. Through intensive field sampling campaigns, I found that the hyporheic zone can be a persistent source of N even in this low nutrient environment. Next, I combined historic sample data and remote sensing analysis to estimate how much N is stored in an MDV stream corridor. My results indicate that up to 103 times more N is stored in this system than is exported each year, with most of this storage in the shallow (< 10 cm) hyporheic zone. Lastly, I examined 25 years of data for 10 streams to assess how stream corridor processes control concentration-discharge relationships. I found that in the absence of hillslope connectivity, stream corridor processes alone can maintain chemostasis – relatively small concentration changes with large fluctuations in streamflow – of both geogenic solutes and primary nutrients. My analysis also revealed that solutes subject to greater control by biological processes exhibit more variability within chemostatic relationships than weathering solutes that are only minimally influenced by biota.

Altogether, this research advances understanding of processes that are difficult to measure or are often overlooked in typical studies of temperate stream corridors. My findings provide insight into the surprising ways in which N is mobilized, transformed, and retained due to stream corridor connectivity in intermittent stream systems with few N inputs.

10aAntarctica10ahyporheic zone10anitrogen cycling10astreams1 aSingley, Joel, G.1 aHinckley, Eve-Lyn, S.1 aGooseff, Michael, N. uhttps://www.proquest.com/docview/257259312703499nas a2200229 4500008004100000245016600041210006900207260001200276300001100288490000700299520269000306653002302996653001503019653004103034653001603075653002403091653002003115100002203135700002203157700002403179856006603203 2021 eng d00aSupporting simultaneous air revitalization and thermal control in a crewed habitat with temperate Chlorella vulgaris and eurythermic Antarctic Chlorophyta0 aSupporting simultaneous air revitalization and thermal control i c08/2021 a7097460 v123 a

Including a multifunctional, bioregenerative algal photobioreactor for simultaneous air revitalization and thermal control may aid in carbon loop closure for long-duration surface habitats. However, using water-based algal media as a cabin heat sink may expose the contained culture to a dynamic, low temperature environment. Including psychrotolerant microalgae, native to these temperature regimes, in the photobioreactor may contribute to system stability. This paper assesses the impact of a cycled temperature environment, reflective of spacecraft thermal loops, to the oxygen provision capability of temperate Chlorella vulgaris and eurythermic Antarctic Chlorophyta. The tested 28-min temperature cycles reflected the internal thermal control loops of the International Space Station (C. vulgaris, 9–27°C; Chlorophyta-Ant, 4–14°C) and included a constant temperature control (10°C). Both sample types of the cycled temperature condition concluded with increased oxygen production rates (C. vulgaris; initial: 0.013 mgO2 L-1, final: 3.15 mgO2 L–1 and Chlorophyta-Ant; initial: 0.653 mgO2 L–1, final: 1.03 mgO2 L–1) and culture growth, suggesting environmental acclimation. Antarctic sample conditions exhibited increases or sustainment of oxygen production rates normalized by biomass dry weight, while both C. vulgaris sample conditions decreased oxygen production per biomass. However, even with the temperature-induced reduction, cycled temperature C. vulgaris had a significantly higher normalized oxygen production rate than Antarctic Chlorophyta. Chlorophyll fluorometry measurements showed that the cycled temperature conditions did not overly stress both sample types (FV/FM: 0.6–0.75), but the Antarctic Chlorophyta sample had significantly higher fluorometry readings than its C. vulgaris counterpart (F = 6.26, P < 0.05). The steady state C. vulgaris condition had significantly lower fluorometry readings than all other conditions (FV/FM: 0.34), suggesting a stressed culture. This study compares the results to similar experiments conducted in steady state or diurnally cycled temperature conditions. Recommendations for surface system implementation are based off the presented results. The preliminary findings imply that both C. vulgaris and Antarctic Chlorophyta can withstand the dynamic temperature environment reflective of a thermal control loop and these data can be used for future design models.

10aair revitalization10aAntarctica10abioregenerative life support systems10aChlorophyta10aMcMurdo Dry Valleys10athermal control1 aMatula, Emily, E.1 aNabity, James, A.1 aMcKnight, Diane, M. uhttps://www.frontiersin.org/article/10.3389/fmicb.2021.70974602152nas a2200253 4500008004100000245012600041210006900167260001200236300001600248490000700264520133900271100002201610700002101632700002501653700002001678700002201698700001701720700002201737700002201759700001901781700002201800700002301822856005301845 2021 eng d00aThermal legacy of a large paleolake in Taylor Valley, East Antarctica, as evidenced by an airborne electromagnetic survey0 aThermal legacy of a large paleolake in Taylor Valley East Antarc c08/2021 a3577 - 35930 v153 a

Previous studies of the lakes of the McMurdo Dry Valleys have attempted to constrain lake level history, and results suggest the lakes have undergone hundreds of meters of lake level change within the last 20 000 years. Past studies have utilized the interpretation of geologic deposits, lake chemistry, and ice sheet history to deduce lake level history; however a substantial amount of disagreement remains between the findings, indicating a need for further investigation using new techniques. This study utilizes a regional airborne resistivity survey to provide novel insight into the paleohydrology of the region. Mean resistivity maps revealed an extensive brine beneath the Lake Fryxell basin, which is interpreted as a legacy groundwater signal from higher lake levels in the past. Resistivity data suggest that active permafrost formation has been ongoing since the onset of lake drainage and that as recently as 1500–4000 years BP, lake levels were over 60 m higher than present. This coincides with a warmer-than-modern paleoclimate throughout the Holocene inferred by the nearby Taylor Dome ice core record. Our results indicate Mid to Late Holocene lake level high stands, which runs counter to previous research finding a colder and drier era with little hydrologic activity throughout the last 5000 years.

1 aMyers, Krista, F.1 aDoran, Peter, T.1 aTulaczyk, Slawek, M.1 aFoley, Neil, T.1 aBording, Thue, S.1 aAuken, Esben1 aDugan, Hilary, A.1 aMikucki, Jill, A.1 aFoged, Nikolaj1 aGrombacher, Denys1 aVirginia, Ross, A. uhttps://tc.copernicus.org/articles/15/3577/2021/02753nas a2200325 4500008004100000022001400041245011500055210007300170260001200243300001800255490000800273520178400281653001002065653001402075653001602089653000802105653001002113653001002123653001402133653001102147100002802158700002102186700003302207700002202240700002202262700002402284700002902308700002102337856006902358 2021 eng d a2169-895300aYear‐round and long‐term phytoplankton dynamics in Lake Bonney, a permanently ice‐covered Antarctic lake0 aYear‐round and long‐term phytoplankton dynamics in Lake Bonney a c04/2021 ae2020JG0059250 v1263 a

Lake Bonney (McMurdo Dry Valleys, east Antarctica) represents a year‐round refugium for life adapted to permanent extreme conditions. Despite intensive research since the 1960s, due to the logistical constraints posed by 4‐months of 24‐h darkness, knowledge of how the resident photosynthetic microorganisms respond to the polar winter is limited. In addition, the lake level has risen by more than 3 m since 2004: impacts of rapid lake level rise on phytoplankton community structure is also poorly understood. From 2004 to 2015 an in situ submersible spectrofluorometer (bbe FluoroProbe) was deployed in Lake Bonney during the austral summer to quantify the vertical structure of four functional algal groups (green algae, mixed algae, and cryptophytes, cyanobacteria). During the 2013–2014 field season the Fluoroprobe was mounted on autonomous cable‐crawling profilers deployed in both the east and west lobes of Lake Bonney, obtaining the first daily phytoplankton profiles through the polar night. Our findings showed that phytoplankton communities were differentially impacted by physical and chemical factors over long‐term versus seasonal time scales. Following a summer of rapid lake level rise (2010–2011), an increase in depth integrated chlorophyll a (chl‐a) occurred in Lake Bonney caused by stimulation of photoautotrophic green algae. Conversely, peaks in chl‐a during the polar night were associated with an increase in mixotrophic haptophytes and cryptophytes. Collectively our data reveal that phytoplankton groups possessing variable trophic abilities are differentially competitive during seasonal and long‐term time scales owing to periods of higher nutrients (photoautotrophs) versus light/energy limitation (mixotrophs).

10aalgae10aAntarctic10afluorometry10aice10alakes10alight10aprofiling10awinter1 aPatriarche, Jeffrey, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aWinslow, Luke, A.1 aMyers, Krista, F.1 aBuelow, Heather, N.1 aMorgan-Kiss, Rachael, M.1 aDoran, Peter, T. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG00592502509nas a2200205 4500008004100000245012600041210006900167260005300236490000900289520180200298653002502100653001502125653001702140653002402157653002002181653002302201100002502224700001702249856003702266 2020 eng d00aAnalysis of acid-leachable barium, copper, iron, lead, & zinc concentrations in Taylor Valley, Antarctic stream sediments0 aAnalysis of acidleachable barium copper iron lead zinc concentra aColumbus, OHbThe Ohio State Universityc05/20200 vB.S.3 a

The purpose of this study is to assess the concentrations of Barium (Ba), Copper (Cu), Iron (Fe), Lead (Pb), and Zinc (Zn) in sediment samples obtained from the Wales and Commonwealth streams located in Taylor Valley, Antarctica. These samples were collected at seven sample sites (three in Wales Glacier and four in Commonwealth Glacier) in 0 to 2 cm, 2 to 4 cm, 4 to 6 cm, and 6 to 8 cm depth increments which resulted in 28 total samples. After the collection process, these samples underwent a volumetric 1:5 sediment: 10% HCl leach for 48 hours, filtration through 4-µm pore-size, cellulose acetate membrane filters, and inductively coupled plasma mass spectrometry (ICP-MS) analyses in the Trace Element Research Laboratory at The Ohio State University. Upon completion of the analyses, results showed that the Wales samples had a higher average concentration of every metal element overall and at each depth increment when compared to the Commonwealth samples. In addition to the weak-acid leachate metal analyses, a second aliquot of one sediment profile from each stream was analyzed at Villanova University for the 210Pb activity via gamma spectroscopy. This was done to estimate the sedimentation rates at each of these sites. From the sedimentation rates, sedimentation fluxes were calculated for each element for each sediment profile at each of these sites. The data demonstrated that Fe is the most abundant element while Pb is the least abundant. Lastly, upon examination of results, it was found that the concentrations of these metals are often higher in samples collected closer to the surface. These findings suggest these streams, and their sources, have had little, if any, impact by anthropogenic input of metals, and that metal fluxes to the sediments are low.

10aacid-leachable metal10aAntarctica10ageochemistry10aMcMurdo Dry Valleys10apolar sediments10asedimentation rate1 aPiergallini, Brianna1 aLyons, Berry uhttp://hdl.handle.net/1811/9177204249nas a2200253 4500008004100000245009000041210006900131260001200200490000600212520350100218653002003719653002003739653001303759100001903772700002003791700002203811700002403833700002503857700001903882700001203901700001703913700002103930856004403951 2020 eng d00aChange in Pictures: Creating best practices in archiving ecological imagery for reuse0 aChange in Pictures Creating best practices in archiving ecologic c09/20200 v43 a

The research data repository of the Environmental Data Initiative (EDI) is building on over 30 years of data curation research and experience in the National Science Foundation-funded US Long-Term Ecological Research (LTER) Network. It provides mature functionalities, well established workflows, and now publishes all ‘long-tail’ environmental data. High quality scientific metadata are enforced through automatic checks against community developed rules and the Ecological Metadata Language (EML) standard. Although the EDI repository is far along in making its data findable, accessible, interoperable, and reusable (FAIR), representatives from EDI and the LTER are developing best practices for the edge cases in environmental data publishing. One of these is the vast amount of imagery taken in the context of ecological research, ranging from wildlife camera traps to plankton imaging systems to aerial photography. Many images are used in biodiversity research for community analyses (e.g., individual counts, species cover, biovolume, productivity), while others are taken to study animal behavior and landscape-level change.

Some examples from the LTER Network include: using photos of a heron colony to measure provisioning rates for chicks (Clarkson and Erwin 2018) or identifying changes in plant cover and functional type through time (Peters et al. 2020). Multi-spectral images are employed to identify prairie species. Underwater photo quads are used to monitor changes in benthic biodiversity (Edmunds 2015). Sosik et al. (2020) used a continuous Imaging FlowCytobot to identify and measure phyto- and microzooplankton. Cameras at McMurdo Dry Valleys assess snow and ice cover on Antarctic lakes allowing estimation of primary production (Myers 2019).

It has been standard practice to publish numerical data extracted from images in EDI; however, the supporting imagery generally has not been made publicly available. Our goal in developing best practices for documenting and archiving these images is for them to be discovered and re-used. Our examples demonstrate several issues. The research questions, and hence, the image subjects are variable. Images frequently come in logical sets of time series. The size of such sets can be large and only some images may be contributed to a dedicated specialized repository. Finally, these images are taken in a larger monitoring context where many other environmental data are collected at the same time and location.

Currently, a typical approach to publishing image data in EDI are packages containing compressed (ZIP or tar) files with the images, a directory manifest with additional image-specific metadata, and a package-level EML metadata file. Images in the compressed archive may be organized within directories with filenames corresponding to treatments, locations, time periods, individuals, or other grouping attributes. Additionally, the directory manifest table has columns for each attribute. Package-level metadata include standard coverage elements (e.g., date, time, location) and sampling methods. This approach of archiving logical ‘sets’ of images reduces the effort of providing metadata for each image when most information would be repeated, but at the expense of not making every image individually searchable. The latter may be overcome if the provided manifest contains standard metadata that would allow searching and automatic integration with other images.

10adata repository10aecological data10ametadata1 aGries, Corinna1 aBeaulieu, Stace1 aBrown, Renée, F.1 aGastil-Buhl, Gastil1 aElmendorf, Sarah, C.1 aHsieh, Hsun-Yi1 aKui, Li1 aMaurer, Greg1 aPorter, John, H. uhttps://biss.pensoft.net/article/59082/03380nas a2200205 4500008004100000245009700041210006900138260005400207490001000261520267200271653001002943653001402953653002902967653002202996653002603018653003203044100002603076700002403102856004803126 2020 eng d00aCharacterization of spatial and environmental influences on stream diatoms and cyanobacteria0 aCharacterization of spatial and environmental influences on stre aBoulder, CObUniversity of Colorado Boulderc20200 vPh.D.3 a

Primary producing algae form the basis of carbon fixation, oxygen production, and food webs in aquatic ecosystems globally. However, human activities disrupt climate and freshwater physicochemistry. These impacts alter the health of algal communities and the ecosystem services algae provide. Meanwhile, spatial processes like dispersal and landscape characteristics like geology also influence algal structure and function. Diatoms are indicators of stream health and are model organisms for understanding the processes underlying microbial biogeography. Benthic cyanobacteria present risks to human health through the proliferation of toxin-producing blooms. With this dissertation, I investigate the ecosystem processes that influence diatom and cyanobacterial community composition and taxon distributions. My goal is to advance the understanding of ecosystem controls on algal biogeography and to characterize taxon-specific autecology for use in environmental management. First, I measured the extent of wind-mediated dispersal of benthic diatoms across aquatic habitats to better understand how community composition is structured by spatial processes across the McMurdo Dry Valleys polar desert in Antarctica. I found that inter-habitat dispersal is common but less influential on community composition than intra-habitat factors such as environmental conditions. I then used non-linear, multivariable modeling to assess the relative influences of climate, watershed characteristics, and in-stream stressors on the relative abundances of 268 diatom taxa across gradients of human impact in the northeast United States. My results indicate diatom taxa are affected by different suites of environmental conditions but that taxa belong to ecological guilds based on shared responsiveness to environmental factors. Finally, I applied multivariable modeling towards understanding the effects of aquatic stressors, including herbicides and persistent organic pollutants, on the distributions of benthic cyanobacteria across northeast U.S. streams. I found that watershed characteristics, streamflow, and herbicides were more influential than light availability, water temperature, and nutrients on the distributions of potentially toxigenic cyanobacterial genera. Collectively, this research expands the knowledge of how benthic algal communities and taxon distributions are structured at large spatial scales along gradients of unimpacted and human-altered environmental conditions. I provide a novel modeling framework and taxon-specific autecological information that can be applied to environmental assessments of stream health and future algal research.

10aalgae10adispersal10aenvironmental assessment10ahuman disturbance10ametacommunity ecology10aspecies distribution models1 aSchulte, Nicholas, O.1 aMcKnight, Diane, M. uhttps://www.proquest.com/docview/247621626302207nas a2200205 4500008004100000245010800041210006900149260001200218520152500230100001601755700001401771700002301785700001901808700002201827700001401849700001901863700002101882700002901903856006901932 2020 eng d00aChlamydomonas sp. UWO 241 exhibits high cyclic electron flow and rewired metabolism under high salinity0 aChlamydomonas sp UWO 241 exhibits high cyclic electron flow and  c03/20203 a

The Antarctic green alga Chlamydomonas sp. UWO 241 (UWO 241) is adapted to permanent low temperatures, hypersalinity, and extreme shade. one of the most striking phenotypes of UWO 241 is an altered photosystem I (PSI) organization and constitutive PSI cyclic electron flow (CEF). To date, little attention has been paid to CEF during long-term stress acclimation, and the consequences of sustained CEF in UWO 241 are not known. In this study, we combined photobiology, proteomics, and metabolomics to understand the underlying role of sustained CEF in high salinity stress acclimation. High salt-grown UWO 241 exhibited increased thylakoid proton motive flux and an increased capacity for non-photochemical quenching. Under high salt, a significant proportion of the upregulated enzymes were associated with the Calvin Benson Bassham Cycle, carbon storage metabolism, and protein translation. Two key enzymes of the Shikimate pathway, DAHP synthase and chorismate synthase, were also upregulated, as well as indole-3-glycerol phosphate synthase, an enzyme involved in the biosynthesis of L-tryptophan and indole acetic acid. In addition, several compatible solutes (glycerol, proline, and sucrose) accumulated to high levels in high salt-grown UWO 241 cultures. We suggest that UWO 241 maintains constitutively high CEF through the associated PSI-cytochrome b6f supercomplex to support robust growth and strong photosynthetic capacity under a constant growth regime of low temperatures and high salinity.

1 aKalra, Isha1 aWang, Xin1 aCvetkovska, Marina1 aJeong, Jooyeon1 aMcHargue, William1 aZhang, Ru1 aHüner, Norman1 aYuan, Joshua, S.1 aMorgan-Kiss, Rachael, M. uhttp://www.plantphysiol.org/content/early/2020/04/03/pp.19.0128001864nas a2200193 4500008004100000245012800041210006900169260001200238520119500250653002401445653001801469653002501487100001801512700001801530700002101548700001401569700001801583856006901601 2020 eng d00aClimate from the McMurdo Dry Valleys, Antarctica, 1986 – 2017: Surface air temperature trends and redefined summer season0 aClimate from the McMurdo Dry Valleys Antarctica 1986 2017 Surfac c05/20203 a

The weather of the McMurdo Dry Valleys, Antarctica, the largest ice‐free region of the Antarctica, has been continuously monitored since 1985 with currently 14 operational meteorological stations distributed throughout the valleys. Because climate is based on a 30‐year record of weather, this is the first study to truly define the contemporary climate of the McMurdo Dry Valleys. Mean air temperature and solar radiation based on all stations were ‐20°C and 102 W m‐2, respectively. Depending on the site location, the mean annual air temperatures on the valleys floors ranged between ‐15°C and ‐30°C, and mean annual solar radiation varied between 72 W m‐2 and 122 W m‐2. Surface air temperature decreased by 0.7°C per decade from 1986 to 2006 at Lake Hoare station (longest continuous record), after which the record is highly variable with no trend. All stations with sufficiently long records showed similar trend shifts in 2005 ±1 year. Summer is defined as November through February, using a physically based process: up‐valley warming from the coast associated with a change in atmospheric stability.

10aMcMurdo Dry Valleys10asummer season10aweather observations1 aObryk, M., K.1 aDoran, P., T.1 aFountain, A., G.1 aMyers, M.1 aMcKay, C., P. uhttps://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD03218002447nas a2200181 4500008004100000245007900041210006900120260001200189490000700201520187300208100002002081700002602101700002002127700002402147700001902171700002102190856005402211 2020 eng d00aA digital archive of human activity in the McMurdo Dry Valleys, Antarctica0 adigital archive of human activity in the McMurdo Dry Valleys Ant c05/20200 v123 a

Over the last half century, the McMurdo Dry Valleys (MDV) of East Antarctica have become a globally important site for scientific research and environmental monitoring. Historical data can make important contributions to current research activities and environmental management in Antarctica but tend to be widely scattered and difficult to access. We address this need in the MDV by compiling over 5000 historical photographs, sketches, maps, oral interviews, publications, and other archival resources into an online digital archive. The data have been digitized and georeferenced using a standardized metadata structure, which enables intuitive searches and data discovery via an online interface. The ultimate aim of the archive is to create as comprehensive as possible a record of human activity in the MDV to support ongoing research, management, and conservation efforts. This is a valuable tool for scientists seeking to understand the dynamics of change in lakes, glaciers, and other physical systems, as well as humanistic inquiry into the history of the Southern Continent. In addition to providing benchmarks for understanding change over time, the data can help target field sampling for studies working under the assumption of a pristine landscape by enabling researchers to identify the date and extent of past human activities. The full database is accessible via a web browser-based interface hosted by the McMurdo Long Term Ecological Research site: http://mcmurdohistory.lternet.edu/ (last access: 5 May 2020). The complete metadata data for all resources in the database are also available at the Environmental Data Initiative: https://doi.org/10.6073/pasta/6744cb28a544fda827805db123d36557 (Howkins et al., 2019).

1 aHowkins, Adrian1 aChignell, Stephen, M.1 aGullett, Poppie1 aFountain, Andrew, G1 aBrett, Melissa1 aPreciado, Evelin uhttps://www.earth-syst-sci-data.net/12/1117/2020/03399nas a2200193 4500008004100000245013900041210006900180260005400249490001000303520272200313653001303035653000903048653002403057653001403081653001303095100002403108700002503132856004803157 2020 eng d00aThe effect of sediment on hydrological and biogeochemical connectivity of glaciers within the McMurdo Dry Valley ecosystem, Antarctica0 aeffect of sediment on hydrological and biogeochemical connectivi aBoulder, CObUniversity of Colorado Boulderc20200 vPh.D.3 a

Glaciers are an integral part of polar and alpine landscapes, providing water, inorganic, and organic material subsidies to downstream ecosystems. These subsides regulate downstream temperature, streamflow, and sediment supplies. Warming in high altitude and high latitude environments due to climate change is resulting in rapid and substantial mass loss of glaciers. In order to better predict impacts and future change to glaciers and downstream environments, we endeavor to better understand glacier physical and biogeochemical processes. Glaciers in the McMurdo Dry Valleys (MDVs) of Antarctica are very sensitive to slight changes in the energy balance. Small temperature or solar radiation increases can result in outsize increases in glacier melt, which is the main source of water for the MDV ecosystem. Sediment on the glacier surface is thought to be a key factor driving both melt and biogeochemical cycling on glaciers. This dissertation examines the distribution of sediment on the MDVs glacier surfaces, how it may have driven recent glacier morphological change, and identifies sediment-driven biogeochemical processes on the MDV glaciers. To do so, we carried out field data collection, field- and lab-based nutrient uptake experiments, geospatial analysis, and coupled sediment and energy balance modeling. We find that the glacier surfaces have changed in response to recent warm events by increasing roughness and the density of meltwater channels on the glacier surface. The increase in roughness occurred in already rough areas that serve as collection points for wind- and water-transported sediment. The rough surfaces and sediment have low albedo and can absorb a higher amount of energy, spurring additional melt. The distribution of sediment on the surface and in the top meter of ice is a reflection of patterns of wind deposition and seasonal melt on the glacier. The total amount of sediment in the top meter of ice agrees with previously measured rates of sediment deposition and follows a valley-wide pattern. The depth of the peak sediment concentration in the top meter of ice is a function of the thermal history of the glacier– both summer energy balance and winter sublimation rates. We also find that the biota living in the sediment is capable of removing nutrients from glacier melt water, modulating the amount and form of nutrients delivered to downstream ecosystems. This research clarifies the role of glaciers within the larger MDV ecosystem. It also advances our understanding of surficial glacier melt and biogeochemistry, which can improve predictions of how the functional role of glaciers within their larger ecosystems will evolve due to climate change.

10aglaciers10aLTER10aMcMurdo Dry Valleys10ameltwater10asediment1 aBergstrom, Anna, J.1 aGooseff, Michael, N. uhttps://www.proquest.com/docview/240827383902314nas a2200265 4500008004100000245012500041210006900166260001200235490000700247520147000254653001501724653001101739653001701750653001801767653001101785653004001796100002201836700001501858700002301873700002201896700002401918700002101942700002101963856006401984 2020 eng d00aEnergetic and environmental constraints on the community structure of benthic microbial mats in Lake Fryxell, Antarctica0 aEnergetic and environmental constraints on the community structu c02/20200 v963 a

Ecological communities are regulated by the flow of energy through environments. Energy flow is typically limited by access to photosynthetically active radiation (PAR) and oxygen concentration (O2). The microbial mats growing on the bottom of Lake Fryxell, Antarctica, have well-defined environmental gradients in PAR and (O2). We analyzed the metagenomes of layers from these microbial mats to test the extent to which access to oxygen and light controls community structure. We found variation in the diversity and relative abundances of Archaea, Bacteria and Eukaryotes across three (O2) and PAR conditions: high (O2) and maximum PAR, variable (O2) with lower maximum PAR, and low (O2) and maximum PAR. We found distinct communities structured by the optimization of energy use on a millimeter-scale across these conditions. In mat layers where (O2) was saturated, PAR structured the community. In contrast, (O2) positively correlated with diversity and affected the distribution of dominant populations across the three habitats, suggesting that meter-scale diversity is structured by energy availability. Microbial communities changed across covarying gradients of PAR and (O2). The comprehensive metagenomic analysis suggests that the benthic microbial communities in Lake Fryxell are structured by energy flow across both meter- and millimeter-scales.

10aAntarctica10aenergy10aLake Fryxell10amicrobial mat10aOxygen10aPhotosynthetically Active Radiation1 aDillon, Megan, L.1 aHawes, Ian1 aJungblut, Anne, D.1 aMackey, Tyler, J.1 aEisen, Jonathan, A.1 aDoran, Peter, T.1 aSumner, Dawn, Y. uhttps://academic.oup.com/femsec/article/96/2/fiz207/569719602205nas a2200205 4500008004100000245012400041210006900165260001200234300001300246490000700259520150700266100002201773700001501795700002301810700002201833700002401855700002101879700002101900856007801921 2020 eng d00aEnvironmental control on the distribution of metabolic strategies of benthic microbial mats in Lake Fryxell, Antarctica0 aEnvironmental control on the distribution of metabolic strategie c04/2020 ae02310530 v153 a

Ecological theories posit that heterogeneity in environmental conditions greatly affects community structure and function. However, the degree to which ecological theory developed using plant- and animal-dominated systems applies to microbiomes is unclear. Investigating the metabolic strategies found in microbiomes are particularly informative for testing the universality of ecological theories because microorganisms have far wider metabolic capacity than plants and animals. We used metagenomic analyses to explore the relationships between the energy and physicochemical gradients in Lake Fryxell and the metabolic capacity of its benthic microbiome. Statistical analysis of the relative abundance of metabolic marker genes and gene family diversity shows that oxygenic photosynthesis, carbon fixation, and flavin-based electron bifurcation differentiate mats growing in different environmental conditions. The pattern of gene family diversity points to the likely importance of temporal environmental heterogeneity in addition to resource gradients. Overall, we found that the environmental heterogeneity of photosynthetically active radiation (PAR) and oxygen concentration ([O2]) in Lake Fryxell provide the framework by which metabolic diversity and composition of the community is structured, in accordance with its phylogenetic structure. The organization of the resulting microbial ecosystems are consistent with the maximum power principle and the species sorting model.

1 aDillon, Megan, L.1 aHawes, Ian1 aJungblut, Anne, D.1 aMackey, Tyler, J.1 aEisen, Jonathan, A.1 aDoran, Peter, T.1 aSumner, Dawn, Y. uhttps://journals.plos.org/plosone/article?id=10.1371/journal.pone.023105302597nas a2200229 4500008004100000245011900041210006900160260001200229520184900241653001502090653001802105653002602123653000902149653001502158653001902173100002102192700002402213700002002237700002102257700002202278856006702300 2020 eng d00aEstimating microbial mat biomass in the McMurdo Dry Valleys, Antarctica using satellite imagery and ground surveys0 aEstimating microbial mat biomass in the McMurdo Dry Valleys Anta c09/20203 a

Cyanobacterial mat communities are the main drivers of primary productivity in the McMurdo Dry Valleys, Antarctica. These microbial communities form laminar mats on desert pavement surfaces adjacent to glacial meltwater streams, ponds, and lakes. The low-density nature of these communities and their patchy distribution make assessments of distribution, biomass, and productivity challenging. We used satellite imagery coupled with in situ surveying, imaging, and sampling to systematically estimate microbial mat biomass in selected wetland regions in Taylor Valley, Antarctica. On January 19th, 2018, the WorldView-2 multispectral satellite acquired an image of our study areas, where we surveyed and sampled seven 100 m2 plots of microbial mats for percent ground cover, ash-free dry mass (AFDM), and pigment content (chlorophyll-a, carotenoids, and scytonemin). Multispectral analyses revealed spectral signatures consistent with photosynthetic activity (relatively strong reflection at near-infrared wavelengths and relatively strong absorption at visible wavelengths), with average normalized difference vegetation index (NDVI) values of 0.09 to 0.28. Strong correlations of microbial mat ground cover (R2 = 0.84), biomass (R2 = 0.74), chlorophyll-a content (R2 = 0.65), and scytonemin content (R2 = 0.98) with logit transformed NDVI values demonstrate that satellite imagery can detect both the presence of microbial mats and their key biological properties. Using the NDVI—biomass correlation we developed, we estimate carbon (C) stocks of 21,715 kg (14.7 g C m−2) in the Canada Glacier Antarctic Specially Protected Area, with an upper and lower limit of 74,871 and 6312 kg of C, respectively.

10aAntarctica10amicrobial mat10amultispectral imagery10aNDVI10aNostocales10aremote sensing1 aPower, Sarah, N.1 aSalvatore, Mark, R.1 aSokol, Eric, R.1 aStanish, Lee, F.1 aBarrett, John, E. uhttps://link.springer.com/article/10.1007%2Fs00300-020-02742-y03261nas a2200241 4500008004100000245013300041210006900174260001200243490000600255520247400261653001502735653002202750653001402772653001102786653001902797100002002816700002202836700002202858700002402880700002402904700002102928856007002949 2020 eng d00aEvaluating alternative metacommunity hypotheses for diatoms in the McMurdo Dry Valleys using simulations and remote sensing data0 aEvaluating alternative metacommunity hypotheses for diatoms in t c09/20200 v83 a

Diatoms are diverse and widespread freshwater Eukaryotes that make excellent microbial subjects for addressing questions in metacommunity ecology. In the McMurdo Dry Valleys of Antarctica, the simple trophic structure of glacier-fed streams provides an ideal outdoor laboratory where well-described diatom assemblages are found within two cyanobacterial mat types, which occupy different habitats and vary in coverage within and among streams. Specifically, black mats of Nostoc spp. occur in marginal wetted habitats, and orange mats (Oscillatoria spp. and Phormidium spp.) occur in areas of consistent stream flow. Despite their importance as bioindicators for changing environmental conditions, the role of dispersal in structuring dry valley diatom metacommunities remains unclear. Here, we use MCSim, a spatially explicit metacommunity simulation package for R, to test alternative hypotheses about the roles of dispersal and species sorting in maintaining the biodiversity of diatom assemblages residing in black and orange mats. The spatial distribution and patchiness of cyanobacterial mat habitats was characterized by remote imagery of the Lake Fryxell sub-catchment in Taylor Valley. The available species pool for diatom metacommunity simulation scenarios was informed by the Antarctic Freshwater Diatoms Database, maintained by the McMurdo Dry Valleys Long Term Ecological Research program. We used simulation outcomes to test the plausibility of alternative community assembly hypotheses to explain empirically observed patterns of freshwater diatom biodiversity in the long-term record. The most plausible simulation scenarios suggest species sorting by environmental filters, alone, was not sufficient to maintain biodiversity in the Fryxell Basin diatom metacommunity. The most plausible scenarios included either (1) neutral models with different immigration rates for diatoms in orange and black mats or (2) species sorting by a relatively weak environmental filter, such that dispersal dynamics also influenced diatom community assembly, but there was not such a strong disparity in immigration rates between mat types. The results point to the importance of dispersal for understanding current and future biodiversity patterns for diatoms in this ecosystem, and more generally, provide further evidence that metacommunity theory is a useful framework for testing hypotheses about microbial community assembly.

10aAntarctica10aBacillariophyceae10adispersal10aNostoc10astream ecology1 aSokol, Eric, R.1 aBarrett, John, E.1 aKohler, Tyler, J.1 aMcKnight, Diane, M.1 aSalvatore, Mark, R.1 aStanish, Lee, F. uhttps://www.frontiersin.org/article/10.3389/fevo.2020.521668/full01971nas a2200181 4500008004100000245008500041210006900126260005200195520137400247100002101621700002101642700001801663700002101681700001301702700002001715700002001735856003401755 2020 eng d00aFollowing the Astrobiology Roadmap: Origins, Habitability and Future Exploration0 aFollowing the Astrobiology Roadmap Origins Habitability and Futu aNorfolk, United KingdombCaister Academic Press3 a

Astrobiology asks three fundamental questions as outlined by the NASA Astrobiology Roadmap: 1. How did Life begin and evolve?; Is there Life elsewhere in the Universe?; and, What is the future of Life on Earth? As we gain perspective on how Life on Earth arose and adapted to its many niches, we too gain insight into how a planet achieves habitability. Here on Earth, microbial Life has evolved to exist in a wide range of habitats from aquatic systems to deserts, the human body, and the International Space Station (ISS). Landers, rovers, and orbiter missions support the search for signatures of Life beyond Earth, by generating data on surface and subsurface conditions of other worlds. These have provided evidence for water activity, supporting the potential for extinct or extant Life. To investigate the putative ecologies of these systems, we study extreme environments on Earth. Several locations on our planet provide analog settings to those we have detected or expect to find on neighboring and distant worlds. Whereas, the field of space biology uses the ISS and low gravity analogs to gain insight on how transplanted Earth-evolved organisms will respond to extraterrestrial environments. Modern genomics allows us to chronicle the genetic makeup of such organisms and provides an understanding of how Life adapts to various extreme environments.

1 aO'Rourke, Aubrie1 aZoumplis, Angela1 aWilburn, Paul1 aLee, Michael, D.1 aLee, Zhi1 aVecina, Marissa1 aMercader, Kysha uhttps://www.caister.com/astro02303nas a2200265 4500008004100000245012500041210006900166260001200235520144100247653001901688653002001707653002001727653001901747653002901766100002301795700001801818700001801836700002501854700001901879700001701898700001701915700002001932700002401952856006101976 2020 eng d00aGenetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet0 aGenetic diversity of soil invertebrates corroborates timing esti c08/20203 a

During austral summer field seasons between 1999 and 2018, we sampled at 91 locations throughout southern Victoria Land and along the Transantarctic Mountains for six species of endemic microarthropods (Collembola), covering a latitudinal range from 76.0°S to 87.3°S. We assembled individual mitochondrial cyto-chrome c oxidase subunit 1 (COI) sequences (n = 866) and found high levels of sequence divergence at both small (<10 km) and large (>600 km) spatial scales for four of the six Collembola species. We applied molecular clock estimates and assessed genetic divergences relative to the timing of past glacial cycles, including collapses of the West Antarctic Ice Sheet (WAIS). We found that genetically distinct lineages within three species have likely been isolated for at least 5.54 My to 3.52 My, while the other three species diverged more recently (<2 My). We suggest that Collembola had greater dispersal opportunities under past warmer climates, via flotation along coastal margins. Similarly increased opportunities for dispersal may occur under contemporary climate warming scenarios, which could influence the genetic structure of extant populations. As Collembola are a living record of past landscape evolution within Antarctica, these findings provide biological evidence to support geological and glaciological estimates of historical WAIS dynamics over the last ca. 5 My.

10aclimate change10amicroarthropods10amolecular clock10aphylogeography10aterrestrial biodiversity1 aCollins, Gemma, E.1 aHogg, Ian, D.1 aConvey, Peter1 aSancho, Leopoldo, G.1 aCowan, Don, A.1 aLyons, Berry1 aAdams, Byron1 aWall, Diana, H.1 aGreen, T., G. Allan uhttps://www.pnas.org/content/early/2020/08/19/200792511702540nas a2200289 4500008004100000245012600041210006900167260001200236490000800248520163000256653002101886653001501907653001701922653001501939653002401954653001901978100002101997700002102018700001902039700002402058700001902082700001702101700002402118700001902142700001702161856007202178 2020 eng d00aGeochemistry of aeolian material from the McMurdo Dry Valleys, Antarctica: Insights into Southern Hemisphere dust sources0 aGeochemistry of aeolian material from the McMurdo Dry Valleys An c10/20200 v5473 a

In the Southern Hemisphere, the major sources of dust and other aeolian materials are from Patagonia, South Africa, Australia, and New Zealand. Dust from Patagonia and New Zealand has been identified in ice cores throughout Antarctica, suggesting that during arid and windy periods, such as glacial periods, dust can be entrained and transported onto the continent. However, little information exists on modern Antarctic dust sources, transport, and its role in the Southern Hemisphere dust cycle. We present the first geochemical characterization of aeolian materials collected at five heights (between 5 cm and 100 cm) above the surface in four valleys within the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Our mineralogy data indicate that these materials are primarily derived from local rocks of the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and Granite Harbor Intrusives, with varying contributions of each rock type dependent on the valley location. While major oxide, trace element and rare earth element data show that low elevation and coastal locations (with respect to the Ross Sea) are dominated by local sources, high elevation and inland locations have accumulated both local materials and dust from other distant Southern Hemisphere sources. This far-traveled material may not be accumulating today, but represents a paleo source that is resuspended from the soils. By geochemically “fingerprinting” aeolian materials from the MDV, we can better inform future studies on the transport of materials within Antarctica and between Southern Hemisphere land masses.

10aaeolian material10aAntarctica10amajor oxides10amineralogy10arare earth elements10atrace elements1 aDiaz, Melisa, A.1 aWelch, Susan, A.1 aSheets, J., M.1 aWelch, Kathleen, A.1 aKhan, Alia, L.1 aAdams, Byron1 aMcKnight, Diane, M.1 aCary, Craig, S1 aLyons, Berry uhttps://www.sciencedirect.com/science/article/pii/S0012821X2030404002119nas a2200217 4500008004100000245007600041210006900117260001200186520131800198653001101516653003001527653002801557653002201585653002401607653001201631653001801643100002401661700002101685700002001706856017501726 2020 eng d00aGIS tool to predict photosynthetically active radiation in a Dry Valley0 aGIS tool to predict photosynthetically active radiation in a Dry c04/20203 a

Understanding primary productivity is a core research area of the National Science Foundation's Long-Term Ecological Research Network. This study presents the development of the GIS-based Topographic Solar Photosynthetically Active Radiation (T-sPAR) toolbox for Taylor Valley. It maps surface photosynthetically active radiation using four meteorological stations with ~20 years of data. T-sPAR estimates were validated with ground-truth data collected at Taylor Valley's major lakes during the 2014–15 and 2015–16 field seasons. The average daily error ranges from 0.13 mol photons m-2 day-1 (0.6%) at Lake Fryxell to 3.8 mol photons m-2 day-1 (5.8%) at Lake Hoare. We attribute error to variability in terrain and sun position. Finally, a user interface was developed in order to estimate total daily surface photosynthetically active radiation for any location and date within the basin. T-sPAR improves upon existing toolboxes and models by allowing for the inclusion of a statistical treatment of light attenuation due to cloud cover. The T-sPAR toolbox could be used to inform biological sampling sites based on radiation distribution, which could collectively improve estimates of net primary productivity, in some cases by up to 25%.

10aArcMap10aautomated weather station10adigital elevation model10aice-covered lakes10aMcMurdo Dry Valleys10aR model10aTaylor Valley1 aAcosta, Dimitri, R.1 aDoran, Peter, T.1 aMyers, Madeline uhttps://www.cambridge.org/core/journals/antarctic-science/article/gis-tool-to-predict-photosynthetically-active-radiation-in-a-dry-valley/BD0BE4FF6A8F3DAAF32D69879728707801957nas a2200133 4500008004100000245010200041210006900143260005300212490000900265520146100274100002201735700002401757856004201781 2020 eng d00aGlacial meltwater modeling to simulate lake water budget (1996-2013) in Taylor Valley, Antarctica0 aGlacial meltwater modeling to simulate lake water budget 1996201 aPortland, ORbPortland State Universityc01/20200 vM.S.3 a

The McMurdo Dry Valleys (MDV), the largest ice-free region (4,500 km2) in Antarctica, are a polar desert with an average annual temperature of -18 ̊C. In Taylor Valley, one of the MDV, closed-basin, perennially ice-covered lakes occupy the valley floor. Their water balance is controlled by inflow from glacial meltwater runoff and loss due to sublimation, making them sensitive indicators of climate. In this study, a physically-based model of glacier meltwater and lake ice sublimation is adapted to explain modern (1996 to 2013) lake-level variations. Meltwater model results were improved by the inclusion of MODIS remotely-sensed albedo measurements (E = 0.47; nRMSE = 0.73). After 2008 the meltwater model significantly under-predicted streamflow and only through decreasing albedo by -30% (equivalent to a decrease of -0.18 on average) did the results match observations (E = 0.79; nRMSE = 0.45). This study provides the first estimate of direct (unmeasured) glacier inflow to the lakes, 69%, 73% and 28%, and sublimation loss rates, 0.37 m yr-1, 0.24 m yr-1 and 0.16 m yr-1, for Lakes Bonney, Hoare and Fryxell, respectively. Despite similar meltwater volumes entering Lakes Bonney and Fryxell, the difference in basin hypsometry results in a much faster lake rise at Bonney from 2002-13. If future climate conditions match current (1996-2013) conditions, all lakes will rise through the end of the century.

1 aCross, Julian, M.1 aFountain, Andrew, G uhttps://archives.pdx.edu/ds/psu/3080603683nas a2200997 4500008004100000245008200041210006900123260001200192490000600204520084100210100002601051700001901077700002001096700001401116700002501130700002501155700001701180700001701197700001901214700002601233700002301259700002701282700002301309700002101332700003101353700001801384700002101402700002001423700003001443700001501473700002001488700001901508700002501527700002301552700001901575700002101594700001701615700002201632700002101654700002601675700002301701700001101724700001701735700002201752700002101774700003101795700002401826700002201850700001501872700002201887700001801909700001701927700002501944700002201969700001901991700002702010700001602037700001802053700002202071700003202093700002302125700002302148700002002171700002202191700002002213700002702233700001802260700002102278700001902299700002302318700001502341700002302356700002202379700002402401700002102425700002302446700002102469700001802490700001802508700001902526700001402545700002802559700001702587700002702604856005402631 2020 eng d00aA global database of soil nematode abundance and functional group composition0 aglobal database of soil nematode abundance and functional group  c03/20200 v73 a

As the most abundant animals on earth, nematodes are a dominant component of the soil community. they play critical roles in regulating biogeochemical cycles and vegetation dynamics within and across landscapes and are an indicator of soil biological activity. Here, we present a comprehensive global dataset of soil nematode abundance and functional group composition. This dataset includes 6,825 georeferenced soil samples from all continents and biomes. For geospatial mapping purposes these samples are aggregated into 1,933 unique 1-km pixels, each of which is linked to 73 global environmental covariate data layers. Altogether, this dataset can help to gain insight into the spatial distribution patterns of soil nematode abundance and community composition, and the environmental drivers shaping these patterns.

1 avan den Hoogen, Johan1 aGeisen, Stefan1 aWall, Diana, H.1 aWardle, D1 aTraunspurger, Walter1 ade Goede, Ron, G. M.1 aAdams, Byron1 aAhmad, Wasim1 aFerris, Howard1 aBardgett, Richard, D.1 aBonkowski, Michael1 aCampos-Herrera, Raquel1 aCares, Juvenil, E.1 aCaruso, Tancredi1 aCaixeta, Larissa, de Brito1 aChen, Xiaoyun1 aCosta, Sofia, R.1 aCreamer, Rachel1 aCastro, José, da Cunha e1 aDam, Marie1 aDjigal, Djibril1 aEscuer, Miguel1 aGriffiths, Bryan, S.1 aGutiérrez, Carmen1 aHohberg, Karin1 aKalinkina, Daria1 aKardol, Paul1 aKergunteuil, Alan1 aKorthals, Gerard1 aKrashevska, Valentyna1 aKudrin, Alexey, A.1 aLi, Qi1 aLiang, Wenju1 aMagilton, Matthew1 aMarais, Mariette1 aMartín, José, Antonio Ro1 aMatveeva, Elizaveta1 aMayad, El, Hassan1 aMzough, E.1 aMulder, Christian1 aMullin, Peter1 aNeilson, Roy1 aNguyen, T., A. Duong1 aNielsen, Uffe, N.1 aOkada, Hiroaki1 aRius, Juan, Emilio Pal1 aPan, Kaiwen1 aPeneva, Vlada1 aPellissier, Loïc1 ada Silva, Julio, Carlos Per1 aPitteloud, Camille1 aPowers, Thomas, O.1 aPowers, Kirsten1 aQuist, Casper, W.1 aRasmann, Sergio1 aMoreno, Sara, Sánchez1 aScheu, Stefan1 aSetälä, Heikki1 aSushchuk, Anna1 aTiunov, Alexei, V.1 aTrap, Jean1 aVestergård, Mette1 aVillenave, Cecile1 aWaeyenberge, Lieven1 aWilschut, Rutger1 aWright, Daniel, G.1 aKeith, Aidan, M.1 aYang, Jiue-in1 aSchmidt, Olaf1 aBouharroud, R.1 aFerji, Z.1 avan der Putten, Wim, H.1 aRouth, Devin1 aCrowther, Thomas, Ward uhttps://www.nature.com/articles/s41597-020-0437-302015nas a2200217 4500008004100000245016100041210006900202260001200271490000700283520122000290653001501510653001801525653002301543653003901566653001601605653003001621100002301651700002901674700002401703856007001727 2020 eng d00aGlycerol is an osmoprotectant in two Antarctic Chlamydomonas species from an ice-covered saline lake and is synthesized by an unusual bidomain enzyme0 aGlycerol is an osmoprotectant in two Antarctic IChlamydomonasI s c08/20200 v113 a

Glycerol, a compatible solute, has previously been found to act as an osmoprotectant in some marine Chlamydomonas species and several species of Dunaliella from hypersaline ponds. Recently, Chlamydomonas reinhardtii and Dunaliella salina were shown to make glycerol with an unusual bidomain enzyme, which appears to be unique to algae, that contains a phosphoserine phosphatase and glycerol-3-phosphate dehydrogenase. Here we report that two psychrophilic species of Chlamydomonas (C. spp. UWO241 and ICE-MDV) from Lake Bonney, Antarctica also produce high levels of glycerol to survive in the lake’s saline waters. Glycerol concentration increased linearly with salinity and at 1.3 M NaCl, exceeded 400 mM in C. sp. UWO241, the more salt-tolerant strain. We also show that both species expressed several isoforms of the bidomain enzyme. An analysis of one of the isoforms of C. sp. UWO241 showed that it was strongly upregulated by NaCl and is thus the likely source of glycerol. These results reveal another adaptation of the Lake Bonney Chlamydomonas species that allow them to survive in an extreme polar environment.

10aAntarctica10aChlamydomonas10aglycerol synthesis10aglycerol-3-phosphate dehydrogenase10aLake Bonney10aphosphoserine phosphatase1 aRaymond, James, A.1 aMorgan-Kiss, Rachael, M.1 aStahl-Rommel, Sarah uhttps://www.frontiersin.org/articles/10.3389/fpls.2020.01259/full02262nas a2200145 4500008004100000245013600041210006900177260001200246520154000258100002001798700002301818700002101841700002001862856023401882 2020 eng d00aThe influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting0 ainfluence of environmental microseismicity on detection and inte c07/20203 a

Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as ‘true’ seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.

1 aCarr, Chris, G.1 aCarmichael, J., D.1 aPettit, Erin, C.1 aTruffer, Martin uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/influence-of-environmental-microseismicity-on-detection-and-interpretation-of-smallmagnitude-events-in-a-polar-glacier-setting/E1A441425341F677117509351F3C676302448nas a2200217 4500008004100000245010000041210006900141260001200210490000700222520174400229100001201973700001901985700002702004700002102031700001602052700001702068700002902085700002302114700002102137856007202158 2020 eng d00aMethane production in the oxygenated water column of a perennially ice‐covered Antarctic lake0 aMethane production in the oxygenated water column of a perennial c01/20200 v653 a

Aerobic methane production in aquatic ecosystems impacts the global atmospheric budget of methane, but the extent, mechanism, and taxa responsible for producing this greenhouse gas are not fully understood. Lake Bonney (LB), a perennially ice‐covered Antarctic lake, has cold hypersaline waters underlying an oxygenated freshwater layer. We present temporal methane concentration profiles in LB indicating methane production in the oxygenated (> 200% air saturation) water. Experiments amended with methylphosphonate (MPn) yielded methane generation, suggesting in situ methanogenesis via the carbon‐phosphorus (C‐P) lyase pathway. Enrichment cultures from the lake were used to isolate five bacterial strains capable of generating methane when supplied with MPn as the sole P source. Based on 16S rRNA gene sequencing, the isolates belong to the Proteobacteria (closely related to Marinomonas, Hoeflea, and Marinobacter genera) and Bacteroidetes (Algoriphagus genus). 16S rRNA metagenomic sequencing confirms the presence of these taxa in LB. None of the isolated species were reported to be capable to produce methane. In addition, orthologs of the phosphoenolpyruvate mutase gene (PepM) and methylphosphonate synthase (MPnS), enzymes involved in phosphonate and MPn biosynthesis, were widely spread in the LB shotgun metagenomic libraries; genes related to C‐P lyase pathways (phn gene clusters) were also abundant. 16S rRNA and mcrA genes of anaerobic methanogens were absent in both 16S rRNA and metagenomics libraries. These data reveal that in situ aerobic biological methane production is likely a significant source of methane in LB.

1 aLi, Wei1 aDore, John, E.1 aSteigmeyer, August, J.1 aCho, Yong‐Joon1 aKim, Ok-Sun1 aLiu, Yongqin1 aMorgan-Kiss, Rachael, M.1 aSkidmore, Mark, L.1 aPriscu, John, C. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.1125702112nas a2200229 4500008004100000245006600041210006600107260001200173490000700185520130800192653001901500653001901519653002001538653002301558653001301581100002801594700002201622700002201644700002401666700002301690856016901713 2020 eng d00aModeling present and future ice covers in two Antarctic lakes0 aModeling present and future ice covers in two Antarctic lakes c02/20200 v663 a

Antarctic lakes with perennial ice covers provide the opportunity to investigate in-lake processes without direct atmospheric interaction, and to study their ice-cover sensitivity to climate condi- tions. In this study, a numerical model – driven by radiative, atmospheric and turbulent heat fluxes from the water body beneath the ice cover – was implemented to investigate the impact of climate change on the ice covers from two Antarctic lakes: west lobe of Lake Bonney (WLB) and Crooked Lake. Model results agreed well with measured ice thicknesses of both lakes (WLB – RMSE= 0.11 m over 16 years of data; Crooked Lake – RMSE= 0.07 m over 1 year of data), and had acceptable results with measured ablation data at WLB (RMSE= 0.28 m over 6 years). The differences between measured and modeled ablation occurred because the model does not consider interannual variability of the ice optical properties and seasonal changes of the lake’s thermal structure. Results indicate that projected summer air temperatures will increase the ice-cover annual melting in WLB by 2050, but that the ice cover will remain peren- nial through the end of this century. Contrarily, at Crooked Lake the ice cover becomes ephem- eral most likely due to the increase in air temperatures.

10aclimate change10aenergy balance10aice and climate10aice-sheet modeling10alake ice1 aEcheverría, Sebastián1 aHausner, Mark, B.1 aBambach, Nicolás1 aVicuña, Sebastián1 aSuárez, Francisco uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/modeling-present-and-future-ice-covers-in-two-antarctic-lakes/9306439ADD5492BC05F3BAF0E076B1C302368nas a2200229 4500008004100000245007900041210006900120260001200189520162900201653002401830653001301854653002101867653002001888653001401908653002501922100002401947700002501971700002201996700002302018700002402041856007302065 2020 eng d00aNutrient uptake in the supraglacial stream network of an Antarctic glacier0 aNutrient uptake in the supraglacial stream network of an Antarct c08/20203 a

In polar regions, where many glaciers are cold‐based (frozen to their beds), biological communities on the glacier surface can modulate and transform nutrients, controlling downstream delivery. However, it remains unclear whether supraglacial streams are nutrient sinks or sources and the rates of nutrient processing. In order to test this, we conducted tracer‐injections in three supraglacial streams (62 to 123 m long) on Canada Glacier in the Taylor Valley, of the McMurdo Dry Valleys, Antarctica. We conducted a series of additions including: nitrate (N), N + phosphate (P), N+ P + glucose (C), and N+C. In two reaches, N‐only additions resulted in N uptake. The third reach showed net N release during the N‐only addition, but high N uptake in the N+P addition, indicating P‐limitation or N+P co‐limitation. Co‐injecting C did not increase N‐uptake. Additionally, in these systems at low N concentrations the streams can be a net source of nitrogen. We confirmed these findings using laboratory‐based nutrient incubation experiments on sediment collected from stream channels on Canada Glacier and two other glaciers in the Taylor Valley. Together, these results suggest there is active biological processing of nutrients occurring in these supraglacial streams despite low sediment cover, high flow velocities and cold temperatures, modifying the input signals to proglacial streams. As glaciers world‐wide undergo rapid change, these findings further our understanding of how melt generated on glacier surfaces set the initial nutrient signature for subglacial and downstream environments.

10aMcMurdo Dry Valleys10anitrogen10anutrient tracers10anutrient uptake10asediments10asupraglacial streams1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aSingley, Joel, G.1 aCohen, Matthew, J.1 aWelch, Kathleen, A. uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG00567901899nas a2200133 4500008004100000245012300041210007100164260001200235520137500247100003101622700002101653700002301674856006801697 2020 eng d00aPicocyanobacterial cells in near‐surface air above terrestrial and freshwater substrates in Greenland and Antarctica0 aPicocyanobacterial cells in near‐surface air above terrestrial a c03/20203 a

Bioaerosols are an important component of the total atmospheric aerosol load, with implications for human health, climate feedbacks, and the distribution and dispersal of microbial taxa. Bioaerosols are sourced from marine, freshwater, and terrestrial surfaces, with different mechanisms potentially responsible for releasing biological particles from these substrates. Little is known about the production of freshwater and terrestrial bioaerosols in polar regions. We used portable collection devices to test for the presence of picocyanobacterial aerosols above freshwater and soil substrates in the southwestern Greenland tundra and the McMurdo Dry Valleys of Antarctica. We show that picocyanobacterial cells are present in the near‐surface air at concentrations ranging from 2,431 to 28,355 cells m^−3 of air, with no significant differences among substrates or between polar regions. Our concentrations are lower than those measured using the same methods in temperate ecosystems. We suggest that aerosolization is an important process linking terrestrial and aquatic ecosystems in these polar environments, and that future work is needed to explore aerosolization mechanisms and taxon‐specific aerosolization rates. Our study is a first step toward understanding the production of bioaerosols in extreme environments dominated by microbial life.

1 aTrout‐Haney, Jessica, V.1 aHeindel, Ruth, C1 aVirginia, Ross, A. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/1758-2229.1283202051nas a2200253 4500008004100000245010800041210006900149260001200218520110900230653001201339653001401351653002401365653001701389653001901406653001701425100002401442700002501466700002201491700002001513700002101533700002101554700001601575856020601591 2020 eng d00aRemote characterization of photosynthetic communities in the Fryxell basin of Taylor Valley, Antarctica0 aRemote characterization of photosynthetic communities in the Fry c03/20203 a

We investigate the spatial distribution, spectral properties and temporal variability of primary producers (e.g. communities of microbial mats and mosses) throughout the Fryxell basin of Taylor Valley, Antarctica, using high-resolution multispectral remote-sensing data. Our results suggest that photosynthetic communities can be readily detected throughout the Fryxell basin based on their unique near-infrared spectral signatures. Observed intra- and inter-annual variability in spectral signatures are consistent with short-term variations in mat distribution, hydration and photosynthetic activity. Spectral unmixing is also implemented in order to estimate mat abundance, with the most densely vegetated regions observed from orbit correlating spatially with some of the most productive regions of the Fryxell basin. Our work establishes remote sensing as a valuable tool in the study of these ecological communities in the McMurdo Dry Valleys and demonstrates how future scientific investigations and the management of specially protected areas could benefit from these tools and techniques.

10aecology10ahydrology10aMcMurdo Dry Valleys10amicrobiology10aremote sensing10aspectroscopy1 aSalvatore, Mark, R.1 aBorges, Schuyler, R.1 aBarrett, John, E.1 aSokol, Eric, R.1 aStanish, Lee, F.1 aPower, Sarah, N.1 aMorin, Paul uhttps://www.cambridge.org/core/journals/antarctic-science/article/remote-characterization-of-photosynthetic-communities-in-the-fryxell-basin-of-taylor-valley-antarctica/8576F6BB1BCFDCA8409F5EA96CA00C6F01902nas a2200181 4500008004100000245011100041210006900152260003900221490000900260520124000269653001901509653002401528653002601552653001801578100002601596700002901622856006901651 2020 eng d00aResponse of microbial communities to climatic disturbances in Lake Bonney, McMurdo Dry Valleys, Antarctica0 aResponse of microbial communities to climatic disturbances in La aOxford, OHbMiami Universityc20200 vM.S.3 a

The McMurdo Dry Valleys is a polar desert ecosystem which composes the largest ice-free area in Antarctica, with the exception of perennially ice-covered lakes and ponds. The lakes in the valleys are the only landscape unit that support metabolic activity year-round. Recent increases in air temperature and solar radiation have led to a chain of disturbances altering the environmental conditions of these lakes. In this study, we test the impact of climatic disturbances on microbial communities in Lake Bonney, one of the lakes in the MDV. Through an integrated approach of combining field studies on natural communities in the lake (in situ) and laboratory experiments on algal isolates (ex situ), this study will attempt to understand how phytoplankton, eukaryal and bacterial communities respond to simulated disturbances. Results from the in situ experiments showed that the moat is a unique and stressful environment for under-ice communities and that under-ice shallow communities are highly sensitive to climatic disturbances. The ex situ experiments showed that certain phytoplankton species, like the chlorophytes, are more resistant to environmental alterations and thus will outcompete other phytoplankton species.

10aclimate change10aMcMurdo Dry Valleys10amicrobial communities10aphytoplankton1 aSherwell, Shasten, S.1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami159595868836487702115nas a2200181 4500008004100000245013800041210006900179260001200248520140900260653001501669653001701684653003601701653002901737653004501766100002601811700002001837856007601857 2020 eng d00aThe rise of technocratic environmentalism: the United States, Antarctica, and the globalisation of the environmental impact statement0 arise of technocratic environmentalism the United States Antarcti c05/20203 a

Environmental impact statements (EISs), and the related environmental impact assessments (EIAs) which precede them, have become central elements of environmental management, governance, and policy worldwide since their introduction in the United States in 1970. Assessing environmental impact has a particular force and centrality within modern Antarctic environmental management and governance too. This article investigates the ways in which the United States used EISs and EIAs in Antarctica between 1970 and 1982 – during their first decade of existence in US law and during a geopolitically and scientifically vibrant decade in Antarctic affairs – as a way of illuminating the broader conceptual and historical aspects of this central, though understudied, environmental governance tool and framework. We historicise and draw attention to the EIS – individually, as a regulatory genre, and as a genre that articulates regional, global and planetary environments – as highly influential and powerful documents demanding attention from environmental historians and historical geographers. We argue that the prominence of EISs in Antarctica arose because they appealed to top-down, process-oriented approaches favoured in Antarctic governance – a technocratic environmentalism – and because of their spatial elements, particularly their tendency to upscaling.

10aAntarctica10aConservation10aEnvironmental impact statements10aEnvironmental protection10aNational Environmental Policy Act (NEPA)1 aAntonello, Alessandro1 aHowkins, Adrian uhttps://www.sciencedirect.com/science/article/abs/pii/S030574882030027X03158nas a2200181 4500008004100000245011200041210006900153260001200222300001200234490000700246520256300253100002402816700002502840700002002865700002102885700002202906856004802928 2020 eng d00aThe seasonal evolution of albedo across glaciers and the surrounding landscape of Taylor Valley, Antarctica0 aseasonal evolution of albedo across glaciers and the surrounding c03/2020 a769-7880 v143 a

The McMurdo Dry Valleys (MDVs) of Antarctica are a polar desert ecosystem consisting of alpine glaciers, ice-covered lakes, streams, and expanses of vegetation-free rocky soil. Because average summer temperatures are close to 0 ∘C, the MDV ecosystem in general, and glacier melt dynamics in particular, are both closely linked to the energy balance. A slight increase in incoming radiation or change in albedo can have large effects on the timing and volume of meltwater. However, the seasonal evolution or spatial variability of albedo in the valleys has yet to fully characterized. In this study, we aim to understand the drivers of landscape albedo change within and across seasons. To do so, a box with a camera, GPS, and shortwave radiometer was hung from a helicopter that flew transects four to five times a season along Taylor Valley. Measurements were repeated over three seasons. These data were coupled with incoming radiation measured at six meteorological stations distributed along the valley to calculate the distribution of albedo across individual glaciers, lakes, and soil surfaces. We hypothesized that albedo would decrease throughout the austral summer with ablation of snow patches and increasing sediment exposure on the glacier and lake surfaces. However, small snow events (<6 mm water equivalent) coupled with ice whitening caused spatial and temporal variability of albedo across the entire landscape. Glaciers frequently followed a pattern of increasing albedo with increasing elevation, as well as increasing albedo moving from east to west laterally across the ablation zone. We suggest that spatial patterns of albedo are a function of landscape morphology trapping snow and sediment, longitudinal gradients in snowfall magnitude, and wind-driven snow redistribution from east to west along the valley. We also compare our albedo measurements to the MODIS albedo product and found that overall the data have reasonable agreement. The mismatch in spatial scale between these two datasets results in variability, which is reduced after a snow event due to albedo following valley-scale gradients of snowfall magnitude. These findings highlight the importance of understanding the spatial and temporal variability in albedo and the close coupling of climate and landscape response. This new understanding of landscape albedo can constrain landscape energy budgets, better predict meltwater generation on from MDV glaciers, and how these ecosystems will respond to changing climate at the landscape scale.

1 aBergstrom, Anna, J.1 aGooseff, Michael, N.1 aMyers, Madeline1 aDoran, Peter, T.1 aCross, Julian, M. uhttps://www.the-cryosphere.net/14/769/2020/02038nas a2200205 4500008004100000245010100041210006900142260001200211520136000223653001501583653001801598653002201616653001701638653001301655653002201668100002501690700001901715700001701734856008101751 2020 eng d00aShotgun metagenomics reveal a diverse assemblage of protists in a model Antarctic soil ecosystem0 aShotgun metagenomics reveal a diverse assemblage of protists in  c08/20203 a

The soils of the McMurdo Dry Valleys (MDV) of Antarctica are established models for understanding fundamental processes in soil ecosystem functioning (e.g. ecological tipping points, community structuring, and nutrient cycling) because the extreme physical environment drastically reduces biodiversity and ecological complexity. Understanding the functioning of MDV soils requires in‐depth knowledge of the diversity of MDV soil species. Protists, which contribute significantly to soil ecosystem functioning worldwide, remain poorly characterized in the MDV. To better assess the diversity of MDV protists, we performed shotgun metagenomics on 18 sites representing a variety of landscape features and edaphic variables. Our results show MDV soil protists are diverse at both the genus (155 of 281 eukaryote genera) and family (120) levels, but comprise only 6% of eukaryotic reads. Protists are structured by moisture, total N, and distance from the local coast, and possess limited richness in arid (<5% moisture) and at high elevation sites, known drivers of communities in the MDV. High relative diversity and broad distribution of protists in our study promotes these organisms as key members of MDV soil microbiomes and the MDV as a useful system for understanding the contribution of soil protists to the structure of soil microbiomes.

10aAntarctica10aextremophiles10afunctional groups10ametagenomics10aprotozoa10asoil microbiology1 aThompson, Andrew, R.1 aGeisen, Stefan1 aAdams, Byron uhttps://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.1519802966nas a2200205 4500008004100000245011200041210006900153260001200222490000600234520228000240100002102520700002202541700002302563700002602586700002102612700001502633700002402648700001702672856007102689 2020 eng d00aSilicon isotopes reveal a non-glacial source of silicon to Crescent Stream, McMurdo Dry Valleys, Antarctica0 aSilicon isotopes reveal a nonglacial source of silicon to Cresce c06/20200 v83 a

In high latitude environments, silicon is supplied to river waters by both glacial and non-glacial chemical weathering. The signal of these two end-members is often obscured by biological uptake and/or groundwater input in the river catchment. McMurdo Dry Valleys streams in Antarctica have no deep groundwater input, no connectivity between streams and no surface vegetation cover, and thus provide a simplified system for us to constrain the supply of dissolved silicon (DSi) to rivers from chemical weathering in a glacial environment. Here we report dissolved Si concentrations, germanium/silicon ratios (Ge/Si) and silicon isotope compositions (δ30SiDSi) in Crescent Stream, McMurdo Dry Valleys for samples collected between December and February in the 2014−2015, 2015−2016, and 2016−2017 austral seasons. The δ30SiDSi compositions and DSi concentrations are higher than values reported in wet-based glacial meltwaters, and form a narrow cluster within the range of values reported for permafrost dominated Arctic Rivers. High δ30SiDSi compositions, ranging from +0.90‰ to +1.39‰, are attributed to (i) the precipitation of amorphous silica during freezing of waters in isolated pockets of the hyporheic zone in the winter and the release of Si from unfrozen pockets during meltwater-hyporheic zone exchange in the austral summer, and (ii) additional Si isotope fractionation via long-term Si uptake in clay minerals and seasonal Si uptake into diatoms superimposed on this winter-derived isotope signal. There is no relationship between δ30SiDSi compositions and DSi concentrations with seasonal and daily discharge, showing that stream waters contain DSi that is in equilibrium with the formation of secondary Si minerals in the hyporheic zone. We show that δ30SiDSi compositions can be used as tracers of silicate weathering in the hyporheic zone and possible tracers of freeze-thaw conditions in the hyporheic zone. This is important in the context of the ongoing warming in McMurdo Dry Valleys and the supply of more meltwaters to the hyporheic zone of McMurdo Dry Valley streams.

1 aHirst, Catherine1 aOpfergelt, Sophie1 aGaspard, François1 aHendry, Katharine, R.1 aHatton, Jade, E.1 aWelch, Sue1 aMcKnight, Diane, M.1 aLyons, Berry uhttps://www.frontiersin.org/articles/10.3389/feart.2020.00229/full02674nas a2200253 4500008004100000245007700041210006900118260001200187490000600199520187800205100002102083700002602104700002102130700002202151700001902173700002502192700002102217700002202238700001702260700002302277700002502300700002402325856007102349 2020 eng d00aSilicon isotopic composition of dry and wet-based glaciers in Antarctica0 aSilicon isotopic composition of dry and wetbased glaciers in Ant c07/20200 v83 a

Glaciers and ice sheets export significant amounts of silicon (Si) to downstream ecosystems, impacting local and potentially global biogeochemical cycles. Recent studies have shown Si in Arctic glacial meltwaters to have an isotopically distinct signature when compared to non-glacial rivers. This is likely linked to subglacial weathering processes and mechanochemical reactions. However, there are currently no silicon isotope (δ30Si) data available from meltwater streams in Antarctica, limiting the current inferences on global glacial silicon isotopic composition and its drivers. To address this gap, we present dissolved silicon (DSi), δ30SiDSi, and major ion data from meltwater streams draining a polythermal glacier in the region of the West Antarctic Peninsula (WAP; King George Island) and a cold-based glacier in East Antarctica [Commonwealth Stream, McMurdo Dry Valleys (MDV)]. These data, alongside other global datasets, improve our understanding of how contrasting glacier thermal regime can impact upon Si cycling and therefore the δ30SiDSi composition. We find a similar δ30SiDSi composition between the two sites, with the streams on King George Island varying between -0.23 and +1.23‰ and the Commonwealth stream varying from -0.40 to +1.14‰. However, meltwater streams in King George Island have higher DSi concentrations, and the two glacial systems exhibit opposite DSi – δ30SiDSi trends. These contrasts likely result from differences in weathering processes, specifically the role of subglacial processes (King George Island) and, supraglacial processes followed by in-stream weathering in hyporheic zones (Commonwealth Stream). These findings are important when considering likely changes in nutrient fluxes from Antarctic glaciers under climatic warming scenarios and consequent shifts in glacial thermal regimes.

1 aHatton, Jade, E.1 aHendry, Katharine, R.1 aHirst, Catherine1 aOpfergelt, Sophie1 aHenkel, Susann1 aSilva-Busso, Adrián1 aWelch, Susan, A.1 aWadham, Jemma, L.1 aLyons, Berry1 aBagshaw, Elizabeth1 aStaubwasser, Michael1 aMcKnight, Diane, M. uhttps://www.frontiersin.org/articles/10.3389/feart.2020.00286/full01789nas a2200205 4500008004100000245008500041210006900126260001200195520112400207653001601331653001801347653001001365653001501375653001601390100001901406700002101425700002201446700002101468856009401489 2020 eng d00aSubglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica0 aSubglacial brine flow and windinduced internal waves in Lake Bon c02/20203 a

Brine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

10aDry valleys10ahypersalinity10alakes10aproglacial10atemperature1 aLawrence, Jade1 aDoran, Peter, T.1 aWinslow, Luke, A.1 aPriscu, John, C. uhttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S095410202000003602357nas a2200205 4500008004100000245012200041210006900163260001200232490000700244520163100251100002501882700002701907700001801934700002501952700002501977700002902002700002502031700002302056856007202079 2020 eng d00aVertical stratification and stability of biogeochemical processes in the deep saline waters of Lake Vanda, Antarctica0 aVertical stratification and stability of biogeochemical processe c03/20200 v653 a

Lake Vanda is a permanently ice-covered lake in the McMurdo Dry Valleys of Antarctica. Its bottom waters remain stratified year-round because of a strong salinity-driven density gradient. We have assessed spatial patterns in and relationships between major biogeochemical processes in the water column of Lake Vanda. Samples were collected in the austral summers of 2008 and 2011 to measure concentrations of metabolites associated with a suite of biogeochemical processes across the deep salinity gradient. The shapes of the resulting geochemical profiles were consistent between 2008 and 2011. Metabolite production and consumption rates were estimated using a reactive transport model based on the assumption that vertical diffusion was the only activephysical transport process. We validated this model for nitrification by using stable isotope incubations to show that this process was only active at depths predicted by the model. No nitrification activity was observed at 68 m depth in spite of overlapping oxygen and ammonium gradients. We attribute this lack of activity to the competitive inhibition of ammonia monooxygenase by methane. Net nitrous oxide and nitrate consumption were observed in the oxic water column, providing evidence of aerobic denitrification. The depth of maximum net oxygen production did not coincide with the deep chlorophyll maxima (at 59.3, 63, and 68.2 m) measured in the same profile. Finally, the integrated sulfide oxidation rate was high compared with other oxidation processes, indicating that sulfide was an important electron donor for the water column microbial community.

1 aSchutte, Charles, A.1 aSamarkin, Vladimir, A.1 aPeters, Brian1 aMadigan, Michael, T.1 aBowles, Marshall, W.1 aMorgan-Kiss, Rachael, M.1 aCasciotti, Karen, L.1 aJoye, Samantha, B. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.1132702684nas a2200265 4500008004100000022001400041245014900055210006900204260001200273490000600285520185300291653001502144653002502159653000902184653001802193653001702211100001502228700001802243700001602261700001202277700001402289700002102303700002902324856006502353 2019 eng d a0166-859500aThe Antarctic psychrophiles Chlamydomonas spp. UWO241 and ICE-MDV exhibit differential restructuring of photosystem I in response to iron0 aAntarctic psychrophiles iChlamydomonasi spp UWO241 and ICEMDV ex c02/20190 v93 a

Chlamydomonas sp. UWO241 is a psychrophilic alga isolated from the deep photic zone of a perennially ice-covered Antarctic lake (east lobe Lake Bonney, ELB). Past studies have shown that C. sp. UWO241 exhibits constitutive downregulation of photosystem I (PSI) and high rates of PSI-associated cyclic electron flow (CEF). Iron levels in ELB are in the nanomolar range leading us to hypothesize that the unusual PSI phenotype of C. sp. UWO241 could be a response to chronic Fe-deficiency. We studied the impact of Fe availability in C. sp. UWO241, a mesophile, C. reinhardtii SAG11-32c, as well as a psychrophile isolated from the shallow photic zone of ELB, Chlamydomonas sp. ICE-MDV. Under Fe-deficiency, PsaA abundance and levels of photooxidizable P700 (ΔA820/A820) were reduced in both psychrophiles relative to the mesophile. Upon increasing Fe, C. sp. ICE-MDV and C. reinhardtii exhibited restoration of PSI function, while C. sp. UWO241 exhibited only moderate changes in PSI activity and lacked almost all LHCI proteins. Relative to Fe-excess conditions (200 μM Fe2+), C. sp. UWO241 grown in 18 μM Fe2+ exhibited downregulation of light harvesting and photosystem core proteins, as well as upregulation of a bestrophin-like anion channel protein and two CEF-associated proteins (NdsS, PGL1). Key enzymes of starch synthesis and shikimate biosynthesis were also upregulated. We conclude that in response to variable Fe availability, the psychrophile C. sp. UWO241 exhibits physiological plasticity which includes restructuring of the photo-chemical apparatus, increased PSI-associated CEF, and shifts in downstream carbon metabolism toward storage carbon and secondary stress metabolites.

10aAntarctica10aCyclic electron flow10aIron10aPhotosystem I10aPsychrophile1 aCook, Greg1 aTeufel, Amber1 aKalra, Isha1 aLi, Wei1 aWang, Xin1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/article/10.1007/s11120-019-00621-002353nas a2200397 4500008004100000245012200041210006900163260001200232490000600244520115100250100002101401700002501422700002101447700002101468700001401489700002201503700001701525700002201542700001701564700002001581700002001601700002401621700002201645700001901667700002401686700002401710700001701734700002301751700002001774700001801794700002401812700002201836700002401858700001901882856005401901 2019 eng d00aBiotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem0 aBiotic interactions are an unexpected yet critical control on th c02/20190 v23 a

Abiotic and biotic factors control ecosystem biodiversity, but their relative contributions remain unclear. The ultraoligotrophic ecosystem of the Antarctic Dry Valleys, a simple yet highly heterogeneous ecosystem, is a natural laboratory well-suited for resolving the abiotic and biotic controls of community structure. We undertook a multidisciplinary investigation to capture ecologically relevant biotic and abiotic attributes of more than 500 sites in the Dry Valleys, encompassing observed landscape heterogeneities across more than 200 km2. Using richness of autotrophic and heterotrophic taxa as a proxy for functional complexity, we linked measured variables in a parsimonious yet comprehensive structural equation model that explained significant variations in biological complexity and identified landscape-scale and fine-scale abiotic factors as the primary drivers of diversity. However, the inclusion of linkages among functional groups was essential for constructing the best-fitting model. Our findings support the notion that biotic interactions make crucial contributions even in an extremely simple ecosystem.

1 aLee, Charles, K.1 aLaughlin, Daniel, C.1 aBottos, Eric, M.1 aCaruso, Tancredi1 aJoy, Kurt1 aBarrett, John, E.1 aBrabyn, Lars1 aNielsen, Uffe, N.1 aAdams, Byron1 aWall, Diana, H.1 aHopkins, D., W.1 aPointing, Steve, B.1 aMcDonald, Ian, R.1 aCowan, Don, A.1 aBanks, Jonathan, C.1 aStichbury, Glen, A.1 aJones, Irfon1 aZawar-Reza, Peyman1 aKaturji, Marwan1 aHogg, Ian, D.1 aSparrow, Ashley, D.1 aStorey, Bryan, C.1 aGreen, T., G. Allan1 aCary, Craig, S uhttps://www.nature.com/articles/s42003-018-0274-502485nas a2200229 4500008004100000245009100041210006900132260001200201490000600213520181500219653001302034653002802047653001102075653001302086653001002099653002102109653002102130653002502151100001702176700002002193856004202213 2019 eng d00aBiotic interactions in experimental Antarctic soil microcosms vary with abiotic stress0 aBiotic interactions in experimental Antarctic soil microcosms va c08/20190 v33 a

Biotic interactions structure ecological communities but abiotic factors affect the strength of these relationships. These interactions are difficult to study in soils due to their vast biodiversity and the many environmental factors that affect soil species. The McMurdo Dry Valleys (MDV), Antarctica, are relatively simple soil ecosystems compared to temperate soils, making them an excellent study system for the trophic relationships of soil. Soil microbes and relatively few species of nematodes, rotifers, tardigrades, springtails, and mites are patchily distributed across the cold, dry landscape, which lacks vascular plants and terrestrial vertebrates. However, glacier and permafrost melt are expected to cause shifts in soil moisture and solutes across this ecosystem. To test how increased moisture and salinity affect soil invertebrates and their biotic interactions, we established a laboratory microcosm experiment (4 community × 2 moisture × 2 salinity treatments). Community treatments were: (1) Bacteria only (control), (2) Scottnema (S. lindsayae + bacteria), (3) Eudorylaimus (E. antarcticus + bacteria), and (4) Mixed (S. lindsayae + E. antarcticus + bacteria). Salinity and moisture treatments were control and high. High moisture reduced S. lindsayae adults, while high salinity reduced the total S. lindsayae population. We found that S. lindsayae exerted top-down control over soil bacteria populations, but this effect was dependent on salinity treatment. In the high salinity treatment, bacteria were released from top-down pressure as S. lindsayae declined. Ours was the first study to empirically demonstrate, although in lab microcosm conditions, top-down control in the MDV soil food web.

10abacteria10abiological interactions10adesert10anematode10apolar10asoil communities10atop-down effects10atrophic interactions1 aShaw, Ashley1 aWall, Diana, H. uhttps://www.mdpi.com/2571-8789/3/3/5702977nas a2200121 4500008004100000245014300041210006900184260005700253490001000310520246100320100002202781856005202803 2019 eng d00aCharacterizing photobioregenerative technology for simulataneous thermal control and air revitalization of spacecraft and surface habitats0 aCharacterizing photobioregenerative technology for simulataneous aBoulder, CObUniversity of Colorado Boulderc11/20190 vPh.D.3 a

Algal photobioreactors have been researched as potential solutions to air revitalization in a spacecraft cabin environment by absorbing CO2 and producing O2 through photosynthesis. This photosynthesis, and consumption of produced biomass, theoretically provides a closed-loop solution for long-duration spaceflight. Addressing multiple spaceflight requirements simultaneously with algae has the potential to reduce launch mass, power and volume of future Environmental Control and Life Support (ECLS) systems. Additionally, inoculating algal culture into a water-based thermal cooling loops (flight-proven standard of active cooling found on the International Space Station (ISS)) could incorporate simultaneous air revitalization and thermal control into a common system. However, this imparts rapid, extreme thermal swings on algal cells not evolved for culture in a transient thermal environment. Therefore, the effect of dynamic thermal environments on the CO2/O2 turnover of algae was characterized to provide a first-order assessment of system feasibility. This research characterizes the effect of dynamic environments, both transient thermal environments and varying levels of CO2 concentration, on metabolic processes of the algal culture. Experiments using Antarctic algal species were included to investigate if cold-acclimated algae are more efficient than Chlorella at CO2/O2 turnover in the active cooling environment. The simultaneous heat and mass transfer coefficients of a nonporous, gas-permeable membrane were characterized, and membrane models developed for future design considerations. A photobioreactor system was designed with considerations for gravity-independence, prototyped, and tested using parameters defined by the ISS cabin environment. A failure modes and effect analysis distilled lessons learned from the previous experiments, which also informs the use of algae for bioregenerative life support. In conclusion, the resulting values from the previous characterization experiments, along with values found in literature, were used to make a first-order mass-balance comparison between current ISS ECLSS and photobioregenerative technologies. This work serves as an initial evaluation of the feasibility for using an algal photobioreactor for simultaneous air revitalization and active thermal control of a spacecraft or surface habitat.

1 aMatula, Emily, E. uhttps://scholar.colorado.edu/asen_gradetds/258/02939nas a2200241 4500008004100000245010800041210006900149260001200218300001100230490000800241520220100249653000902450653001602459653003202475653001302507653001302520100001602533700001802549700001402567700001502581700002902596856007202625 2019 eng d00aCommunity response of microbial primary producers to salinity is primarily driven by nutrients in lakes0 aCommunity response of microbial primary producers to salinity is c12/2019 a1340010 v6963 a

Higher microbial diversity was frequently observed in saline than fresh waters, but the underlying mechanisms remains unknown, particularly in microbial primary producers (MPP). MPP abundance and activity are notably constrained by high salinity, but facilitated by high nutrients. It remains to be ascertained whether and how nutrients regulate the salinity constraints on MPP abundance and community structure. Here we investigated the impact of nutrients on salinity constraints on MPP abundance and diversity in undisturbed lakes with a wide salinity range on the Tibetan Plateau. MPP community was explored using quantitative PCR, terminal restriction fragment length polymorphism and sequencing of cloning libraries targeting form IC cbbL gene. The MPP community structure was sorted by salinity into freshwater (salinity<1‰), saline (1‰ < salinity<29‰) and hypersaline (salinity>29‰) lakes. Furthermore, while MPP abundance, diversity and richness were significantly constrained with increasing salinity, these constraints were mitigated by enhancing total organic carbon (TOC) and total nitrogen (TN) contents in freshwater and saline lakes. In contrast, the MPP diversity increased significantly with the salinity in hypersaline lakes, due to the mitigation of enhancing TOC and TN contents and salt-tolerant MPP taxa. The mitigating effect of nutrients was more pronounced in saline than in freshwater and hypersaline lakes. The MPP compositions varied along salinity, with Betaproteobacteria dominating both the freshwater and saline lakes and Gammaproteobacteria dominating the hypersaline lakes. We concluded that high nutrients could mitigate the salinity constraining effects on MPP abundance, community richness and diversity. Our findings offer a novel insight into the salinity effects on primary producers and highlight the interactive effects of salinity and nutrients on MPP in lakes. These findings can be used as a baseline to illuminate the effects of increased anthropogenic activities altering nutrient dynamics on the global hydrological cycle and the subsequent responses thereof by MPP communities.

10acbbL10alake waters10amicrobial primary producers10anutrient10asalinity1 aYue, Linyan1 aKong, Weidong1 aJi, Mukan1 aLiu, Jinbo1 aMorgan-Kiss, Rachael, M. uhttps://www.sciencedirect.com/science/article/pii/S004896971933978602475nas a2200229 4500008004100000020002200041245008100063210006900144260004400213300001300257520171900270653001201989653002202001653002502023653003102048653001702079100001502096700002102111700002302132700002402155856006602179 2019 eng d a978-3-030-16775-200aComplex Structure but Simple Function in Microbial Mats from Antarctic Lakes0 aComplex Structure but Simple Function in Microbial Mats from Ant aChambSpringer International Publishing a91 - 1203 a

Microbial mats growing under the permanent ice cover of Antarctic lakes occupy an exceptionally low-disturbance regime. Constant temperature, the absence of bioturbation or physical disturbance from wind action or ice formation allow mats to accumulate, as annual growth layers, over many decades or even centuries. In so doing they often assume decimetre scale, three-dimensional morphologies such as elaborate pinnacle structures and conical mounds. Here we combine existing and new information to describe microbial structures in three Antarctic lakes—simple prostrate mats in Lake Hoare, emergent cones in Lake Untersee and elaborate pinnacles in Lake Vanda. We attempt to determine whether structures emerge simply from uncoordinated organism-environment interactions or whether they represent an example of “emergent complexity”, within which some degree of self-organisation occurs to confer a holistic functional advantage to component organisms. While some holistic advantages were evident from the structures—the increase in surface area allows greater biomass and overall productivity and nutrient exchange with overlying water—the structures could also be understood in terms of potential interactions between individuals, their orientation and their environment. The data lack strong evidence of coordinated behaviour directed towards holistic advantages to the structure, though hints of coordinated behaviour are present as non-random distributions of structural elements. The great size of microbial structures in Antarctic lakes, and their relatively simple community composition, makes them excellent models for more focused research on microbial cooperation.

10abiofilm10amicrobial ecology10amicrobial structures10aself-organising structures10astromatolite1 aHawes, Ian1 aSumner, Dawn, Y.1 aJungblut, Anne, D.1 aHurst, Christon, J. uhttps://link.springer.com/chapter/10.1007/978-3-030-16775-2_402367nas a2200205 4500008004100000245011400041210006900155260001200224300001400236490000800250520166200258100002501920700002701945700002801972700002602000700002002026700002002046700002102066856007402087 2019 eng d00aDifferential incorporation of bacteria, organic matter, and inorganic ions into lake ice during ice formation0 aDifferential incorporation of bacteria organic matter and inorga c02/2019 a585 - 6000 v1243 a

The segregation of bacteria, inorganic solutes, and total organic carbon between liquid water and ice during winter ice formation on lakes can significantly influence the concentration and survival of microorganisms in icy systems, and their roles in biogeochemical processes. Our study quantifies the distributions of bacteria and solutes between liquid and solid water phases during progressive freezing. We simulated lake ice formation in mesocosm experiments using water from perennially (Antarctica) and seasonally (Alaska and Montana, USA) ice covered lakes. We then computed concentration factors and effective segregation coefficients, which are parameters describing the incorporation of bacteria and solutes into ice. Experimental results revealed that, contrary to major ions, bacteria were readily incorporated into ice and did not concentrate in the liquid phase. The organic matter incorporated into the ice was labile, amino acid-like material, differing from the humic-like compounds that remained in the liquid phase. Results from a control mesocosm experiment (dead bacterial cells) indicated that viability of bacterial cells did not influence the incorporation of free bacterial cells into ice, but did have a role in the formation and incorporation of bacterial aggregates. Together, these findings demonstrate that bacteria, unlike other solutes, were preferentially incorporated into lake-ice during our freezing experiments, a process controlled mainly by the initial solute concentration of the liquid water source, regardless of cell viability.

1 aSantibáñez, Pamela1 aMichaud, Alexander, B.1 aVick-Majors, Trista, J.1 aD’Andrilli, Juliana1 aChiuchiolo, Amy1 aHand, Kevin, P.1 aPriscu, John, C. uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JG00482501931nas a2200229 4500008004100000245010800041210006900149260001200218490000700230520115400237100002101391700001701412700001701429700002401446700002401470700001601494700001601510700001701526700001501543700002301558856012001581 2019 eng d00aDiurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica0 aDiurnal chemistry of two contrasting stream types Taylor Valley  c06/20190 v983 a

Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.

1 aHarmon, Mark, E.1 aLeslie, D.L.1 aLyons, Berry1 aWelch, Kathleen, A.1 aMcKnight, Diane, M.1 aChudaev, O.1 aKharaka, Y.1 aHarmon, R.S.1 aMillot, R.1 aShouakar-Stash, O. uhttps://www.e3s-conferences.org/articles/e3sconf/abs/2019/24/e3sconf_wri-162018_01020/e3sconf_wri-162018_01020.html02573nas a2200265 4500008004100000022001400041245010400055210006900159260001200228300001400240490000700254520177600261653002002037653002102057653001502078653001702093653002402110653001202134653002502146100001202171700002002183700001602203700002902219856005902248 2019 eng d a0948-305500aDrivers of protistan community autotrophy and heterotrophy in chemically stratified Antarctic lakes0 aDrivers of protistan community autotrophy and heterotrophy in ch c01/2019 a225 - 2390 v823 a

Single-celled, eukaryotic microorganisms, known as protists, are responsible for 2 important, yet opposing, metabolic activities within aquatic food webs. They are major primary producers and highly active predators in marine and fresh water systems. While genomics has accelerated in recent years for this taxonomically diverse group, our understanding of the metabolic capabilities of most protists remains limited. It is also poorly understood how protist trophic mode is affected by biotic and abiotic factors, and therefore it is difficult to predict how events such as global climate change will affect the balance between autotrophic and heterotrophic activities in protist communities. To address open questions regarding how protist metabolic versatility is influenced by their environment, we characterized the potential for carbon fixation versus organic carbon degradation using enzymatic assays (RubisCO and β-D-glucosaminidase, respectively) within the water columns of ice-covered lakes in McMurdo Dry Valleys (MDV), Antarctica. Steep physical and chemical gradients in the water columns, microorganism domination and minimal allochthonous inputs makes the MDV lakes uniquely suited to investigate environment-microbe interactions. Spatial trends in RubisCO and β-D-glucosaminidase activities were lake-specific and vertically stratified within the water columns. Moreover, bottom-up drivers controlling the activity of C-fixation vs. organic C-degradation among the MDV protist communities were distinct between the upper photic vs. the deep, aphotic zones. We conclude that differential controls over major C-cycling enzymes have important implications on the influence of environmental change on the carbon and nutrient cycles in the MDV lakes.

10aAntarctic lakes10aAquatic protists10aAutotrophy10aHeterotrophy10aMcMurdo Dry Valleys10aRubisCO10aβ-D-glucosaminidase1 aLi, Wei1 aDolhi-Binder, J1 aCariani, ZE1 aMorgan-Kiss, Rachael, M. uhttps://www.int-res.com/abstracts/ame/v82/n3/p225-239/02611nas a2200253 4500008004100000245011600041210006900157260001200226520177500238653001202013653002502025653003202050653001402082653002402096100002102120700002202141700002802163700002102191700002302212700002102235700001502256700002302271856006302294 2019 eng d00aEnvironmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica0 aEnvironmental controls on bacteriohopanepolyol profiles of benth c07/20193 a

Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. As a result, the detection of BHT II in the sedimentary record and fluctuations in the relative abundance of BHT II may inform reconstructions of nitrogen cycling and ocean redox changes through the geological record. However, there are uncertainties concerning the sources of BHT II and whether or not BHT II is produced in abundance in non‐marine environments, both of which are pertinent to interpretations of BHT II signatures in sediments. To address these questions, we investigate the BHP composition of benthic microbial mats from Lake Fryxell, Antarctica. Lake Fryxell is a perennially ice‐covered lake with a sharp oxycline in a density‐stabilized water column. We describe the diversity and abundance of BHPs in benthic microbial mats across a transect from oxic to anoxic conditions. Generally, BHP abundances and diversity vary with the morphologies of microbial mats, which were previously shown to reflect local environmental conditions, such as irradiance and oxygen and sulfide concentrations. BHT II was identified in mats that exist within oxic to anoxic portions of the lake. However, anammox bacteria have yet to be identified in Lake Fryxell. We examine our results in the context of BHPs as biomarkers in modern and ancient environments.

10aanammox10abacteriohopanepolyol10abacteriohopanetetrol isomer10abiomarker10aMcMurdo Dry Valleys1 aMatys, Emily, D.1 aMackey, Tyler, J.1 aGrettenberger, Christen1 aMueller, Elliott1 aJungblut, Anne, D.1 aSumner, Dawn, Y.1 aHawes, Ian1 aSummons, Roger, E. uhttps://onlinelibrary.wiley.com/doi/full/10.1111/gbi.1235302504nas a2200229 4500008004100000245007200041210006700113260001200180490000800192520178600200100001701986700002202003700002202025700002402047700001502071700002902086700002502115700002102140700002002161700002002181856007302201 2019 eng d00aThe Geochemistry of Englacial Brine From Taylor Glacier, Antarctica0 aGeochemistry of Englacial Brine From Taylor Glacier Antarctica c03/20190 v1243 a

Blood Falls is a hypersaline, iron‐rich discharge at the terminus of the Taylor Glacier in the McMurdo Dry Valleys, Antarctica. In November 2014, brine in a conduit within the glacier was penetrated and sampled using clean‐entry techniques and a thermoelectric melting probe called the IceMole. We analyzed the englacial brine sample for filterable iron (fFe), total Fe, major cations and anions, nutrients, organic carbon, and perchlorate. In addition, aliquots were analyzed for minor and trace elements and isotopes including δD and δ18O of water, δ34S and δ18O of sulfate, 234U, 238U, δ11B, 87Sr/86Sr, and δ81Br. These measurements were made in order to (1) determine the source and geochemical evolution of the brine and (2) compare the chemistry of the brine to that of nearby hypersaline lake waters and previous supraglacially sampled collections of Blood Falls outflow that were interpreted as end‐member brines. The englacial brine had higher Cl− concentrations than the Blood Falls end‐member outflow; however, other constituents were similar. The isotope data indicate that the water in the brine is derived from glacier melt. The H4SiO4 concentrations and U and Sr isotope suggest a high degree of chemical weathering products. The brine has a low N:P ratio of ~7.2 with most of the dissolved inorganic nitrogen in the form of NH4+. Dissolved organic carbon concentrations are similar to end‐member outflow values. Our results provide strong evidence that the original source of solutes in the brine was ancient seawater, which has been modified with the addition of chemical weathering products.

1 aLyons, Berry1 aMikucki, Jill, A.1 aGerman, Laura, A.1 aWelch, Kathleen, A.1 aWelch, Sue1 aGardner, Christopher, B.1 aTulaczyk, Slawek, M.1 aPettit, Erin, C.1 aKowalski, Julia1 aDachwald, Bernd uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG00441102216nas a2200193 4500008004100000245012200041210006900163260001200232520155300244653001501797653001701812653002101829653002901850653001801879100002101897700001501918700001701933856007201950 2019 eng d00aThe geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances0 ageochemistry of glacial deposits in Taylor Valley Antarctica Com c05/20193 a

Wet-based glacial deposits have been used traditionally as an analog for upper continental crust (UCC) abundances. To provide more information on the validity of using glacial deposits from wet-based glaciers, samples deposited by the dry-based polar glaciers located in Taylor Valley, Antarctica, were collected. Stream channel sediments, comprised of igneous, metamorphic, and sedimentary rocks initially deposited as glacial tills by polar glaciers, were analyzed by XRF, ICP-MS, and SEM. Based on the Chemical Index of Alteration values and A–CN–K ternary diagram, there are low levels of chemical weathering in these tills. Additionally, major and trace element geochemical data are compared to the average UCC values. The observed discrepancies between the mean UCC and Antarctic samples develop from the existence of mafic components, most likely the McMurdo Volcanic Group and Ferrar Dolerite, being present in the Taylor Valley tills. Even though the mafic material typically comprises 3–7% of the till, the volcanic rocks have a significant influence on the tills’ bulk geochemistry. The existence of this mafic fraction in the dry-based glacial tills results from the reduced rate of weathering, as compared to wet-based glaciers. Geochemical analyses of the dry-based glacial tills in polar deserts, such as those found in Taylor Valley, may provide a better representative composition of the original material than wet-based glaciers and need to be incorporated into upper continental crust calculations.

10aAntarctica10ageochemistry10aglacial deposits10apolar dry-based glaciers10aTaylor Valley1 aDowling, Carolyn1 aWelch, Sue1 aLyons, Berry uhttps://www.sciencedirect.com/science/article/pii/S088329271930124603820nas a2200217 4500008004100000245015200041210006900193260004000262490000800302520300700310653003203317653003303349653001703382653002403399653002103423653002503444653003903469100002503508700002103533856004803554 2019 eng d00aHeterotrophic protists as useful models for studying microbial food webs in a model soil ecosystem and the universality of complex unicellular life0 aHeterotrophic protists as useful models for studying microbial f aProvo, UTbBrigham Young University0 vPhD3 a

Heterotrophic protists, consisting largely of the Cercozoa, Amoebozoa, Ciliophora, Discoba and some Stramenopiles, are a poorly characterized component of life on Earth. They play an important ecological role in soil communities and provide key insights into the nature of one of life’s most enigmatic evolutionary transitions: the development of the complex unicell. Soil ecosystems are crucial to the functioning of global biogeochemical cycles (e.g. carbon and nitrogen) but are at risk of drastic change from anthropogenic climate change. Heterotrophic protists are the primary regulators of bacterial diversity in soils and as such play integral roles in biogeochemical cycling, nutrient mobilization, and trophic cascades in food webs under stress. Understanding the nature of these changes requires examining the rates, diversity, and resiliency of interactions that occur between soil organisms. However, soils are the most taxonomically diverse ecosystems on Earth and disentangling the complexities of dynamic and varied biotic interactions in them requires a unique model system. The McMurdo Dry Valleys of Antarctica, one of the harshest terrestrial environments on Earth, serve as a model soil ecosystem owing to their highly reduced biological diversity. Exploring the functioning of heterotrophic protists in these valleys provides a way to test the applicability of this model system to other soil food webs. However, very little is known about their taxonomic diversity, which is a strong predictor of function. Therefore, I reviewed the Antarctic literature to compile a checklist of all known terrestrial heterotrophic protists in Antarctica. I found significant geographical, methodological, and taxonomic biases and outlined how to address these in future research programs. I also conducted a molecular survey of whole soil communities using 18 shotgun metagenomes representing major landscape features of the McMurdo Dry Valleys. The results revealed the dominance of Cercozoa and point to an Antarctic heterotrophic protist soil community that is taxonomically diverse and reflects the structure and composition of communities at lower latitudes. To investigate whether biotic interactions or abiotic factors were a larger driver for Antarctic heterotrophic protists, I conducted variation partitioning using environmental data (e.g. moisture, pH and electrical conductivity). Biotic variables were more significant and accounted for more of the variation than environmental variables. Taken together, it is clear that heterotrophic protists play key ecological roles in this ecosystem. Deeper insights into the ecology of these organisms in the McMurdo Dry Valleys also have implications for the search for complex unicellular life in our universe. I discuss the theoretical underpinnings of searching for these forms of life outside of Earth, conclude that they are likely to occur, and postulate how future missions could practically search for complex unicells.

10aheterotrophic soil protists10akey evolutionary innovations10alife on Mars10aMcMurdo Dry Valleys10anetwork analysis10ashotgun metagenomics10auniversal complex unicellular life1 aThompson, Andrew, R.1 aAdams, Byron, J. uhttps://www.proquest.com/docview/231063197702639nas a2200301 4500008004100000245008400041210006900125260001200194520169800206653001501904653002101919653002401940653002701964653001301991100002102004700002602025700001702051700001602068700002502084700002502109700001702134700002202151700002302173700002002196700002402216700002402240856007302264 2019 eng d00aThe hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica0 ahydroecology of an ephemeral wetland in the McMurdo Dry Valleys  c11/20193 a

The McMurdo Dry Valleys (MDV) is a polar desert on the coast of East Antarctica where ephemeral wetlands become hydrologically active during warm and sunny summers when sub‐surface flows are generated from melting snowfields. To understand the structure and function of polar wetland ecosystems, we investigated the hydroecology of one such wetland, the Wormherder Creek wetland, during the warm and sunny summer of 2008 – 2009, when the wetland was hydrologically reactivated. Conservative tracer (LiCl) was injected for a 2‐hour period into a stream above the wetland to determine flow path orientations and hydrologic residence times. Tracer results indicated that surface water is rapidly exchanged with wetland groundwater and wetland residence times may exceed two austral summers. Major ion concentrations were uniform in samples from surface water and shallow groundwater throughout the wetland. Microbial mats in the wetland had high autotrophic index values (the ratios of chlorophyll a [Chl‐a]/ash‐free dry mass [AFDM]), ranging from 9‐38 μg Chl‐a/mg AFDM, indicative of actively photosynthesizing mat communities. The diatom communities in the mats were relatively uniform compared to those in mats from regularly flowing MDV streams, with four endemic and one widespread diatom taxa of the genus Luticola accounting for an average of 86% of the community. These results indicate that the hydrologic characteristics of the wetland contribute to uniform geochemical conditions. In turn, uniform geochemical conditions may explain the high autotrophic index values of the microbial mats and relatively low spatial variation of the diatom community.

10aAntarctica10adesert hydrology10adiatom biodiversity10ahyporheic interactions10awetlands1 aWlostowski, Adam1 aSchulte, Nicholas, O.1 aAdams, Byron1 aBall, Becky1 aEsposito, Rhea, M.M.1 aGooseff, Michael, N.1 aLyons, Berry1 aNielsen, Uffe, N.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aWelch, Kathleen, A.1 aMcKnight, Diane, M. uhttps://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG00515302158nas a2200229 4500008004100000245010300041210006900144260003900213490000900252520137700261653001001638653002801648653003801676653002401714653001901738653001801757653002301775653001601798100001601814700002901830856006901859 2019 eng d00aImpact of simulated polar night on Antarctic mixotrophic and strict photoautotrophic phytoplankton0 aImpact of simulated polar night on Antarctic mixotrophic and str aOxford, OHbMiami Universityc20180 vM.S.3 a

Phytoplankton in polar regions experience long periods of continuous darkness annually during the polar night. Due to difficulties in performing field work during this period, it is largely unknown how phytoplankton endure this extreme transition from 24-hour daylight in the fall to several months of total darkness in the austral winter. The primary goal of this study was to compare physiological and photosynthetic responses of several Antarctic phytoplankton of variable trophic abilities (pure photosynthetic vs. mixotrophic) to simulated polar night conditions, including the transition seasons before and after winter. Two distinct responses were observed to extended darkness: (1) strict photoautotrophs (Chlamydomonas sp. ICE-MDV and Chlamydomonas sp. UWO241) exhibited functional downregulation their photosynthetic processes in the winter, followed by a lag phase of several days during mimicked spring, and (2) mixotrophs (Isochrysis sp. MDV and Geminigera cryophila) maintained functional photosynthetic apparatus, increased heterotrophy through the winter, and exhibited immediate growth upon return to light incubation. These differing responses to mimicked polar night conditions could represent two different strategies for surviving the long period of darkness in the phytoplankton’s natural environment.

10aalgae10aAntarctic phytoplankton10achlorophyll fluorescence analysis10aMcMurdo Dry Valleys10aPhotosynthesis10aphytoplankton10apolar microbiology10apolar night1 aCariani, ZE1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami154720459996908102449nas a2200169 4500008004100000245008400041210006900125260001200194490000700206520189300213100003002106700002102136700002202157700001502179700002302194856006202217 2019 eng d00aIn a PICL: The sedimentary deposits and facies of perennially ice-covered lakes0 aIn a PICL The sedimentary deposits and facies of perennially ice c04/20190 v663 a

Perennially ice‐covered lakes can have significantly different facies than open‐water lakes because sediment is transported onto the ice, where it accumulates, and sand grains preferentially melt through to be deposited on the lake floor. To characterize the facies in these lakes, sedimentary deposits from five Antarctic perennially ice‐covered lakes were described using lake‐bottom observations, underwater video and images, and sediment cores. One lake was dominated by laminated microbial mats and mud (derived from an abutting glacier), with disseminated sand and rare gravel. The other four lakes were dominated by laminated microbial mats and moderately well to moderately sorted medium to very coarse sand with sparse granules and pebbles; they contained minor interstitial or laminated mud (derived from streams and abutting glaciers). The sand was disseminated or localized in mounds and 1 m to more than 10 m long elongate ridges. Mounds were centimetres to metres in diameter; conical, elongate or round in shape; and isolated or deposited near or on top of one another. Sand layers in the mounds had normal, inverse, or no grading. Nine mixed mud and sand facies were defined for perennially ice‐covered lakes based on the relative proportion of mud to sand and the style of sand deposition. While perennially ice‐covered lake facies overlap with other ice‐influenced lakes and glaciomarine facies, they are characterized by a paucity of grains coarser than granules, a narrow range in sand grain sizes, and inverse grading in the sand mounds. These facies can be used to infer changes in ice cover through time and to identify perennially ice‐covered lakes in the rock record. Ancient perennially ice‐covered lakes are expected on Earth and Mars, and their characterization will provide new insights into past climatic conditions and habitability.

1 aRivera-Hernandez, Frances1 aSumner, Dawn, Y.1 aMackey, Tyler, J.1 aHawes, Ian1 aAndersen, Dale, T. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/sed.1252202372nas a2200193 4500008004100000245016100041210006900202260001200271490000700283520165600290653002101946653002601967653002701993653001702020653002902037100001202066700002902078856007102107 2019 eng d00aInfluence of environmental drivers and potential interactions on the distribution of microbial communities from three permanently stratified Antarctic lakes0 aInfluence of environmental drivers and potential interactions on c05/20190 v103 a

The McMurdo Dry Valley (MDV) lakes represent unique habitats in the microbial world. Perennial ice covers protect liquid water columns from either significant allochthonous inputs or seasonal mixing, resulting in centuries of stable biogeochemistry. Extreme environmental conditions including low seasonal photosynthetically active radiation (PAR), near freezing temperatures, and oligotrophy have precluded higher trophic levels from the food webs. Despite these limitations, diverse microbial life flourishes in the stratified water columns, including Archaea, bacteria, fungi, protists, and viruses. While a few recent studies have applied next generation sequencing, a thorough understanding of the MDV lake microbial diversity and community structure is currently lacking. Here we used Illumina MiSeq sequencing of the 16S and 18S rRNA genes combined with a microscopic survey of key eukaryotes to compare the community structure and potential interactions among the bacterial and eukaryal communities within the water columns of Lakes Bonney (east and west lobes, ELB, and WLB, respectively) and Fryxell (FRX). Communities were distinct between the upper, oxic layers and the dark, anoxic waters, particularly among the bacterial communities residing in WLB and FRX. Both eukaryal and bacterial community structure was influenced by different biogeochemical parameters in the oxic and anoxic zones. Bacteria formed complex interaction networks which were lake-specific. Several eukaryotes exhibit potential interactions with bacteria in ELB and WLB, while interactions between these groups in the more productive FRX were relatively rare.

10aAquatic protists10aenvironmental drivers10aheterotrophic bacteria10ainteractions10aMcMurdo Dry Valley lakes1 aLi, Wei1 aMorgan-Kiss, Rachael, M. uhttps://www.frontiersin.org/articles/10.3389/fmicb.2019.01067/full02147nas a2200193 4500008004100000022001400041245007800055210006900133260001200202490000700214520142200221653002201643653001801665653002001683653002501703100002801728700002101756856017601777 2019 eng d a0954-102000aInorganic carbon fixation in ice-covered lakes of the McMurdo Dry Valleys0 aInorganic carbon fixation in icecovered lakes of the McMurdo Dry c04/20190 v723 a

Inorganic carbon fixation, usually mediated by photosynthetic microorganisms, is considered to form the base of the food chain in aquatic ecosystems. In high-latitude lakes, lack of sunlight owing to seasonal solar radiation limits the activity of photosynthetic plankton during the polar winter, causing respiration-driven demand for carbon to exceed supply. Here, we show that inorganic carbon fixation in the dark, driven by organisms that gain energy from chemical reactions rather than sunlight (chemolithoautotrophs), provides a significant influx of fixed carbon to two permanently ice-covered lakes (Fryxell and East Bonney). Fryxell, which has higher biomass per unit volume of water, had higher rates of inorganic dark carbon fixation by chemolithoautotrophs than East Bonney (trophogenic zone average 1.0 µg C l−1 d−1 vs 0.08 µg C l−1 d−1, respectively). This contribution from dark carbon fixation was partly due to the activity of ammonia oxidizers, which are present in both lakes. Despite the potential importance of new carbon input by chemolithoautotrophic activity, both lakes remain net heterotrophic, with respiratory demand for carbon exceeding supply. Dark carbon fixation increased the ratio of new carbon supply to respiratory demand from 0.16 to 0.47 in Fryxell, and from 0.14 to 0.22 in East Bonney.

10aammonia oxidation10acarbon budget10achemoautotrophy10achemolithoautotrophy1 aVick-Majors, Trista, J.1 aPriscu, John, C. uhttps://www.cambridge.org/core/journals/antarctic-science/article/inorganic-carbon-fixation-in-icecovered-lakes-of-the-mcmurdo-dry-valleys/4B5CA9E91C85B307EFDA69F8D7B5BFD902300nas a2200289 4500008004100000245009400041210006900135260001200204490000800216520140200224653002001626653001501646653002001661653002401681653001401705653001901719100001901738700002501757700002401782700002601806700002201832700001901854700002501873700002401898700002401922856006401946 2019 eng d00aSabbea gen. nov., a new diatom genus (Bacillariophyta) from continental Antarctica0 aiSabbea gen novi a new diatom genus Bacillariophyta from contine c09/20190 v4183 a

The non-marine diatom flora of the Antarctic Continent includes several endemic taxa recorded over the past 100 years. One of these taxa, Navicula adminensis D.Roberts & McMinn, was described from the Vestfold Hills, East Antarctica. Detailed light and scanning electron microscopy observations have shown that based on its morphological features, the species does not belong to the genus Navicula sensu stricto. To determine the most closely related genera to N. adminensis, the morpho- logical features of Adlafia, Kobayasiella, Envekadea, Stenoneis, Berkeleya, Climaconeis, and Parlibellus were compared with those of N. adminensis. Although each of these genera shows one or more similar features, none of them accommodates the salient morphological characteristics of N. adminensis. Therefore, a new genus, Sabbea gen. nov., is herein described, and Navicula adminensis is formally transferred to the new genus as Sabbea adminensis comb. nov. The genus Sabbea is characterized by uniseriate striae composed of small, rounded areolae occluded externally by individual hymenes, a rather simple raphe structure with straight, short proximal ends and short terminal raphe fissures, open girdle bands with double perforation and a very shallow mantle.

10aBacillariophyta10aCape Royds10aEast Antarctica10aMcMurdo Dry Valleys10anew genus10aVestfold Hills1 aBishop, Jordan1 aKopalová, Kateřina1 aDarling, Joshua, P.1 aSchulte, Nicholas, O.1 aKohler, Tyler, J.1 aMcMinn, Andrew1 aSpaulding, Sarah, A.1 aMcKnight, Diane, M.1 aVan de Vijver, Bart uhttps://www.mapress.com/j/pt/article/view/phytotaxa.418.1.202454nas a2200289 4500008004100000022001400041245011100055210006900166260001200235300001600247490000700263520153600270653001501806653001501821653003701836653002101873653002401894653003201918100002001950700001601970700002601986700002102012700001402033700002302047700001502070856007902085 2019 eng d a1558-842400aMeteorological connectivity from regions of high biodiversity within the McMurdo Dry Valleys of Antarctica0 aMeteorological connectivity from regions of high biodiversity wi c11/2019 a2437 - 24520 v583 a

Meteorological connectivity between biological hot spots of the McMurdo Dry Valleys (MDVs) of Antarctica is thought to play a role in species distribution and abundance through the aeolian transport of bioaerosols. Understanding the potential role of such meteorological connectivity requires an understanding of near-surface wind flow within and between valley airsheds. To address this, we applied Lagrangian wind trajectory modeling to mesoscale (spatial resolution of ~1 km) weather model output to predict connectivity pathways, focusing on regions of high biodiversity. Our models produce maps of a likelihood metric of wind connectivity that demonstrate the synoptic and mesoscale dependence of connections between local, near-local, and nonlocal areas on wind transport, modulated by synoptic weather and topographic forcing. These connectivity areas can have spatial trends modulated by the synoptic weather patterns and locally induced topographically forced winds. This method is transferrable to other regions of Antarctica for broader terrestrial, coastal, and offshore ecological connectivity research. Also, our analysis and methods can inform better placement of aeolian dust and bioaerosol samplers in the McMurdo Dry Valleys, provide preliminary guidelines behind the meteorological controls of sediment transport and smaller particle distribution, and present quantifiable knowledge informing new hypotheses around the potential of wind acting as a physical driver for biological connectivity in the MDVs.

10aAntarctica10aatmosphere10abiosphere-atmosphere interaction10amesoscale models10amesoscale processes10anumerical analysis/modeling1 aKaturji, Marwan1 aKhan, Basit1 aSprenger, Michael, A.1 aDatta, Rajasweta1 aJoy, Kurt1 aZawar-Reza, Peyman1 aHawes, Ian uhttps://journals.ametsoc.org/view/journals/apme/58/11/jamc-d-18-0336.1.xml01860nas a2200253 4500008004100000245011500041210006900156260001200225490000600237520106300243100002101306700001801327700002201345700002101367700002101388700002001409700001901429700002201448700002401470700002201494700002001516700001701536856005301553 2019 eng d00aNematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals0 aNematodes in a polar desert reveal the relative role of biotic i c02/20190 v23 a

Abiotic factors are major determinants of soil animal distributions and their dominant role is pronounced in extreme ecosystems, with biotic interactions seemingly playing a minor role. We modelled co-occurrence and distribution of the three nematode species that dominate the soil food web of the McMurdo Dry Valleys (Antarctica). Abiotic factors, other biotic groups, and autocorrelation all contributed to structuring nematode species distributions. However, after removing their effects, we found that the presence of the most abundant nematode species greatly, and negatively, affected the probability of detecting one of the other two species. We observed similar patterns in relative abundances for two out of three pairs of species. Harsh abiotic conditions alone are insufficient to explain contemporary nematode distributions whereas the role of negative biotic interactions has been largely underestimated in soil. The future challenge is to understand how the effects of global change on biotic interactions will alter species coexistence.

1 aCaruso, Tancredi1 aHogg, Ian, D.1 aNielsen, Uffe, N.1 aBottos, Eric, M.1 aLee, Charles, K.1 aHopkins, D., W.1 aCary, Craig, S1 aBarrett, John, E.1 aGreen, T., G. Allan1 aStorey, Bryan, C.1 aWall, Diana, H.1 aAdams, Byron uhttp://www.nature.com/articles/s42003-018-0260-y01803nas a2200133 4500008004100000022001800041245011100059210006900170250000800239260002200247520132400269100002001593856005601613 2019 eng d a978042942970500aPlacing the past: The McMurdo Dry Valleys and the problem of geographical specificity in Antarctic history0 aPlacing the past The McMurdo Dry Valleys and the problem of geog a1st aLondonbRoutledge3 a

This chapter uses the history of the McMurdo Dry Valleys to think about the problem of geographical specificity in Antarctica. As the largest predominantly ice-free region in the Antarctic continent, the McMurdo Dry Valleys are in some ways quite different from the surrounding landscape. But despite this difference, the region has been used by scientists to make broad claims about Antarctica as a whole. While using the McMurdo Dry Valleys in this way helps to increase the relevance of the research conducted in this part of the continent, it also risks ‘flattening’ the rest of Antarctica and assuming that there are connections and similarities where none may exist. These risks of flattening the continent are arguably exacerbated by the concept of the Anthropocene, which assumes a universal human impact across the planet. Such observations call for a nuanced understanding of regions such as the McMurdo Dry Valleys which acknowledge the specificity of place, but also consider how they fit into the broader picture of Antarctic history. The paper concludes by arguing that a one-size-fits-all vision of the Anthropocene does not seem appropriate for thinking about the past, present, or future of a continent where we are only just coming to appreciate the richness and diversity of place.

1 aHowkins, Adrian uhttps://www.taylorfrancis.com/books/e/978042942970501888nas a2200301 4500008004100000245004500041210004100086260001200127300001300139490000600152520103800158100001501196700002301211700002801234700002401262700002201286700002501308700001401333700002301347700002401370700002201394700002001416700002601436700001601462700002301478700001601501856006901517 2019 eng d00aThe polar regions in a 2°C warmer world0 apolar regions in a 2°C warmer world c12/2019 aeaaw98830 v53 a

Over the past decade, the Arctic has warmed by 0.75°C, far outpacing the global average, while Antarctic tem- peratures have remained comparatively stable. As Earth approaches 2°C warming, the Arctic and Antarctic may reach 4°C and 2°C mean annual warming, and 7°C and 3°C winter warming, respectively. Expected consequences of increased Arctic warming include ongoing loss of land and sea ice, threats to wildlife and traditional human livelihoods, increased methane emissions, and extreme weather at lower latitudes. With low biodiversity, Antarctic ecosystems may be vulnerable to state shifts and species invasions. Land ice loss in both regions will contribute substantially to global sea level rise, with up to 3 m rise possible if certain thresholds are crossed. Mitigation efforts can slow or reduce warming, but without them northern high latitude warming may accelerate in the next two to four decades. International cooperation will be crucial to foreseeing and adapting to expected changes.

1 aPost, Eric1 aAlley, Richard, B.1 aChristensen, Torben, R.1 aMacias-Fauria, Marc1 aForbes, Bruce, C.1 aGooseff, Michael, N.1 aIler, Amy1 aKerby, Jeffrey, T.1 aLaidre, Kristin, L.1 aMann, Michael, E.1 aOlofsson, Johan1 aStroeve, Julienne, C.1 aUlmer, Fran1 aVirginia, Ross, A.1 aWang, Muyin uhttp://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aaw988301525nas a2200145 4500008004100000245008300041210006900124260001200193490000800205520102800213100002201241700002101263700002101284856007401305 2019 eng d00aPrediction of ice-free conditions for a perennially ice-covered Antarctic lake0 aPrediction of icefree conditions for a perennially icecovered An c02/20190 v1243 a

Although perennially ice-covered Antarctic lakes have experienced variable ice thicknesses over the past several decades, future ice thickness trends and associated aquatic biological responses under projected global warming remain unknown. Heat stored in the water column in chemically stratified Antarctic lakes that have mid-depth temperature maxima, can significantly influence the ice thickness trends via upward heat flux to the ice/water interface. We modeled ice thickness of the west of lobe of Lake Bonney, Antarctica based on possible future climate scenarios utilizing a 1D thermodynamic model that accounts for surface radiative fluxes as well as the heat flux associated with the temperature evolution of the water column. Model results predict that the ice cover of Lake Bonney will shift from perennial to seasonal within one to four decades, a change that will drastically influence ecosystem processes within the lake.

1 aObryk, Maciek, K.1 aDoran, Peter, T.1 aPriscu, John, C. uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JF00475601897nas a2200133 4500008004100000245008000041210006900121260001200190520131700202100002501519700002301544700001701567856017901584 2019 eng d00aProvisional checklist of terrestrial heterotrophic protists from Antarctica0 aProvisional checklist of terrestrial heterotrophic protists from c11/20193 a

Heterotrophic soil protists encompass lineages that are both evolutionarily ancient and highly diverse, providing an untapped wealth of scientific insight. Yet the diversity of free-living heterotrophic terrestrial protists is still largely unknown. To contribute to our understanding of this diversity, we present a checklist of heterotrophic protists currently reported from terrestrial Antarctica, for which no comprehensive evaluation currently exists. As a polar continent, Antarctica is especially susceptible to rising temperatures caused by anthropogenic climate change. Establishing a baseline for future conservation efforts of Antarctic protists is therefore important. We performed a literature search and found 236 taxa identified to species and an additional 303 taxa identified to higher taxonomic levels in 54 studies spanning over 100 years of research. Isolated by distance, climate and the circumpolar vortex, Antarctica is the most extreme continent on Earth: it is not unreasonable to think that it may host physiologically and evolutionarily unique species of protists, yet currently most species discovered in Antarctica are considered cosmopolitan. Additional sampling of the more extreme intra-continental zones will probably result in the discovery of more novel and unique taxa.

1 aThompson, Andrew, R.1 aPowell, Gareth, S.1 aAdams, Byron uhttps://www.cambridge.org/core/journals/antarctic-science/article/provisional-checklist-of-terrestrial-heterotrophic-protists-from-antarctica/DC08D89ABDC5AF2CC83E38B1C6F1F78C03892nas a2200949 4500008004100000245007900041210006900120260001200189490000800201520116600209100002601375700001901401700001701420700001901437700002501456700001401481700002501495700001701520700001701537700002601554700002601580700002301606700002701629700002301656700002101679700003101700700001801731700002101749700002001770700003001790700001501820700002001835700001901855700002501874700002301899700001901922700002101941700001701962700002201979700002102001700002602022700002302048700001102071700001702082700002202099700002102121700003102142700002402173700002202197700002202219700001802241700001702259700002502276700002202301700001902323700002702342700001602369700001802385700002202403700003202425700002302457700002302480700002002503700002202523700002002545700002702565700001802592700002102610700001902631700002302650700001502673700002202688700002302710700002202733700002402755700002002779700002102799700002302820700001802843700002702861856005402888 2019 eng d00aSoil nematode abundance and functional group composition at a global scale0 aSoil nematode abundance and functional group composition at a gl c08/20190 v5723 a

Soil organisms are a crucial part of the terrestrial biosphere. Despite their importance for ecosystem functioning, few quantitative, spatially explicit models of the active belowground community currently exist. In particular, nematodes are the most abundant animals on Earth, filling all trophic levels in the soil food web. Here we use 6,759 georeferenced samples to generate a mechanistic understanding of the patterns of the global abundance of nematodes in the soil and the composition of their functional groups. The resulting maps show that 4.4 ± 0.64 × 1020 nematodes (with a total biomass of approximately 0.3 gigatonnes) inhabit surface soils across the world, with higher abundances in sub-Arctic regions (38% of total) than in temperate (24%) or tropical (21%) regions. Regional variations in these global trends also provide insights into local patterns of soil fertility and functioning. These high-resolution models provide the first steps towards representing soil ecological processes in global biogeochemical models and will enable the prediction of elemental cycling under current and future climate scenarios.

1 avan den Hoogen, Johan1 aGeisen, Stefan1 aRouth, Devin1 aFerris, Howard1 aTraunspurger, Walter1 aWardle, D1 ade Goede, Ron, G. M.1 aAdams, Byron1 aAhmad, Wasim1 aAndriuzzi, Walter, S.1 aBardgett, Richard, D.1 aBonkowski, Michael1 aCampos-Herrera, Raquel1 aCares, Juvenil, E.1 aCaruso, Tancredi1 aCaixeta, Larissa, de Brito1 aChen, Xiaoyun1 aCosta, Sofia, R.1 aCreamer, Rachel1 aCastro, José, Mauro da C1 aDam, Marie1 aDjigal, Djibril1 aEscuer, Miguel1 aGriffiths, Bryan, S.1 aGutiérrez, Carmen1 aHohberg, Karin1 aKalinkina, Daria1 aKardol, Paul1 aKergunteuil, Alan1 aKorthals, Gerard1 aKrashevska, Valentyna1 aKudrin, Alexey, A.1 aLi, Qi1 aLiang, Wenju1 aMagilton, Matthew1 aMarais, Mariette1 aMartín, José, Antonio Ro1 aMatveeva, Elizaveta1 aMayad, El, Hassan1 aMulder, Christian1 aMullin, Peter1 aNeilson, Roy1 aNguyen, T., A. Duong1 aNielsen, Uffe, N.1 aOkada, Hiroaki1 aRius, Juan, Emilio Pal1 aPan, Kaiwen1 aPeneva, Vlada1 aPellissier, Loïc1 ada Silva, Julio, Carlos Per1 aPitteloud, Camille1 aPowers, Thomas, O.1 aPowers, Kirsten1 aQuist, Casper, W.1 aRasmann, Sergio1 aMoreno, Sara, Sánchez1 aScheu, Stefan1 aSetälä, Heikki1 aSushchuk, Anna1 aTiunov, Alexei, V.1 aTrap, Jean1 avan der Putten, W1 aVestergård, Mette1 aVillenave, Cecile1 aWaeyenberge, Lieven1 aWall, Diana, H.1 aWilschut, Rutger1 aWright, Daniel, G.1 aYang, Jiue-in1 aCrowther, Thomas, Ward uhttps://www.nature.com/articles/s41586-019-1418-602017nas a2200133 4500008004100000245011800041210006900159260005700228490000900285520149000294100002001784700002101804856005801825 2019 eng d00aSpatiotemporal impact of snow on underwater photosynthetically active radiation in Taylor Valley, East Antarctica0 aSpatiotemporal impact of snow on underwater photosynthetically a aBaton Rouge, LAbLouisiana State Universityc08/20190 vM.S.3 a

The role of snow on underwater photosynthetically active radiation (UW PAR) in the McMurdo Dry Valleys (MDVs) has been understudied due to lack of a detailed snowfall record. Research has shown that a relationship between snow cover and UW PAR exists, but the extent has never been evaluated in great detail. Although annual snowfall values in the MDVs are low (3 to 50 mm water equivalent annually), trends of increasing snowfall on the continent under future warming conditions could lead to an increased role for snow in regulating UW PAR (and associated primary productivity). Here, I discuss evidence from the snowfall record, surface PAR, and UW PAR, of the influence of snowfall on UW PAR in the major lakes of Taylor Valley. This study aims to quantify the spatiotemporal impact of lake ice snow packs on UW PAR in Taylor Valley from field surveys, long-term UW PAR, and meteorological data. Lake Fryxell has the strongest seasonality to precipitation, which decreases inland. On average, Lake Fryxell also has the most days with snow cover on the lake ice. Lake Hoare is experiencing an increase in Fall snow persistence since the 2007 snow year. Snow less than 0.5 mm snow water equivalent (SWE) can suppress UW PAR by 40%. The calendar day that snow falls often determines whether phototrophs will switch from photosynthesis to respiration, which suggests the importance to seasonality in determining the impact of snow on photoautotrophs and lake-wide carbon budget.

1 aMyers, Madeline1 aDoran, Peter, T. uhttps://digitalcommons.lsu.edu/gradschool_theses/496501983nas a2200133 4500008004100000245011300041210007100154260001200225490000700237520149300244100002101737700002201758856006901780 2019 eng d00aUnimodal productivity–diversity relationships among bacterial communities in a simple polar soil ecosystem0 aUnimodal productivity–diversity relationships among bacterial co c07/20190 v213 a

Unlike other macroecological principles, relationships between productivity and diversity have not been effectively tested for microbial communities. Here we describe an experiment in which the availability of resources to soil bacterial communities was manipulated in a model system, the McMurdo Dry Valleys of Antarctica. Mannitol additions were used to simulate a productivity gradient such that a response in bacterial biomass production, taxonomic diversity and functioning (e.g., enzyme activity) were induced. Resource amendment induced a positive linear response in microbial productivity (P < 0.001) but a unimodal (hump‐shaped) response in microbial diversity at multiple taxonomic scales (P = 0.035). Putative oligotrophic (e.g., phyla Nitrospirae and Cyanobacteria) and copiotrophic (e.g., phylum Proteobacteria) taxa were apparent through substantial community turnover along the resource gradient. Soil enzyme activity was inversely related to bacterial biomass but positively related to diversity, suggesting the latter may be a stronger control over enzyme‐mediated decomposition. The mechanisms behind this pattern are consistent with macroecological theory of a shift from environmental (e.g., stress tolerance) to biotic (e.g., competition) drivers with increasing resource availability. This evidence is among the first of its kind to document a significant unimodal productivity–diversity relationship for soil bacteria.

1 aGeyer, Kevin, M.1 aBarrett, John, E. uhttps://onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.1463902534nas a2200229 4500008004100000245010900041210006900150260001200219300001600231490000800247520179600255100002102051700001702072700002402089700001502113700002302128700001902151700002402170700001902194700001702213856007402230 2018 eng d00aAeolian material transport and its role in landscape connectivity in the McMurdo Dry Valleys, Antarctica0 aAeolian material transport and its role in landscape connectivit c12/2018 a3323 - 33370 v1233 a

Arid regions, particularly polar and alpine desert environments, have diminished landscape connectivity compared to temperate regions due to limited and/or seasonal hydrological processes. For these environments, aeolian processes play a particularly important role in landscape evolution and biotic community vitality through nutrient and solute additions. The McMurdo Dry Valleys (MDV) are the largest ice-free area in Antarctica and are potentially a major source of aeolian material for the continent. From this region, samples were collected at five heights (~5, 10, 20, 50, and 100 cm) above the surface seasonally for 2013 through 2015 from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove). Despite significant geological separation and varying glacial histories, low-elevation and coastal sites had similar major ion chemistries, as did high-elevation and inland locations. This locational clustering of compositions was also evident in scanning electron microscopy images and principal component analyses, particularly for samples collected at ~100 cm above the surface. Compared to published soil literature, aeolian material in Taylor Valley demonstrates a primarily down-valley transport of material toward the coast. Soluble N:P ratios in the aeolian material reflect relative nutrient enrichments seen in MDV soils and lakes, where younger, coastal soils are relatively N depleted, while older, up-valley soils are relatively P depleted. The aeolian transport of materials, including water-soluble nutrients, is an important vector of connectivity within the MDV and provides a mechanism to help “homogenize” the geochemistry of both soil and aquatic ecosystems.

1 aDiaz, Melisa, A.1 aAdams, Byron1 aWelch, Kathleen, A.1 aWelch, Sue1 aOpiyo, Stephen, O.1 aKhan, Alia, L.1 aMcKnight, Diane, M.1 aCary, Craig, S1 aLyons, Berry uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JF00458902006nas a2200133 4500008004100000245016300041210006900204260003900273490000900312520143800321100001501759700002901774856006901803 2018 eng d00aAntarctic Chlamydomonas strains C. sp. UWO241 and ICE-MDV exhibit differential restructuring of the photosynthetic apparatus in response to iron0 aAntarctic iChlamydomonasi strains iCi sp UWO241 and ICEMDV exhib aOxford, OHbMiami Universityc20180 vM.S.3 a

As an integral cofactor for many redox-associated processes, iron (Fe) homeostasis is crucial in order to produce sufficient energy for the organism. Fe limitation, or excess, can cause major alterations in the function and structure of the photosynthetic apparatus. Photosynthetic psychrophiles grown under permanent low temperatures exhibit novel adaptations in their photosynthetic apparatus to deal with this permanent stress. The ice-covered lakes of the McMurdo Dry Valleys harbor many species of cold-adapted algae, including Chlamydomonas sp. UWO241 (UWO241). As a consequence of adaptation to multiple permanent extreme conditions, UWO241 exhibits a remodeled photosynthetic apparatus for maintaining redox poise. One unusual characteristic of UWO241 is the absence of a PSI-associated 77K fluorescence emission under a wide range of growth conditions. This phenotype resembles Fe deficiency in other model organisms such as C. reinhardtii. We hypothesized that adaptation to permanent iron deficiency in its native environment may contribute to this unusual phenotype. We compared the effect of Fe availability on the physiology and photobiology of UWO241 with the model C. reinhardtii as well as a second psychrophilic alga, Chlamydomonas sp. ICE-MDV (ICE). The impacts of a restructured photosynthetic apparatus on the unique Fe-associated phenotype in UWO241 will be discussed.

1 aCook, Greg1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami152545562177883601847nas a2200193 4500008004100000022001400041245005200055210005200107260001200159300001400171490000700185520124200192100002201434700002901456700002401485700001501509700001701524856011201541 2018 eng d a0091-761300aBarium and barite dynamics in Antarctic streams0 aBarium and barite dynamics in Antarctic streams c08/2018 a811 - 8140 v463 a

Most natural waters are undersaturated with respect to barite (BaSO4), and while much work has focused on the processes of microbially mediated barite precipitation in undersaturated solutions, particularly in marine environments, little documentation exists on the changes in barite saturation in stream waters. We examined ephemeral glacial meltwater streams in the McMurdo Dry Valleys, Antarctica, that undergo large variations in streamflow and temperature on both a diel and seasonal basis. We measured dissolved Ba in stream water in downstream transects and on a diel cycle, total Ba in stream sediments, algal mats, and lake sediments. Ba concentrations decreased downstream in all four transects, and mineral saturation modeling indicates these waters go from supersaturated to undersaturated with respect to barite in very short distances. Ba is concentrated in stream benthic algal mats at a factor less than observed in marine systems. Both seasonal and diel changes in stream water temperature affect the solubility of barite near glacial sources. Our work shows that both changing stream temperature and the presence of algal materials likely play significant roles in controlling Ba concentrations in polar streams.

1 aSaelens, Elsa, D.1 aGardner, Christopher, B.1 aWelch, Kathleen, A.1 aWelch, Sue1 aLyons, Berry uhttps://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams02347nas a2200193 4500008004100000022001300041245009200054210006900146260001200215300001200227490000800239520173400247100002101981700001702002700001502019700002402034700002302058856007202081 2018 eng d a0016706100aBiogeochemical weathering of soil apatite grains in the McMurdo Dry Valleys, Antarctica0 aBiogeochemical weathering of soil apatite grains in the McMurdo  c01/2018 a136-1450 v3203 a

The biogeochemical weathering of the mineral apatite links the lithosphere to the biosphere by releasing the essential nutrient phosphorus (P) into the soil ecosystem. In Taylor Valley, Antarctica, faster rates of apatite weathering may be responsible for the higher concentrations of bioavailable soil P that exist in the Fryxell Basin as compared to the Bonney Basin. In this study, we use scanning electron microscopy to quantify the morphology and surface etching of individual apatite grains to determine whether the degree of apatite weathering differs between the Fryxell and Bonney Basins as well as saturated and dry soil sediments. We show that apatite grains from the Fryxell Basin are rounder, have fewer intact crystal faces, and are more chemically etched than grains from the Bonney Basin. In the Bonney Basin, apatite grains from dry soils show few signs of chemical dissolution, suggesting that soil moisture is a stronger control on the rate of apatite weathering in the Bonney Basin than in the Fryxell Basin. In addition, etch-pit morphologies in the Bonney Basin are more clearly controlled by the hexagonal crystal structure of apatite, while in the Fryxell Basin, etch pits demonstrate a wide range of morphologies without clear crystallographic control. Higher rates of apatite weathering in the Fryxell Basin may be due to the legacy of the physical abrasion of apatite grains during transport by a warm-based ice sheet, as well as the higher levels of precipitation and soil moisture closer to the coast. Our grain-scale approach provides a new perspective on P cycling in the McMurdo Dry Valleys and has implications for apatite weathering and P dynamics in the early stages of soil development.

1 aHeindel, Ruth, C1 aLyons, Berry1 aWelch, Sue1 aSpickard, Angela, M1 aVirginia, Ross, A. uhttps://www.sciencedirect.com/science/article/pii/S001670611732069402748nas a2200241 4500008004100000245014000041210006900181260004600250300000800296490001000304520196700314653001502281653002102296653002602317653001502343653001902358653001202377653001402389653000902403100001902412700002402431856005102455 2018 eng d00aBiogeochemistry, contaminant transport, and atmospheric exchange in glacial cryoconite meltwater of the McMurdo Dry Valleys, Antarctica0 aBiogeochemistry contaminant transport and atmospheric exchange i aBoulder, CObUniversity of Coloradoc2018 a2450 vPh.D.3 a

Polar regions serve as a global sink for many forms of semi-volatile pollution emitted from low- or midlatitudes of the populated world. This study examined the longrange atmospheric transport, fate, and phase partitioning of semi-volatile organic contaminants from air masses into meltwater and aeolian sediment on six glaciers in the McMurdo Dry Valleys of Antarctica. A novel low-cost, field-portable instrument was developed for the in-situ solid-phase extraction of trace contaminants in extreme environmental conditions without access to electricity or traditional laboratory facilities. Beyond polar research, this equipment is applicable for rapid field extraction and stabilization of samples assessing air and water quality after natural disasters. This is the first published study to identify the presence of anthropogenic perfluorinated compounds in the Transantarctic Mountain region and indicates a longer range of poleward contaminant transport than prior estimates in the Southern Hemisphere. Additional research examined the biochemistry and climatic variability of open and sealed cryoconite holes on glacial surfaces throughout the initial melt, equilibrium, and refreezing periods in 2013–2015. High solute concentrations relative to glacial ice indicate that the pools can remain isolated from hydrologic connectivity for more than a decade. Microbial carbon cycling in pools enclosed by ice led to atmospheric disequilibrium and extreme pH. Analysis of unique air, liquid, and ice stratification in cryoconite holes revealed vertical patterns representing a highly accurate, multi-year record of past weather conditions sensitive enough to identify individual dates. This research identifies fluctuations in atmospheric contaminant transport, specific timeframes for deposition events, and may be used in back-trajectory models to help identify the source and variability of semi-volatile emissions in the Southern hemisphere.

10aAntarctica10aapplied sciences10acontaminant transport10acryoconite10aearth sciences10aglacier10ahydrology10amelt1 aMass, Alex, Q.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/204831467810050nas a2202965 4500008004100000245007300041210006900114260001200183300001200195490000700207520154900214653001701763653001101780653001201791653002101803653001301824653001301837100002001850700002201870700001601892700002201908700002301930700001701953700002801970700002001998700002502018700001802043700002402061700001602085700002202101700002002123700002702143700002002170700002202190700002302212700003102235700002002266700002302286700002702309700002202336700002702358700002702385700001602412700001902428700002302447700002102470700002202491700001802513700002302531700002802554700002502582700002302607700002002630700002902650700002502679700002002704700002602724700002602750700001702776700002402793700002502817700002302842700002202865700001902887700002002906700002102926700002202947700002102969700001802990700001703008700002203025700001703047700002503064700001903089700002603108700002203134700001903156700002103175700001903196700002703215700003003242700002403272700002403296700001703320700002303337700003203360700002103392700002403413700002203437700002903459700001403488700003103502700002303533700001903556700002303575700002603598700001803624700002103642700001603663700001803679700002403697700002103721700002003742700001903762700001703781700001903798700002103817700002003838700002603858700002003884700002003904700002003924700002503944700002003969700002703989700002404016700003304040700001804073700001504091700002304106700002204129700002004151700001704171700002404188700001804212700002404230700002104254700002204275700002104297700002004318700002004338700002804358700002604386700001704412700002104429700001904450700002304469700003104492700002604523700002004549700002704569700002204596700002104618700002204639700002004661700002804681700001804709700002204727700002604749700002004775700001904795700002404814700001804838700002404856700002604880700001804906700002304924700002504947700002804972700002205000700002505022700001505047700001705062700001505079700003105094700001905125700001805144700002605162700002405188700001905212700001805231700002205249700002605271700002405297700002005321700002405341700002105365700002905386700002105415700002205436700002005458700001905478700002405497700002505521700002105546700002805567700001905595700002205614700001505636700002605651700002105677700002105698700002505719700002205744700001905766700002805785700002305813700002605836700002105862700002105883700002705904700002805931700002105959700001905980700001905999700003006018700002106048700002406069700003206093700003606125700001806161700001606179700002206195700002306217700001906240700001806259700001506277700002106292700002606313700003306339700001706372700002006389700002106409700002406430700002106454700002206475700001906497700002306516700002106539700001806560700002806578700003406606700002406640700002106664700001806685700002006703700003206723700002606755700002706781700002906808700003106837700002106868700002306889700002506912700002106937700002306958700002506981700001607006856006207022 2018 eng d00aBioTIME: A database of biodiversity time series for the Anthropocene0 aBioTIME A database of biodiversity time series for the Anthropoc c07/2018 a760-7860 v273 a

Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene.

Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record.

Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year.

Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates.

Software format: .csv and .SQL.

10abiodiversity10aglobal10aspatial10aspecies richness10atemporal10aturnover1 aDornelas, Maria1 aAntão, Laura, H.1 aMoyes, Faye1 aBates, Amanda, E.1 aMagurran, Anne, E.1 aAdam, Dušan1 aAkhmetzhanova, Asem, A.1 aAppeltans, Ward1 aArcos, José, Manuel1 aArnold, Haley1 aAyyappan, Narayanan1 aBadihi, Gal1 aBaird, Andrew, H.1 aBarbosa, Miguel1 aBarreto, Tiago, Egydio1 aBässler, Claus1 aBellgrove, Alecia1 aBelmaker, Jonathan1 aBenedetti-Cecchi, Lisandro1 aBett, Brian, J.1 aBjorkman, Anne, D.1 aBłażewicz, Magdalena1 aBlowes, Shane, A.1 aBloch, Christopher, P.1 aBonebrake, Timothy, C.1 aBoyd, Susan1 aBradford, Matt1 aBrooks, Andrew, J.1 aBrown, James, H.1 aBruelheide, Helge1 aBudy, Phaedra1 aCarvalho, Fernando1 aCastañeda-Moya, Edward1 aChen, Chaolun, Allen1 aChamblee, John, F.1 aChase, Tory, J.1 aCollier, Laura, Siegwart1 aCollinge, Sharon, K.1 aCondit, Richard1 aCooper, Elisabeth, J.1 aCornelissen, Hans, C.1 aCotano, Unai1 aCrow, Shannan, Kyle1 aDamasceno, Gabriella1 aDavies, Claire, H.1 aDavis, Robert, A.1 aDay, Frank, P.1 aDegraer, Steven1 aDoherty, Tim, S.1 aDunn, Timothy, E.1 aDurigan, Giselda1 aDuffy, Emmett1 aEdelist, Dor1 aEdgar, Graham, J.1 aElahi, Robin1 aElmendorf, Sarah, C.1 aEnemar, Anders1 aErnest, S., K. Morgan1 aEscribano, Rubén1 aEstiarte, Marc1 aEvans, Brian, S.1 aFan, Tung-Yung1 aFarah, Fabiano, Turini1 aFernandes, Luiz, Loureiro1 aFarneda, Fábio, Z.1 aFidelis, Alessandra1 aFitt, Robert1 aFosaa, Anna, Maria1 aFranco, Geraldo, Antonio Da1 aFrank, Grace, E.1 aFraser, William, R.1 aGarcía, Hernando1 aGatti, Roberto, Cazzolla1 aGivan, Or1 aGorgone-Barbosa, Elizabeth1 aGould, William, A.1 aGries, Corinna1 aGrossman, Gary, D.1 aGutierréz, Julio, R.1 aHale, Stephen1 aHarmon, Mark, E.1 aHarte, John1 aHaskins, Gary1 aHenshaw, Donald, L.1 aHermanutz, Luise1 aHidalgo, Pamela1 aHiguchi, Pedro1 aHoey, Andrew1 aVan Hoey, Gert1 aHofgaard, Annika1 aHoleck, Kristen1 aHollister, Robert, D.1 aHolmes, Richard1 aHoogenboom, Mia1 aHsieh, Chih-hao1 aHubbell, Stephen, P.1 aHuettmann, Falk1 aHuffard, Christine, L.1 aHurlbert, Allen, H.1 aIvanauskas, Natália, Macedo1 aJaník, David1 aJandt, Ute1 aJażdżewska, Anna1 aJohannessen, Tore1 aJohnstone, Jill1 aJones, Julia1 aJones, Faith, A. M.1 aKang, Jungwon1 aKartawijaya, Tasrif1 aKeeley, Erin, C.1 aKelt, Douglas, A.1 aKinnear, Rebecca1 aKlanderud, Kari1 aKnutsen, Halvor1 aKoenig, Christopher, C.1 aKortz, Alessandra, R.1 aKrál, Kamil1 aKuhnz, Linda, A.1 aKuo, Chao-Yang1 aKushner, David, J.1 aLaguionie-Marchais, Claire1 aLancaster, Lesley, T.1 aLee, Cheol, Min1 aLefcheck, Jonathan, S.1 aLévesque, Esther1 aLightfoot, David1 aLloret, Francisco1 aLloyd, John, D.1 aLópez-Baucells, Adrià1 aLouzao, Maite1 aMadin, Joshua, S.1 aMagnússon, Borgþór1 aMalamud, Shahar1 aMatthews, Iain1 aMcFarland, Kent, P.1 aMcGill, Brian1 aMcKnight, Diane, M.1 aMcLarney, William, O.1 aMeador, Jason1 aMeserve, Peter, L.1 aMetcalfe, Daniel, J.1 aMeyer, Christoph, F. J.1 aMichelsen, Anders1 aMilchakova, Nataliya1 aMoens, Tom1 aMoland, Even1 aMoore, Jon1 aMoreira, Carolina, Mathias1 aMüller, Jörg1 aMurphy, Grace1 aMyers-Smith, Isla, H.1 aMyster, Randall, W.1 aNaumov, Andrew1 aNeat, Francis1 aNelson, James, A.1 aNelson, Michael, Paul1 aNewton, Stephen, F.1 aNorden, Natalia1 aOliver, Jeffrey, C.1 aOlsen, Esben, M.1 aOnipchenko, Vladimir, G.1 aPabis, Krzysztof1 aPabst, Robert, J.1 aPaquette, Alain1 aPardede, Sinta1 aPaterson, David, M.1 aPélissier, Raphaël1 aPeñuelas, Josep1 aPérez-Matus, Alejandro1 aPizarro, Oscar1 aPomati, Francesco1 aPost, Eric1 aPrins, Herbert, H. T.1 aPriscu, John, C.1 aProvoost, Pieter1 aPrudic, Kathleen, L.1 aPulliainen, Erkki1 aRamesh, B., R.1 aRamos, Olivia, Mendivil1 aRassweiler, Andrew1 aRebelo, Jose, Eduardo1 aReed, Daniel, C.1 aReich, Peter, B.1 aRemillard, Suzanne, M.1 aRichardson, Anthony, J.1 aRichardson, Paul1 avan Rijn, Itai1 aRocha, Ricardo1 aRivera-Monroy, Victor, H.1 aRixen, Christian1 aRobinson, Kevin, P.1 aRodrigues, Ricardo, Ribeiro1 aRossa-Feres, Denise, de Cerquei1 aRudstam, Lars1 aRuhl, Henry1 aRuz, Catalina, S.1 aSampaio, Erica, M.1 aRybicki, Nancy1 aRypel, Andrew1 aSal, Sofia1 aSalgado, Beatriz1 aSantos, Flavio, A. M.1 aSavassi-Coutinho, Ana, Paula1 aScanga, Sara1 aSchmidt, Jochen1 aSchooley, Robert1 aSetiawan, Fakhrizal1 aShao, Kwang-Tsao1 aShaver, Gaius, R.1 aSherman, Sally1 aSherry, Thomas, W.1 aSiciński, Jacek1 aSievers, Caya1 ada Silva, Ana, Carolina1 ada Silva, Fernando, Rodrigues1 aSilveira, Fabio, L.1 aSlingsby, Jasper1 aSmart, Tracey1 aSnell, Sara, J.1 aSoudzilovskaia, Nadejda, A.1 aSouza, Gabriel, B. G.1 aSouza, Flaviana, Maluf1 aSouza, Vinícius, Castro1 aStallings, Christopher, D.1 aStanforth, Rowan1 aStanley, Emily, H.1 aSterza, José, Mauro1 aStevens, Maarten1 aStuart-Smith, Rick1 aSuarez, Yzel, Rondon1 aSupp, Sarah uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/geb.1272901794nas a2200181 4500008004100000245015800041210006900199260001200268300001400280490000600294520113500300100002201435700002101457700001601478700002201494700002401516856007201540 2018 eng d00aCatch and release: Hyporheic retention and mineralization of N-fixing Nostoc sustains downstream microbial mat biomass in two polar desert streams0 aCatch and release Hyporheic retention and mineralization of Nfix c07/2018 a357 - 3640 v33 a

 

Much work has been performed to investigate controls on nitrogen (N) uptake in streams, yet the fate of assimilated N is comparatively poorly resolved. Here, we use in-stream fixed N as an isotopic tracer to study the fate of assimilated N in glacial meltwater streams. We characterized d15N signatures of Oscillatorean, Chlorophyte, and N-fixing Nostoc mats over the lengths of two streams, and transported particulate organic matter (POM) in one. POM was isotopically most similar to Nostoc, which always had values near the atmospheric standard, suggesting N-fixation. Other mat types were depleted upstream, and became progressively enriched downstream, indicating a shift in N source. These results collectively show that Nostoc-derived N is mobilized, mineralized, and increasingly assimilated downstream as more depleted glacier-derived N is exhausted, demonstrating the importance of organic matter processing to balancing elemental budgets, and improving our understanding of nutrient cycling in lotic environments.

 

1 aKohler, Tyler, J.1 aStanish, Lee, F.1 aLiptzin, D.1 aBarrett, John, E.1 aMcKnight, Diane, M. uhttps://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lol2.1008702146nas a2200193 4500008004100000245011200041210006900153260001200222490000600234520149600240653001501736653002101751653002701772653002501799653001901824100001901843700001701862856007301879 2018 eng d00aDissolved Trace and Minor Elements in Cryoconite Holes and Supraglacial Streams, Canada Glacier, Antarctica0 aDissolved Trace and Minor Elements in Cryoconite Holes and Supra c04/20180 v63 a

 

We present a synthesis of the trace element chemistry in melt on the surface Canada Glacier, Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica (∼78◦S). The MDV is largely ice-free. Low accumulation rates, strong winds, and proximity to the valley floor make these glaciers dusty in comparison to their inland counterparts. This study examines both supraglacial melt streams and cryoconite holes. Supraglacial streams on the lower Canada Glacier have median dissolved (<0.4 μm) concentrations of Fe, Mn, As, Cu, and V of 71.5, 75.5, 3.7, 4.6, and 4.3 nM. All dissolved Cd concentrations and the vast majority of Pb values are below our analytical detection (i.e., 0.4 and 0.06 nM). Chemical behavior did not follow similar trends for eastern and western draining waters. Heterogeneity likely reflects distinctions eolian deposition, rock:water ratios, and hydrologic connectivity. Future increases in wind-delivered sediment will likely drive dynamic responses in melt chemistry. For elements above detection limits, dissolved concentrations in glacier surface melt are within an order of magnitude of concentrations observed in proglacial streams (i.e., flowing on the valley floor). The Fe enrichment of cryoconite water relative to N, P, or Si exceeds enrichment observed in marine phytoplankton. This suggests that the glacier surface is an important source of Fe to downstream ecosystems.

 

10aAntarctica10acryoconite holes10aglacier melt chemistry10asupraglacial streams10atrace elements1 aFortner, Sarah1 aLyons, Berry uhttp://journal.frontiersin.org/article/10.3389/feart.2018.00031/full01630nas a2200169 4500008004100000245008200041210006900123260001200192490000600204520109200210100002201302700002401324700002101348700001701369700001601386856005801402 2018 eng d00aDrivers of solar radiation variability in the McMurdo Dry Valleys, Antarctica0 aDrivers of solar radiation variability in the McMurdo Dry Valley c03/20180 v83 a

 

Annually averaged solar radiation in the McMurdo Dry Valleys, Antarctica has varied by over 20 W m−2 during the past three decades; however, the drivers of this variability are unknown. Because small differences in radiation are important to water availability and ecosystem functioning in polar deserts, determining the causes are important to predictions of future desert processes. We examine the potential drivers of solar variability and systematically eliminate all but stratospheric sulfur dioxide. We argue that increases in stratospheric sulfur dioxide increase stratospheric aerosol optical depth and decrease solar intensity. Because of the polar location of the McMurdo Dry Valleys (77–78°S) and relatively long solar ray path through the stratosphere, terrestrial solar intensity is sensitive to small differences in stratospheric transmissivity. Important sources of sulfur dioxide include natural (wildfires and volcanic eruptions) and anthropogenic emission.

 

1 aObryk, Maciek, K.1 aFountain, Andrew, G1 aDoran, Peter, T.1 aLyons, Berry1 aEastman, R. uhttp://www.nature.com/articles/s41598-018-23390-7.pdf02262nas a2200181 4500008004100000022001400041245010300055210006900158260001200227300001600239490000800255520165500263100002201918700001701940700001501957700002401972856008401996 2018 eng d a2169-895300aFe and Nutrients in Coastal Antarctic Streams: Implications for Primary Production in the Ross Sea0 aFe and Nutrients in Coastal Antarctic Streams Implications for P c12/2018 a3507 - 35220 v1233 a

The Southern Ocean (SO) has been an area of biogeochemical interest due to the presence of macronutrients (N, P, and Si) but lack of the expected primary production response, which is thought to be primarily due to Fe limitation. Because primary production is associated with increased drawdown of atmospheric CO2, it is important to quantify the fluxes of Fe and other nutrients into the SO. Here we present data from subaerial streams that flow into the Ross Sea, a sector of the coastal SO. Water samples were collected in the McMurdo Dry Valleys, Antarctica, and analyzed for macronutrients and Fe to determine the potential impact of terrestrial water input on the biogeochemistry of coastal oceanic waters. The physiochemical forms of Fe were investigated through analysis of three operationally defined forms: acid-dissolvable Fe (no filtration), filterable Fe (<0.4 μm), and dissolved Fe (<0.2 μm). The combined average flux from two McMurdo Dry Valley streams was approximately 240 moles of filterable Fe per year. The dissolved fraction of Fe made up 18%–27% of the filterable Fe. The stream data yield an average filterable stoichiometry of N3P1Si100Fe0.8, which is substantially different from the planktonic composition and suggests that these streams are a potential source of Fe and P, relative to N and Si, to coastal phytoplankton communities. While the Fe flux from these streams is orders of magnitude less than estimated eolian and iceberg sources, terrestrial streams are expected to become a more significant source of Fe to the Ross Sea in the future.

1 aOlund, Sydney, A.1 aLyons, Berry1 aWelch, Sue1 aWelch, Kathleen, A. uhttps://agupubs.pericles-prod.literatumonline.com/doi/full/10.1029/2017JG00435204018nas a2200217 4500008004100000245011800041210006900159260004000228490001000268520328000278653002403558653002703582653002103609653002703630653002003657653002403677653001803701100001303719700001703732856005103749 2018 eng d00aGenomics and transcriptomics of Antarctic nematodes reveal drivers of life history evolution and genome evolution0 aGenomics and transcriptomics of Antarctic nematodes reveal drive aProvo, UTbBrigham Young University0 vPh.D.3 a

Elemental stoichiometry defines a critical understanding of the relationship between nutrient availability and usage throughout different levels of the biological community. We found there is a link between available phosphorus (P), cellular phosphorus, and nematode development as postulated by the growth rate hypothesis (GRH). I predicted that in a P-poor environment, cellular RNA concentrations would be lower than they are in P-rich environment, and thus the 18srRNA expression level will have reduced. To most efficiently regulate the uptake of limited P, I predicted that nematodes in P-poor environments would decrease the number of copies of the 18s rRNA gene in their genome. I measured life history traits as well as rRNA gene expression and gene copy number. We found that elemental stoichiometry predicts evolutionary changes consistent with the Growth Rate Hypothesis. We sequenced and assembled a draft genome of P. murrayi. Although we expected to find genes responsible for stress tolerance, we hypothesized that in response to strong selection pressure associated with living in a simplified ecosystem, over time the genome of P. murrayi should have undergone significant decay (gene loss) relative to species in ecosystems structured more strongly by biotic interactions. We found significantly fewer genes in P. murrayi. To compare patterns of gene expression between two highly divergent Antarctic nematode species, we sequenced and assembled the transcriptomes of S. lindsayae and P. murrayi. Under laboratory conditions at 4  ̊C, S. lindsayae had significantly lower rates of gene expression but expressed a significantly larger number of genes. We speculate that the differences in gene expression are correlated with life history traits (developmental rates) while the differences in the number of genes expressed can be explained by their different genetic systems (S. lindsayae is amphimictic, P. murrayi is parthenogenic) and the soil environments to which they are adapted. Since we previously showed that differences in available P content can influence the evolution of gene expression via gene copy number, and that this ultimately influences growth rate, we wondered how much of this response is driven by genetics versus how strongly these patterns are driven by temperature. To better understand this, we maintained wild type populations of P. murrayi in P-rich and P-poor conditions at 5  ̊C, 10  ̊C and 15 ̊C in the laboratory for over 40 generations and sequenced the transcriptomes prepared from each treatment group. We found that nutrient levels played an important role in gene expression when the temperature is optimal for P. murrayi culturing and that temperature is more important in gene expression when the available P is limited. This work underscores the utility of using principles of elemental stoichiometry coupled with genomic and transcriptomics research tools to make and test predictions about life history evolution. The results of my work also inform inferences about the ways in which nutrient availability also drives the organization of trophic interactions and ultimately ecosystems.

10aAntarctic nematodes10aCaenorhabditis elegans10agenome evolution10agrowth rate hypothesis10aPlectus murrayi10aScottnema lindsayae10atranscriptome1 aXue, Xia1 aAdams, Byron uhttps://search.proquest.com/docview/208189900302633nas a2200133 4500008004100000245016300041210006900204260005700273490000900330520205900339100002202398700002102420856005802441 2018 eng d00aGroundwater and thermal legacy of a large paleolake in Taylor Valley, East Antarctica as evidenced by airborne electromagnetic and sedimentological techniques0 aGroundwater and thermal legacy of a large paleolake in Taylor Va aBaton Rouge, LAbLouisiana State Universityc07/20180 vM.S.3 a

During the Last Glacial Maximum, grounded ice in the Ross Sea extended into the otherwise ice-free McMurdo Dry Valleys, creating a series of large ice dammed paleolakes. Grounded ice within the mouth of Taylor Valley allowed for lake levels to reach elevations not possible at modern day and formed what is known as Glacial Lake Washburn (GLW). GLW extended from the eastern portion of Taylor Valley roughly 20 km west to a level ~300 m higher than modern day Lake Fryxell. The formation and existence of GLW has been debated, though previous studies correlate the timing of GLW with early Holocene grounded ice. Evidence of GLW has largely been constrained to the interpretation of glacial deposits and fluvial features such as lacustrine deposits, strandlines, and preserved paleodeltas. GIS and remote sensing techniques paired with regional resistivity data provide new insight into the paleohydrology of the region.

To quantify the extent of GLW, paleodelta locations were mapped using high resolution LiDAR digital elevation models and satellite imagery. Delta topset elevations were correlated between three streams in Fryxell basin to determine paleolake levels. Additionally, mean resistivity maps generated from airborne electromagnetic survey data (SkyTEM) reveal an extensive groundwater system within Fryxell basin which is interpreted as a legacy groundwater signal from GLW. Resistivity data suggests that active permafrost formation has been ongoing since onset of lake drainage, and that lake levels were over 60 m higher than modern only 1,000 – 2,000 yr BP. This coincides with a warmer than modern paleoclimate inferred by ice core records, indicating a dynamic hydrological system that is highly sensitive to small changes in climate. As global temperatures increase, Lake Fryxell will continue to experience highly variable lake levels. Lakes and groundwater within the McMurdo Dry Valleys are critical to understanding impacts on the broader ecosystem which is largely driven by the availability of liquid water.

1 aMyers, Krista, F.1 aDoran, Peter, T. uhttps://digitalcommons.lsu.edu/gradschool_theses/477602094nas a2200241 4500008004100000245014400041210006900185260001200254490000600266520131100272653002001583653001401603653001701617653001501634653001501649653002401664653001301688653002201701100001701723700002201740700002401762856006601786 2018 eng d00aThe impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited0 aimpact of fossil fuel burning related to scientific activities i c04/20180 v63 a

 

Fossil fuel use associated with scienti c activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx for the 2015–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.

 

10acarbon dynamics10aemissions10afossil fuels10ahelicopter10amanagement10aMcMurdo Dry Valleys10anitrogen10ascience activites1 aLyons, Berry1 aSaelens, Elsa, D.1 aWelch, Kathleen, A. uhttps://www.elementascience.org/article/10.1525/elementa.288/02931nas a2200205 4500008004100000245011300041210006900154260001200223490000600235520222200241100002202463700002402485700002402509700002302533700002402556700002102580700002102601700003302622856007002655 2018 eng d00aLocal and Regional Scale Heterogeneity Drive Bacterial Community Diversity and Composition in a Polar Desert0 aLocal and Regional Scale Heterogeneity Drive Bacterial Community c08/20180 v93 a

The distribution of organisms in an environment is neither uniform nor random but is instead spatially patterned. The factors that control this patterning are complex and the underlying mechanisms are poorly understood. Soil microbes are critical to ecosystem function but exhibit highly complex distributions and community dynamics due in large part to the scale-dependent effects of environmental heterogeneity. To better understand the impact of environmental heterogeneity on the distribution of soil microbes, we sequenced the 16S rRNA gene from bacterial communities in the microbe-dominated polar desert ecosystem of the McMurdo Dry Valleys (MDV), Antarctica. Significant differences in key edaphic variables and alpha diversity were observed among the three lake basins of the Taylor Valley (Kruskal–Wallis; pH: χ2 = 68.89, P < 0.001, conductivity: χ2 = 35.03, P < 0.001, observed species: χ2 = 7.98, P = 0.019 and inverse Simpson: χ2 = 18.52, P < 0.001) and each basin supported distinctive microbial communities (ANOSIM R = 0.466, P = 0.001, random forest ratio of 14.1). However, relationships between community structure and edaphic characteristics were highly variable and contextual, ranging in magnitude and direction across regional, basin, and local scales. Correlations among edaphic factors (pH and soil conductivity) and the relative abundance of specific phyla were most pronounced along local environmental gradients in the Lake Fryxell basin where Acidobacteria, Bacteroidetes, and Proteobacteria declined while Deinococcus–Thermus and Gemmatimonadetes increased with soil conductivity (all P < 0.1). Species richness was most strongly related to the soil conductivity gradient present within this study system. We suggest that the relative importance of pH versus soil conductivity in structuring microbial communities is related to the length of edaphic gradients and the spatial scale of sampling. These results highlight the importance of conducting studies over large ranges of key environmental gradients and across multiple spatial scales to assess the influence of environmental heterogeneity on the composition and diversity of microbial communities.

1 aFeeser, Kelli, L.1 aVan Horn, David, J.1 aBuelow, Heather, N.1 aColman, Daniel, R.1 aMcHugh, Theresa, A.1 aOkie, Jordan, G.1 aSchwartz, Egbert1 aTakacs-Vesbach, Cristina, D. uhttps://www.frontiersin.org/article/10.3389/fmicb.2018.01928/full01901nas a2200169 4500008004100000245010500041210006900146260004900215490000900264520132500273653001301598653001201611653001301623100002401636700002601660856004501686 2018 eng d00aMicrobial and CO2 responses to water stresses show decreased productivity and diversity through time0 aMicrobial and CO2 responses to water stresses show decreased pro aProvo, UTbBrigham Young Universityc05/20180 vM.S.3 a

Some bacterial taxa when stimulated by water additions will break dormancy, grow, and become dominant members of the community and contribute significant pulses of CO2 associated with the rewetting event. These pulses of activity are associated with high levels of bacterial productivity in soils. (Aanderud et al. 2011) We examined the bacterial taxa that resuscitate and become metabolically active following two forms of water stress (soil drying- rewetting and freeze-thaw cycles) and we captured and measured the CO2 emanating from those soils. Specifically, We used target metagenomics, which uses a specific gene pool within bacteria that is associated with a function of an ecological process, in this case active (16S rRNA communities) bacteria and all bacteria (16S rRNA communities) during drying-rewetting and freeze-thaw cycles. We measured an array of community dynamics (i.e., evenness, richness, diversity, relative abundance of taxa, and network analyses between taxa) as dry soils are rewetted and as frozen soils thaw multiple times in three cold desert soils. Soils from all three locations exhibited some similar bacterial taxa and gene function but were large in part their own community derived from the evolutionary history of the continent in which they reside.

10adormancy10aPiCRUST10aturnover1 aRobinson, David, M.1 aAanderud, Zachary, T. uhttps://scholarsarchive.byu.edu/etd/683004038nas a2200205 4500008004100000245015700041210006900198260001200267300001600279490000800295520333900303100001903642700002103661700002403682700001503706700002403721700001703745700002403762856004603786 2018 eng d00aNear-surface refractory black carbon observations in the atmosphere and snow in the McMurdo Dry Valleys, Antarctica and potential impacts of foehn winds0 aNearsurface refractory black carbon observations in the atmosphe c01/2018 a2877 - 28870 v1233 a

Measurements of light absorbing particles in the boundary layer of the high southern latitudes are scarce, particularly in the McMurdo Dry Valleys (MDV), Antarctica. During the 2013 - 2014 austral summer near-surface boundary layer refractory black carbon (rBC) aerosols were measured in air by a single particle soot photometer (SP2) at multiple locations in the MDV. Near-continuous rBC atmospheric measurements were collected at Lake Hoare Camp (LH) over two months and for several hours at more remote locations away from established field camps. We investigated periods dominated by both up and down-valley winds to explore the causes of differences in rBC concentrations and size distributions. Snow samples were also collected in a 1m pit on a glacier near the camp. The range of concentrations rBC in snow were 0.3 1.2 ± 0.3 μg-rBC/L-H2O, and total organic carbon were 0.3 1.4 ± 0.3 mg/L. The rBC concentrations measured in this snow pit are not sufficient to reduce surface albedo, however, there is potential for accumulation of rBC on snow and ice surfaces at low elevation throughout the MDV which were not measured as part of this study. At LH, the average background rBC mass aerosol concentrations was 1.3 ng/m3. rBC aerosol mass concentrations were slightly lower, 0.09 1.3 ng/m3, at the most remote sites in the MDV. Concentration spikes as high as 200 ng/m3 were observed at LH, associated with local activities. During a foehn wind event, the average rBC mass concentration increased to 30-50 ng m-3. Here we show the rBC increase could be due to resuspension of locally produced BC from generators, rocket toilets, and helicopters, which may remain on the soil surface until redistributed during high wind events. Quantification of local production and long-range atmospheric transport of rBC to the MDV is necessary for understanding the impacts of this species on regional climate. 

 

1 aKhan, Alia, L.1 aMcMeeking, Gavin1 aSchwarz, Joshua, P.1 aXian, Peng1 aWelch, Kathleen, A.1 aLyons, Berry1 aMcKnight, Diane, M. uhttp://doi.wiley.com/10.1002/2017JD02769602670nas a2200181 4500008004100000245011700041210006900158260001200227300001400239490000700253520207300260100002602333700001702359700002202376700002302398700002002421856004702441 2018 eng d00aObserved trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change0 aObserved trends of soil fauna in the Antarctic Dry Valleys early c02/2018 a312 - 3210 v993 a

Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cool- ing trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compen- sated for the declining numbers of the dominant species. Interannual variation in the propor- tion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common spe- cies to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but signif- icant positive relationship with soil moisture. Our findings show that combining an under- standing of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abun- dance and diversity of soil fauna. 

1 aAndriuzzi, Walter, S.1 aAdams, Byron1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://doi.wiley.com/10.1002/ecy.2090/full02241nas a2200241 4500008004100000245018900041210006900230260001200299300001600311490000700327520137700334653001501711653001801726653001301744653001701757653002001774100002801794700003201822700002301854700002601877700003301903856006301936 2018 eng d00aPhotoecology of the Antarctic cyanobacterium Leptolyngbya sp. BC1307 brought to light through community analysis, comparative genomics and in vitro photophysiology0 aPhotoecology of the Antarctic cyanobacterium iLeptolyngbyai sp B c11/2018 a5279 - 52930 v273 a

Cyanobacteria are important photoautotrophs in extreme environments such as the McMurdo Dry Valleys, Antarctica. Terrestrial Antarctic cyanobacteria experience constant darkness during the winter and constant light during the summer which influences the ability of these organisms to fix carbon over the course of an annual cycle. Here, we present a unique approach combining community structure, genomic and photophysiological analyses to understand adaptation to Antarctic light regimes in the cyanobacterium Leptolyngbya sp. BC1307. We show that Leptolyngbya sp. BC1307 belongs to a clade of cyanobacteria that inhabits near‐surface environments in the McMurdo Dry Valleys. Genomic analyses reveal that, unlike close relatives, Leptolyngbya sp. BC1307 lacks the genes necessary for production of the pigment phycoerythrin and is incapable of complimentary chromatic acclimation, while containing several genes responsible for known photoprotective pigments. Photophysiology experiments confirmed Leptolyngbya sp. BC1307 to be tolerant of short‐term exposure to high levels of photosynthetically active radiation, while sustained exposure reduced its capacity for photoprotection. As such, Leptolyngbya sp. BC1307 likely exploits low‐light microenvironments within cyanobacterial mats in the McMurdo Dry Valleys.

10aAntarctica10acyanobacteria10agenomics10aphotoecology10aphotophysiology1 aChrismas, Nathan, A. M.1 aWilliamson, Christopher, J.1 aYallop, Marian, L.1 aAnesio, Alexandre, M.1 aSánchez-Baracaldo, Patricia uhttps://onlinelibrary.wiley.com/doi/full/10.1111/mec.1495302508nas a2200181 4500008004100000245017000041210006900211260001200280300001600292490000700308520183400315100002302149700002102172700002202193700002302215700002102238856006702259 2018 eng d00aThe physical limnology of a permanently ice-covered and chemically stratified Antarctic lake using high resolution spatial data from an autonomous underwater vehicle0 aphysical limnology of a permanently icecovered and chemically st c05/2018 a1234 - 12520 v633 a

We used an Environmentally Non-Disturbing Under-ice Robotic ANtarctic Explorer to make measurements of conductivity and temperature in Lake Bonney, a chemically stratified, permanently ice-covered Antarctic lake that abuts Taylor Glacier, an outlet glacier from the Polar Plateau. The lake is divided into two lobes – East Lobe Bonney (ELB) and West Lobe Bonney (WLB), each with unique temperature and salinity profiles. Most of our data were collected in November 2009 from WLB to examine the influence of the Taylor Glacier on the structure of the water column. Temperatures adjacent to the glacier face between 20 m and 22 m were 38C colder than in the rest of WLB, due to latent heat transfer associated with melting of the submerged glacier face and inflow of cold brines that originate beneath the glacier. Melting of the glacier face into the salinity gradient below the chemocline generates a series of nearly horizontal intrusions into WLB that were previously documented in profiles measured with 3 cm vertical resolution in 1990–1991. WLB and ELB are connected by a narrow channel through which water can be exchanged over a shallow sill that controls the position of the chemocline in WLB. A complex exchange flow appears to exist through the narrows, driven by horizontal density gradients and melting at the glacier face. Superimposed on the exchange is a net west- to-east flow generated by the higher volume of meltwater inflows to WLB. Both of these processes can be expected to be enhanced in the future as more meltwater is produced. 

1 aSpigel, Robert, H.1 aPriscu, John, C.1 aObryk, Maciek, K.1 aStone, William, C.1 aDoran, Peter, T. uhttp://onlinelibrary.wiley.com/wol1/doi/10.1002/lno.10768/full02179nas a2200121 4500008004100000245006300041210006300104260002600167520172200193100002201915700002901937856009101966 2018 eng d00aPhysiological and Biochemical Adaptations of Psychrophiles0 aPhysiological and Biochemical Adaptations of Psychrophiles aBoca RatonbCRC Press3 a

The cold biosphere encompasses many microorganism-dominated habitats that rely on light-dependent primary production. Within these environments, there are numerous physical and chemical factors limiting metabolism and growth that the microorganisms must overcome. The psychrophilic microorganisms discussed herein integrate a complex spectrum of adaptive strategies to survive these physiological challenges, including genome evolution, enzyme structure and catalysis rate changes, cryoprotectant formation, and a multitude of photosynthetic adaptations. Psychrophilic organisms also hold the key to biotechnical advances and the future, such that psychrophilic enzymes are used for everything from laboratory reagents and industrial work to medical research and environmental sustainability. Researchers have learned to exploit psychrophiles’ efficiency at low temperatures (i.e., cooler washing machines and energy-saving, cost-effective enzyme production), their higher energy activity (thus allowing lower concentrations of needed catalysts, reducing costs and procedure time), and their ability to contribute to hydrocarbon bioremediation. Although psychrophilic microbes exist in numerous habitats and undergo various adaptive strategies, an understanding of what makes an organism psychrophilic is still unknown in a large majority of cold-adapted organisms, and thus future investigations are needed regarding cold adaptation and their biotechnological potential. Even as research has increased over the last decade, new technological advances and high-throughput DNA sequencing will continue to provide information about cold adaptation or the mechanisms needed for survival in a changing world.

1 aTeufel, Amber, G.1 aMorgan-Kiss, Rachael, M. uhttps://www.taylorfrancis.com/books/e/9781498774932/chapters/10.1201%2F9781315154695-902340nas a2200181 4500008004100000022001300041245009000054210006900144260001200213490000800225520176100233100001601994700001702010700002202027700002002049700002302069856006602092 2018 eng d a0038071700aSoil biological responses to C, N and P fertilization in a polar desert of Antarctica0 aSoil biological responses to C N and P fertilization in a polar  c07/20180 v1223 a

 

In the polar desert ecosystem of the McMurdo Dry Valleys of Antarctica, biology is constrained by available liquid water, low temperatures, as well as the availability of organic matter and nutrient elements. These soil ecosystems are climate-sensitive, where projected future warming may have profound effects on biological communities and biogeochemical cycling. Warmer temperatures will mobilize meltwater from permafrost and glaciers, may increase precipitation and may be accompanied by pulses of nutrient availability. Enhanced water and nutrient availability have the potential to greatly influence desert soil biology and ecosystem processes. The objectives of this 5-year study were to determine which nutrient elements (C, N, P) are most limiting to dry valley soil communities and whether landscape history (i.e., in situ soil type and stoichiometry) influences soil community response to nutrient additions. After 3 years of no noticeable response, soil CO2 flux was significantly higher under addition of C+ N than the other treatments, regardless of in situ soil stoichiometry, but microbial biomass and invertebrate abundance were variable and not influenced in the same manner. A stable isotope incubation suggests that fertilization increases C and N mineralization from organic matter via stimulating microbial activity, with loss of both the applied treatments as well in situ C and N. However, these responses are relatively short-lived, suggesting long-term impacts on C and N cycling would only occur if meltwater and nutrient pulses are sustained over time, a scenario that is increasingly likely for the dry valleys.

 

1 aBall, Becky1 aAdams, Byron1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A. uhttp://linkinghub.elsevier.com/retrieve/pii/S003807171830108102240nas a2200145 4500008004100000245010800041210006900149260001200218490000800230520171900238100002101957700002501978700001702003856007402020 2018 eng d00aSoil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica0 aSoil Moisture Controls the Thermal Habitat of Active Layer Soils c01/20180 v1233 a

Antarctic soil ecosystems are strongly controlled by abiotic habitat variables. Regional climate change in the McMurdo Dry Valleys is expected to cause warming over the next century, leading to an increase in frequency of freeze-thaw cycling in the soil habitat. Previous studies show that physiological stress associated with freeze-thaw cycling adversely affects invertebrate populations by decreasing abundance and positively selecting for larger body sizes. However, it remains unclear whether or not climate warming will indeed enhance the frequency of annual freeze-thaw cycling and associated physiological stresses. This research quantifies the frequency, rate, and spatial heterogeneity of active layer freezing to better understand how regional climate change may affect active layer soil thermodynamics, and, in turn, affect soil macroinvertebrate communities. Shallow active layer temperature, specific conductance, and soil moisture were observed along natural wetness gradients. Field observations show that the frequency and rate of freeze events are nonlinearly related to freezable soil moisture (θf). Over a 2 year period, soils at θf < 0.080 m3/m3 experienced between 15 and 35 freeze events and froze rapidly compared to soils with θf > 0.080 m3/m3, which experienced between 2 and 6 freeze events and froze more gradually. A numerical soil thermodynamic model is able to simulate observed freezing rates across a range of θf, reinforcing a well-known causal relationship between soil moisture and active layer freezing dynamics. Findings show that slight increases in soil moisture can potentially offset the effect of climate warming on exacerbating soil freeze-thaw cycling.

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aAdams, Byron uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JG00401802513nas a2200277 4500008004100000245010700041210006900148260001200217300001600229490000700245520169000252653001201942653001601954653001601970653001401986653001502000653001602015100002602031700002102057700002402078700001702102700001702119700002002136700002402156856005502180 2018 eng d00aSpatial and temporal patterns of microbial mats and associated invertebrates along an Antarctic stream0 aSpatial and temporal patterns of microbial mats and associated i c10/2018 a1911–19210 v413 a

 

Microbial biofilms are biological hotspots in many alpine and polar ecosystems, but the controls on and functional significance of their fauna are little known. We studied cyanobacterial mats and the underlying sediment in a glacial meltwater stream in the McMurdo Dry Valleys, Antarctica. We investigated mat biomass (total and phototrophic), diatoms, and micro-meiofauna (nematodes, rotifers, and tardigrades) at nine sites along a 1670 m stream reach in a cold, low-flow growing season, and in a warmer growing season in which peak flows (above 100 L s−1) scoured the mats. Diatom and invertebrate communities were not related, but mat biomass in the low-flow year was negatively related to nematode abundance, including that of the omnivore Eudorylaimus. In the high-flow year that followed, invertebrate abundance was reduced in the mats, diatom community structure was altered, and mat biomass was higher. The difference in invertebrate abundance between years was greater in mats in upstream reaches, where the greatest increases in flow velocity may have occurred, and was negligible in mats in downstream reaches as well as in the sediment beneath the mats. Integrating our results with previous findings, we generate two predictive hypotheses to be tested in glacial meltwater streams: (1) under peak flows invertebrates decline in the microbial mats, while (2) the sediment beneath the mats is a refuge from the flow disturbance. Our results also suggest that, under stable flow conditions, microinvertebrate grazers could exert top-down control on microbial mat biomass.

 

10adiatoms10aDisturbance10aDry valleys10aEpilithon10aMicrofauna10aStream flow1 aAndriuzzi, Walter, S.1 aStanish, Lee, F.1 aSimmons, Breana, L.1 aJaros, Chris1 aAdams, Byron1 aWall, Diana, H.1 aMcKnight, Diane, M. uhttp://link.springer.com/10.1007/s00300-018-2331-402332nas a2200193 4500008004100000245017900041210006900220260001200289300001600301490000700317520164300324100001701967700001701984700002202001700001702023700002302040700002002063856005502083 2018 eng d00aStable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore–predator in Taylor Valley, Antarctica0 aStable C and N isotope ratios reveal soil food web structure and c05/2018 a1013–10180 v413 a

Soil food webs of the McMurdo Dry Valleys, Antarctica are simple. These include primary trophic levels of mosses, algae, cyanobacteria, bacteria, archaea, and fungi, and their protozoan and metazoan consumers (including relatively few species of nematodes, tardigrades, rotifers, and microarthropods). These biota are patchily distributed across the landscape, with greatest faunal biodiversity associated with wet soil. Understanding trophic structure is critical to studies of biotic interactions and distribution; yet, McMurdo Dry Valley soil food web structure has been inferred from limited laboratory culturing and micro- scopic observations. To address this, we measured stable isotope natural abundance ratios of C (13C/12C) and N (15N/14N) for di erent metazoan taxa (using whole body biomass) to determine soil food web structure in Taylor Valley, Antarctica. Nitrogen isotopes were most useful in di erentiating trophic levels because they fractionated predictably at higher trophic levels. Using 15N/14N, we found that three trophic levels were present in wet soil habitats. While cyanobacterial mats were the primary trophic level, the nematode Plectus murrayi, tardigrade Acutuncus antarcticus, and rotifers composed a secondary trophic level of grazers. Eudorylaimus antarcticus had a 15N/14N ratio that was 2–4‰ higher than that of grazers, indicating that this species is the sole member of a tertiary trophic level. Understanding the trophic positions of soil fauna is critical to predictions of current and future species interactions and their distributions for the McMurdo Dry Valleys, Antarctica.

1 aShaw, Ashley1 aAdams, Byron1 aBarrett, John, E.1 aLyons, Berry1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-017-2243-802975nas a2200289 4500008004100000245013500041210006900176260001200245490000600257520199400263653002902257653002302286653002402309653003102333653002602364653002602390100002602416700002402442700001602466700002002482700002202502700002602524700002502550700002302575700001702598856007002615 2018 eng d00aStoichiometric Shifts in Soil C:N:P Promote Bacterial Taxa Dominance, Maintain Biodiversity, and Deconstruct Community Assemblages0 aStoichiometric Shifts in Soil CNP Promote Bacterial Taxa Dominan c07/20180 v93 a

Imbalances in C:N:P supply ratios may cause bacterial resource limitations and constrain biogeochemical processes, but the importance of shifts in soil stoichiometry are complicated by the nearly limitless interactions between an immensely rich species pool and a multiple chemical resource forms. To more clearly identify the impact of soil C:N:P on bacteria, we evaluated the cumulative effects of single and coupled long-term nutrient additions (i.e., C as mannitol, N as equal concentrations NH4 + and NO3 − , and P as Na3PO4) and water on communities in an Antarctic polar desert, Taylor Valley. Untreated soils possessed relatively low bacterial diversity, simplified organic C sources due to the absence of plants, limited inorganic N, and excess soil P potentially attenuating links between C:N:P. After 6 years of adding resources, an alleviation of C and N colimitation allowed one rare Micrococcaceae, an Arthrobacter species, to dominate, comprising 47% of the total community abundance and elevating soil respiration by 136% relative to untreated soils. The addition of N alone reduced C:N ratios, elevated bacterial richness and diversity, and allowed rare taxa relying on ammonium and nitrite for metabolism to become more abundant [e.g., nitrite oxidizing Nitrospira species (Nitrosomonadaceae), denitrifiers utilizing nitrite (Gemmatimonadaceae) and members of Rhodobacteraceae with a high affinity for ammonium]. Based on community co-occurrence networks, lower C:P ratios in soils following P and CP additions created more diffuse and less connected communities by disrupting 73% of species interactions and selecting for taxa potentially exploiting abundant P. Unlike amended nutrients, water additions alone elicited no lasting impact on communities. Our results suggest that as soils become nutrient rich a wide array of outcomes are possible from species dominance and the deconstruction of species interconnectedness to the maintenance of biodiversity.

10aecological stoichiometry10aLake Fryxell Basin10aMcMurdo Dry Valleys10anetwork community modeling10anutrient colimitation10aSolirubrobacteriaceae1 aAanderud, Zachary, T.1 aSaurey, Sabrina, D.1 aBall, Becky1 aWall, Diana, H.1 aBarrett, John, E.1 aMuscarella, Mario, E.1 aGriffin, Natasha, A.1 aVirginia, Ross, A.1 aAdams, Byron uhttps://www.frontiersin.org/article/10.3389/fmicb.2018.01401/full01835nas a2200169 4500008004100000245013700041210006900178260001200247300001800259490000700277520122000284100002101504700002501525700002401550700001701574856007401591 2018 eng d00aTransit times and rapid chemical equilibrium explain chemostasis in glacial meltwater streams in the McMurdo Dry Valleys, Antarctica0 aTransit times and rapid chemical equilibrium explain chemostasis c12/2018 a13322 - 133310 v453 a

Fluid  transit  time  is  understood  to  be  an  important  control  on  the  shape  of concentration-discharge (C-q) relationships, yet empirical evidence supporting this linkage is limited. We investigated C-q relationships for weathering-derived solutes across seven Antarctic glacial meltwate streams. We hypothesized that (H1) solute fluxes in McMurdo Dry Valley streams are reaction limited so that C-q relationships are characterized by dilution and that (H2) transit time explains between-stream variability in the degree of C-q dilution. Results show that C-q relationships are chemostatic because solute equilibrium times are shorter than stream corridor fluid transit times. Between-stream variability in the efficiency of solute production is positively correlated with transit time, suggesting that transit time is an important control on the solute export regime. These results provide empirical evidence for the controls on weathering-derived C-q relationships and have important implications for Antarctic ecosystems and solute export regimes of watersheds worldwide.

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aLyons, Berry uhttps://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL08036907387nas a2200145 4500008004100000245013200041210006900173260003000242300000800272490001000280520680100290100001707091700002007108856011307128 2018 eng d00aTrophic relationships in soil communities how abiotic stress affects biotic interactions in the McMurdo Dry Valleys, Antarctica0 aTrophic relationships in soil communities how abiotic stress aff bColorado State University a1190 vPh.D.3 a

Understanding of the distribution and complexity of soil food webs and their role in ecosystem processes is limited. This is partially due to the difficulty studying the enormous diversity of species in belowground ecosystems and identifying the many roles of this diversity in ecosystem processes. Despite this, there is strong interest in understanding how the soil food web contributes to ecosystem processes such as decomposition, nutrient cycling, and carbon cycling. Yet, before we can fully understand how soil food webs are linked to ecosystem processes, more information is needed on their complex trophic interactions and how soil food webs respond to changing environmental variables. The McMurdo Dry Valleys in Antarctica provide an excellent opportunity to study soil communities and their trophic interactions because of soil food web simplicity and limited ecological interactions that are not easily distinguished in more diverse systems. However, it is unknown whether trophic interactions actually play a role in structuring soil communities in this ecosystem and whether these interactions are affected by environmental factors. The aim of this dissertation is to disentangle those questions.

In the first chapter of this dissertation, I give the background for my research. I introduce the challenges for studying soil biodiversity and its food web structure. Next, I discuss the usefulness of the McMurdo Dry Valleys as a simple, model system for researching trophic interactions in soil. The details of the current understanding of the McMurdo Dry Valley soil food web are demonstrated and I have highlighted gaps in this knowledge. In the second chapter of this dissertation, I address the question: What trophic interactions are present in the McMurdo Dry Valley soils? Here, I sought to elucidate the soil food web structure using stable isotopes (particularly 15N) and I present isotopic signatures for soil fauna taxa for one location in Taylor Valley, Antarctica. The natural abundance of 13C and 15N were measured for soil fauna and microbial mats sampled in both wet and dry soils near Von Guerard stream. This study revealed that three trophic levels were present in wet soils at this location and two trophic levels were present in dry soil. This is the first isotopic confirmation of Eudorylaimus antarcticus (Nematoda) as an omnivore-predator (in wet soil habitat), and challenges long-held assumptions of trophic simplicity of the McMurdo Dry Valley region.

Building on the findings of Chapter 2, Chapter 3 seeks to expand the understanding of dry valley food webs and the role of trophic interactions in structuring communities under environmental change. Specifically, I address the question: How do environmental variables (soil salinity and moisture) affect dry valley soil taxa and their trophic interactions? I show the results of a laboratory microcosm experiment on how elevated salinity and moisture affect four soil communities. Using soil collected from Taylor Valley, Antarctica, bacteria, bacteria with Scottnema lindsayae, bacteria with E. antarcticus, and bacteria with both S. lindsayae and E. antarcticus were established in microcosms under control or high salinity treatments and control or high moisture treatments (full factorial design). The results of this experiment showed that S. lindsayae has top down effects on bacterial abundance under control salinity but these top down effects were alleviated under high salinity. This study is the first to empirically show that biological interactions structure dry valley soil communities.

The fourth chapter follows the conclusions of Chapters 2 and 3, and seeks to determine food web structure and trophic interactions at the landscape scale in the McMurdo Dry Valleys. I sampled soil from 160 sites across 8 valleys ranging from the coast to high elevation near the polar plateau to address the question: How does the soil food web and its organic carbon sources vary across the McMurdo Dry Valley landscape with distance from coast and elevation? These valleys represent a temperature and moisture gradient, which affects ecosystem primary productivity. This study revealed that food web structure varies by habitat – the most diverse and complex trophic interactions exist in wet habitat near the coast where resources are more abundant. However, in dry habitat, where organic carbon resources are scarce, up to two trophic levels exist. These results build off of Chapter 2, and show that E. antarcticus can occupy either a predator trophic position when resources are high (wet soil) or a primary consumer position when resources are low (dry soil). Since climate-driven increases in hydrological connectivity are expected to alter soil moisture and resources, the distribution and abundance of soil biodiversity and their biotic interactions in formerly dry soil habitats may ultimately shift.

In Chapter 5, I asked if the lessons learned about soil food webs in the McMurdo Dry Valleys apply to a more complex ecosystem? In this study, I used soil nematode communities from the Loch Vale Watershed (Rocky Mountain National Park, Colorado) to test whether long-term nitrogen addition affected soil food web structure and function. Results from this study indicated that a faster-cycling, bacterial food web was prevalent in N-addition plots, as evidenced by abundance of r-selected bacterivore nematodes. Previously, lower bacterial abundance and soil carbon were found in the N-addition plots (compared to control) and the results presented in this dissertation suggest that these changes are likely trophic. Along with Chapter 3, the evidence that I present here support the hypothesis for top-down effects of microbivore nematodes on bacteria, which is consistent in subalpine and Antarctic soils.

In summary, through both field and laboratory experiments, my PhD project has: 1) defined the soil food web structure of the McMurdo Dry Valleys using stable isotopes; 2) revealed how top down interactions affect bacteria populations and how elevated stress (e.g. soil salinity) relieves the top down pressure; 3) showed how the soil food web structure varies across the landscape of the McMurdo Dry Valleys, Antarctica as related to soil C sources; and 4) shown how nitrogen addition affects soil food web dynamics in Colorado sub-alpine soil nematode community (Loch Vale Watershed, LVWS, Rocky Mountain National Park). These results have informed our understanding of soil communities and their trophic relationships in polar and subalpine ecosystems.

1 aShaw, Ashley1 aWall, Diana, H. uhttp://search.proquest.com/openview/0d494a3f115b75da1c7a2464e341808f/1?pq-origsite=gscholar&cbl=18750&diss=y02937nas a2200157 4500008004100000245006000041210006000101260001200161300001400173490000700187520246500194100001702659700001402676700002402690856006502714 2017 eng d00aCa isotopic geochemistry of an Antarctic aquatic system0 aCa isotopic geochemistry of an Antarctic aquatic system c01/2017 a882 - 8910 v443 a

The McMurdo Dry Valleys, Antarctica, are a polar desert ecosystem. The hydrologic system of the dry valleys is linked to climate with ephemeral streams that flow from glacial melt during the austral summer. Past climate variations have strongly influenced the closed-basin, chemically stratified lakes on the valley floor. Results of previous work point to important roles for both in-stream processes (e.g., mineral weathering, precipitation and dissolution of salts) and in-lake processes (e.g., mixing with paleo-seawater and calcite precipitation) in determining the geochemistry of these lakes. These processes have a significant influence on calcium (Ca) biogeochemistry in this aquatic ecosystem, and thus variations in Ca stable isotope compositions of the waters can aid in validating the importance of these processes. We have analyzed the Ca stable isotope compositions of streams and lakes in the McMurdo Dry Valleys. The results validate the important roles of weathering of aluminosilicate minerals and/or CaCO3 in the hyporheic zone of the streams, and mixing of lake surface water with paleo-seawater and precipitation of Ca-salts during cryo-concentration events to form the deep lake waters. The lakes in the McMurdo Dry Valleys evolved following different geochemical pathways, evidenced by their unique, nonsystematic Ca isotope signatures. 

1 aLyons, Berry1 aBullen, T1 aWelch, Kathleen, A. uhttp://onlinelibrary.wiley.com/doi/10.1002/2016GL071169/full02723nas a2200229 4500008004100000245015600041210006900197260001200266300001600278490000700294520192000301100002202221700002102243700002402264700002002288700002502308700001702333700002402350700002902374700002502403856006502428 2017 eng d00aCharacterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales0 aCharacterizing hyporheic exchange processes using highfrequency  c05/2017 a4124 - 41410 v533 a

Concentration-discharge (C-Q) relationships are often used to quantify source water contributions and biogeochemical processes occurring within catchments, especially during discrete hydrological events. Yet, the interpretation of C-Q hysteresis is often confounded by complexity of the critical zone, such as numerous source waters and hydrochemical nonstationarity. Consequently, researchers must often ignore important runoff pathways and geochemical sources/sinks, especially the hyporheic zone because it lacks a distinct hydrochemical signature. Such simplifications limit efforts to identify processes responsible for the transience of C-Q hysteresis over time. To address these limitations, we leverage the hydrologic simplicity and long-term, high-frequency Q and electrical conductivity (EC) data from streams in the McMurdo Dry Valleys, Antarctica. In this two end-member system, EC can serve as a proxy for the concentration of solutes derived from the hyporheic zone. We utilize a novel approach to decompose loops into subhysteretic EC-Q dynamics to identify individual mechanisms governing hysteresis across a wide range of timescales. We find that hydrologic and hydraulic processes govern EC response to diel and seasonal Q variability and that the effects of hyporheic mixing processes on C-Q transience differ in short and long streams. We also observe that variable hyporheic turnover rates govern EC-Q patterns at daily to interannual timescales. Last, subhysteretic analysis reveals a period of interannual freshening of glacial meltwater streams related to the effects of unsteady flow on hyporheic exchange. The subhysteretic analysis framework we introduce may be applied more broadly to constrain the processes controlling C-Q transience and advance understanding of catchment evolution. 

1 aSingley, Joel, G.1 aWlostowski, Adam1 aBergstrom, Anna, J.1 aSokol, Eric, R.1 aTorrens, Christa, L.1 aJaros, Chris1 aWilson, Colleen, E.1 aHendrickson, Patrick, J.1 aGooseff, Michael, N. uhttp://onlinelibrary.wiley.com/doi/10.1002/2016WR019739/full01371nas a2200157 4500008004100000020002200041245012600063210006900189250000600258260001300264520081000277100001701087700001801104700002401122856006701146 2017 eng d a978-3-319-57056-300aThe Climate of Snow and Ice as Boundary Condition for Microbial Life in Psychrophiles: From Biodiversity to Biotechnology0 aClimate of Snow and Ice as Boundary Condition for Microbial Life a2 bSpringer3 a

The microclimate and structure of snow and ice are a boundary condition as well as a matrix for a large spectrum of microbial life under alpine and polar conditions. Biological activity critically depends on the supply of energy, water and nutrients, with solar radiation as the prime source of energy, varying with latitude and altitude. The energy balance at the snow or ice surface provides the boundary condition for the fluxes of energy and water to the snow and ice, with important latitudinal differences from the temperate to the polar regions. The extreme situations of sunlit rocks surrounded by snow and the environment of Antarctic cryoconite holes, where ice, water, solar radiation and nutrients interact in particular ways, closes this review on ice and its effect on microbial life.

1 aMargesin, R.1 aKuhn, Michael1 aFountain, Andrew, G uhttp://link.springer.com/content/pdf/10.1007/978-3-319-57057-002880nas a2200625 4500008004100000245007400041210006900115260001200184490000800196520106500204100002301269700002101292700002101313700001601334700001801350700002301368700002201391700002301413700002201436700002001458700002701478700002001505700002301525700002801548700002301576700002201599700002101621700002401642700002001666700002401686700001601710700001501726700001801741700002201759700002701781700001901808700002401827700002201851700002101873700002801894700002201922700002201944700001701966700002101983700001902004700002202023700001802045700002702063700002302090700002302113700002202136700001602158700003202174856004802206 2017 eng d00aA communal catalogue reveals Earth’s multiscale microbial diversity0 acommunal catalogue reveals Earth s multiscale microbial diversit c11/20170 v5513 a

Our growing awareness of the microbial world’s importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth’s microbial diversity.

1 aThompson, Luke, R.1 aSanders, Jon, G.1 aMcDonald, Daniel1 aAmir, Amnon1 aLadau, Joshua1 aLocey, Kenneth, J.1 aPrill, Robert, J.1 aTripathi, Anupriya1 aGibbons, Sean, M.1 aAckermann, Gail1 aNavas-Molina, Jose, A.1 aJanssen, Stefan1 aKopylova, Evguenia1 aVázquez-Baeza, Yoshiki1 aGonzález, Antonio1 aMorton, James, T.1 aMirarab, Siavash1 aXu, Zhenjiang, Zech1 aJiang, Lingjing1 aHaroon, Mohamed, F.1 aKanbar, Jad1 aZhu, Qiyun1 aSong, Se, Jin1 aKosciolek, Tomasz1 aBokulich, Nicholas, A.1 aLefler, Joshua1 aBrislawn, Colin, J.1 aHumphrey, Gregory1 aOwens, Sarah, M.1 aHampton-Marcell, Jarrad1 aBerg-Lyons, Donna1 aMcKenzie, Valerie1 aFierer, Noah1 aFuhrman, Jed, A.1 aClauset, Aaron1 aStevens, Rick, L.1 aShade, Ashley1 aPollard, Katherine, S.1 aGoodwin, Kelly, D.1 aJansson, Janet, K.1 aGilbert, Jack, A.1 aKnight, Rob1 aConsortium, The, Earth Micr uhttps://www.nature.com/articles/nature2462102219nas a2200133 4500008004100000245013600041210006900177260004400246490000900290520170700299100002502006700001702031856003702048 2017 eng d00aComparing the Weathering Environment of Permian and Modern Antarctic Proglacial Lake Sediments: Mineralogical and Geochemical Study0 aComparing the Weathering Environment of Permian and Modern Antar aColumbus, OHbThe Ohio State University0 vB.S.3 a

The Antarctic continent has been in a polar to subpolar position since the Permian period. Although it has experienced milder climates over this time period as evidenced by corals in the fossil record, Antarctica did undergo extensive glaciation during the Permian. This is based on the abundance of Permian tillites (sedimentary rocks derived from glacier tills) found in the Transantarctic Mountains. In this research, I have compared Permian age proglacial lake sediments that are associated with tilites to modern proglacial lake siltstones and mudstones from Antarctica. This was done to determine the climate, especially the amount of glacier melt that occurred when these Permian sediments were deposited. The modern lake sediments are deposited in perennially ice-covered lakes by ephemeral streams that only flow 6 to 12 weeks a year. The geochemical analyses of the Permian samples and the modern sediments from Lake Hoare in the McMurdo Dry Valleys suggest that the Permian samples are more highly chemically weathered than the modern sediments. The mineralogy of Lake Hoare sediments contain more primary minerals than chemical weathering produced minerals in the Pagoda Formation rocks, thus supporting the geochemical analysis that the Pagoda Formation minerals have been more weathered. All these data suggest that the Permian lake samples were deposited in a warmer, more hydrogeologically active environment than were the modern lake sediments. These data support previously published sedimentological and paleontological data that the Pagoda samples were deposited under more temperate or warm-based proglacial conditions than what is observed in the McMurdo Dry Valleys today.

1 aBrewster, Shelby, A.1 aLyons, Berry uhttp://hdl.handle.net/1811/8076300851nas a2200265 4500008004100000245009100041210006900132260001200201300001400213490000600227100002500233700002200258700001700280700002100297700002400318700001700342700002400359700002100383700002000404700003300424700003100457700002300488700002000511856005400531 2017 eng d00aDecadal ecosystem response to an anomalous melt season in a polar desert in Antarctica0 aDecadal ecosystem response to an anomalous melt season in a pola c09/2017 a1334-13380 v11 aGooseff, Michael, N.1 aBarrett, John, E.1 aAdams, Byron1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aSokol, Eric, R.1 aTakacs-Vesbach, Cristina, D.1 aVandegehuchte, Martijn, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://www.nature.com/articles/s41559-017-0253-001830nas a2200193 4500008004100000245014200041210006900183260001200252300001400264490000700278520115100285100001801436700002601454700002401480700003301504700001701537700002001554856006201574 2017 eng d00aDecoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys0 aDecoupled responses of soil bacteria and their invertebrate cons c10/2017 a1242-12490 v203 a

Altered temperature profiles resulting in increased warming and freeze–thaw cycle (FTC) frequency pose great ecological challenges to organisms in alpine and polar ecosystems. We performed a laboratory microcosm experiment to investigate how temperature variability affects soil bacterial cell numbers, and abundance and traits of soil microfauna (the microbivorous nematode Scottnema lindsayae) from McMurdo Dry Valleys, Antarctica. FTCs and constant freezing shifted nematode body size distribution towards large individuals, driven by higher mortality among smaller individuals. FTCs reduced both bacterial and nematode abundance, but bacterial cell numbers also declined under warming, demonstrating decoupled consumer–prey responses. We predict that higher occurrence of FTCs in cold ecosystems will select for large body size within soil microinvertebrates and overall reduce their abundance. In contrast, warm temperatures without FTCs could lead to divergent responses in soil bacteria and their microinvertebrate consumers, potentially affecting energy and nutrient transfer rates in soil food webs of cold ecosystems.

1 aKnox, Matthew1 aAndriuzzi, Walter, S.1 aBuelow, Heather, N.1 aTakacs-Vesbach, Cristina, D.1 aAdams, Byron1 aWall, Diana, H. uhttp://onlinelibrary.wiley.com/doi/10.1111/ele.12819/full03366nas a2200205 4500008004100000245009200041210006900133260001200202300001400214490000700228520274200235100001902977700001802996700001903014700001503033700001903048700002303067700002403090856004603114 2017 eng d00aDissolved black carbon in the global cryosphere: Concentrations and chemical signatures0 aDissolved black carbon in the global cryosphere Concentrations a c06/2017 a6226-62340 v443 a

Black carbon (BC) is derived from the incomplete combustion of biomass and fossil fuels and can enhance glacial recession when deposited on snow and ice surfaces. Here we explore the influence of environmental conditions and the proximity to anthropogenic sources on the concentration and composition of dissolved black carbon (DBC), as measured by benzenepolycaroxylic acid (BPCA) markers, across snow, lakes, and streams from the global cryosphere. Data are presented from Antarctica, the Arctic, and high alpine regions of the Himalayas, Rockies, Andes, and Alps. DBC concentrations spanned from 0.62 μg/L to 170 μg/L. The median and (2.5, 97.5) quantiles in the pristine samples were 1.8 μg/L (0.62, 12), and nonpristine samples were 21 μg/L (1.6, 170). DBC is susceptible to photodegradation when exposed to solar radiation. This process leads to a less condensed BPCA signature. In general, DBC across the data set was composed of less polycondensed DBC. However, DBC from the Greenland Ice Sheet (GRIS) had a highly condensed BPCA molecular signature. This could be due to recent deposition of BC from Canadian wildfires. Variation in DBC appears to be driven by a combination of photochemical processing and the source combustion conditions under which the DBC was formed. Overall, DBC was found to persist across the global cryosphere in both pristine and nonpristine snow and surface waters. The high concentration of DBC measured in supraglacial melt on the GRIS suggests that DBC can be mobilized across ice surfaces. This is significant because these processes may jointly exacerbate surface albedo reduction in the cryosphere. 

1 aKhan, Alia, L.1 aWagner, Sasha1 aJaffé, Rudolf1 aXian, Peng1 aWilliams, Mark1 aArmstrong, Richard1 aMcKnight, Diane, M. uhttp://doi.wiley.com/10.1002/2017GL07348501933nas a2200181 4500008004100000245012100041210006900162260001200231490000600243520129900249100002001548700001901568700002101587700002001608700002501628700002501653856007301678 2017 eng d00aDiversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient0 aDiversity and Distribution of Freshwater Aerobic Anoxygenic Phot c02/20170 v83 a

Aerobic anoxygenic phototrophs (AAPs) have been shown to exist in numerous marine and brackish environments where they are hypothesized to play important ecological roles. Despite their potential significance, the study of freshwater AAPs is in its infancy and limited to local investigations. Here, we explore the occurrence, diversity and distribution of AAPs in lakes covering a wide latitudinal gradient: Mongolian and German lakes located in temperate regions of Eurasia, tropical Great East African lakes, and polar permanently ice-covered Antarctic lakes. Our results show a widespread distribution of AAPs in lakes with contrasting environmental conditions and confirm that this group is composed of different members of the Alpha- and Betaproteobacteria. While latitude does not seem to strongly influence AAP abundance, clear patterns of community structure and composition along geographic regions were observed as indicated by a strong macro-geographical signal in the taxonomical composition of AAPs. Overall, our results suggest that the distribution patterns of freshwater AAPs are likely driven by a combination of small-scale environmental conditions (specific of each lake and region) and large-scale geographic factors (climatic regions across a latitudinal gradient).

1 aFerrera, Isabel1 aSarmento, Hugo1 aPriscu, John, C.1 aChiuchiolo, Amy1 aGonzález, José, M.1 aGrossart, Hans-Peter uhttp://journal.frontiersin.org/article/10.3389/fmicb.2017.00175/full02077nas a2200181 4500008004100000245016100041210006900202260001200271490000600283520140000289100002601689700002601715700003301741700002001774700002101794700002501815856005501840 2017 eng d00aEarly diverging lineages within Cryptomycota and Chytridiomycota dominate the fungal communities in ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aEarly diverging lineages within Cryptomycota and Chytridiomycota c11/20170 v73 a

Antarctic ice-covered lakes are exceptional sites for studying the ecology of aquatic fungi under conditions of minimal human disturbance. In this study, we explored the diversity and community composition of fungi in five permanently covered lake basins located in the Taylor and Miers Valleys of Antarctica. Based on analysis of the 18S rRNA sequences, we showed that fungal taxa represented between 0.93% and 60.32% of the eukaryotic sequences. Cryptomycota and Chytridiomycota dominated the fungal communities in all lakes; however, members of Ascomycota, Basidiomycota, Zygomycota, and Blastocladiomycota were also present. Of the 1313 fungal OTUs identified, the two most abundant, belonging to LKM11 and Chytridiaceae, comprised 74% of the sequences. Significant differences in the community structure were determined among lakes, water depths, habitat features (i.e., brackish vs. freshwaters), and nucleic acids (DNA vs. RNA), suggesting niche differentiation. Network analysis suggested the existence of strong relationships among specific fungal phylotypes as well as between fungi and other eukaryotes. This study sheds light on the biology and ecology of basal fungi in aquatic systems. To our knowledge, this is the first report showing the predominance of early diverging lineages of fungi in pristine limnetic ecosystems, particularly of the enigmatic phylum Cryptomycota.

1 aRojas-Jimenez, Keilor1 aWurzbacher, Christian1 aBourne, Elizabeth, Charlotte1 aChiuchiolo, Amy1 aPriscu, John, C.1 aGrossart, Hans-Peter uhttps://www.nature.com/articles/s41598-017-15598-w02279nas a2200133 4500008004100000245013700041210006900178260004800247490000900295520174300304100001902047700002102066856005802087 2017 eng d00aEvidence of subglacial brine inflow and wind-induced mixing from high resolution temperature measurements in Lake Bonney, Antarctica0 aEvidence of subglacial brine inflow and windinduced mixing from  aBaton Rouge, LAbLouisiana State University0 vM.S.3 a

Hypersaline brine beneath Taylor Glacier enters proglacial West Lobe Lake Bonney (WLB) subglacially as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the water column of WLB. Because of the extremely high salinities below the chemocline in WLB, density is determined almost entirely by salinity and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude in to the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. This study is the first to definitively identify subglacial brine intrusions in WLB, since the absence of an open water moat in the winter prevents brine entry from the surface at Blood Falls. High resolution thermistors and CTDs deployed year-round beneath the perennial ice cover demonstrate that brine intrusions can influence the thermal stratification of the water column near the glacier terminus for the majority of the year, and that the effects diminish with distance from the glacier terminus. High volumes of brine inflow alter the density stratification of the water column at the depth of the intrusion and cause turbulent mixing near the glacier terminus. High resolution measurements also reveal internal water movements associated with katabatic wind events, a novel finding that challenges long held assumptions about the stability of the WLB water column. The long term records of Blood Falls flow and of temperature anomalies in WLB indicate that brine release from the subglacial system has been a persistent feature in the region for decades, with implications for the geochemistry and biology of WLB.

1 aLawrence, Jade1 aDoran, Peter, T. uhttps://digitalcommons.lsu.edu/gradschool_theses/434302715nas a2200133 4500008004100000245011000041210006900151260002600220490000900246520222000255100002202475700001702497856006702514 2017 eng d00aFe and Nutrients in Coastal Antarctic Streams: Implications for Marine Primary Production in the Ross Sea0 aFe and Nutrients in Coastal Antarctic Streams Implications for M bOhio State University0 vM.S.3 a

The Southern Ocean (SO) has been an area of much biogeochemical interest due to the role of Fe limitation for primary production. Primary production is associated with increased carbon sequestration, making it important to characterize and quantify the fluxes of Fe and other nutrients to the ocean. Water samples were collected in the McMurdo Dry Valleys, Antarctica (MDV) from four subaerial streams flowing into the Ross Sea. They were analyzed for macronutrients (N, P, Si) and Fe to determine the potential impact of terrestrial water input on the biogeochemistry of coastal oceanic waters. Our stream data yield an average filterable composition of N3P1 Si100Fe0.8, which is substantially different from the planktonic composition as demonstrated by empirical measurements, and suggests that these streams are a potential source of Fe and P, relative to N and Si, to coastal phytoplankton communities.

The behavior and potential colloidal/nanoparticulate speciation of the Fe in these streams was investigated through analysis of three physiochemical forms of Fe - environmentally active Fe (acid-soluble/no filtration), filterable Fe (filtered through 0.4 μm), and dissolved Fe (filtered through 0.2 μm). It has been suggested that the dissolved fraction is mainly nanoparticulate and represents a more bioavailable form of Fe, as compared with colloids and particles. Overall, the combined average annual flux from two MDV streams is approximately 240 moles fFe yr-1, which is consistent with previously predicted values. The dissolved fraction of Fe (<0.2 μm) was between 18% and 27% percent of the fFe, meaning the fFe pool is mostly colloidal. While the Fe flux from these streams is several orders of magnitude less than aeolian and iceberg sources, terrestrial streams are expected to become a more significant source of Fe to the Ross Sea. As the Antarctic climate warms, ice-free regions similar to the MDV should increase in extent and glacier melt. This study questions how, and in what quantities, Fe is solubilized and transported from the landscape into the SO to better inform predictions of Fe fluxes following continued warming.
1 aOlund, Sydney, A.1 aLyons, Berry uhttp://rave.ohiolink.edu/etdc/view?acc_num=osu149269789434354602308nas a2200217 4500008004100000022001400041245010100055210006900156260001200225300001400237490000700251520161900258100002501877700001601902700002001918700002201938700002401960700001801984700002402002856006402026 2017 eng d a0722-406000aFreshwater diatom biogeography and the genus Luticola: an extreme case of endemism in Antarctica0 aFreshwater diatom biogeography and the genus Luticola an extreme c03/2017 a1185-11960 v403 a

Historical views have characterized Antarctica as a frozen desert with low diversity, although recent studies suggest that this may not be true for microscopic organisms. For microbes, assessing endemism in the Antarctic region has been particularly important, especially against a backdrop of debate regarding their presumed cosmopolitan nature. To contribute to this conversation, we highlight the observed endemism of the freshwater diatom genus Luti- cola in Antarctica by synthesizing the results of a modern high-resolution taxonomy from the Continental, Maritime, and sub-Antarctic regions. We report that Luticola has one of the highest endemic rates of any diatom genus in Antarctica, in terms of total number of species (taxon endemism) and percentage of the entire genus (phylogenetic endemism). Of the over 200 species of Luticola globally, nearly 20% (43) occur in the Antarctic, with 42 of these being endemic. Within regions, Maritime Antarctica has the largest number of Luticola species and endemics (28 and 23, respectively), followed by Continental Antarctica (14, 9) and sub-Antarctic islands (8, 6). Thus, 38 of the 42 endemics are found in a single region only. While the timing of Luticola diversi cation has not been established, fossil evidence suggests recent invasions and/or diversi cation over a relatively short geologic timescale. Understanding the origin and evolution of endemic diatom species in Antarctica will help us better understand microbial biogeography, as well as assess and interpret impacts of large-scale environmental change taking place at southern latitudes.

1 aKociolek, J. Patrick1 aKopalova, K1 aHamsher, S., E.1 aKohler, Tyler, J.1 aVan de Vijver, Bart1 aConvey, Peter1 aMcKnight, Diane, M. uhttps://link.springer.com/article/10.1007/s00300-017-2090-700489nas a2200121 4500008004100000245011200041210006900153260004400222490000900266100002200275700001700297856005300314 2017 eng d00aThe geochemistry of minor cations within Antarctic stream water: Determining the role of the hyporheic zone0 ageochemistry of minor cations within Antarctic stream water Dete aColumbus, OHbThe Ohio State University0 vB.A.1 aSaelens, Elsa, D.1 aLyons, Berry uhttp://library.ohio-state.edu/record=b8218699~S701634nas a2200217 4500008004100000245010200041210006900143260001200212300001400224490000600238520092200244100002401166700002901190700002201219700002101241700002501262700002401287700001301311700002101324856007101345 2017 eng d00aHigh-resolution elevation mapping of the McMurdo Dry Valleys, Antarctica, and surrounding regions0 aHighresolution elevation mapping of the McMurdo Dry Valleys Anta c07/2017 a435 - 4430 v93 a

We present detailed surface elevation measurements for the McMurdo Dry Valleys, Antarctica derived from aerial lidar surveys flown in the austral summer of 2014–2015 as part of an effort to understand geomorphic changes over the past decade. Lidar return density varied from 2 to > 10 returns  m−2 with an average of about 5  returns  m−2. Vertical and horizontal accuracies are estimated to be 7 and 3 cm, respectively. In addition to our intended targets, other ad hoc regions were also surveyed including the Pegasus flight facility and two regions on Ross Island, McMurdo Station, Scott Base (and surroundings), and the coastal margin between Cape Royds and Cape Evans. These data are included in this report and data release. The combined data are freely available at https://doi.org/10.5069/G9D50JX3.

1 aFountain, Andrew, G1 aFernandez-Diaz, Juan, C.1 aObryk, Maciek, K.1 aLevy, Joseph, S.1 aGooseff, Michael, N.1 aVan Horn, David, J.1 aMorin, P1 aShrestha, Ramesh uhttps://www.earth-syst-sci-data.net/9/435/2017/essd-9-435-2017.pdf02751nas a2200181 4500008004100000022001300041245010100054210006900155260001200224300001200236490000800248520216000256100002502416700002102441700002402462700001702486856006602503 2017 eng d a0169555X00aHydrologic connectivity and implications for ecosystem processes - Lessons from naked watersheds0 aHydrologic connectivity and implications for ecosystem processes c01/2017 a63 - 710 v2773 a

Hydrologic connectivity has received great attention recently as our conceptual models of watersheds and water quality have evolved in the past several decades. However, the structural complexity of most temperate watersheds (i.e. connections among shallow soils, deep aquifers, the atmosphere and streams) and the dynamic seasonal changes that occur within them (i.e., plant senescence which impacts evapotranspiration) create significant challenges to characterizing or quantifying hydrologic connectivity. The McMurdo Dry Valleys, a polar desert in Antarctica, provide a unique opportunity to study hydrologic connectivity because there is no vegetative cover (and therefore no transpiration), and no deep aquifers connected to surface soils or streams. Glacier melt provides stream flow to well-established channels and closed-basin, ice-covered lakes on the valley floor. Streams are also connected to shallow hyporheic zones along their lengths, which are bounded at ~75 cm depth by ice-cemented permafrost. These hydrologic features and connections provide water for and underpin biological communities. Hence, exchange of water among them provides a vector for exchange of energy and dissolved solutes. Connectivity is dynamic on timescales of a day to a flow season (6–12 weeks), as streamflow varies over these timescales. The timescales over which these connections occur is also dynamic. Exchanges between streams and hyporheic zones, for example, have been estimated to be as short as hours to as long as several weeks. These exchanges have significant implications for the biogeochemistry of these systems and the biotic communities in each feature. Here we evaluate the lessons we can learn about hydrologic connectivity in the MDV watersheds that are simplified in the context of processes occurring and water reservoirs included in the landscape, yet are sensitive to climate controls and contain substantial physical heterogeneity. We specifically explore several metrics that are simple and/or commonly employed in hydrologic analyses and interpret them in the context of connectivity between and among hydrologic features.

1 aGooseff, Michael, N.1 aWlostowski, Adam1 aMcKnight, Diane, M.1 aJaros, Chris uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X1630248302884nas a2200133 4500008004100000245012700041210006900168260004800237490001000285520235800295100002102653700002502674856005102699 2017 eng d00aHydrologic connectivity in the McMurdo Dry Valleys, Antarctica: Water-mediated mass and energy fluxes in streams and soils0 aHydrologic connectivity in the McMurdo Dry Valleys Antarctica Wa aBoulder, CObUniversity of Colorado Boulder0 vPh.D.3 a

Chapter 1 synthesizes 20 years of stream gauge observations (discharge, water temperature, and specific conductance) to assess patterns of hydrologic connectivity between glaciers, streams and lakes. Results reveal hydrologic patterns across daily, annual and inter-annual timescales, which together characterize the hydrologic regime of MDV streams. Also, stream gauge data display a relationship between stream length and hydrologic regime. Longer streams are more intermittent, warmer, and saltier than shorter streams. This work provides physical context for understanding biological differences among MDV streams, while providing a methodological template for quantifying hydrologic connectivity.

Chapter 2 investigates the nature of concentration-discharge relationships for weathering-derived solutes in MDV streams. The relative simplicity of MDV “watersheds” permits the use of concentration-discharge relationships to infer hydrologic and chemical mixing dynamics occurring along the river corridor. Long-term stream geochemical data show that weathering derived solutes exhibit chemostatic C-Q relationships. Chemostasis implies that rates of solute production and/or mobilization scale proportionately with stream discharge. A numerical weathering and solute transport model suggests that chemostasis is maintained by a positive relationship between weathering rate and discharge along the stream corridor.

Finally, Chapters 3 and 4 investigate water-mediated energy fluxes within the soil habitat. Nematode communities in MDV are highly sensitive to the thermodynamic regime of active layer soils. Soil moisture and air temperature data were collected across natural wetness gradients adjacent to fluvial features to assess the control of soil moisture on the soil thermal regime. Observations show that wetter soils freeze less frequently and more gradually than drier soils. Also, a numerical soil heat transfer model suggests that increases in soil moisture and air temperature result in warmer average habitat temperature, an extension of the duration of time the soil habitat spends above freezing, and a reduction in the rate and frequency of freezing. The results of this chapter provide a physical context for understanding current and future patterns of ecosystem structure and function in MDV soils.

1 aWlostowski, Adam1 aGooseff, Michael, N. uhttps://scholar.colorado.edu/cven_gradetds/77/02691nas a2200229 4500008004100000022001400041245015500055210006900210260001200279490000700291520189400298653003402192653001902226653002402245653002202269653002302291100002202314700001202336700002002348700002902368856006402397 2017 eng d a0722-406000aImpact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach0 aImpact of nitrogen and phosphorus on phytoplankton production an c05/20170 v403 a

Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MDV), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. Phytoplankton communities residing in the oligotrophic water columns are highly responsive to pulses in nutrient availability; however, there is a lack of understanding on whether specific phytoplankton groups are more competitive during a summer flood event and how shifts in the phytoplankton community may influence heterotrophic bacteria. A bioassay approach in 3-l bottles was used to investigate the influence of inorganic nitrogen and phosphorus availability on planktonic communities from the oligotrophic upper waters of two chemically distinct MDV lakes (Lakes Bonney and Fryxell) which differ in their external inputs and water column N/P stoichiometry. While microbial community responses varied between lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity was generally uncoupled; however, shifts in bacterial community diversity were observed in bioassays amended with either P or NP. We suggest that climate-associated increases in phytoplankton production and concomitant shifts in diversity will influence MDV bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production.

10aAlgal–bacteria interactions10aclimate change10aMcMurdo Dry Valleys10aNutrient bioassay10aPrimary production1 aTeufel, Amber, G.1 aLi, Wei1 aKiss, Andor, J.1 aMorgan-Kiss, Rachael, M. uhttps://link.springer.com/article/10.1007/s00300-016-2025-802255nas a2200193 4500008004100000245007900041210006900120260001200189300001400201490000800215520163600223100002001859700002501879700002401904700002101928700002201949700002401971856006601995 2017 eng d00aImpacts of permafrost degradation on a stream in Taylor Valley, Antarctica0 aImpacts of permafrost degradation on a stream in Taylor Valley A c05/2017 a205 - 2130 v2853 a

The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (b 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems.

1 aSudman, Zachary1 aGooseff, Michael, N.1 aFountain, Andrew, G1 aLevy, Joseph, S.1 aObryk, Maciek, K.1 aVan Horn, David, J. uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X1630846700637nas a2200157 4500008004100000245015300041210007000194260001200264300001200276490000700288100002200295700002100317700002100338700002700359856009300386 2017 eng d00aThe influence of föhn winds on Glacial Lake Washburn and palaeotemperatures in the McMurdo Dry Valleys, Antarctica, during the Last Glacial Maximum0 ainfluence of föhn winds on Glacial Lake Washburn and palaeotempe c10/2017 a457-4670 v291 aObryk, Maciek, K.1 aDoran, Peter, T.1 aWaddington, E.D.1 aMcKay, Christopher, P. uhttps://www.cambridge.org/core/product/identifier/S0954102017000062/type/journal_article00535nas a2200145 4500008004100000245008700041210006900128260001200197300001200209490000700221100002100228700002400249700002300273856009300296 2017 eng d00aLandscape-scale soil phosphorus variability in the McMurdo Dry Valleys, Antarctica0 aLandscapescale soil phosphorus variability in the McMurdo Dry Va c06/2017 a252-2630 v291 aHeindel, Ruth, C1 aSpickard, Angela, M1 aVirginia, Ross, A. uhttps://www.cambridge.org/core/product/identifier/S0954102016000742/type/journal_article02832nas a2200145 4500008004100000245009600041210006900137260001200206300001400218490000700232520234000239100002002579700002502599856006202624 2017 eng d00aLife cycle size dynamics in Didymosphenia geminata (Bacillariophyceae)0 aLife cycle size dynamics in iDidymosphenia geminatai Bacillariop c06/2017 a652 - 6630 v533 a

Didymosphenia geminata has received a great deal of attention in the last 25 years, and considerable effort has gone into determining the origin, ecological impact, and economic consequences of its invasive behavior. While environmental conditions are a controlling influence in distribution, the extreme success of the species may be tied to its basic biology and life history. Little is known, however, about population dynamics, size restoration and reproduction of D. geminata. The objective of this study was to determine the temporal patterns in cell size frequency, size restoration strategy, and synchronization of life cycles between populations in close proximity. We implemented FlowCam technology to measure the length of more than 100,000 D. geminata cells from two sites in South Boulder Creek, Colorado over 1 year. We applied finite mixture modeling to uncover temporal patterns in size distribution. Our results show that collections of D. geminata exhibited a complex, multimodal size distribution, almost always containing four overlapping age cohorts. We failed to observe direct visual evidence of the sexual phase. Multiple abrupt and directional shifts in size distribution, however, were documented providing conclusive evidence of cell size restoration. Lastly, nodules in close proximity were asynchronous with respect to size frequency profiles and size diminution, highlighting the relevance of spatial heterogeneity in in situ diatom size dynamics. This study is the first to document the complexity of diatom cell size distribution in a lotic system, size restoration in D. geminata, and the variability in rates of size reduction at microhabitat spatial scales. 

1 aBishop, Ian, W.1 aSpaulding, Sarah, A. uhttp://onlinelibrary.wiley.com/doi/10.1111/jpy.12528/full02800nas a2200133 4500008004100000245009000041210006900131260004800200490000900248520230200257100002802559700002102587856005802608 2017 eng d00aLong-term and over winter phytoplankton community dynamics in Lake Bonney, Antarctica0 aLongterm and over winter phytoplankton community dynamics in Lak aBozeman, MTbMontana State Universityc20170 vM.S.3 a

Lake Bonney is a hypersaline permanently ice-covered lake in the Taylor Valley, Antarctica that hosts simplified microbial food-webs. Studied since the 1960s, there are many aspects which are poorly understood. Logistical constraints have prevented sampling during the austral winter, a 4-month period of 24-hour darkness. Our knowledge of how the resident photosynthetic microorganisms respond during this period is limited. With inputs from ephemeral glacial-melt streams the lake level (stage) of Bonney has risen more than 3 m since 2004. With no outflow streams, the only known water loss is via ablation of the permanent ice-cover. A study of the spatial and temporal changes in the phytoplankton community structure during this period of rapid lake level rise is lacking. During the summers (November-January) from 2004-05 to 2014-15 an in situ submersible spectrofluorometer was deployed in Lake Bonney to quantify the chlorophyll-a concentrations (microgram L -1) of four functional groups of microalgae (green algae, brown/mixed algae, cryptophytes, cyanobacteria) using known excitation/emission spectra. During the 2013-14 field season this same instrument was mounted on autonomous cable-crawling profilers deployed in both east and west lobes of Lake Bonney, obtaining the first ever daily profiles of chlorophyll-a concentration at an annual scale. Following a summer of rapid lake level rise (2010-11), an increasing trend in depth integrated chlorophyll-a concentration was observed in Lake Bonney. During the same period, the nutrient poor surface water has become increasingly dominated by green algae. Dramatic shifts were also observed in the phytoplankton communities during the polar night. The highest concentrations of mean chlorophyll-a were measured during the 24-hour darkness. Algal spectral groups containing species capable of a mixotrophic metabolism (brown/mixed and cryptophytes) increased in concentration and relative abundance when photosynthetically active radiation was unavailable. This work provides valuable contributions to our knowledge of long-term and year-round phytoplankton community dynamics in Lake Bonney, and improves our understanding of the metabolic strategies employed by organisms in this high latitude permanently ice-covered lake.

1 aPatriarche, Jeffrey, D.1 aPriscu, John, C. uhttps://scholarworks.montana.edu/xmlui/handle/1/1280302036nas a2200145 4500008004100000245014100041210006900182260001200251490000700263520148900270100002301759700002901782700001701811856006201828 2017 eng d00aMultiple ice-binding proteins of probable prokaryotic origin in an Antarctic lake alga, Chlamydomonas sp. ICE-MDV (Chlorophyceae)0 aMultiple icebinding proteins of probable prokaryotic origin in a c08/20170 v533 a

Ice‐associated algae produce ice‐binding proteins (IBPs) to prevent freezing damage. The IBPs of the three chlorophytes that have been examined so far share little similarity across species, making it likely that they were acquired by horizontal gene transfer (HGT). To clarify the importance and source of IBPs in chlorophytes, we sequenced the IBP genes of another Antarctic chlorophyte, Chlamydomonas sp. ICE‐MDV (Chlamy‐ICE). Genomic DNA and total RNA were sequenced and screened for known ice‐associated genes. Chlamy‐ICE has as many as 50 IBP isoforms, indicating that they have an important role in survival. The IBPs are of the DUF3494 type and have similar exon structures. The DUF3494 sequences are much more closely related to prokaryotic sequences than they are to sequences in other chlorophytes, and the chlorophyte IBP and ribosomal 18S phylogenies are dissimilar. The multiple IBP isoforms found in Chlamy‐ICE and other algae may allow the algae to adapt to a greater variety of ice conditions than prokaryotes, which typically have a single IBP gene. The predicted structure of the DUF3494 domain has an ice‐binding face with an orderly array of hydrophilic side chains. The results indicate that Chlamy‐ICE acquired its IBP genes by HGT in a single event. The acquisitions of IBP genes by this and other species of Antarctic algae by HGT appear to be key evolutionary events that allowed algae to extend their ranges into polar environments.

1 aRaymond, James, A.1 aMorgan-Kiss, Rachael, M.1 aValentin, K. uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.1255002127nas a2200217 4500008004100000245010900041210006900150260001200219300001600231490000700247520142800254100001501682700001801697700003301715700001601748700002001764700002001784700002101804700001601825856006801841 2017 eng d00aNiche specialization of bacteria in permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aNiche specialization of bacteria in permanently icecovered lakes c06/2017 a2258 - 22710 v193 a

Perennially ice‐covered lakes in the McMurdo Dry Valleys, Antarctica, are chemically stratified with depth and have distinct biological gradients. Despite long‐term research on these unique environments, data on the structure of the microbial communities in the water columns of these lakes are scarce. Here, we examined bacterial diversity in five ice‐covered Antarctic lakes by 16S rRNA gene‐based pyrosequencing. Distinct communities were present in each lake, reflecting the unique biogeochemical characteristics of these environments. Further, certain bacterial lineages were confined exclusively to specific depths within each lake. For example, candidate division WM88 occurred solely at a depth of 15 m in Lake Fryxell, whereas unknown lineages of Chlorobi were found only at a depth of 18 m in Lake Miers, and two distinct classes of Firmicutes inhabited East and West Lobe Bonney at depths of 30 m. Redundancy analysis revealed that community variation of bacterioplankton could be explained by the distinct conditions of each lake and depth; in particular, assemblages from layers beneath the chemocline had biogeochemical associations that differed from those in the upper layers. These patterns of community composition may represent bacterial adaptations to the extreme and unique biogeochemical gradients of ice‐covered lakes in the McMurdo Dry Valleys.

1 aKwon, Miye1 aKim, Mincheol1 aTakacs-Vesbach, Cristina, D.1 aLee, Jaejin1 aHong, Soon, Gyu1 aKim, Sang, Jong1 aPriscu, John, C.1 aKim, Ok-Sun uhttps://onlinelibrary.wiley.com/doi/pdf/10.1111/1462-2920.1372102681nas a2200133 4500008004100000245008100041210006900122260003800191490000900229520214800238100002202386700002602408856011302434 2017 eng d00aNitrate Dynamics Under Unsteady and Intermittent Flow in an Antarctic Stream0 aNitrate Dynamics Under Unsteady and Intermittent Flow in an Anta bUniversity of Colorado at Boulder0 vM.S.3 a

Low order streams are a primary vector and modulator for the transport of anthropogenically derived reactive nitrogen, especially as nitrate (NO3–). A large proportion of low orders streams experience short-term unsteady and intermittent flow conditions, and the prevalence of these dynamics is likely to increase due to climate change and human management. While such hydrologic variability is recognized as an important first-order control on the transport of NO3–, prior reliance on manual sampling has resulted in a disparity between our understanding physical and hydrochemical dynamics at short-timescales, such that a large gap exists in our understanding of how unsteady and intermittent sub-daily discharge affects instream NO3– transport patterns. To address this challenge, I used in situ sensors to collect high-frequency (i.e., 15 minute) NO3– concentration and discharge data in an ephemeral, oligotrophic glacial meltwater stream in the McMurdo Dry Valleys, Antarctica. I analyzed concentration-discharge relationships using a power-law framework to identify a flow threshold that governed NO3– transport dynamics. I observed relative chemostasis of NO3– during large magnitude diel flood pulsing events. This suggests that biological and physical processes controlling the transport and transformation of NO3–, and N more generally, are likely to exhibit spatial and temporal variability at very short timescales in response to extreme hydrologic variability. Such spatiotemporal variability in N processing dynamics has not been included in prior conceptual models of N cycling in MDV streams. As such, I propose a conceptual model in which short-term flow pulsing and cessation shift sediment redox conditions and microbial processes such that the shallow hyporheic zone temporally becomes a net source and storage zone for a spatially distributed pool of NO3–. The results of this approach will inform understanding of how highly variable hydrological conditions measured at very short timescales interacts with instream biogeochemical processes to control N transport.

1 aSingley, Joel, G.1 aHinckley, Eve-Lyn, S. uhttp://search.proquest.com/openview/88a6ce6614e2a0cfc757c8fd7a887504/1?pq-origsite=gscholar&cbl=18750&diss=y03232nas a2200169 4500008004100000245012600041210006900167260001200236300001000248490000600258520266000264100002102924700003302945700002502978700002203003856003703025 2017 eng d00aPrimary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem0 aPrimary productivity as a control over soil microbial diversity  c07/2017 ae33770 v53 a

Primary production is the fundamental source of energy to foodwebs and ecosystems, and is thus an important constraint on soil communities. This coupling is particularly evident in polar terrestrial ecosystems where biological diversity and activity is tightly constrained by edaphic gradients of productivity (e.g., soil moisture, organic carbon availability) and geochemical severity (e.g., pH, electrical conductivity). In the McMurdo Dry Valleys of Antarctica, environmental gradients determine numerous properties of soil communities and yet relatively few estimates of gross or net primary productivity (GPP, NPP) exist for this region. Here we describe a survey utilizing pulse amplitude modulation (PAM) fluorometry to estimate rates of GPP across a broad environmental gradient along with belowground microbial diversity and decomposition. PAM estimates of GPP ranged from an average of 0.27 mmol O2/m2/s in the most arid soils to an average of 6.97 mmol O2/m2/s in the most productive soils, the latter equivalent to 217 g C/m2/y in annual NPP assuming a 60 day growing season. A diversity index of four carbon-acquiring enzyme activities also increased with soil productivity, suggesting that the diversity of organic substrates in mesic environments may be an additional driver of microbial diversity. Overall, soil productivity was a stronger predictor of microbial diversity and enzymatic activity than any estimate of geochemical severity. These results highlight the fundamental role of environmental gradients to control community diversity and the dynamics of ecosystem-scale carbon pools in arid systems. 

1 aGeyer, Kevin, M.1 aTakacs-Vesbach, Cristina, D.1 aGooseff, Michael, N.1 aBarrett, John, E. uhttps://peerj.com/articles/3377/02500nas a2200157 4500008004100000245012100041210006900162260001200231300001200243490000800255520197300263100002002236700002102256700002202277856004302299 2017 eng d00aA simulation-based approach to understand how metacommunity characteristics influence emergent biodiversity patterns0 asimulationbased approach to understand how metacommunity charact c05/2017 a723-7370 v1263 a

To understand controls over biodiversity, it is necessary to take a multi-scale approach to understand how local and regional factors a ect the community assembly processes that drive emergent patterns.  is need is re ected in the growing use of the metacommunity concept to interpret multi-scale measures of biodiversity, including metrics derived from diversity partitioning (e.g. a, b and g diversity) and variation partitioning (e.g. spatial and environmental components of compositional turnover) techniques. However, studies have shown limited success using these metrics to characterize underlying community assembly dynamics. Here we demonstrate how a metacommunity simulation package (MCSim) can be used to evaluate when and how biodiversity metrics can be used to make inferences about metacommunity characteristics. We examined a wide range of parameter settings representing ecologically relevant scenarios. We used artificial neural networks (ANNs) to assess the sensitivity of diversity and variation partitioning metrics (calculated from simulation outcomes) to metacommunity parameter settings. In the scenarios examined in this study, the niche-neutral gradient strongly in uenced most biodiversity metrics, metacommunity size exhibited a marginal influence over some metrics, and dispersal dynamics only a ected a subset of variation partitioning outcomes. Variation partitioning response curves along the niche-neutral gradient were not monotonic; however, simulation outcomes suggest other biodiversity metrics (e.g. dissimilarity saturation) can be used in combination with variation partitioning metrics to make inferences about metacommunity properties. With the growing availability of archived ecological data, we expect future work will apply simulation-based techniques to better understand links between biodiversity and the metacommunity characteristics that are presumed to control the underlying community assembly processes.

1 aSokol, Eric, R.1 aBrown, Bryan, L.1 aBarrett, John, E. uhttp://doi.wiley.com/10.1111/oik.0369003009nas a2200133 4500008004100000245011500041210006900156260002600225490000900251520251000260100002102770700001702791856006702808 2017 eng d00aSpatial and Temporal Geochemical Characterization of Aeolian Material from the McMurdo Dry Valleys, Antarctica0 aSpatial and Temporal Geochemical Characterization of Aeolian Mat bOhio State University0 vM.S.3 a

Aeolian processes play an important role in the transport of both geological and biological materials globally, on the biogeochemistry of ecosystems, and in landscape evolution. As the largest ice free area on the Antarctic continent (approximately 4800 km2), the McMurdo Dry Valleys (MDV) are potentially a major source of aeolian material for Antarctica, but information on the spatial and temporal variability of this material is needed to understand its soluble and bulk geochemistry, deposition and source, and hence influence on ecosystem dynamics. 53 samples of aeolian material from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove) were collected at five heights (5, 10, 20, 50, 100 cm) above the surface seasonally for 2013 through 2015. The sediment was analyzed for soluble solids, total and organic carbon, minerology, and bulk chemistry. Of the soluble component, the major anions varied between Cl- and HCO3-, and the major cation was Na+ for all sites. Soluble N:P ratios in the aeolian material reflect nutrient limitations seen in MDV soils, where younger, coastal soils are N-limited, while older, up valley soils are P-limited. Material from East Lake Bonney was P-limited in the winter samples, but N-limited in the full year samples, suggesting different sources of material based on season. Analysis of soluble salts in aeolian material in Taylor Valley compared to published soil literature demonstrates a primarily down valley transport of materials from Taylor Glacier towards the coast. The bulk chemistry suggests that the aeolian material is highly unweathered (CIA values less than 60 %), but scanning electron microscope images show alteration for some individual sediment grains. The mineralogy was reflective of local rocks, specifically the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and granite, but variations in major oxide percentages and rare earth element signatures could not be explained by mixing lines between these four rock types. This potentially suggests that there may be an additional, and possibly distant, source of aeolian material to the MDV that is not accounted for. This work provides the first fully elevated spatial and temporal analysis of the geochemistry of aeolian material from the Dry Valleys, and contributes to a better understanding of sediment provenance and how aeolian deposition may affect surface biological communities.

1 aDiaz, Melisa, A.1 aLyons, Berry uhttp://rave.ohiolink.edu/etdc/view?acc_num=osu150046821614772503797nas a2200157 4500008004100000245012100041210007100162260001200233300001600245490000700261520325100268100001703519700002403536700001703560856006203577 2017 eng d00aA temporal stable isotopic (δ18O, δD, d-excess) comparison in glacier meltwater streams, Taylor Valley, Antarctica0 atemporal stable isotopic δ18O δD dexcess comparison in glacier m c08/2017 a3069 - 30830 v313 a

In this paper, we describe the importance of hyporheic dynamics within Andersen Creek and Von Guerard Stream, Taylor Valley, Antarctica, from the 20102011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheiczone sampling. The water δ18O and δD values were isotopically lighter in the beginning and heavier later in the season. Dexcess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary endmembers (glacier meltwater and hyporheic zone). Hyporheiczone influence on the channel water was variable with a strong control on streamwater chemistry, except at highest discharges. This work supports previous research indicating that Von Guerard Stream has a large, widespread hyporheic zone that varies in size with time and discharge. Andersen Creek, with a smaller hyporheic zone, displayed hyporheiczone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheiczone hydrology is described seasonally. In midDecember, the hyporheic zone is a dynamic system exchanging with the glacier meltwater in the channel, and with diminishing flow in January, the hyporheic zone drains back into the channel flow also impacting stream chemistry. This work adds new information on the role of hyporheic zonestream interaction in these glacier meltwater streams. 

1 aLeslie, D.L.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://onlinelibrary.wiley.com/doi/10.1002/hyp.11245/full02451nas a2200193 4500008004100000245011100041210006900152260001200221300001400233490000700247520180200254100002402056700002302080700002102103700002502124700002002149700002402169856006402193 2017 eng d00aThermal autecology describes the occurrence patterns of four benthic diatoms in McMurdo Dry Valley streams0 aThermal autecology describes the occurrence patterns of four ben c06/2017 a2381-23960 v403 a

Benthic microbial mats in the glacial-fed melt- water streams are hotspots of productivity in the McMurdo Dry Valleys (MDV), Antarctica. Benthic diatoms are common in these mats and the[45 primarily endemic taxa represent the most diverse group of eukaryotes in the MDV. In this harsh polar desert, streams are thermally dynamic with daily water temperatures varying 6–9 °C and daily maximum temperatures as high as 15 °C. Stream temperature may play a role in determining growth rates and survival strategies. To understand taxon-specific adaptations to their environment, we measured the growth rates of unialgal cultures of four diatom taxa (Psammothidium papilio, Hantzschia abundans, Hantzschia amphioxys, and Hantzschia amphioxys f. muelleri) under three temperature conditions (7.6, 10, and 15 °C) that were representative of maximum daily stream temperatures. We found that P. papilio exhibited a constant growth rate across the full temperature range; this species is most common in streams that begin to flow early in the summer and with less variable thermal regimes. Growth rates for H. abundans were greatest at 15 °C, but showed a non-linear relationship with temperature. H. amphioxys f. muelleri

grew faster than the other taxa studied and thrived at 10 °C. Hantzschia amphioxys grew only at the two lower temperatures. These results aligned with the observed relationships between each taxon’s relative abundance and stream temperatures in the long-term record maintained by the MDV Long-Term Ecological Research program. Overall, our observations suggest that differences in thermal optima may be one factor contributing to and maintaining the diversity of benthic diatom flora in the MDV.
1 aDarling, Joshua, P.1 aGarland, Deena, D.1 aStanish, Lee, F.1 aEsposito, Rhea, M.M.1 aSokol, Eric, R.1 aMcKnight, Diane, M. uhttps://link.springer.com/article/10.1007/s00300-017-2151-y01407nas a2200445 4500008004100000245007700041210006900118260001200187490005900199100002200258700002400280700001900304700002100323700002100344700001900365700002400384700002000408700001700428700002400445700001700469700002300486700001900509700002100528700002000549700002100569700002200590700002300612700002500635700001800660700002200678700002300700700002300723700002500746700001800771700002000789700002400809700002600833700002500859856007700884 2016 eng d00aAerobiology Over Antarctica – A New Initiative for Atmospheric Ecology0 aAerobiology Over Antarctica A New Initiative for Atmospheric Eco c02/20160 v7767961946103149272350113651344451428464791101239365741 aPearce, David, A.1 aAlekhina, Irina, A.1 aTerauds, Aleks1 aWilmotte, Annick1 aQuesada, Antonio1 aEdwards, Arwyn1 aDommergue, Aurelien1 aSattler, Birgit1 aAdams, Byron1 aMagalhaes, Catarina1 aChu, Wan-Loy1 aLau, Maggie, C. Y.1 aCary, Craig, S1 aSmith, David, J.1 aWall, Diana, H.1 aEguren, Gabriela1 aMatcher, Gwynneth1 aBradley, James, A.1 ade Vera, Jean-Pierre1 aElster, Josef1 aHughes, Kevin, A.1 aCuthbertson, Lewis1 aBenning, Liane, G.1 aGunde-Cimerman, Nina1 aConvey, Peter1 aHong, Soon, Gyu1 aPointing, Steve, B.1 aPellizari, Vivian, H.1 aVincent, Warwick, F. uhttp://journal.frontiersin.org/Article/10.3389/fmicb.2016.00016/abstract02857nas a2200133 4500008004100000245008900041210006900130260002900199300000800228490001000236520233500246100002802581856011402609 2016 eng d00aBiogeochemical processes in Antarctic aquatic environments: Linkages and limitations0 aBiogeochemical processes in Antarctic aquatic environments Linka bMontana State University a2280 vPh.D.3 a

The research presented in this dissertation focused on microbially-mediated biogeochemical processes and microbial ecology in Antarctic lakes and seawater. The major objective of my research was to examine the impact of environmentally imposed energetic constraints on nutrient cycling in mirobially-dominated systems. I used three ice-covered aquatic environments as natural laboratories for my investigations. The permanently ice-covered lakes of the McMurdo Dry Valleys (MCM) are located in Victoria Land, East Antarctica. The MCM have been studied intensively as part of the McMurdo Long Term Ecological Research Project since 1993. My work built on the extensive MCM dataset via high-throughput DNA sequencing to examine microbial communities from all three domains of life during the transition to winter, and by quantifying rates of dark inorganic carbon-fixation. This worked showed the importance of flexible metabolisms in the microbial ecosystems of the MCM lakes. The ocean beneath the McMurdo Ice Shelf (MIS) is the gateway between the Ross Sea and the dark ocean of the Ross Ice Shelf cavity. The area supports a biological carbon pump that is important in ocean biogeochemistry. Ice shelves around Antarctica are under threat of collapse, but little is known about the ecosystems beneath them. My work used a combination of biogeochemical measurements and assessment of microbial community structure to characterize the ecosystem beneath the MIS and its connections to the open ocean. The data showed the importance of nutrients advected from open water to the MIS cavity and projected an organic carbon deficit farther from the ice shelf edge. Subglacial Lake Whillans lies 800 m beneath the surface of the West Antarctic Ice Sheet near the end of a hydrological continuum that terminates in the ocean beneath the Ross Ice Shelf. Primarily through the use of biogeochemical rate measurements and determinations of organic matter quantity and quality, this work established the presence of an active microbial ecosystem in the subglacial lake, and estimated the annual subglacial flux of carbon and nutrients to the ocean under the ice shelf. Together, these projects show the importance of microbial activity in regional biogeochemical processes and of metabolic flexibility under energy-limited conditions.

1 aVick-Majors, Trista, J. uhttps://search.proquest.com/openview/9118336399cac113f488d77fb07bce26/1?pq-origsite=gscholar&cbl=18750&diss=y01022nas a2200289 4500008004100000245010700041210006900148260001200217300001400229490000700243100002800250700002200278700002500300700001900325700002000344700002700364700002500391700002600416700002300442700001700465700001900482700002000501700002100521700001800542700002100560856015100581 2016 eng d00aBiogeochemistry and microbial diversity in the marine cavity beneath the McMurdo Ice Shelf, Antarctica0 aBiogeochemistry and microbial diversity in the marine cavity ben c11/2015 a572 - 5860 v611 aVick-Majors, Trista, J.1 aAchberger, Amanda1 aSantibáñez, Pamela1 aDore, John, E.1 aHodson, Timothy1 aMichaud, Alexander, B.1 aChristner, Brent, C.1 aAi, Jill., Mikucki Ji1 aSkidmore, Mark, L.1 aPowell, Ross1 aAdkins, Peyton1 aBarbante, Carlo1 aMitchell, Andrew1 aScherer, Reed1 aPriscu, John, C. uhttp://doi.wiley.com/10.1002/lno.v61.2http://doi.wiley.com/10.1002/lno.10234http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Flno.1023401706nas a2200145 4500008004100000245009500041210006900136260001200205520122100217100001901438700001901457700001401476700002401490856004601514 2016 eng d00aDissolved black carbon in Antarctic lakes: chemical signatures of past and present sources0 aDissolved black carbon in Antarctic lakes chemical signatures of c06/20163 a

The perennially ice-covered, closed-basin lakes in the McMurdo Dry Valleys, Antarctica, serve as sentinels for understanding the fate of dissolved black carbon from glacial sources in aquatic ecosystems. Here we show that dissolved black carbon can persist in freshwater and saline surface waters for thousands of years, while preserving the chemical signature of the original source materials. The ancient brines of the lake bottom waters have retained dissolved black carbon with a woody chemical signature, representing long-range transport of black carbon from wildfires. In contrast, the surface waters are enriched in contemporary black carbon from fossil fuel combustion. Comparison of samples collected 25 years apart from the same lake suggests that the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes are likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.

1 aKhan, Alia, L.1 aJaffé, Rudolf1 aDing, Yan1 aMcKnight, Diane, M. uhttp://doi.wiley.com/10.1002/2016GL06860900939nas a2200217 4500008004100000022001400041245011900055210006900174260001200243100001600255700002000271700002200291700002100313700002500334700002000359700002400379700001700403700002200420700002400442856025500466 2016 eng d a0722-406000aEvidence for dispersal and habitat controls on pond diatom communities from the McMurdo Sound Region of Antarctica0 aEvidence for dispersal and habitat controls on pond diatom commu c02/20161 aSakaeva, A.1 aSokol, Eric, R.1 aKohler, Tyler, J.1 aStanish, Lee, F.1 aSpaulding, Sarah, A.1 aHowkins, Adrian1 aWelch, Kathleen, A.1 aLyons, Berry1 aBarrett, John, E.1 aMcKnight, Diane, M. uhttp://link.springer.com/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6http://link.springer.com/content/pdf/10.1007/s00300-016-1901-6.pdfhttp://link.springer.com/article/10.1007/s00300-016-1901-6/fulltext.html02886nas a2200133 4500008004100000245007600041210006900117260002900186300000800215490001000223520238000233100002502613856011402638 2016 eng d00aFactors influencing the abundance of microorganisms in icy environments0 aFactors influencing the abundance of microorganisms in icy envir bMontana State University a2360 vPh.D.3 a

Microbial life can easily live without us; we, however, cannot survive without the global catalysis and environmental transformations it provides (Falkowski et al., 2008). Despite of the key role of microbes on Earth, microbial community characteristics are not explicitly part of climate models because our understanding of their responses to long-term environmental and climatic processes is limited. In this study, I developed a Flow Cytometric protocol to access a long-term record of non-photosynthetic prokaryotic cell concentration archived in the West Antarctic Ice-Sheet (WAIS; chapter 2). The WD ice core was retrieved between 2009 and 2011 to a depth of 3,405 m, extending back to 68,000 before 1950. Once a 17,400 year-record of prokaryotic cell concentration was acquired, I investigated its temporal variability and patterns, determined the potential sources of prokaryotic cells between the Last Glacial Maximum and the early Holocene, and assessed the environmental factors that might have the largest influence on the prokaryotic response (chapter 3). The observed patterns in the prokaryotic record are linked to large-scale controls of the Southern Ocean and West Antarctica Ice-Sheet. The main research findings presented here about the first prokaryotic record are: (i) airborne prokaryotic cell concentration does respond to long-term climatic and environmental processes, (ii) the processes of deglaciation, sea level rise and sea-ice fluctuation were key; the abundance of prokaryotic cells covariate with ssNa and black carbon, and (iii) the prokaryotic cell record variate on millennial time scale with cycles of 1,490-years. In addition, I studied congelation ice (i.e., ice forms as liquid water freezes) from ice-covered lakes to understand prokaryotic cell segregation between liquid and solid phases during the physical freezing process. Five mesocosm experiments were designed to understand prokaryotic responses to the progressive freezing in concert with field observations from ice-covered lakes from Barrow, Alaska. As a result of this last study (chapter 4), I concluded that prokaryotic cells are preferentially incorporated in the ice with segregation coefficients (Keff) between 0.8–4.4, which are higher than for major ions. Prokaryotic cells avoid rejection more effectively from the ice matrix.

1 aSantibáñez, Pamela uhttps://search.proquest.com/openview/eb36d8ca7f2f1308b69e87a6c37f0a72/1?pq-origsite=gscholar&cbl=18750&diss=y00694nas a2200205 4500008004100000022001400041245012500055210006900180260001600249300001400265490000700279100002000286700001800306700002300324700001900347700002000366700001700386700002300403856006200426 2016 eng d a0831-279600aGenetic diversity among populations of Antarctic springtails (Collembola) within the Mackay Glacier ecotone 10 aGenetic diversity among populations of Antarctic springtails Col cJan-09-2016 a762 - 7700 v591 aBeet, Clare, R.1 aHogg, Ian, D.1 aCollins, Gemma, E.1 aCowan, Don, A.1 aWall, Diana, H.1 aAdams, Byron1 aWilson, John-James uhttp://www.nrcresearchpress.com/doi/10.1139/gen-2015-019401744nas a2200205 4500008004100000022001400041245006100055210005900116260001200175300001400187490000700201520112200208653001501330653001301345653001701358100002401375700002401399700002101423856009401444 2016 eng d a0022-143000aGlaciers in equilibrium, McMurdo Dry Valleys, Antarctica0 aGlaciers in equilibrium McMurdo Dry Valleys Antarctica c07/2016 a976 - 9890 v623 a

The McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, often <±0.06 m w.e. Typically, winter is the accumulation season, but significant snow storms can occur any time of year occasionally making summer the accumulation season. The yearly equilibrium line altitude is poorly correlated with mass balance because the elevation gradient of mass balance on each glacier can change dramatically from year to year. Most likely, winds redistribute the light snowfall disrupting the normal gradient of increasing mass balance with elevation. Reconstructed cumulative mass balance shows that the glaciers have lost <2 m w.e. over the past half century and area changes show minimal retreat. In most cases these changes are less than the uncertainty and the glaciers are considered in equilibrium. Since 2000, however, the glaciers have lost mass despite relatively stable summer air temperatures suggesting a different mechanism in play. Whether this trend is a harbinger of future changes or a temporary excursion is unclear.

10aAntarctica10aglaciers10amass balance1 aFountain, Andrew, G1 aBasagic, Hassan, J.1 aNiebuhr, Spencer uhttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214301600086102953nas a2200169 4500008004100000245010500041210006900146260001200215300001400227490000700241520241100248100001502659700002302674700002202697700002102719856004302740 2016 eng d00aGrowth dynamics of a laminated microbial mat in response to variable irradiance in an Antarctic lake0 aGrowth dynamics of a laminated microbial mat in response to vari c02/2016 a396 - 4100 v613 a
  1. Laminated microbial mats are important ecosystem components of perennially ice-covered Antarctic dry valley lakes. In order to understand better their response to changing environment, we made observations and carried out a manipulation experiment to determine their response to variations in irradiance in Lake Hoare (77°38′ S, 162°53′ E).
  2. Ice transparency was the most variable parameter that affected benthic light dose, both spatially and between years. Patterns of lamina accrual corresponded to irradiance history, with laminae that were initiated in high transmission years thicker than those from low transmission years.
  3. A shading experiment confirmed that accrual of lamina thickness, calcite precipitation and ash-free dry mass were determined by irradiance, but photosynthetic biomass and phototrophic species composition were less affected.
  4. Buried laminae decomposed only slowly over time, with potentially viable phototrophs many laminae down into the microbial mat. Decay rate increased only slightly with shading.
  5. We conclude that the microbial mats in Lake Hoare are characterised by remarkable stability, with slow accumulation rates and turnover of biomass over time. Photosynthetic biomass and species composition appeared to be stable across long time periods, with interannual variation in lamination pattern due to differential accumulation of extracellular polysaccharide and representing the visible expression of annual growth conditions.
1 aHawes, Ian1 aJungblut, Anne, D.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttp://doi.wiley.com/10.1111/fwb.1271500691nas a2200157 4500008004100000245015400041210006900195260001600264300001400280490000800294100002400302700001800326700001700344700002400361856014800385 2016 eng d00aHigh levels of intraspecific genetic divergences revealed for Antarctic springtails: evidence for small-scale isolation during Pleistocene glaciation0 aHigh levels of intraspecific genetic divergences revealed for An cJan-09-2016 a166 - 1780 v1191 aBennett, Kristi, R.1 aHogg, Ian, D.1 aAdams, Byron1 aHebert, Paul, D. N. uhttps://academic.oup.com/biolinnean/article-lookup/doi/10.1111/bij.12796https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fbij.1279600649nas a2200169 4500008004100000022001400041245017800055210006900233260001200302300001600314490000700330100002200337700002300359700002200382700002100404856005400425 2016 eng d a0016-803300aHigh-resolution ground-penetrating radar profiles of perennial lake ice in the McMurdo Dry Valleys, Antarctica: Horizon attributes, unconformities, and subbottom penetration0 aHighresolution groundpenetrating radar profiles of perennial lak c01/2016 aWA13 - WA200 v811 aDugan, Hilary, A.1 aArcone, Steven, A.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttp://library.seg.org/doi/10.1190/geo2015-0159.100639nas a2200205 4500008004100000245007600041210006900117260001200186300001300198490000700211100001700218700002500235700001700260700002400277700001700301700002500318700002100343700001700364856005200381 2016 eng d00aHydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica0 aHydrological Controls on Ecosystem Dynamics in Lake Fryxell Anta c07/2016 ae01590380 v111 aHerbei, Radu1 aRytel, Alexander, L.1 aLyons, Berry1 aMcKnight, Diane, M.1 aJaros, Chris1 aGooseff, Michael, N.1 aPriscu, John, C.1 aHewitt, Judi uhttp://dx.plos.org/10.1371/journal.pone.015903801797nas a2200253 4500008004100000022001400041245007900055210006900134260001200203300001400215490000700229520101000236100002401246700001601270700001701286700002101303700002001324700002501344700002201369700002101391700002801412700002301440856008001463 2016 eng d a0006-356800aThe Impact of a Large-Scale Climate Event on Antarctic Ecosystem Processes0 aImpact of a LargeScale Climate Event on Antarctic Ecosystem Proc c10/2016 a848 - 8630 v663 a

Extreme climate and weather events, such as a drought, hurricanes, or ice storms, can strongly imprint ecosystem processing and may alter ecosystem structure. Ecosystems in extreme environments are particularly vulnerable because of their adaptation to severe limitations in energy, water, or nutrients. The vulnerability can be expressed as a relatively long-lasting ecosystem response to a small or brief change in environmental conditions. Such an event occurred in Antarctica and affected two vastly different ecosystems: a marine-dominated coastal system and a terrestrial polar desert. Both sites experienced winds that warmed air temperatures above the 0°C threshold, resulting in extensive snow and ice melt and triggering a series of cascading effects through the ecosystems that are continuing to play out more than a decade later. This highlights the sensitivity of Antarctic ecosystems to warming events, which should occur more frequently in the future with global climate warming.

1 aFountain, Andrew, G1 aSaba, Grace1 aAdams, Byron1 aDoran, Peter, T.1 aFraser, William1 aGooseff, Michael, N.1 aObryk, Maciek, K.1 aPriscu, John, C.1 aStammerjohn, Sharon, E.1 aVirginia, Ross, A. uhttp://academic.oup.com/bioscience/article-pdf/66/10/848/7510601/biw110.pdf00658nas a2200193 4500008004100000022001400041245011300055210007100168260001200239300001400251490000700265100001800272700002000290700002300310700003100333700001900364700001700383856006400400 2016 eng d a0722-406000aImpact of diurnal freeze–thaw cycles on the soil nematode Scottnema lindsayae in Taylor Valley, Antarctica0 aImpact of diurnal freeze–thaw cycles on the soil nematode Scottn c04/2016 a583 - 5920 v391 aKnox, Matthew1 aWall, Diana, H.1 aVirginia, Ross, A.1 aVandegehuchte, Martijn, L.1 aSan Gil, Inigo1 aAdams, Byron uhttps://link.springer.com/article/10.1007/s00300-015-1809-604197nas a2200253 4500008004100000245012900041210006900170260003900239490001000278520331600288653001503604653002503619653002903644653002903673653002103702653001903723653002403742653002303766653001703789653002303806100002203829700002903851856006303880 2016 eng d00aInfluence of abiotic drivers (light and nutrients) on photobiology and diversity of Antarctic lake phytoplankton communities0 aInfluence of abiotic drivers light and nutrients on photobiology aOxford, OHbMiami Universityc20160 vPh.D.3 a

Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global climate change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MCM), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. By better understanding how Antarctic lake communities respond to mimicked climate change, we can more accurately predict how they will react to further temperature changes in the future. We began by investigating the influence of inorganic nitrogen and phosphorus availability on planktonic communities residing in the oligotrophic upper waters of two chemically distinct MCM lakes (Lakes Bonney and Fryxell) which differ in their external inputs as well as water column N:P stoichiometry. Although microbial community responses varied between the lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity were largely uncoupled across all enrichments. We suggest that climate-associated shifts in phytoplankton diversity influence the bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production. To monitor the physiological adaptations that occur over time and depth, we then transplanted two dominant phytoplankton, Chlamydomonas sp. ICE- MDV and Isochrysis sp. MDV back into the Lake Bonney water column. Our results demonstrated that both organisms are specialists for surviving specific depths of the water column and are capable of acclimating to their native environment within a short period of time, and that the chlorophyte Chlamydomonas sp. ICE-MDV most likely makes this adjustment via photoacclimation and accumulating chlorophyll-a per cell. The final study presented here investigated whether or not the dominant chlorophyte, Chlamydomonas sp. ICE-MDV has retained the ability to respond to a diel 12-hour day/night cycle. Although light levels in MCM lakes remain low during the austral summers, daily irradiation varies by as much as tenfold during the course of the day, resulting in a circadian-like light cycle for organisms residing there. With decreased ice coverage on the lakes due to climate change and increased melt, it is likely that these light variations will become amplified over time. This study tested for the presence of a circadian rhythm under various light quality, light quantity, and temperature conditions and demonstrated that although a diel rhythm was maintained in terms of growth and several photochemical parameters, a true circadian rhythm was not identified. Although it is predicted that photosynthetic communities in polar regions will be more responsive to climate warming and episodic events, the complexity of these systems provides numerous challenges to understanding how these organism will adapt in the future.

10aAntarctica10abacterial production10aChlamydomonas sp ICE MDV10aChlorophyll fluorescence10acircadian rhythm10aclimate change10aMcMurdo Dry Valleys10anutrient amendment10aphotobiology10aPrimary production1 aTeufel, Amber, G.1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami146841156403056nas a2200133 4500008004100000245014700041210006900188260003900257490001000296520251200306100001202818700002902830856006302859 2016 eng d00aInfluence of environmental drivers and interactions on the microbial community structures in permanently stratified meromictic Antarctic lakes0 aInfluence of environmental drivers and interactions on the micro aOxford, OHbMiami Universityc20160 vPh.D.3 a

The microbial loop plays important roles in the cycling of energy, carbon and elements in aquatic ecosystems. Viruses, bacteria, Archaea and microbial eukaryotes are key players in global carbon cycle and biogeochemical cycles. Investigating microbial diversity and community structure is crucial first step for understanding the ecological functioning in aquatic environment. Meromictic lakes are bodies of water and exhibit permanent stratification of major physical and chemical environmental factors. Microbial consortia residing in permanently stratified lakes exhibit relatively constant spatial stratification throughout the water column and are adapted to vastly different habitats within the same water. Pristine perennially-ice-covered lakes (Lake Bonney, Lake Fryxell and Lake Vanda) are meromictic lakes located in the McMurdo Dry Valleys (MDV) of Southern Victoria Land, Antarctica. The lakes have isolated water bodies and extremely stable strata that vary physically, chemically, and biologically within and between the water columns. The unique characteristics support microbially dominated food webs in these lakes.

In the research presented here, we gathered new understanding of how environmental drivers influence microbial community structure in these aquatic ecosystems. We explored the lake microbial ecology from three major approaches: 1). Assess trophic activities in the natural environment and identify potential environmental drivers impacting heterotrophic (β Glucosaminidase) and autotrophic (Ribulose 1,5 bisphosphate carboxylase) enzyme activities; 2). Resolve the protist community composition (i.e. autotrophic, heterotrophic and mixotrophic groups) based on high throughput sequencing and bioinformatics. Identify how the community structures correlate with specific environmental and biological factors; 3). Reveal the diversity of potential microbial interactions between the microorganisms in the MDV lakes at individual cell level, and investigate how the interactions vary between organisms with different nutritional strategies.

Studies of polar microbial communities on the cusp of environmental change will be important for predicting how microbial communities in low latitude aquatic systems will respond. This study expands the understanding of how environmental drivers interact with microbial communities in the Antarctica lakes, and provide new information to predict how the community structure will alter as response to climate changes.

1 aLi, Wei1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami146975731602462nas a2200193 4500008004100000022001300041245008800054210006900142260001600211300001400227490000800241520184200249100002102091700002202112700002302134700002502157700001502182856007102197 2016 eng d a0921818100aLake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica0 aLake Vanda A sentinel for climate change in the McMurdo Sound Re cJan-09-2016 a213 - 2270 v1443 a

Lake Vanda is a perennially ice-covered, meromictic, endorheic lake located in the McMurdo Dry Valleys of Antarctica, and an exceptional sentinel of climate change within the region. Lake levels rose 15 m over the past 68 years in response to climate-driven variability in ice-cover sublimation, meltwater production, and annual discharge of the Onyx River, the main source of water to the lake. Evidence from a new bathymetric map and water balance model combined with annual growth laminations in benthic mats suggest that the most recent filling trend began abruptly 80 years ago, in the early 1930s. This change increased lake volume by > 50%, triggered the formation of a new, upper, thermohaline convection cell, and cooled the lower convection cell by at least 2 °C and the bottom-most waters by at > 4 °C. Additionally, the depth of the deep chlorophyll a maximum rose by > 2 m, and deep-growing benthic algal mats declined while shallow benthic mats colonized freshly inundated areas. We attribute changes in hydrology to regional variations in air flow related to the strength and position of the Amundsen Sea Low (ASL) pressure system which have increased the frequency of down-valley, föhn winds associated with surface air temperature warming in the McMurdo Dry Valleys. The ASL has also been implicated in the recent warming of the Antarctic Peninsula, and provides a common link for climate-related change on opposite sides of the continent. If this trend persists, Lake Vanda should continue to rise and cool over the next 200 years until a new equilibrium lake level is achieved. Most likely, future lake rise will lead to isothermal conditions not conducive to thermohaline convection, resulting in a drastically different physical, biogeochemical, and biological structure than observed today.

1 aCastendyk, Devin1 aObryk, Maciek, K.1 aLeidman, Sasha, Z.1 aGooseff, Michael, N.1 aHawes, Ian uhttp://www.sciencedirect.com/science/article/pii/S092181811530014X00845nas a2200193 4500008004100000022001400041245014300055210006900198260001600267300001400283490000700297100002100304700002800325700002900353700003300382700002200415700002100437856019300458 2016 eng d a0006-356800aMicrobial Community Dynamics in Two Polar Extremes: The Lakes of the McMurdo Dry Valleys and the West Antarctic Peninsula Marine Ecosystem0 aMicrobial Community Dynamics in Two Polar Extremes The Lakes of  cJan-10-2016 a829 - 8470 v661 aBowman, Jeff, S.1 aVick-Majors, Trista, J.1 aMorgan-Kiss, Rachael, M.1 aTakacs-Vesbach, Cristina, D.1 aDucklow, Hugh, W.1 aPriscu, John, C. uhttps://academic.oup.com/bioscience/article-lookup/doi/10.1093/biosci/biw103https://academic.oup.com/bioscience/article/66/10/829/2236137/Microbial-Community-Dynamics-in-Two-Polar-Extremes00676nas a2200181 4500008004100000245012900041210006900170260001200239490000600251100002400257700002000281700002400301700002200325700002500347700002100372700003300393856006800426 2016 eng d00aMicrobial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica0 aMicrobial Community Responses to Increased Water and Organic Mat c07/20160 v71 aBuelow, Heather, N.1 aWinter, Ara, S.1 aVan Horn, David, J.1 aBarrett, John, E.1 aGooseff, Michael, N.1 aSchwartz, Egbert1 aTakacs-Vesbach, Cristina, D. uhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.0104000604nas a2200169 4500008004100000245007900041210006900120260001600189490000600205100002200211700002500233700002700258700002100285700002300306700002800329856007700357 2016 eng d00aMicrobial Community Structure of Subglacial Lake Whillans, West Antarctica0 aMicrobial Community Structure of Subglacial Lake Whillans West A cOct-09-20170 v71 aAchberger, Amanda1 aChristner, Brent, C.1 aMichaud, Alexander, B.1 aPriscu, John, C.1 aSkidmore, Mark, L.1 aVick-Majors, Trista, J. uhttp://journal.frontiersin.org/Article/10.3389/fmicb.2016.01457/abstract00761nas a2200241 4500008004100000022001400041245009900055210006900154260001200223300001400235490000700249100002300256700001500279700002200294700001800316700002100334700002100355700002400376700001900400700002700419700001800446856005500464 2016 eng d a0099-224000aMicrobial Mat Communities along an Oxygen Gradient in a Perennially Ice-Covered Antarctic Lake0 aMicrobial Mat Communities along an Oxygen Gradient in a Perennia c01/2016 a620 - 6300 v821 aJungblut, Anne, D.1 aHawes, Ian1 aMackey, Tyler, J.1 aKrusor, Megan1 aDoran, Peter, T.1 aSumner, Dawn, Y.1 aEisen, Jonathan, A.1 aHillman, Colin1 aGoroncy, Alexander, K.1 aStams, A., J. uhttp://aem.asm.org/lookup/doi/10.1128/AEM.02699-1502725nas a2200133 4500008004100000245007400041210006900115260004200184490001000226520224900236100002702485700002102512856005802533 2016 eng d00aMicrobially mediated biogeochemical cycles in polar ice covered lakes0 aMicrobially mediated biogeochemical cycles in polar ice covered  aBozeman, MTbMontana State University0 vPh.D.3 a

Lakes are important sites for globally-relevant biogeochemical cycles mediated by microorganisms. In the Arctic, seasonally ice covered thermokarst lakes are a large component in Earth's carbon cycle due to their methane emissions from organic carbon degradation. In the Antarctic, over 400 unexplored lakes exist beneath the Antarctic ice sheet with unknown biogeochemical contributions to the Earth system. This dissertation seeks to investigate the biogeochemical role of microorganisms in the lake habitat and how they interact with the seasonal and permanent ice covers of lakes in polar environments. Microbiologically clean hot water drilling was used to access a subglacial lake beneath Antarctica's ice to collect, for the first time, intact sediment and water samples. Laboratory experiments on Arctic and Antarctic, seasonally and perennially, respectively, ice covered lakes were used to investigate the impact of lake ice freezing regimes on microorganisms. My results show that subglacial lake sediments beneath the West Antarctic Ice Sheet contain solute ratios that suggest relict marine sediments were deposited during previous interglacial periods. Microbial activity overprints the marine geochemical signature to produce fluxes of ions into the Subglacial Lake Whillans water column, which ultimately drains to the Southern Ocean. Microbial activity in Subglacial Lake Whillans is partially fueled by biologically-formed methane diffusing from below our deepest collected (~38 cm) subglacial sediment samples. The ice above Subglacial Lake Whillans appears to be an important source of molecular oxygen for microorganisms to drive oxidative physiologies. My experimental evidence shows microorganisms incorporate into lake ice cover to, potentially, avoid increasing stressors from progressive lake ice freezing. Taken together, the results from this dissertation reinforce the hypothesis that subglacial environments beneath the Antarctic ice sheet are habitats for life. Further, the microorganisms in subglacial lakes participate in globally-relevant biogeochemical cycles. Here, I extend the extent of the biosphere and show sediments at the base of ice sheets are an active component of the Earth system.

1 aMichaud, Alexander, B.1 aPriscu, John, C. uhttps://scholarworks.montana.edu/xmlui/handle/1/1379302072nas a2200193 4500008004100000245010300041210006900144260005100213490000900264520138000273653003401653653004201687653002201729653002401751653001201775100002401787700002201811856004501833 2016 eng d00aModeling Surface Photosynthetic Active Radiation in Taylor Valley, McMurdo Dry Valleys, Antarctica0 aModeling Surface Photosynthetic Active Radiation in Taylor Valle aChicago, ILbUniversity of Illinois at Chicago0 vM.S.3 a

Understanding primary productivity is a core research area of the National Science Foundation’s Long-Term Ecological Research Network. This study maps surface Photosynthetically Active Radiation (PAR) using long term data collected by a meteorological network in the McMurdo Dry Valleys. Four stations with ~20 years of records were used to correct T-sPAR, a topographic surface PAR model. Maximum expected daily surface PAR at meteorological stations was calculated for Taylor Valley, through statistical analysis of location records using a local regression model that included 84% of all observations. Expected values represent daily surface PAR under cloudless conditions. Daily measured and expected PAR was used to model cloud coverage at each location, corroborating that overcast conditions are positively correlated with proximity to the ocean. Ground-truth data collected for TaylorValley’s major lakes during the 2015/2016 field season were used to validate T-sPAR estimates. The final model approximates total seasonal surface PAR for the Taylor Valley basin. Bi- monthly maps estimate total surface PAR by lake to assist in future sampling site selection. Finally, a user interface was developed to estimate total daily surface PAR by coordinate or surface based on a user input date.

 

10adigital elevation model (DEM)10ageographical information system (GIS)10aice-covered lakes10ameteorological data10aR model1 aAcosta, Dimitri, R.1 aBerkelhammer, Max uhttp://indigo.uic.edu/handle/10027/2118002208nas a2200181 4500008004100000022001400041245010400055210006900159260001200228300001100240520160100251100002201852700002101874700001801895700002701913700002101940856006501961 2016 eng d a0022-143000aModeling the thickness of perennial ice covers on stratified lakes of the Taylor Valley, Antarctica0 aModeling the thickness of perennial ice covers on stratified lak c06/2016 a1 - 103 a
A 1-D ice cover model was developed to predict and constrain drivers of long-term ice thickness trends in chemically stratified lakes of Taylor Valley, Antarctica. The model is driven by surface radiative heat fluxes and heat fluxes from the underlying water column. The model successfully reproduced 16 a (between 1996 and 2012) of ice thickness changes for the west lobe of Lake Bonney (average ice thickness = 3.53 m) and Lake Fryxell (average ice thickness = 4.22 m). Long-term ice thickness trends require coupling with the thermal structure of the water column. The heat stored within the temperature maximum of lakes exceeding a liquid water column depth of 20 m can either impede or facilitate ice thickness change depending on the predominant climatic trend (cooling or warming). As such, shallow (<20 m deep water columns) perennially ice-covered lakes without deep temperature maxima are more sensitive indicators of climate change. The long-term ice thickness trends are a result of surface energy flux and heat flux from the deep temperature maximum in the water column, the latter of which results from absorbed solar radiation.

 

1 aObryk, Maciek, K.1 aDoran, Peter, T.1 aHicks, J., A.1 aMcKay, Christopher, P.1 aPriscu, John, C. uhttp://www.journals.cambridge.org/abstract_S002214301600069101330nas a2200193 4500008004100000245009800041210006900139260004000208490000900248520071900257653001500976653001400991653001501005653001701020653001901037100002101056700002101077856003801098 2016 eng d00aNoble Gas Radioisotope Constraints on Water Residence Time and Solvent Sources in Lake Bonney0 aNoble Gas Radioisotope Constraints on Water Residence Time and S aChicago, ILbUniversity of Illinois0 vM.S.3 a

A noble gas radionuclide analysis of perennially ice covered West Lake Bonney was performed in order to determine water residence time and ice cover timing. Bulk gas samples were collected at four depths in the lake. Krypton and argon gases were selectively isolated from the bulk gas and measurements of 81Kr, 85Kr and 39Ar were made. Radiokrypton and radioargon analyses yielded lower limit ages of 78 to 285 years, significantly younger than expected based on previous dating efforts. It was determined that these new data do not invalidate previous work, but instead offer new insight into the timing of the most recent episode of direct communication between the atmosphere and West Lake Bonney waters.

10aAntarctica10anoble gas10aradioargon10aradiokrypton10aresidence time1 aCronin, Kyle, D.1 aDoran, Peter, T. uhttp://hdl.handle.net/10027/2157002591nas a2200193 4500008004100000245013100041210006900172260001200241300001100253490000700264520191200271100002202183700002402205700002402229700003302253700002402286700001702310856007002327 2016 eng d00aNutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica0 aNutrient treatments alter microbial mat colonization in two glac c03/2016 afiw0490 v923 a

Microbial mats are abundant in many alpine and polar aquatic ecosystems. With warmer temperatures, new hydrologic pathways are developing in these regions and increasing dissolved nutrient fluxes. In the McMurdo Dry Valleys, thermokarsting may release both nutrients and sediment, and has the potential to influence mats in glacial meltwater streams. To test the role of nutrient inputs on community structure, we created nutrient diffusing substrata (NDS) with agar enriched in N, P and N + P, with controls, and deployed them into two Dry Valley streams. We found N amendments (N and N + P) to have greater chlorophyll-a concentrations, total algal biovolume, more fine filamentous cyanobacteria and a higher proportion of live diatoms than other treatments. Furthermore, N treatments were substantially elevated in Bacteroidetes and the small diatom, Fistulifera pelliculosa. On the other hand, species richness was almost double in P and N + P treatments over others, and coccoid green algae and Proteobacteria were more abundant in both streams. Collectively, these data suggest that nutrients have the potential to stimulate growth and alter community structure in glacial meltwater stream microbial mats, and the recent erosion of permafrost and accelerated glacial melt will likely impact resident biota in polar lotic systems here and elsewhere.

1 aKohler, Tyler, J.1 aVan Horn, David, J.1 aDarling, Joshua, P.1 aTakacs-Vesbach, Cristina, D.1 aMcKnight, Diane, M.1 aWagner, Dirk uhttp://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw04902226nas a2200229 4500008004100000245011100041210006900152260001200221300001100233490000700244520146700251100002401718700002201742700002301764700001901787700002201806700002401828700002101852700002001873700003301893856007001926 2016 eng d00aPatterns of bacterial biodiversity in the glacial meltwater streams of the McMurdo Dry Valleys, Antarctica0 aPatterns of bacterial biodiversity in the glacial meltwater stre c08/2016 afiw1480 v923 a

Microbial consortia dominate glacial meltwater streams from polar regions, including the McMurdo Dry Valleys (MDV), where they thrive under physiologically stressful conditions. In this study, we examined microbial mat types and sediments found in 12 hydrologically diverse streams to describe the community diversity and composition within and across sites. Sequencing of the 16S rRNA gene from 129 samples revealed ∼24 000 operational taxonomic units (<97% DNA similarity), making streams the most biodiverse habitat in the MDV. Principal coordinate analyses revealed significant but weak clustering by mat type across all streams (ANOSIM R-statistic = 0.28) but stronger clustering within streams (ANOSIM R-statistic from 0.28 to 0.94). Significant relationships (P < 0.05) were found between bacterial diversity and mat ash-free dry mass, suggesting that diversity is related to the hydrologic regimes of the various streams, which are predictive of mat biomass. However, correlations between stream chemistry and community members were weak, possibly reflecting the importance of internal processes and hydrologic conditions. Collectively, these results suggest that localized conditions dictate bacterial community composition of the same mat types and sediments from different streams, and while MDV streams are hotspots of biodiversity in an otherwise depauperate landscape, controls on community structure are complex and site specific.

1 aVan Horn, David, J.1 aWolf, Caitlin, R.1 aColman, Daniel, R.1 aJiang, Xiaoben1 aKohler, Tyler, J.1 aMcKnight, Diane, M.1 aStanish, Lee, F.1 aYazzie, Terrill1 aTakacs-Vesbach, Cristina, D. uhttp://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw14802242nas a2200181 4500008004100000245012300041210006900164260001200233300001400245490000700259520163300266100002101899700002501920700002401945700001701969700001701986856005702003 2016 eng d00aPatterns of hydrologic connectivity in the McMurdo dry valleys, Antarctica: a synthesis of 20 years of hydrologic data0 aPatterns of hydrologic connectivity in the McMurdo dry valleys A c04/2016 a2958-29750 v303 a

Streams in the McMurdo Dry Valleys (MDVs) of Antarctica moderate an important hydrologic and biogeochemical connection between upland alpine glaciers, valley-bottom soils, and lowland closed-basin lakes. Moreover, MDV streams are simple but dynamic systems ideal for studying interacting hydrologic and ecological dynamics. This work synthesizes 20 years of hydrologic data, collected as part of the MDVs Long-Term Ecological Research project, to assess spatial and temporal dynamics of hydrologic connectivity between glaciers, streams, and lakes. Long-term records of stream discharge (Q), specific electrical conductance (EC), and water temperature (T) from 18 streams were analysed in order to quantify the magnitude, duration, and frequency of hydrologic connections over daily, annual, and inter-annual timescales. At a daily timescale, we observe predictable diurnal variations in Q, EC, and T. At an annual timescale, we observe longer streams to be more intermittent, warmer, and have higher median EC values, compared to shorter streams. Longer streams also behave chemostatically with respect to EC, whereas shorter streams are more strongly characterized by dilution. Inter-annually, we observe significant variability in annual runoff volumes, likely because of climatic variability over the 20 record years considered. Hydrologic connections at all timescales are vital to stream ecosystem structure and function. This synthesis of hydrologic connectivity in the MDVs provides a useful end-member template for assessing hydrologic connectivity in more structurally complex temperate watersheds. 

1 aWlostowski, Adam1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aJaros, Chris1 aLyons, Berry uhttp://onlinelibrary.wiley.com/doi/10.1002/hyp.1081804082nas a2200157 4500008004100000245010000041210006900141260001200210490000700222520353000229100002903759700002503788700001803813700002103831856007203852 2016 eng d00aPhotoadaptation to the polar night by phytoplankton in a permanently ice-covered Antarctic lake0 aPhotoadaptation to the polar night by phytoplankton in a permane c05/20150 v613 a

Photosynthetic microorganisms are a primary source of new organic carbon production in polar ecosystems. Despite their importance, relatively little is known about how they adapt to the bimodal solar cycles that exist at high latitudes. To understand how phytoplankton adapt to the extreme seasonal change in photoperiod, we transplanted cultures of a well-studied laboratory model for photosynthetic cold adaptation, Chlamydomonas raudensis UWO241, back to the water column of Lake Bonney (McMurdo Dry Valleys, Antarctica) at the depth from which it was originally cultured. The organism was suspended at this depth in dialysis tubing to allow the microalga to respond to the in situ light, temperature and dissolved ions. We then integrated in situ biological and chemical measurements with environmental molecular analyses and compared the responses of transplanted C. raudensis cultures with the natural phytoplankton community over the 6-week transition from Antarctic summer (24-h daylight) to polar night (24-h darkness). As solar radiation declined, natural communities exhibited a cessation of inorganic carbon fixation which was accompanied by a downregulation of expression of genes encoding for essential carbon fixation and photochemistry proteins. Transplanted C. raudensis cultures matched natural community trends in the regulation of photochemistry and carbon fixation gene expression, and shifted photochemical function to a shade adapted state in response to the polar night transition. We present a conceptual model for seasonal shifts in microbial community energy and carbon acquisition which integrates past cultivation-based studies in this model photopsychrophile with a body of recent work on adaptation of natural populations to polar night.

1 aMorgan-Kiss, Rachael, M.1 aLizotte, Michael, P.1 aKong, Weidong1 aPriscu, John, C. uhttps://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.1010702602nas a2200133 4500008004100000245008200041210006900123260004200192490000900234520212000243100002702363700002102390856005702411 2016 eng d00aPhysiological characteristics of fungi associated with Antarctic environments0 aPhysiological characteristics of fungi associated with Antarctic aBozeman, MTbMontana State University0 vM.S.3 a

The permanent ice covers on the lakes of Antarctica's McMurdo Dry Valleys region harbor a diverse group of phototrophic and heterotrophic microorganisms that metabolize during the short summer months when solar radiation produces melt inclusions within the ice and provides energy to drive photosynthesis. Laboratory cultures of fungi were obtained from ice cores taken from Lakes Bonney (east lobe) and Chad, and sediments collected from Subglacial Lake Whillans (West Antarctica). Using molecular techniques, the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) was sequenced to identify fungal types and to determine whether they may be unique to this region. Four axenic fungal cultures, Tetracladium ellipsoideum, Lecythophora hoffmannii, Mucor sp., and an unidentified Ascomycota were successfully isolated. These isolates are closely related to organisms that have been previously reported in Antarctica and other cold habitats. The isolates were tested for growth characteristics under various temperature and nutrient regimes. Temperature response experiments revealed that all the isolated fungi were psychrotolerant and growth rates were greatest at 25°C. Of major significance in evaluating the potential of Antarctic fungi as a bioresource is their ability to produce bioactive compounds. Two out of four isolated organisms exhibited antimicrobial activity against several plant pathogens. The metabolic potential and preferred substrate utilization was examined by exposing fungal isolates to a variety of substrates in a 96 well "Biolog" plate. A strong correlation was found among substrate utilization, isolates, temperature and the different carbon substrates. This experiment revealed that the isolated fungi have preferences for different labile carbon substrates at 4°C and 24°C which may imply different physiologies at different times of year in the lake ice-covers. Results from my studies will help understand the role of fungi in lake ice and subglacial lake sediment ecosystems, and the physiology of fungi living in cold environments.

1 aKudalkar, Priyanka, S.1 aPriscu, John, C. uhttps://scholarworks.montana.edu/xmlui/handle/1/983500836nas a2200229 4500008004100000245007200041210006900113260001600182490000600198100002800204700002100232700002200253700002500275700001900300700002700319700002200346700002400368700002300392700002100415710002900436856014100465 2016 eng d00aPhysiological Ecology of Microorganisms in Subglacial Lake Whillans0 aPhysiological Ecology of Microorganisms in Subglacial Lake Whill cMar-10-20180 v71 aVick-Majors, Trista, J.1 aMitchell, Andrew1 aAchberger, Amanda1 aChristner, Brent, C.1 aDore, John, E.1 aMichaud, Alexander, B.1 aMikucki, Jill, A.1 aPurcell, Alicia, M.1 aSkidmore, Mark, L.1 aPriscu, John, C.1 aThe WISSARD Science Team uhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/fullhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/full04020nas a2200241 4500008004100000245019000041210006900231260004000300490001000340520313500350653002103485653001703506653001503523653001903538653001703557653003803574653002903612653001803641653000903659100001903668700002403687856006703711 2016 eng d00aQuantifying sources, distribution, and processing of light absorbing aerosols in the cryosphere: A comparison of dissolved and refractory black carbon in polar and high mountain regions0 aQuantifying sources distribution and processing of light absorbi aBoulder, CObUniversity of Colorado0 vPh.D.3 a

Light absorbing aerosols (LAAs) in snow and ice are one of the least understood parameters in global climate models due to complicated physical processes within the cryosphere and too few in situ observations. Ground observations are limited due to the difficulty of collecting and preserving samples for analysis from remote environments.
In order to help build a larger repository of ground observations, this dissertation explores the concentration and composition of black carbon (BC) in snow and glacial melt-water across the polar regions in the Arctic and Antarctic, as well as major mountain regions such as the Himalayas, Rockies, and Andes Mountains.

Three state-of-the-art methods for BC detection are applied in this dissertation. The first chapter identifies chemical signatures of past and present sources of dissolved black carbon (DBC) in Antarctic lakes, utilizing a DBC molecular marker method. Here we find that DBC with a woody signature is preserved in the deep, ancient brines of Antarctic lake bottom waters. In contrast, the surface waters are enriched in BC from fossil fuels. The second chapter, which also utilizes the DBC molecular marker

iii 

 

technique, explores DBC across the cryosphere. We show that DBC concentrations are surprisingly high in the bottom waters of Antarctic lakes compared to other remote regions of the cryosphere, even those located near point sources. Aged snow also contains higher DBC concentrations than fresh snow suggesting that dry deposition brings the majority of BC to the cryosphere. Additionally, the DBC composition across samples from the cryosphere are similar due to high amounts of solar exposure leading to photodegradation, except in fresh snow with a wildfire signature. The third and fourth chapters utilize the Single Particle Soot Photometer to measure refractory black carbon (rBC). The third chapter also applies spectral albedo measurements and the light absorption heating method to find that coal dust from an active mine in Svalbard, Norway significantly reduces the spectral reflectance of the surrounding Arctic surface snow. The fourth chapter reports aerosol rBC concentrations in the boundary layer of the McMurdo Dry Valleys, as well as in snow from the accumulation area of the Commonwealth Glacier. Here we determine that aerosol concentrations increase during high wind events, but there is no significant trend in deposition in the snow pit. This could be due to sporadic deposition during katabatic wind events.

These findings support the importance of real in-situ observations in order to fully understand the role of BC in the global carbon cycle. It is also evident that local environmental processes can control the concentrations and composition of BC in the cryosphere. These ground-based measurements will likely serve as ground validation for future remote sensing of snow/ice impurities and LAAs deposition models.

 

10aapplied sciences10ablack carbon10acryosphere10aearth sciences10aglacial melt10ahealth and environmental sciences10alight absorbing aerosols10apolar regions10asnow1 aKhan, Alia, L.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/1834518541?accountid=1450300943nas a2200253 4500008004100000022001400041245008700055210006900142260001600211300001400227490000700241100002200248700002100270700002600291700002500317700001200342700002900354700002100383700002100404700002800425700002700453700002200480856018700502 2016 eng d a0006-356800aResponses of Antarctic Marine and Freshwater Ecosystems to Changing Ice Conditions0 aResponses of Antarctic Marine and Freshwater Ecosystems to Chang cJan-10-2016 a864 - 8790 v661 aObryk, Maciek, K.1 aDoran, Peter, T.1 aFriedlaender, Ari, S.1 aGooseff, Michael, N.1 aLi, Wei1 aMorgan-Kiss, Rachael, M.1 aPriscu, John, C.1 aSchofield, Oscar1 aStammerjohn, Sharon, E.1 aSteinberg, Deborah, K.1 aDucklow, Hugh, W. uhttps://academic.oup.com/bioscience/article-lookup/doi/10.1093/biosci/biw109https://academic.oup.com/bioscience/article/66/10/864/2415532/Responses-of-Antarctic-Marine-and-Freshwater01836nas a2200193 4500008004100000245013000041210006900171260001200240300001600252490000700268520116600275100002501441700002401466700002001490700002401510700002401534700001701558856006701575 2016 eng d00aStream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica0 aStream biogeochemical and suspended sediment responses to permaf c03/2016 a1723 - 17320 v133 a

 Stream channels in the McMurdo Dry Valleys are characteristically wide, incised, and stable. At typical flows, streams occupy a fraction of the oversized channels, providing habitat for algal mats. In January 2012, we discovered substantial channel erosion and subsurface thermomechanical erosion undercutting banks of the Crescent Stream. We sampled stream water along the impacted reach and compared concentrations of solutes to the long-term data from this stream ( ∼  20 years of monitoring). Thermokarst-impacted stream water demonstrated higher electrical conductivity, and concentrations of chloride, sulfate, sodium, and nitrate than the long-term medians. These results suggest that this mode of lateral permafrost degradation may substantially impact stream solute loads and potentially fertilize stream and lake ecosystems. The potential for sediment to scour or bury stream algal mats is yet to be determined, though it may offset impacts of associated increased nutrient loads to streams.

1 aGooseff, Michael, N.1 aVan Horn, David, J.1 aSudman, Zachary1 aMcKnight, Diane, M.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf00627nas a2200133 4500008004100000022001300041245014500054210006900199260001200268300001100280490000700291100002000298856017500318 2016 eng d a0967340700aTaylor's Valley: What the History of Antarctica's 'Heroic Era' Can Contribute to Contemporary Ecological Research in the McMurdo Dry Valleys0 aTaylors Valley What the History of Antarcticas Heroic Era Can Co c01/2016 a3 - 280 v221 aHowkins, Adrian uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0967-3407&volume=22&issue=1&spage=3http://www.ingentaconnect.com/content/whp/eh/2016/00000022/00000001/art0000304687nas a2200181 4500008004100000022001400041245015900055210006900214260001200283300001600295490000700311520405500318100001204373700001804385700002904403700001804432856005504450 2016 eng d a0099-224000aUltrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake0 aUltrastructural and SingleCellLevel Characterization Reveals Met c06/2016 a3659 - 36700 v823 a

The McMurdo Dry Valleys (MCM) of southern Victoria Land, Antarctica, harbor numerous ice-covered bodies of water that provide year-round liquid water oases for isolated food webs dominated by the microbial loop. Single-cell microbial eukaryotes (protists) occupy major trophic positions within this truncated food web, ranging from primary producers (e.g., chlorophytes, haptophytes, and cryptophytes) to tertiary predators (e.g., ciliates, dinoflagellates, and choanoflagellates). To advance the understanding of MCM protist ecology and the roles of MCM protists in nutrient and energy cycling, we investigated potential metabolic strategies and microbial interactions of key MCM protists isolated from a well-described lake (Lake Bonney). Fluorescence-activated cell sorting (FACS) of enrichment cultures, combined with single amplified genome/amplicon sequencing and fluorescence microscopy, revealed that MCM protists possess diverse potential metabolic capabilities and interactions. Two metabolically distinct bacterial clades (Flavobacteria and Methylobacteriaceae) were independently associated with two key MCM lake microalgae (Isochrysis and Chlamydomonas, respectively). We also report on the discovery of two heterotrophic nanoflagellates belonging to the Stramenopila supergroup, one of which lives as a parasite ofChlamydomonas, a dominate primary producer in the shallow, nutrient-poor layers of the lake.

IMPORTANCE Single-cell eukaryotes called protists play critical roles in the cycling of organic matter in aquatic environments. In the ice-covered lakes of Antarctica, protists play key roles in the aquatic food web, providing the majority of organic carbon to the rest of the food web (photosynthetic protists) and acting as the major consumers at the top of the food web (predatory protists). In this study, we utilized a combination of techniques (microscopy, cell sorting, and genomic analysis) to describe the trophic abilities of Antarctic lake protists and their potential interactions with other microbes. Our work reveals that Antarctic lake protists rely on metabolic versatility for their energy and nutrient requirements in this unique and isolated environment.

1 aLi, Wei1 aPodar, Mircea1 aMorgan-Kiss, Rachael, M.1 aKelly, R., M. uhttp://aem.asm.org/lookup/doi/10.1128/AEM.00478-1600496nas a2200133 4500008004100000022001400041245011800055210006900173260001200242300001400254490000700268100002100275856006600296 2016 eng d a0006-356800aUnraveling ecosystem responses to climate change on the Antarctic continent through Long-Term Ecological Research0 aUnraveling ecosystem responses to climate change on the Antarcti c10/2016 a799 - 8000 v661 aPriscu, John, C. uhttps://academic.oup.com/bioscience/article/66/10/799/223616603338nas a2200193 4500008004100000022001400041245010600055210006900161260001600230300001400246490000600260520270300266100002102969700002302990700002503013700002603038700002703064856005303091 2015 eng d a1752-089400aAccumulation and marine forcing of ice dynamics in the western Ross Sea during the last deglaciation0 aAccumulation and marine forcing of ice dynamics in the western R cJan-07-2016 a625 - 6280 v83 a

The grounding line of the ice sheet in the Ross Sea, Antarctica, retreated between the Last Glacial Maximum and the present. However, the timing of the retreat and the interplay of factors controlling ice stability in this region1 remain uncertain. Here we use 180 radiocarbon dates to reconstruct the chronology of moraine construction on the headlands adjacent to western McMurdo Sound. On the basis of these dates we then assess the timing of ice expansion and retreat in the Ross drainage system that is fed from both the East and West Antarctic ice sheets. We find that grounded ice in the western Ross Sea achieved its greatest thickness and extent during the last termination, between 12,800 and 18,700 years ago. Maximum ice thickness at our site coincides with a period of high accumulation as recorded by the West Antarctic Ice Sheet Divide ice core2. Recession of the ice sheet from the headland moraines began about 12,800 years ago, despite continued high accumulation and the expansion of land-based glaciers at this time. We therefore suggest that the grounding-line retreat reflects an increased marine influence as sea levels rose and the ocean warmed. We suggest that future instability in the ice sheet grounding line may occur whenever the ocean forcing is stronger than forcing from accumulation.

 
 
1 aHall, Brenda, L.1 aDenton, George, H.1 aHeath, Stephanie, L.1 aJackson, Margaret, S.1 aKoffman, Tobias, N. B. uhttp://www.nature.com/doifinder/10.1038/ngeo247804921nas a2200181 4500008004100000022001400041245008200055210006900137260001200206300001300218520434700231100002104578700001504599700002204614700002304636700002104659856005904680 2015 eng d a0091-761300aAntarctic microbial mats: A modern analog for Archean lacustrine oxygen oases0 aAntarctic microbial mats A modern analog for Archean lacustrine  c10/2015 aG36966.13 a

The evolution of oxygenic photosynthesis was the most important geochemical event in

Earth history, causing the Great Oxidation Event (GOE) ~2.4 b.y. ago. However, evidence is mixed as to whether O2 production occurred locally as much as 2.8 b.y. ago, creating O2 oases, or initiated just prior to the GOE. The biogeochemical dynamics of possible O2 oases have been poorly constrained due to the absence of modern analogs. However, cyanobacteria in microbial mats in a perennially anoxic region of Lake Fryxell, Antarctica, create a 1–2 mm O2-containing layer in the upper mat during summer, providing the first known modern analog for formation of benthic O2 oases. In Lake Fryxell, benthic cyanobacteria are present below the oxycline in the lake. Mat photosynthesis rates were slow due to low photon flux rate (1–2 μmol m-2 s-1) under thick ice cover, but photosynthetic O2 production was sufficient to sustain up to 50 μmol O2 L-1, sandwiched between anoxic overlying water and anoxic sedi- ments. We hypothesize that Archean cyanobacteria could have similarly created O2 oases in benthic mats prior to the GOE. Analogous mats may have been at least partly responsible for geological evidence of oxidative weathering prior to the GOE, and habitats such as Lake Fryxell provide natural laboratories where the impact of benthic O2 oases on biogeochemical signatures can be investigated. 

 

1 aSumner, Dawn, Y.1 aHawes, Ian1 aMackey, Tyler, J.1 aJungblut, Anne, D.1 aDoran, Peter, T. uhttp://geology.gsapubs.org/lookup/doi/10.1130/G36966.103321nas a2200205 4500008004100000022001400041245008600055210006900141260001200210300001600222490000700238520262100245100001702866700002302883700002402906700002502930700001502955700002402970856012102994 2015 eng d a0091-761300aAntarctic streams as a potential source of iron for the Southern Ocean: Figure 1.0 aAntarctic streams as a potential source of iron for the Southern c11/2016 a1003 - 10060 v433 a

Due to iron’s role in oceanic primary production, there has been great interest in quantifying the importance of Fe in regions where concentrations are very low and macronutrients, nitrate and phosphate, are available. Measurements of filterable (i.e., <0.4 μm) Fe concentrations in streams from Taylor Valley, McMurdo Dry Valleys, Antarctica, suggest that coastal-zone stream Fe input to the Southern Ocean could potentially play an important role in primary production in nearshore regions. Filterable Fe (fFe) data from streams in the McMurdo Dry Valleys were used to represent glacier meltwater that flows through ice-free landscape with the potential of transporting Fe to the Antarctic coastal zone. Estimates of potential fFe flux to the Antarctic Peninsula region using our mean fFe concentration of 10.6 µg L–1 combined with an estimate of ice-free area for the Antarctic Peninsula result in an fFe flux of 1.2 × 107 g yr–1. Although small compared to iceberg and aeolian Fe fluxes, future stream input to the Southern Ocean could increase due to glacier retreat and 

1 aLyons, Berry1 aDailey, Kelsey, R.1 aWelch, Kathleen, A.1 aDeuerling, Kelly, M.1 aWelch, Sue1 aMcKnight, Diane, M. uhttp://geology.gsapubs.org/lookup/doi/10.1130/G36989.1http://geology.geoscienceworld.org/lookup/doi/10.1130/G36989.103075nas a2200157 4500008004100000024003700041245014500078210006900223260003500292300000700327490002500334520248000359100002402839700001702863856003702880 2015 eng d ahttp://hdl.handle.net/1811/6888700aChemical Weathering and Mineralogy of McMurdo Dry Valley Streams: Examining the Controls of Current and Future Ephemeral Stream Geochemistry0 aChemical Weathering and Mineralogy of McMurdo Dry Valley Streams aOhio State Universityc05/2015 a380 vUndergraduate Theses3 a

The McMurdo Dry Valleys form the largest ice-free region in Antarctica and are the coldest, driest deserts in the world. But, for approximately 6-12 weeks per year in the austral summer, continuous sunlight and near-freezing temperatures create meltwater streams that descend from the surrounding alpine glaciers. These ephemeral streams are a distinctive feature in the barren dry valley landscape and are important sources of nutrients and solutes from the weathering of streambed and hyporheic zone materials. This setting has been a US National Science Foundation funded Long-Term Ecological Research (LTER) project since 1993. A major goal of the McMurdo LTER is to understand how liquid water, the primary limiting condition for life in Antarctica, is affected by climate variability. The McMurdo Dry Valleys are extremely climate-sensitive and even seemingly small variations in temperature can have a drastic effect on hydrological activity. The McMurdo LTER program has been successful in collecting and analyzing a large amount of stream data pertaining to weathering products but, a more comprehensive analysis and interpretation of the data have yet to be undertaken. Assessment of current and future stream geochemistry is critical to predict the impact of increased water flow due to glacier melt and increasing temperature which could greatly influence the ecological function and biologic diversity in the McMurdo Dry Valleys. Surface sediments were collected at multiple locations from ephemeral streams and analyzed using a scanning electron microscope and x-ray diffraction to determine sediment mineralogy and evidence of chemical weathering. Geochemical reactions were modeled using previously collected stream water data and the USGS PHREEQC software for the speciation calculations and the assessment of the solubility controlling solid phases. Chemical weathering was apparent through visible mineral alteration and the formation of secondary weathering products. Modeling results indicate that stream geochemistry will not significantly be affected by increased water temperature in the future. These results suggest stream geochemistry and chemical weathering may instead be controlled primarily through hydrologic exchange in the hyporheic zone.

1 aScheuermann, Jordan1 aLyons, Berry uhttp://hdl.handle.net/1811/6888708594nas a2200241 4500008004100000022001300041245020300054210006900257260001200326300001400338490000800352520755800360100001907918700002407937700002007961700002407981700002308005700002308028700001708051700002708068700002708095856023008122 2015 eng d a0009254100aComparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes0 aComparison of arsenic and molybdenum geochemistry in meromictic  c05/2015 a110 - 1250 v4043 a

Water samples were collected for arsenic (As) and molybdenum (Mo) analysis from different depths in Lakes Hoare and Fryxell, both of which are located in the Taylor Valley within the McMurdo Dry Valleys of Antarctica. Sampling depths within each lake were chosen to capture variations in As and Mo concentrations and As speciation in the oxic mixolimnia and anoxic monimolimnia of these meromictic lakes. Arsenic concentrations ranged from 0.67 nmol kg− 1 to 3.54 nmol kg− 1 in Lake Hoare and from 1.69 nmol kg− 1 to 17.5 nmol kg− 1 in Lake Fryxell. Molybdenum concentrations varied between 5.05 nmol kg− 1 and 43 nmol kg− 1 in Lake Hoare, and between 3.52 nmol kg− 1 and 25.5 nmol kg− 1 in Lake Fryxell. Concentrations of As and Mo generally increased with depth in the mixolimnion of each lake, consistent with uptake near the ice–water interface by organic particles and/or Fe/Mn oxides/oxyhydroxides, followed by gravitational settling and regeneration/remineralization at depth in the vicinity of the redoxcline. Arsenic concentrations either remained constant (Hoare) or increased with depth (Fryxell) in the anoxic monimolimnia, whereas Mo exhibited dramatic decreases in concentrations across the redoxcline in both lakes. Geochemical modeling predicts that As and Mo occur as thioanions in the anoxic bottom waters of Lakes Hoare and Fryxell, and further that the contrasting behavior of both trace elements reflects the respective reactivity of their thioanions towards Fe-sulfide minerals such as mackinawite (FeS) and/or pyrite (FeS2). More specifically, the geochemical model suggests that Fe-sulfide mineral precipitation in the anoxic monimolimnia of both lakes regulates dissolved sulfide concentrations at levels that are too low for As-sulfide minerals (e.g., orpiment, realgar) to precipitate, whereas mackinawite and/or pyrite react(s) with particle reactive thiomolybdate anions, possibly forming an Fe–Mo–S mineral that precipitates and, hence, leads to Mo removal from solution.

1 aYang, Ningfang1 aWelch, Kathleen, A.1 aMohajerin, Jade1 aTelfeyan, Katherine1 aChevis, Darren, A.1 aGrimm, Deborah, A.1 aLyons, Berry1 aWhite, Christopher, D.1 aJohannesson, Karen, H. uhttp://linkinghub.elsevier.com/retrieve/pii/S0009254115001874http://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0009254115001874?httpAccept=text/plain04455nas a2200121 4500008004100000245007900041210006900120260001200189520398300201100001604184700002304200856011004223 2015 eng d00aControls on diel soil CO2 flux across moisture gradients in a polar desert0 aControls on diel soil CO2 flux across moisture gradients in a po c06/20153 a

The McMurdo Dry Valleys of Antarctica are a climate-sensitive ecosystem, where future projected climate warming will increase liquid water availability to release soil biology from physical limitations and alter ecosystem processes. For example, many studies have shown that CO2 flux, an important aspect of the carbon cycle, is controlled by temperature and moisture, which often overwhelm biotic contributions in desert ecosystems. However, these studies used either single-point measurements during peak times of biological activity or diel cycles at individual locations. Here, we present diel cycles of CO2 flux from a range of soil moisture conditions and a variety of locations and habitats to determine how diel cycles of CO2 flux vary across gradients of wet-to-dry soil and whether the water source influences the diel cycle of moist soil. Soil temperature, water content and microbial biomass significantly influenced CO2 flux. Soil temperature explained most of the variation. Soil CO2 flux moderately increased with microbial biomass, demonstrating a sometimes small but significant role of biological fluxes. Our results show that over gradients of soil moisture, both geochemical and biological fluxes contribute to soil CO2 flux, and physical factors must be considered when estimating biological CO2 flux in systems with low microbial biomass.

1 aBall, Becky1 aVirginia, Ross, A. uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9776001&fileId=S095410201500025503959nas a2200205 4500008004100000022001400041245008900055210006900144260001200213300001600225490000700241520327000248100001403518700002303532700001503555700002303570700002103593700002203614856011703636 2015 eng d a0722-406000aCyanobacterial diversity in benthic mats of the McMurdo Dry Valley lakes, Antarctica0 aCyanobacterial diversity in benthic mats of the McMurdo Dry Vall c01/2015 a1097 - 11100 v383 a
Perennially ice-covered, meromictic lakes in the McMurdo Dry Valleys, Antarctica, are useful models to study the relationship between cyanobacterial and environmental variables. They have rich benthic cyanobacterial mat accumulations and stable stratification of physical and chemical conditions. Here, we evaluated cyanobacteria from benthic mats from multiple depths in three geographically separated ice-covered lakes, Lakes Vanda, Hoare and Joyce, using 16S rRNA gene clone libraries. We identified 19 ribotypes, mostly Oscillatoriales and several
Chroococcales, as well as potentially novel cyanobacterial ribotypes. The majority of ribotype diversity was shared between lakes, and only a weak relationship between ribotype community structure and environmental variables was evident. Multivariate analysis of all lake–depth combinations implied that photosynthetically active radiation, dissolved reactive phosphorus and conductivity were potentially important for shaping benthic communities in McMurdo Dry Valley lakes. Cyanobacterial-specific pigment signature analysis by high-performance liquid chromatography
showed that the cyanobacterial communities responded to light conditions similarly, irrespective of community composition. The results imply a capability within a suite of cyanobacteria to colonise, adapt and grow across broad environmental ranges and geographic space, and such adaptability may provide a high degree of community resistance and resilience to future climate-driven environmental change in Antarctic terrestrial aquatic
ecosystems.
1 aZhang, L.1 aJungblut, Anne, D.1 aHawes, Ian1 aAndersen, Dale, T.1 aSumner, Dawn, Y.1 aMackey, Tyler, J. uhttp://link.springer.com/10.1007/s00300-015-1669-0http://link.springer.com/content/pdf/10.1007/s00300-015-1669-001657nas a2200229 4500008004100000245008700041210006900128260001600197300000900213490000600222520097300228100002201201700001401223700001601237700002301253700001701276700002201293700002101315700002201336700001401358856005501372 2015 eng d00aDeep groundwater and potential subsurface habitats beneath an Antarctic dry valley0 aDeep groundwater and potential subsurface habitats beneath an An cApr-04-2017 a68310 v63 aThe occurrence of groundwater in Antarctica, particularly in the ice-free regions and along the coastal margins is poorly understood. Here we use an airborne transient electromagnetic (AEM) sensor to produce extensive imagery of resistivity beneath Taylor Valley. Regional-scale zones of low subsurface resistivity were detected that are inconsistent with the high resistivity of glacier ice or dry permafrost in this region. We interpret these results as an indication that liquid, with sufficiently high solute content, exists at temperatures well below freezing and considered within the range suitable for microbial life. These inferred brines are widespread within permafrost and extend below glaciers and lakes. One system emanates from below Taylor Glacier into Lake Bonney and a second system connects the ocean with the eastern 18 km of the valley. A connection between these two basins was not detected to the depth limitation of the AEM survey (~350 m).1 aMikucki, Jill, A.1 aAuken, E.1 aTulaczyk, S1 aVirginia, Ross, A.1 aSchamper, C.1 aSørensen, K., I.1 aDoran, Peter, T.1 aDugan, Hilary, A.1 aFoley, N. uhttp://www.nature.com/doifinder/10.1038/ncomms783101522nas a2200181 4500008004100000022001400041245007100055210006900126260001200195300001400207490000700221520096100228100002101189700002401210700001701234700002401251856006501275 2015 eng d a0954-102000aExperimental formation of pore fluids in McMurdo Dry Valleys soils0 aExperimental formation of pore fluids in McMurdo Dry Valleys soi c04/2015 a163 - 1710 v273 a

The aim of the study was to determine if soil salt deliquescence and brine hydration can occur under laboratory conditions using natural McMurdo Dry Valleys soils. The experiment was a laboratory analogue for the formation of isolated patches of hypersaline, damp soil, referred to as ‘wet patches’. Soils were oven dried and then hydrated in one of two humidity chambers: one at 100% relative humidity and the second at 75% relative humidity. Soil hydration is highly variable, and over the course of 20 days of hydration, ranged from increases in water content by mass from 0–16% for 122 soil samples from Taylor Valley. The rate and absolute amount of soil hydration correlates well with the soluble salt content of the soils but not with grain size distribution. This suggests that the formation of bulk pore waters in these soils is a consequence of salt deliquescence and hydration of the brine from atmospheric water vapour.

1 aLevy, Joseph, S.1 aFountain, Andrew, G1 aLyons, Berry1 aWelch, Kathleen, A. uhttp://www.journals.cambridge.org/abstract_S095410201400047902358nas a2200229 4500008004100000022001400041245011300055210006900168260001200237490000600249520163400255100002801889700001901917700001901936700002401955700001601979700001701995700001902012700002002031700002102051856005602072 2015 eng d a2150-892500aFostering ecological data sharing: collaborations in the International Long Term Ecological Research Network0 aFostering ecological data sharing collaborations in the Internat c10/20150 v63 a

The International Long Term Ecological Research (ILTER) Network was established in 1993 and is now composed of thirty-eight national networks representing a diversity of ecosystems around the globe. Data generated by the ILTER Network are valuable for scientists addressing broad spatial and temporal scale research questions, but only if these data can be easily discovered, accessed, and understood. Challenges to publishing ILTER data have included unequal distribution among networks of information management expertise, user-friendly tools, and resources. Language and translation have also been issues. Despite these significant obstacles, ILTER information managers have formed grassroots partnerships and collaborated to provide information management training, adopt a common metadata standard, develop information management tools useful throughout the network, and organize scientist/information manager workshops that encourage scientists to share and integrate data. Throughout this article, we share lessons learned from the successes of these grassroots international partnerships to inform others who wish to collaborate internationally on projects that depend on data sharing entailing similar management challenges.
 

1 aVanderbilt, Kristin, L.1 aLin, Chau-Chin1 aLu, Sheng-Shan1 aKassim, Abd, Rahman1 aHe, Honglin1 aGuo, Xuebing1 aSan Gil, Inigo1 aBlankman, David1 aPorter, John, H. uhttp://www.esajournals.org/doi/10.1890/ES14-00281.100595nas a2200157 4500008004100000245013400041210006900175260001200244300000800256490000800264100002200272700002500294700002400319700002500343856006900368 2015 eng d00aThe genus Luticola D.G.Mann (Bacillariophyta) from the McMurdo Sound Region, Antarctica, with the description of four new species0 agenus Luticola DGMann Bacillariophyta from the McMurdo Sound Reg c10/2015 a1030 v2081 aKohler, Tyler, J.1 aKopalová, Kateřina1 aVan de Vijver, Bart1 aKociolek, J. Patrick uhttps://www.biotaxa.org/Phytotaxa/article/view/phytotaxa.208.2.100932nas a2200265 4500008004100000022001400041245013400055210006900189260001200258300001400270490000800284100002300292700002800315700001600343700002000359700002500379700002200404700002100426700001700447700002300464700002200487700002400509700001600533856011700549 2015 eng d a0029-854900aGlobal environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments0 aGlobal environmental change and the nature of aboveground net pr c04/2015 a935 - 9470 v1771 aSmith, Melinda, D.1 aLa Pierre, Kimberly, J.1 aCollins, SL1 aKnapp, Alan, K.1 aGross, Katherine, L.1 aBarrett, John, E.1 aFrey, Serita, D.1 aGough, Laura1 aMiller, Robert, J.1 aMorris, James, T.1 aRustad, Lindsey, E.1 aYarie, John uhttp://link.springer.com/10.1007/s00442-015-3230-9http://link.springer.com/content/pdf/10.1007/s00442-015-3230-903050nas a2200205 4500008004100000245007900041210006900120260004600189300000700235490000900242520242000251653001502671653001602686653001902702653001102721653001602732100002002748700002502768856005102793 2015 eng d00aThe impacts of thermokarst activity on a stream in the McMurdo Dry Valleys0 aimpacts of thermokarst activity on a stream in the McMurdo Dry V aBoulder, CObUniversity of Coloradoc2015 a700 vM.S.3 a

The McMurdo Dry Valleys (MDV) of Antarctica are a unique ice-free landscape that is host to vibrant ecosystems despite the harsh environment (<10 cm water equivalent/yr, -20°C mean air temperature). Aquatic ecosystems in the MDV are dependent on the ephemeral glacial runoff streams which feed the closed basin perennially ice covered lakes. The upland zones of the Dry Valleys have been shown to have some of the slowest ground surface change rates in the world. However, recent observations in the coastal valley transition zones suggest that this area may be nearing a threshold of rapid landscape change.

One of the recent observations that supports this idea is the discovery of extensive thermokarst degradation (permafrost thaw features) along the banks of Crescent Stream in Taylor Valley. In 2012, a large stretch of the West Branch of Crescent Stream was found to have significant thermokarst bank failures, while the adjacent East Branch was found to be unaffected. The thermokarst impacts within this setting are important to understand because of the disturbances that massive sediment loading can impose on downstream biological communities.

Annually repeated terrestrial LiDAR scans (3) were compared to determine the rates of ground surface change due to thermokarst degradation. It was found that the areal extent of the thermokarst was decreasing, however the average linear rates of retreat remained constant. Field measurements including, pebble counts, fine sediment counts, and sieve samples were analyzed to determine the effects of the thermokarst on the stream bed material. It was found that the West Branch and the reach downstream of the confluence were consistently finer than the unaffected East Branch. This suggests that the finer bed material is due to the thermokarst bank degradation. Stream power was calculated for multiple reaches to be used as a metric for the mobilization of the streambed material. It was found that both branches infrequently experience flows substantial enough to mobilize the bed material. Even the finer bed material of the impacted West Branch reach required flows that had a 5 % chance of exceedance for mobilization of the bed. These findings suggest the West Branch of Crescent Stream and the biota supported by this branch of the stream, continue to adjust to the sediment introduced from the thermokarst bank degradation.

10aAntarctica10aDry valleys10aearth sciences10astream10athermokarst1 aSudman, Zachary1 aGooseff, Michael, N. uhttps://search.proquest.com/docview/171758257300637nas a2200193 4500008004100000022001300041245008600054210006900140260001200209300001200221490000800233100002000241700002100261700002300282700002400305700002600329700002200355856006600377 2015 eng d a0304380000aLinking management to biodiversity in built ponds using metacommunity simulations0 aLinking management to biodiversity in built ponds using metacomm c01/2015 a36 - 450 v2961 aSokol, Eric, R.1 aBrown, Bryan, L.1 aCarey, Cayelan, C.1 aTornwall, Brett, M.1 aSwan, Christopher, M.1 aBarrett, John, E. uhttp://linkinghub.elsevier.com/retrieve/pii/S030438001400491802538nas a2200205 4500008004100000245010400041210006900145260001200214300001200226490000700238520189000245100002202135700002102157700001902178700001302197700001602210700001702226700002402243856006502267 2015 eng d00a Long-Term Hydrologic Control of Microbial Mat Abundance in McMurdo Dry Valley Streams, Antarctica.0 aLongTerm Hydrologic Control of Microbial Mat Abundance in McMurd c03/2015 a310-3270 v183 a

Given alterations in global hydrologic regime, we examine the role of hydrology in regulating stream microbial mat abundance in the McMurdo Dry Valleys, Antarctica. Here, perennial mats persist as a desiccated crust until revived by summer streamflow, which varies inter-annually, and has increased since the 1990s. We predicted high flows to scour mats, and intra-seasonal drying to slow growth. Responses were hypothesized to differ based on mat location within streams, along with geomorphology, which may promote (high coverage) or discourage (low coverage) accrual. We compared hydrologic trends with the biomass of green and orange mats, which grow in the channel, and black mats growing at stream margins for 16 diverse stream transects over two decades. We found mat biomass collectively decreased during first decade coinciding with low flows, and increased following elevated discharges. Green mat biomass showed the greatest correlations with hydrology and was stimulated by discharge in high coverage transects, but negatively correlated in low coverage due to habitat scour. In contrast, orange mat biomass was negatively related to flow in high coverage transects, but positively correlated in low coverage because of side-channel expansion. Black mats were weakly correlated with all hydrologic variables regardless of coverage. Lastly, model selection indicated the best combination of predictive hydrologic variables for biomass differed between mat types, but also high and low coverage transects. These results demonstrate the importance of geomorphology and species composition to modeling primary production, and will be useful in predicting ecological responses of benthic habitats to altered hydrologic regimes.

1 aKohler, Tyler, J.1 aStanish, Lee, F.1 aCrisp, Stenven1 aKoch, J.1 aLiptzin, D.1 aBaeseman, J.1 aMcKnight, Diane, M. uhttp://link.springer.com/article/10.1007%2Fs10021-014-9829-600801nas a2200253 4500008004100000022001400041245008400055210006900139260001200208300000800220490000700228100003400235700002400269700002200293700002600315700002500341700002400366700001700390700002200407700002300429700002600452700002200478856004700500 2015 eng d a1445-522600aMitochondrial DNA analyses reveal widespread tardigrade diversity in Antarctica0 aMitochondrial DNA analyses reveal widespread tardigrade diversit c12/2015 a5780 v291 aVelasco-Castrillon, Alejandro1 aMcInnes, Sandra, J.1 aSchultz, Mark, B.1 aArroniz-Crespo, Maria1 aD'Haese, Cyrille, A.1 aGibson, John, A. E.1 aAdams, Byron1 aPage, Timothy, J.1 aAustin, Andrew, D.1 aCooper, Steven, J. B.1 aStevens, Mark, I. uhttp://www.publish.csiro.au/?paper=IS1401902696nas a2200217 4500008004100000022001400041245013900055210006900194260001200263300000900275490000800284520194700292100002102239700002402260700001802284700002202302700002502324700001902349700003302368856007702401 2015 eng d a0962-845200aNiche and metabolic principles explain patterns of diversity and distribution: theory and a case study with soil bacterial communities0 aNiche and metabolic principles explain patterns of diversity and c05/2015 a26300 v2823 a

The causes of biodiversity patterns are controversial and elusive due to complex environmental variation, covarying changes in communities, and lack of baseline and null theories to differentiate straightforward causes from more complex mechanisms. To address these limitations, we developed general diversity theory integrating metabolic principles with niche-based community assembly. We evaluated this theory by investigating patterns in the diversity and distribution of soil bacteria taxa across four orders of magnitude variation in spatial scale on an Antarctic mountainside in low complexity, highly oligotrophic soils. Our theory predicts that lower temperatures should reduce taxon niche widths along environmental gradients due to decreasing growth rates, and the changing niche widths should lead to contrasting α- and β-diversity patterns. In accord with the predictions, α-diversity, niche widths and occupancies decreased while β-diversity increased with increasing elevation and decreasing temperature. The theory also successfully predicts a hump-shaped relationship between α-diversity and pH and a negative relationship between α-diversity and salinity. Thus, a few simple principles explained systematic microbial diversity variation along multiple gradients. Such general theory can be used to disentangle baseline effects from more complex effects of temperature and other variables on biodiversity patterns in a variety of ecosystems and organisms.

 

 

1 aOkie, Jordan, G.1 aVan Horn, David, J.1 aStorch, David1 aBarrett, John, E.1 aGooseff, Michael, N.1 aKopsova, Lenka1 aTakacs-Vesbach, Cristina, D. uhttp://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2014.263006572nas a2200169 4500008004100000245008400041210006900125520601300194100001906207700002406226700001506250700001906265700001706284700002106301700002406322856005606346 2015 eng d00aPatterns and processes of salt efflorescences in the McMurdo region, Antarctica0 aPatterns and processes of salt efflorescences in the McMurdo reg3 a

Evaporite salts are abundant around the McMurdo region, Antarctica (~78°S) due to very low precipitation, low relative humidity, and limited overland flow. Hygroscopic salts in the McMurdo Dry Valleys (MDVs) are preferentially formed in locations where liquid water is present in the austral summer, including along ephemeral streams, ice-covered lake boundaries, or shallow groundwater tracks. In this study, we collected salts from the Miers, Garwood, and Taylor Valleys on the Antarctic continent, as well as around McMurdo Station on Ross Island in close proximity to water sources with the goal of understanding salt geochemistry in relationship to the hydrology of the area. Halite is ubiquitous; sodium is the major cation (ranging from 70%–90% of cations by meq kg−1 sediment) and chloride is the major anion (>50%) in nearly all samples. However, a wide variety of salt phases and morphologies are tentatively identified through scanning electron microscopy (SEM) and X-ray diffraction (XRD) work. We present new data that identifies trona (Na3(CO3)(HCO3)·2H2O), tentative gaylussite (Na2Ca(CO3)2·5H2O), and tentative glauberite (Na2Ca(SO4)2) in the MDV, of which the later one has not been documented previously. Our work allows for the evaluation of processes that influence brine evolution on a local scale, consequently informing assumptions underlying large-scale processes (such as paleoclimate) in the MDV. Hydrological modeling conducted in FREZCHEM and PHREEQC suggests that a model based on aerosol deposition alone in low elevations on the valley floor inadequately characterizes salt distributions found on the surfaces of the soil because it does not account for other hydrologic inputs/outputs. Implications for the salt distributions include their use as tracers for paleolake levels, geochemical tracers of ephemeral water tracks or “wet patches” in the soil, indicators of chemical weathering products, and potential delineators of ecological communities.

1 aBisson, K., M.1 aWelch, Kathleen, A.1 aWelch, Sue1 aSheets, J., M.1 aLyons, Berry1 aLevy, Joseph, S.1 aFountain, Andrew, G uhttp://aaarjournal.org/doi/abs/10.1657/AAAR0014-02403401nas a2200241 4500008004100000245013400041210006900175260004000244300000800284490001000292520259800302653001002900653001502910653002402925653001902949653001602968653001902984653002403003653001903027100002203046700002403068856006703092 2015 eng d00aPhysical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica0 aPhysical and chemical controls on the abundance and composition  aBoulder, CObUniversity of Colorado a2720 vPh.D.3 a

 

The McMurdo Dry Valleys of Antarctica are a cold, dry desert, yet perennial microbial mats are abundant in the ephemeral glacial meltwater streams that flow during austral summers. Three types of mats are present (orange, black, and green), and are primarily comprised of filamentous cyanobacteria, Nostoc, and chlorophytes, respectively. Mat types furthermore occupy distinct habitats within streams, utilizing the benthos, hyporheic zone, and water column, which expose them to different environmental conditions. Due to a lack of lateral inflows, allochthonous organic inputs, and negligible grazing activity, these streams are ideal for the controlled ecological study of microbial mats. Here, I investigated how mats will respond to physical disturbance, alterations in the hydrologic regime, and nutrient liberation from permafrost melt in the future. Specifically, I: 1) quantified and characterized the regrowth of mat biomass, community structure, and elemental stoichiometry after a scouring disturbance, 2) investigated how geomorphology and taxonomic identity influences the response of mat biomass to hydrologic regime in transects monitored over two decades, and 3) evaluated relationships between water chemistry and the elemental and isotopic composition of mat types over longitudinal and valley-wide gradients in Taylor Valley. I found that mats recovered ~20-50% of their biomass over the course of an austral summer following scour. Algal communities were significantly different in composition between disturbed and control treatments, but all samples naturally varied in species and elemental stoichiometry over the study period. When the long- term record of mat biomass was compared with hydrologic variables, stream channel mats (orange and green) had the greatest correlations, while marginal mats (black) showed weaker relationships with flow regime. Relationships also differed as a function of stream geomorphology, indicating the importance of substrata and gradient in conjunction with discharge. Lastly, mats showed unique elemental and isotopic compositions. Green and orange mats within the stream channel most reflected water column nutrient concentrations, while black mats showed significant nitrogen fixation. These results highlight the importance of taxonomic identity and habitat to modeling primary production here and elsewhere, and provide insight to how stream microbial mat communities are formed, maintained, and ultimately persist in an isolated polar desert.

 

10aalgae10aAntarctica10abiological sciences10aclimate change10aDisturbance10aearth sciences10aMcMurdo Dry Valleys10amicrobial mats1 aKohler, Tyler, J.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/1690497718?accountid=1450302023nam a2200133 4500008004100000020002200041245004800063210004300111260002200154300000800176520161400184100002001798856007101818 2015 eng d a978-0-7456-7080-500aThe Polar Regions: An Environmental History0 aPolar Regions An Environmental History aCambridgebPolity a2483 a

The environmental histories of the Arctic and Antarctica are characterised by contrast and contradiction. These are places that have witnessed some of the worst environmental degradation in recent history. But they are also the locations of some of the most farsighted measures of environmental protection. They are places where people have sought to conquer nature through exploration and economic development, but in many ways they remain wild and untamed. They are the coldest places on Earth, yet have come to occupy an important role in the science and politics of global warming. 

Despite being located at opposite ends of the planet and being significantly different in many ways, Adrian Howkins argues that the environmental histories of the Arctic and Antarctica share much in common and have often been closely connected. This book also argues that the Polar Regions are strongly linked to the rest of the world, both through physical processes and through intellectual and political themes. As places of inherent contradiction, the Polar Regions have much to contribute to the way we think about environmental history and the environment more generally.

1 aHowkins, Adrian uhttp://www.wiley.com/WileyCDA/WileyTitle/productCd-0745670806.html00864nas a2200217 4500008004100000245020400041210006900245260001200314300001600326490000700342100002400349700001600373700002400389700002500413700001700438700001300455700001700468700002100485700002100506856011900527 2015 eng d00aPotential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams0 aPotential for realtime understanding of coupled hydrologic and b c08/2015 a6725 - 67380 v511 aMcKnight, Diane, M.1 aCozzetto, K1 aCullis, James, D.S.1 aGooseff, Michael, N.1 aJaros, Chris1 aKoch, J.1 aLyons, Berry1 aNeupauer, R., M.1 aWlostowski, Adam uhttp://doi.wiley.com/10.1002/2015WR017618http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2F2015WR01761802527nas a2200181 4500008004100000245016700041210006900208260001200277300001600289490000700305520184500312100002102157700002402178700002402202700002102226700001702247856008102264 2015 eng d00aPressure-driven, shoreline currents in a perennially ice-covered, pro-glacial lake in Antarctica, identified from a LiCl tracer injected into a pro-glacial stream0 aPressuredriven shoreline currents in a perennially icecovered pr c05-2015 a2212 - 22310 v293 a

The distribution of streamwater within ice-covered lakes influences sub-ice currents, biological activity and shoreline morphology. Perennially ice-covered lakes in the McMurdo Dry Valleys, Antarctica, provide an excellent natural laboratory to study hydrologic–limnologic interactions under ice cover. For a 2 h period on 17 December 2012, we injected a lithium chloride tracer into Andersen Creek, a pro-glacial stream flowing into Lake Hoare. Over 4 h, we collected 182 water samples from five stream sites and 15 ice boreholes. Geochemical data showed that interflow travelled West of the stream mouth along the shoreline and did not flow towards the lake interior. The chemistry of water from Andersen Creek was similar to the chemistry of water below shoreline ice. Additional evidence for Westward flow included the morphology of channels on the ice surface, the orientation of ripple marks in lake sediments at the stream mouth and equivalent temperatures between Andersen Creek and water below shoreline ice. Streamwater deflected to the right of the mouth of the stream, in the opposite direction predicted by the Coriolis force. Deflection of interflow was probably caused by the diurnal addition of glacial runoff and stream discharge to the Eastern edge of the lake, which created a strong pressure gradient sloping to the West. This flow directed stream momentum away from the lake interior, minimizing the impact of stream momentum on sub-ice currents. It also transported dissolved nutrients and suspended sediments to the shoreline region instead of the lake interior, potentially affecting biological productivity and bedform development.

1 aCastendyk, Devin1 aMcKnight, Diane, M.1 aWelch, Kathleen, A.1 aNiebuhr, Spencer1 aJaros, Chris uhttp://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.1035202661nas a2200145 4500008004100000245006100041210006000102260004000162300000800202490000700210520218500217100002202402700002402424856006702448 2015 eng d00aQuantifying long-term geomorphology of Antarctic streams0 aQuantifying longterm geomorphology of Antarctic streams aBoulder, CObUniversity of Colorado a1850 vMS3 a

 

In 1994, 16 stream transects were established in the McMurdo Dry Valleys of Antarctica beginning a long term data set characterizing microbial communities and channel geometry. The transects were established to record microbial mat dynamics and stream geomorphology. To accomplish this, the transects were surveyed for points of interest outside and inside the stream channel. Beginning in 2010 the microbial surveys received ground based LiDAR support. This allowed for greater resolution in mapping and analyzing stream morphology than traditional surveying methods. The purpose of this study was to overlap the traditional methods of surveying individual points of interest with a data cloud representing the entire stream transect to be able to continue the microbial study into the future unabated. Using surveyed microbial mats as an indicator of a location in time, a history of channel elevations was created for 7 transects. In general, the streams have not changed significantly in the 20 year record, with exceptions being the steep channel of Bohner Stream, and Huey Creek, which receives large sediment loads from the sharply incised upstream channel, both of which saw large variations in maximum bed change exceeding 75cm and 150 cm respectively. In addition to creating an elevation history, relative bed change was plotted against the ash free dry mass of the microbial mats sampled to determine the resilience of the mats. It was found that microbial mats are more abundant in areas of near zero change. The four microbial mats studied however, which include green, black, orange, and red mats, differed greatly in adaptability with regards to bed change. Green microbial mats, which are typically hidden under large immobile rocks, were not often found in areas with any significant bed change. Conversely, orange mats were found in the most dynamic parts of the stream bed with outliers seen in areas with change exceeding 50 cm with. Finally black microbial mats had the largest values of ash free dry mass indicating the largest resilience to the scouring effects of high flow.

 

1 aCrisp, Steven, W.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/1727444346?accountid=1450304908nas a2200193 4500008004100000022001300041245008800054210006900142260001600211300001200227490000700239520413400246100002304380700002204403700002004425700001804445700002104463856023004484 2015 eng d a0883292700aReconstructing the evolution of Lake Bonney, Antarctica using dissolved noble gases0 aReconstructing the evolution of Lake Bonney Antarctica using dis cJan-07-2015 a46 - 610 v583 a

Lake Bonney (LB), located in Taylor valley, Antarctica, is a perennially ice-covered lake with two lobes, West Lake Bonney (WLB) and East Lake Bonney (ELB), which are separated by a narrow ridge. Numerous studies have attempted to reconstruct the evolution of LB because of its sensitivity to climatic variations and the lack of reliable millennial-scale continental records of climate in this region of Antarctica. However, these studies are limited by the availability of accurate lacustrine chronologies. Here, we attempt to better constrain the chronology of LB and thus, the evolution of past regional climate by estimating water residence times based on He, Ne and Ar concentrations and isotopic ratios in both WLB and ELB.

3He and 4He excesses up to two and three orders of magnitude and 35–150 times the atmospheric values are observed for WLB and ELB samples, respectively. In comparison, while measured 40Ar/36Ar ratios are atmospheric (∼295.5) in ELB, WLB samples display 40Ar/36Ar ratios of up to ∼315 reflecting addition of radiogenic 40Ar. Both4He and 40Ar excesses clearly identify the addition of subglacial discharge (SGD) from underneath Taylor Glacier into WLB at depths of 25 m and 35 m. He isotopic ratios suggest that He excesses are predominantly crustal (>93%) in origin with small mantle contributions (<7%). These crustal 4He and 40Ar excesses are used together with basement rock production rates of these isotopes to derive first-order approximations of water residence times for both lobes. Numerous factors capable of affecting water residence times are evaluated and corrected 4He and 40Ar water ages are used to place further constrains into the reconstruction of both WLB and ELB history. Combined 4He and 40Ar ages in WLB suggest maximum water residence times of ∼250 kyrs BP. These results support the presence of remnant water from proglacial lakes that existed during Marine Isotope Stage 7 (160–240 kyrs) in WLB, in agreement with previous studies. In comparison, 4He ages in ELB are much younger (<27 kyrs BP) and display a complex evolutionary history that is very different from WLB. 4He ages also suggest that the ELB ice cover formed significantly earlier (∼1.5 kyrs BP) than previously reported. The timing of these hydrologic changes in ELB appears to correspond to regional and global climatic events that are recorded in both the Taylor Dome ice-core record as well as in other Dry Valley Lakes.

1 aWarrier, Rohit, B.1 aCastro, Clara, M.1 aHall, Chris, M.1 aKenig, Fabien1 aDoran, Peter, T. uhttp://linkinghub.elsevier.com/retrieve/pii/S088329271500044Xhttp://api.elsevier.com/content/article/PII:S088329271500044X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S088329271500044X?httpAccept=text/plain04273nas a2200193 4500008004100000022001400041245007400055210006900129260001600198300001400214490000700228520366500235100002203900700002103922700002503943700002203968700002403990856006504014 2015 eng d a0954-102000aRecovery of Antarctic stream epilithon from simulated scouring events0 aRecovery of Antarctic stream epilithon from simulated scouring e cJan-08-2015 a341 - 3540 v273 a

Microbial mats are common in polar streams and often dominate benthic biomass. Climate change may be enhancing the variability of stream flows in the Antarctic, but so far studies investigating mat responses to disturbance have been limited in this region. Mat regrowth was evaluated following disturbance by experimentally scouring rocks from an ephemeral McMurdo Dry Valley stream over two summers (2001–02 and 2012–13). Mats were sampled at the beginning and resampled at the end of the flow season. In 2012–13, mats were additionally resampled mid-season along with previously undisturbed controls. In 2001–02 rocks regained 47% of chlorophyll aand 40% of ash-free dry mass by the end of the summer, while in 2012–13 rocks regrew 18% and 27%, respectively. Mat stoichiometry differed between summers, and reflected differences in biomass and discharge. Oscillatoria spp. were greatest on scoured rocks and Phormidium spp. on undisturbed rocks. Small diatoms Humidophila andFistulifera spp. increased throughout the summer in all mats, with the latter more abundant in scoured communities. Collectively, these data suggest that mats are variable intra-annually, responsive to hydrology and require multiple summers to regrow initial biomass once lost. These results will aid the interpretation of long-term data, as well as inform Antarctic Specially Managed Area protocols.

1 aKohler, Tyler, J.1 aChatfield, Ethan1 aGooseff, Michael, N.1 aBarrett, John, E.1 aMcKnight, Diane, M. uhttp://www.journals.cambridge.org/abstract_S095410201500002404591nas a2201033 4500008004100000022001400041245009100055210006900146260001600215300001100231490000700242520199300249100002002242700002202262700001802284700001602302700002002318700001502338700001802353700001502371700001802386700001702404700001602421700001402437700001402451700001702465700001802482700002102500700001602521700001102537700001502548700002002563700001902583700001602602700001802618700001602636700001402652700001602666700001502682700001602697700001602713700001602729700001802745700001602763700001602779700001302795700001802808700001202826700001402838700001402852700001402866700001602880700001402896700001402910700002002924700001102944700001702955700001502972700002502987700001603012700001703028700001703045700001503062700001703077700001403094700001403108700001703122700001803139700001603157700002403173700002303197700001603220700001503236700001603251700001803267700001803285700001803303700001803321700001503339700001803354700002003372700001603392700001503408700001803423700001703441700001303458700002103471856006503492 2015 eng d a0954-102000aA roadmap for Antarctic and Southern Ocean science for the next two decades and beyond0 aroadmap for Antarctic and Southern Ocean science for the next tw cJan-02-2015 a3 - 180 v273 a

Antarctic and Southern Ocean science is vital to understanding natural variability, the processes that govern global change and the role of humans in the Earth and climate system. The potential for new knowledge to be gained from future Antarctic science is substantial. Therefore, the international Antarctic community came together to ‘scan the horizon’ to identify the highest priority scientific questions that researchers should aspire to answer in the next two decades and beyond. Wide consultation was a fundamental principle for the development of a collective, international view of the most important future directions in Antarctic science. From the many possibilities, the horizon scan identified 80 key scientific questions through structured debate, discussion, revision and voting. Questions were clustered into seven topics: i) Antarctic atmosphere and global connections, ii) Southern Ocean and sea ice in a warming world, iii) ice sheet and sea level, iv) the dynamic Earth, v) life on the precipice, vi) near-Earth space and beyond, and vii) human presence in Antarctica. Answering the questions identified by the horizon scan will require innovative experimental designs, novel applications of technology, invention of next-generation field and laboratory approaches, and expanded observing systems and networks. Unbiased, non-contaminating procedures will be required to retrieve the requisite air, biota, sediment, rock, ice and water samples. Sustained year-round access to Antarctica and the Southern Ocean will be essential to increase winter-time measurements. Improved models are needed that represent Antarctica and the Southern Ocean in the Earth System, and provide predictions at spatial and temporal resolutions useful for decision making. A co-ordinated portfolio of cross-disciplinary science, based on new models of international collaboration, will be essential as no scientist, programme or nation can realize these aspirations alone

1 aKennicutt, M.C.1 aChown, Steven, L.1 aCassano, J.J.1 aLiggett, D.1 aPeck, Lloyd, S.1 aMassom, R.1 aRintoul, S.R.1 aStorey, J.1 aVaughan, D.G.1 aWilson, T.J.1 aAllison, I.1 aAyton, J.1 aBadhe, R.1 aBaeseman, J.1 aBarrett, P.J.1 aBell, Elanor, R.1 aBertler, N.1 aBo, S.1 aBrandt, A.1 aBromwich, David1 aCary, Craig, S1 aClark, M.S.1 aConvey, Peter1 aCosta, E.S.1 aCowan, D.1 aDeconto, R.1 aDunbar, R.1 aElfring, C.1 aEscutia, C.1 aFrancis, J.1 aFricker, H.A.1 aFukuchi, M.1 aGilbert, N.1 aGutt, J.1 aHavermans, C.1 aHik, D.1 aHosie, G.1 aJones, C.1 aKim, Y.D.1 aLe Maho, Y.1 aLee, S.H.1 aLeppe, M.1 aLeitchenkov, G.1 aLi, X.1 aLipenkov, V.1 aLochte, K.1 aLópez-Martínez, J.1 aüdecke, C.1 aLyons, Berry1 aMarenssi, S.1 aMiller, H.1 aMorozova, P.1 aNaish, T.1 aNayak, S.1 aRavindra, R.1 aRetamales, J.1 aRicci, C.A.1 aRogan-Finnemore, M.1 aRopert-Coudert, Y.1 aSamah, A.A.1 aSanson, L.1 aScambos, T.1 aSchloss, I.R.1 aShiraishi, K.1 aSiegert, M.J.1 aSimões, J.C.1 aStorey, B.1 aSparrow, M.D.1 aWall, Diana, H.1 aWalsh, J.C.1 aWilson, G.1 aWinther, J.G.1 aXavier, J.C.1 aYang, H.1 aSutherland, W.J. uhttp://www.journals.cambridge.org/abstract_S095410201400067402038nas a2200181 4500008004100000022001400041245011000055210006900165260001200234300000900246490001400255520146300269100001801732700001501750700002201765700002101787856004801808 2015 eng d a1365-207900aSediment transport dynamics on an ice-covered lake: The “floating” boulders of Lake Hoare, Antarctica0 aSediment transport dynamics on an icecovered lake The floating b c04/2015 a1-120 vfirstview3 a

Between 1995 and 2011 a global positioning system survey of 13 boulders and three ablation stakes (long stakes frozen in the ice) on the frozen surface of Lake Hoare was undertaken. Data interpretation illustrates complexities of post-depositional transport dynamics of boulders. Earlier studies on comparable datasets have suggested linear ‘conveyor’ type transport mechanisms for lake surface boulders. Yet explanations for non-linear boulder displacements or ‘walks’ and the mechanisms responsible for movements are inadequate. Two modes of boulder specific movement were observed. First, localized changes in the ice surface promote individual boulder movement (rolling). Second, ice rafting, which indicates the displacement of ‘plates’ of lake ice on which the boulder is located. Ablation stakes used as fixed survey control points support the hypothesis that ice cover moves as discrete plates rather than as a single homogenous mass. Factors that create the conditions to generate either of the two modes of movement may be related to location specific energy budgets. A relationship between average orientations and prevailing wind direction was also observed. The investigation describes the local-scale behaviour of surveyed boulders, and offers methodologies and interpretive frameworks for additional studies of modern and ancient sediment transportation dynamics in Antarctic lacustrine environments.

1 aAllen, P., P.1 aHewitt, R.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttp://dx.doi.org/10.1017/S095410201400055800392nas a2200133 4500008004100000022001400041245003900055210003900094260001200133100002000145700002200165700001500187856005600202 2015 eng d a0028-083600aSoil biodiversity and human health0 aSoil biodiversity and human health c11/20151 aWall, Diana, H.1 aNielsen, Uffe, N.1 aSix, Johan uhttp://www.nature.com/doifinder/10.1038/nature1574401763nas a2200157 4500008004100000245010800041210006900149260001200218300001200230490000700242520123700249100002101486700002501507700002501532856004801557 2015 eng d00aSpatiotemporal Dynamics of Wetted Soils across a Polar Desert Landscape, McMurdo Dry Valleys Antarctica0 aSpatiotemporal Dynamics of Wetted Soils across a Polar Desert La c04/2015 a197-2090 v273 aLiquid water is scarce across the landscape of the McMurdo Dry Valleys (MDV), Antarctica, a 3800 km2 ice-free region, and is chiefly associated with soils that are adjacent to streams and lakes (i.e. wetted margins) during the annual thaw season. However, isolated wetted soils have been observed at locations distal from water bodies. The source of water for the isolated patches of wet soil is potentially generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table, and melting of buried segregation ice formed during winter freezing. High resolution remote sensing data gathered several times per summer in the MDV region were used to determine the spatial and temporal distribution of wet soils. The spatial consistency with which the wet soils occurred was assessed for the 2009–10 to 2011–12 summers. The remote sensing analyses reveal that cumulative area and number of wet soil patches varies among summers. The 2010–11 summer provided the most wetted soil area (10.21 km2) and 2009–10 covered the least (5.38 km2). These data suggest that wet soils are a significant component of the MDV cold desert land system and may become more prevalent as regional climate changes.1 aLangford, Z., L.1 aGooseff, Michael, N.1 aLampkin, Derrick, J. uhttp://dx.doi.org/10.1017/S095410201400060100545nas a2200133 4500008004100000245014400041210006900185260001200254300001200266490000700278100001800285700002000303856008800323 2015 eng d00aTipping the Iceberg: A Collaborative Approach to Redesigning the Undergraduate Research Assignment in an Antarctic History Capstone Seminar0 aTipping the Iceberg A Collaborative Approach to Redesigning the  c03/2015 a339-3700 v481 aHicks, Alison1 aHowkins, Adrian uhttp://scholar.colorado.edu/cgi/viewcontent.cgi?article=1034&context=libr_facpapers02755nas a2200169 4500008004100000020002200041245005500063210005300118260005100171300001200222520220300234100001902437700001802456700002202474700002002496856006902516 2014 eng d a978-3-642-45212-300aAntarctic Terrestrial Microbiology : Invertebrates0 aAntarctic Terrestrial Microbiology Invertebrates aBerlin, HeidelbergbSpringer Berlin Heidelberg a55 - 783 a

Terrestrial invertebrates are the largest permanent residents for much of the Antarctic continent with body lengths < 2 mm for most. The fauna consists of the arthropod taxa Collembola (springtails) and Acari (mites) as well as the microinvertebrates Nematoda, Tardigrada and Rotifera. Diversity in continental Antarctica is lower compared with warmer regions such as the Antarctic Peninsula and the subantarctic islands and several taxa such as the arthropods have considerably restricted distributions. The highest diversity of invertebrates is found along the Transantarctic Mountains of the Ross Sea Region and taxa are likely to be relicts from a warmer past that have survived in glacial refugia. Dispersal among the extremely fragmented Antarctic landscape is likely to be limited to transport via fresh- or salt-waters, particularly for the arthropod taxa, although long-distance wind dispersal is also possible for the microinvertebrates. Invertebrates possess several adaptations to low moisture levels and extreme cold temperatures in Antarctica. For example, nematodes and tardigrades avoid extreme dry and cold temperatures by entering a desiccation-resistant anhydrobiotic state. In contrast, arthropods do not have such a resistant state and freezing is lethal. Adaptations for the arthropod taxa include freeze avoidance and the production of intracellular, antifreeze proteins. Climate changes in Antarctica are likely to pose significant challenges for the invertebrate fauna. Changes in temperature, soil moisture and associated shifts in taxon distributions as well as the potential for non-indigenous species introductions are all likely to have considerable impacts on the Antarctic fauna. From a conservation perspective, there is a pressing need for terrestrial observation networks to record the present state of Antarctic terrestrial ecosystems as well as to monitor impending changes. Biosecurity measures which minimize species introductions or transfers of organisms within Antarctica will be essential.

1 aCowan, Don, A.1 aHogg, Ian, D.1 aStevens, Mark, I.1 aWall, Diana, H. uhttp://link.springer.com/content/pdf/10.1007/978-3-642-45213-0_402177nas a2200217 4500008004100000022001300041245014200054210006900196260001600265300001100281490000700292520131900299100002201618700002201640700002401662700002101686700002101707700003301728700002101761856017701782 2014 eng d a0025332400aAutonomous Year-Round Sampling and Sensing to Explore the Physical and Biological Habitability of Permanently Ice-Covered Antarctic Lakes0 aAutonomous YearRound Sampling and Sensing to Explore the Physica cJan-09-2014 a8 - 170 v483 a

The lakes of the McMurdo Dry Valleys, Antarctica, are some of the only systems on our planet that are perennially ice-covered and support year-round metabolism. As such, these ecosystems can provide important information on conditions and life in polar regions on Earth and on other icy worlds in our solar system. Working in these extreme environments of the Dry Valleys poses many challenges, particularly with respect to data collection during dark winter months when logistical constraints make fieldwork difficult. In this paper, we describe the motivation, design, and challenges for this recently deployed instrumentation in Lake Bonney, a lake that has been the subject of summer research efforts for more than 40 years. The instrumentation deployed includes autonomous water, phytoplankton, and sediment samplers as well as cable-mounted profiling platforms with dissolved gas and fluorometry sensors. Data obtained from these instruments will allow us, for the first time, to define the habitability of this environment during the polar night. We include lessons learned during deployment and recommendations for effective instrument operation in these extreme conditions.

1 aWinslow, Luke, A.1 aDugan, Hilary, A.1 aBuelow, Heather, N.1 aCronin, Kyle, D.1 aPriscu, John, C.1 aTakacs-Vesbach, Cristina, D.1 aDoran, Peter, T. uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0025-3324&volume=48&issue=5&spage=8http://www.ingentaconnect.com/content/mts/mtsj/2014/00000048/00000005/art0000201816nas a2200181 4500008004100000245008400041210006900125260001200194300001200206490000700218520117800225100002101403700002501424700003301449700002501482700002201507856010501529 2014 eng d00aBacterial community composition of divergent soil habitats from a polar desert.0 aBacterial community composition of divergent soil habitats from  c08/2014 a490-4940 v893 aEdaphic factors such as pH, organic matter, and salinity are often the most significant drivers of diversity patterns in soil bacterial communities. Desert ecosystems in particular are model locations for examining such relationships as food web complexity is low and the soil environment is biogeochemically heterogeneous. Here, we present the findings from a 16S rRNA gene sequencing approach used to observe the differences in diversity and community composition among three divergent soil habitats of the McMurdo Dry Valleys, Antarctica. Results show that alpha diversity is significantly lowered in high pH soils, which contain higher proportions of the phyla Acidobacteria and Actinobacteria, while mesic soils with higher soil organic carbon (and ammonium) content contain high proportions of Nitrospira, a nitrite-oxidizing bacteria. Taxonomic community resolution also had a significant impact on our conclusions, as pH was the primary predictor of phylum-level diversity, while moisture was the most significant predictor of diversity at the genus level. Predictive power also increased with increasing taxonomic resolution, suggesting a potential increase in nic1 aGeyer, Kevin, M.1 aAltrichter, Adam, E.1 aTakacs-Vesbach, Cristina, D.1 aGooseff, Michael, N.1 aBarrett, John, E. uhttps://mcm.lternet.edu/content/bacterial-community-composition-divergent-soil-habitats-polar-desert04850nas a2200217 4500008004100000022001300041245007600054210006900130260001200199300001400211490000800225520403500233100001704268700001704285700002204302700001904324700001404343700002404357700002104381856023004402 2014 eng d a0009254100aBoron isotopic geochemistry of the McMurdo Dry Valley lakes, Antarctica0 aBoron isotopic geochemistry of the McMurdo Dry Valley lakes Anta c10/2014 a152 - 1640 v3863 a

 

The geochemistry of boron was investigated in the ice-covered lakes and glacier meltwater streams within Taylor and Wright Valley of the McMurdo Dry Valleys (MCM), Antarctica, in order to achieve a greater understanding of the source of boron to these aquatic systems and how in-lake processes control boron concentration. Selected lake depths (surface and bottom water) and streams were analyzed for boron geochemistry. Boron stable isotope values in these waters span the range of + 12.3‰ to + 51.4‰, which corresponds to the variations from glacier meltwater streams to the hypolimnion of a highly evaporated hypersaline lake. The data demonstrate that the major sources of B to the aquatic system are via terrestrial chemical weathering of aluminosilicates within the stream channels, and a marine source, either currently being introduced by marine-derived aerosols or in the form of ancient seawater. Lakes Fryxell, Hoare, and upper waters of Lake Joyce, which experience more terrestrial influence of aluminosilicate chemical weathering via glacial meltwater streams, display a mixture of these two major sources, while the source of B in the bottom waters of Lake Joyce appears to be primarily of marine origin. Lakes Bonney and Vanda and the Blood Falls brine have a marine-like source whose δ11B values have become more positive by mineral precipitation and/or adsorption. Don Juan Pond displays a terrestrial aluminosilicate influence of a marine-like source. These hypersaline lake waters from Antarctica are similar in δ11B to other hypersaline lake waters globally, suggesting that similar processes control their B geochemistry.

 

 

1 aLeslie, D.L.1 aLyons, Berry1 aWarner, Nathaniel1 aVengosh, Avner1 aOlesik, J1 aWelch, Kathleen, A.1 aDeuerling, Kelly uhttp://linkinghub.elsevier.com/retrieve/pii/S000925411400391Xhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S000925411400391X?httpAccept=text/plain02223nas a2200205 4500008004100000245012900041210006900170260001200239300001200251490000700263520146400270100001701734700002401751700002401775700002501799700002201824700003301846700001501879856012301894 2014 eng d00aCharacterization of Growing Bacterial Populations in McMurdo Dry Valley Soils through Stable Isotope Probing with 18O-water.0 aCharacterization of Growing Bacterial Populations in McMurdo Dry c08/2014 a415-4250 v893 aSoil microbial communities of the McMurdo Dry Valleys, Antarctica (MDV) contain representatives from at least fourteen bacterial phyla. However, given low rates of microbial activity, it is unclear whether this richness represents functioning rather than dormant members of the community. We used stable isotope probing (SIP) with (18) O-water to determine if microbial populations grow in MDV soils. Changes in the microbial community were characterized in soils amended with H2 (18) O and H2 (18) O-organic matter. Sequencing the 16S rRNA genes of the heavy and light fractions of the bacterial community DNA shows that DNA of microbial populations was labeled with (18) O-water, indicating these micro-organisms grew in the MDV soils. Significant differences existed in the community composition of the heavy and light fractions of the H2 (18) O and H2 (18) O-organic matter amended samples (Anosim P < 0.05 of weighted Unifrac distance). Control samples and the light DNA fraction of the H2 (18) O amended samples were dominated by representatives of the phyla Deinococcus-Thermus, Proteobacteria, Planctomyces, Gemmatimonadetes, Actinobacteria and Acidobacteria, whereas Proteobacteria were more prevalent in the heavy DNA fractions from the H2 (18) O-water and the H2 (18) O-water-organic matter treatments. Our results indicate that SIP with H2 (18) O can be used to distinguish active bacterial populations even in this low organic matter environment.1 aSchwartz, E.1 aVan Horn, David, J.1 aBuelow, Heather, N.1 aGooseff, Michael, N.1 aBarrett, John, E.1 aTakacs-Vesbach, Cristina, D.1 aOkie, J.G. uhttps://mcm.lternet.edu/content/characterization-growing-bacterial-populations-mcmurdo-dry-valley-soils-through-stable02282nas a2200181 4500008004100000245010600041210006900147260001200216300001200228490000800240520160500248100001301853700002801866700002901894700002101923700003001944856012601974 2014 eng d00aCiliate diversity, community structure and novel taxa in lakes of the McMurdo Dry Valleys, Antarctica0 aCiliate diversity community structure and novel taxa in lakes of c10/2014 a175-1900 v2273 aWe report an in-depth survey of next-generation DNA sequencing of ciliate diversity and community structure in two permanently ice-covered McMurdo Dry Valley lakes during the austral summer and autumn (November 2007 and March 2008). We tested hypotheses on the relationship between species richness and environmental conditions including environmental extremes, nutrient status, and day length. On the basis of the unique environment that exists in these high-latitude lakes, we expected that novel taxa would be present. Alpha diversity analyses showed that extreme conditions-that is, high salinity, low oxygen, and extreme changes in day length-did not impact ciliate richness; however, ciliate richness was 30% higher in samples with higher dissolved organic matter. Beta diversity analyses revealed that ciliate communities clustered by dissolved oxygen, depth, and salinity, but not by season (i.e., day length). The permutational analysis of variance test indicated that depth, dissolved oxygen, and salinity had significant influences on the ciliate community for the abundance matrices of resampled data, while lake and season were not significant. This result suggests that the vertical trends in dissolved oxygen concentration and salinity may play a critical role in structuring ciliate communities. A PCR-based strategy capitalizing on divergent eukaryotic V9 hypervariable region ribosomal RNA gene targets unveiled two new genera in these lakes. A novel taxon belonging to an unknown class most closely related to Cryptocaryon irritans was also inferred from separate gene phylogenies.1 aYuan, Xu1 aVick-Majors, Trista, J.1 aMorgan-Kiss, Rachael, M.1 aPriscu, John, C.1 aAmaral-Zettler, Linda, A. uhttps://mcm.lternet.edu/content/ciliate-diversity-community-structure-and-novel-taxa-lakes-mcmurdo-dry-valleys-antarctica02195nas a2200157 4500008004100000245014100041210006900182260001200251300001000263490000700273520155900280100002401839700002101863700002401884856012901908 2014 eng d00aDiel flow pulses drive particulate organic matter transport from microbial mats in a glacial meltwater stream in the McMurdo Dry Valleys0 aDiel flow pulses drive particulate organic matter transport from c01/2014 a86-970 v503 a Many glacial meltwater streams in the McMurdo Dry Valleys (MDV) of Antarctica contain abundant microbial mats, representing hot spots of primary production in a barren landscape. These mats persist through the winter in a freeze-dried state and grow in the summer, experiencing a dynamic hydrologic regime as streamflow varies on a diel cycle and with weather conditions. During diel peaks in flow these streams transport particulate organic matter (POM) to the downstream closed-basin lakes. We investigated the spatial and temporal dynamics of POM transport derived from the scouring of microbial mats in Von Guerard Stream of the MDV. The results show clockwise hysteresis effects in POM concentration over diel flood pulses and suggests that POM transport in the MDVs is supply limited. Further studies are required to confirm this and to identify the potential contributing sources of POM. The hysteresis effect was modeled using an approach derived from models of sediment transport in streams. Spatial variations in POM transport indicate that patch-scale variations in bed shear stress and benthic biomass also influence transport which is integrated downstream over several 100's of meters. Large variations in the POM transport dynamics between different diel flood pulses were found to be related to the time since a resetting flood event and the regrowth of potentially mobile benthic biomass, providing further evidence of the importance of supply limitation and flow variability in controlling the organic matter flux of stream ecosystems.1 aCullis, James, D.S.1 aStanish, Lee, F.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/diel-flow-pulses-drive-particulate-organic-matter-transport-microbial-mats-glacial-meltwater00571nas a2200181 4500008004100000022001400041245008700055210006900142260001200211300001200223490000800235100001700243700002000260700002300280700001600303700001800319856005200337 2014 eng d a1313-298900aEcological Biogeography of the Terrestrial Nematodes of Victoria Land, Antarctica0 aEcological Biogeography of the Terrestrial Nematodes of Victoria c06/2015 a29 - 710 v4191 aAdams, Byron1 aWall, Diana, H.1 aVirginia, Ross, A.1 aBroos, Emma1 aKnox, Matthew uhttp://zookeys.pensoft.net/articles.php?id=389900505nas a2200133 4500008004100000245012800041210006900169260001200238300001200250490000700262100001600269700002300285856006300308 2014 eng d00aThe ecological role of moss in a polar desert: implications for aboveground- belowground and terrestrial -aquatic linkages.0 aecological role of moss in a polar desert implications for above c04/2014 a651-6640 v371 aBall, Becky1 aVirginia, Ross, A. uhttp://link.springer.com/article/10.1007/s00300-014-1465-202372nas a2200193 4500008004100000245011200041210006900153260004000222490000900262520168100271653002401952653002301976653003801999653002402037653001002061100001602071700002402087856006702111 2014 eng d00aEcology and biogeography of freshwater diatoms in ponds of McMurdo Dry Valleys and parts of the Ross Island0 aEcology and biogeography of freshwater diatoms in ponds of McMur aBoulder, CObUniversity of Colorado0 vM.S.3 a

 

The McMurdo Dry Valleys (MDVs) and the exposed coastal areas of the nearby Ross Island in Antarctica represent some of the coldest, driest places in the world. However, during the austral summer warmer temperatures and constant sunlight allow microbial life to flourish nearly anywhere there is water. Diatoms are single-celled algae encapsulated in a silica shell and diatom communities constitute an important component of the microbial mats that grow in the streams, lakes and ponds in these regions. As part of the Long Term Ecological Research station in the McMurdo Dry Valleys diatom communities have been studied extensively in the streams over the last 20 years. Although the diatoms present in pond microbial mats at Cape Royds have been previously studied, modern-day knowledge of the characteristics of diatom communities in ponds and small lakes throughout the region is limited. This work sought to find the relationships between water chemistry and diatom community structure in ponds. Because water flow is not a factor in ponds and small lakes, influences of salinity, nutrients, pH and other factors can be more easily distinguished. This study looked at 24 separate bodies of water in the Taylor Valley, Labyrinth region in Wright Valley, Cape Royds and McMurdo Station area on Ross Island. The results suggest that geography, dispersal and historical environmental conditions play a significant role in structuring diatom communities, in addition to water chemistry. The results also expand the knowledge of habitat preferences for some of the species present in this region.

 

10abiological sciences10afreshwater diatoms10ahealth and environmental sciences10aMcMurdo Dry Valleys10aponds1 aSakaeva, A.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/1655818365?accountid=1450302515nas a2200169 4500008004100000022001400041245016900055210006900224260001600293300001400309490000700323520188900330100002102219700002302240700001702263856006502280 2014 eng d a0954-102000aThe effects of high meltwater on the limnology of Lake Fryxell and Lake Hoare, Taylor Valley, Antarctica, as shown by dissolved gas, tritium and chlorofluorocarbons0 aeffects of high meltwater on the limnology of Lake Fryxell and L cJan-08-2014 a331 - 3400 v263 a

Small changes in the availability of liquid water can have profound effects on the water levels, aqueous chemistry and biogeochemical dynamics of the closed-basin, perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica. We have compiled the published and unpublished data on dissolved gas, tritium and chlorofluorocarbons (CFCs) for Lake Fryxell and Lake Hoare to determine the effects of a high meltwater year (2001–02 summer) on the lakes. The dissolved gas, tritium and CFC data indicate that the pulse of freshwater that flowed onto the surfaces of the lakes did not mix extensively with the upper water column. At the bottom of Lake Hoare, the measurable CFC and lower dissolved gas values suggest that the recent meltwater may have mixed with bottom waters. The probable mechanism for this transportation is weak density currents with c. 0.1–1.5% surface water being transported downwards in Lake Hoare. This deep water input, while not constant, may have a significant effect on the chemistry of the bottom waters in Lake Hoare over time. In Lake Fryxell, the tritium and CFC data indicate that the recent meltwater did not significantly affect the bottom water chemistry; therefore, weak density currents may not be present in Lake Fryxell.

1 aDowling, Carolyn1 aPoreda, Robert, J.1 aLyons, Berry uhttp://www.journals.cambridge.org/abstract_S095410201300062X03450nas a2200169 4500008004100000245009600041210006900137260004500206300000800251490001800259520283100277100003003108700001703138700002003155700001803175856008703193 2014 eng d00aElemental Cycling in a Flow-Through Lake in the McMurdo Dry Valleys, Antarctica: Lake Miers0 aElemental Cycling in a FlowThrough Lake in the McMurdo Dry Valle aColumbusbOhio State Universityc06/2014 a1220 vMaster Thesis3 a

The ice-free area in Antarctica known as the McMurdo Dry Valleys has been monitored biologically, meteorologically, hydrologically, and geochemically continuously since the onset of the MCM-LTER in 1993. This area contains a functioning ecosystem living in an extremely delicate environment. Only a few degrees of difference in air temperature can effect on the hydrologic system, making it a prime area to study ongoing climate change. The unique hydrology of Lake Miers, i.e. its flowthrough nature, makes it an ideal candidate to study the mass balance of a McMurdo Dry Valley lake because both input and output concentrations can be analyzed. This study seeks to understand the physical and geochemical hydrology of Lake Miers relative to other MCMDV lakes. Samples were collected from the two inflowing streams, the outflowing stream, and the lake itself at 11 depths to analyze a suite of major cations (Li+ , Na+ , K+ , Mg+ , Ca2+), major anions (Cl- , Br- , F- , SO4 2- , ΣCO2), nutrients (NO2 - , NO3 - , NH4 + , PO4 3- , Si), trace elements (Mo, Rb, Sr, Ba, U, V, Cu, As), water isotopes (δD, δ 18O), and dissolved organic carbon (DOC). The lake acts as a sink for all constituents analyzed, but by amounts varying from ~10% (DOC, NH4 + , and NO2 - ) to PO4 3- at nearly 100%, indicating this lake may be P-limited. Cl- , a typically conservative element, was only 79% retained, which could be due to the late season sample collection, hyperheic zone influences, or other factors. The hyperheic zone’s role in lake and stream iii geochemistry was analyzed with a 24-hour sampling event. The positive relationships between stream flow and solute concentrations indicate that the delta in Miers Valley plays a role in controlling stream geochemistry and future work could help to explain this relationship. Lake depth profiles of trace elements U, V, Cu, and As decrease relative to Cl in the deepest part of the lake, while non-reducing trace elements show increases with depth. SO4 2- and dissolved O2 lake depth profiles decrease from 53 μM and 22.3 mg/L to 18 μM and 1.8 mg/L, respectively, at depth, indicating that the lake bottom is under reducing and near anoxic conditions. Lake depth profiles show that, while the “biological pump” may be a factor controlling lake chemistry, it is masked by the stronger signal of diffusion from the lake bottom sediments and requires future work to understand fully. The “age” of Lake Miers was calculated with a diffusion model to be 84 years, which agrees with other estimates of 100-300 years. The diffusion of solutes from the lake bottom and the redox conditions at depth are two major processes controlling the geochemistry of Lake Miers, and future work can help determine their extent and relationship with other processes.

1 aFair, Alexandria, Corinne1 aLyons, Berry1 aCarey, Anne, E.1 aChin, Yu-Ping uhttps://etd.ohiolink.edu/!etd.send_file?accession=osu1413291502&disposition=inline04232nas a2200193 4500008004100000245010200041210006900143260003400212490001000246520358400256653002003840653001703860653002403877653002203901653003403923100002103957700002203978856003804000 2014 eng d00aEnvironmental Controls Over the Distribution and Function of Antarctic Soil Bacterial Communities0 aEnvironmental Controls Over the Distribution and Function of Ant aBlacksburg, VAbVirginia Tech0 vPh.D.3 a

Microbial community composition plays a vital role in soil biogeochemical cycling. Information that explains the biogeography of microorganisms is consequently necessary for predicting the timing and magnitude of important ecosystem services mediated by soil biota, such as decomposition and nutrient cycling. Theory developed to explain patterns in plant and animal distributions such as the prevalent relationship between ecosystem productivity and diversity may be successfully extended to microbial systems and accelerate an emerging ecological understanding of the "unseen majority." These considerations suggest a need to define the important mechanisms which affect microbial biogeography as well as the sensitivity of community structure/function to changing climatic or environmental conditions. To this end, my dissertation covers three data chapters in which I have 1) examined patterns in bacterial biogeography using gradients of environmental severity and productivity to identify changes in community diversity (e.g. taxonomic richness) and structure (e.g. similarity); 2) detected potential bacterial ecotypes associated with distinct soil habitats such as those of high alkalinity or electrical conductivity and; 3) measured environmental controls over the function (e.g. primary production, exoenzyme activity) of soil organisms in an environment of severe environmental limitations. Sampling was performed in the polar desert of Antarctica's McMurdo Dry Valleys, a model ecosystem which hosts microbially-dominated soil foodwebs and displays heterogeneously distributed soil properties across the landscape. Results for Chapter 2 indicate differential effects of resource availability and geochemical severity on bacterial communities, with a significant productivity-diversity relationship that plateaus near the highest observed concentrations of the limiting resource organic carbon (0.30mg C/g soil). Geochemical severity (e.g. pH, electrical conductivity) primarily affected bacterial community similarity and successfully explained the divergent structure of a subset of samples. 16S rRNA amplicon pyrosequencing further revealed in Chapter 3 the identity of specific phyla that preferentially exist within certain habitats (i.e. Acidobacteria in alkaline soils, Nitrospira in mesic soils) suggesting the presence of niche specialists and spatial heterogeneity of taxa-specific functions (i.e. nitrite oxidation). Additionally, environmental parameters had different explanatory power towards predicting bacterial richness at varying taxonomic scales, from 57% of phylum-level richness with pH to 91% of order- and genus-level richness with moisture. Finally, Chapter 4 details a simultaneous sampling of soil communities and their associated ecosystem functions (primary productivity, enzymatic decomposition) and indicates that the overall organic substrate diversity may be greater in mesic soils where bacterial diversity is also highest, thus a potentially unforeseen driver of community dynamics. I also quantified annual rates of soil production which range between 0.7 - 18.1g C/m2/yr from the more arid to productive soils, respectively. In conclusion, the extension of biogeographical theory for macroorganisms has proven successful and both environmental severity and resource availability have obvious (although different) effects on the diversity and composition of soil microbial communities.

 

10abiogeochemistry10abiogeography10aMcMurdo Dry Valleys10amicrobial ecology10aproductivity/diversity theory1 aGeyer, Kevin, M.1 aBarrett, John, E. uhttp://hdl.handle.net/10919/6441703186nas a2200181 4500008004100000245010400041210006900145260003900214490001000253520255800263653002002821653001602841653002202857653001202879100002102891700002902912856006302941 2014 eng d00aEnvironmental impacts on RubisCO from green algal laboratory isolates to Antarctic lake communities0 aEnvironmental impacts on RubisCO from green algal laboratory iso aOxford, OHbMiami Universityc20140 vPh.D.3 a

Ribulose-1,5-bisphosphate carboxylase oxygenase (RubisCO) is found in a variety of autotrophic microorganisms ranging from green algae, cyanobacteria, and chemoautotrophic bacteria. As this enzyme has the potential to catalyze carboxylation (carbon fixation) or oxygenation (photorespiration) reactions, it is regulated in response to environmental variables at the levels of transcription, translation, and post-translation by the enzyme, RubisCO activase. A combination of laboratory experiments on green algal isolates and field experiments were utilized to gain insight on carbon fixation in permanently ice-covered Antarctic lakes. RubisCO was investigated as a potential target for cold adaptation of carbon fixation in the psychrophilic green alga, Chlamydomonas raudensis UWO241 (UWO241), isolated from Lake Bonney, Antarctica. RubisCO activity, stability, and whole cell carbon fixation were measured for the psychrophile and compared to a closely related mesophilic alga, C. raudensis SAG49.72 (SAG49.72). The effect of environmental factors including light and temperature on UWO241 and SAG49.72 RubisCO activation state, an indirect measurement of RubisCO activase activity, and abundance was investigated using a modified RubisCO carboxylase assay and immunoblotting, respectively. Lastly, maximum potential RubisCO carboxylase activity was determined using a modified activity assay in multiple ice covered Antarctic lakes including Lake Bonney. This data was complemented with lake depth profiles of enzyme abundance determined by quantitative real-time PCR and RubisCO-harboring organism diversity. While purified RubisCO of the psychrophilic green alga did not function optimally at low temperature, whole cell carbon fixation was greater under such conditions, suggesting that the overall process of carbon fixation is modified to function in UWO241. Increased RubisCO abundance at low temperature may contribute to this phenomenon. Low light levels may be important in regulation of RubisCO via RubisCO activase and should be further investigated. Based on community level RubsiCO activity and enzyme abundance, light and RubisCO harboring organisms including eukaryotic algae and cyanobacteria were positively correlated, but this was variable between lakes. Dark carbon fixation was potentially important in lakes west lobe Bonney and Fryxell and this community was negatively correlated with light. Results of targeted physiology and community level experiments led to development of a carbon fixation model for Lake Bonney.

10acarbon fixation10agreen algae10aice-covered lakes10aRubisCO1 aDolhi, Jenna, M.1 aMorgan-Kiss, Rachael, M. uhttp://rave.ohiolink.edu/etdc/view?acc_num=miami140705678302341nas a2200157 4500008004100000245017500041210006900216260001200285300001200297490000700309520168800316100001502004700001402019700002102033856012902054 2014 eng d00aEstimating photosynthetic activity in microbial mats in an ice-covered Antarctic lake using automated oxygen microelectode profiling and variable chlorophyll fluorescence0 aEstimating photosynthetic activity in microbial mats in an iceco c08/2014 a674-6880 v593 a An automated oxygen microprofiler measured a positive flux of oxygen from microbial mats in ice-covered Lake Hoare, Antarctica, from noon, at a photon flux of 20 µmol m−2 s−1, through to midnight (< 2 µmol photons m−2 s−1). Daily average oxygen flux was 200 µmol m−2 h−1; and, whereas it was maximal at noon, when a 10 mm broad concentration peak was observed 5 mm below the mat surface, flux correlated only weakly with irradiance. In contrast, relative electron transfer rate, estimated from variable chlorophyll fluorescence, suggested a linear relationship between photosystem activity and irradiance. This contradiction arose because of the conjunction of photosynthetic production of oxygen deep into these transparent, gelatinous mats (diel oxygen change was observed to 17 mm depth) and oxygen diffusion rates too slow to allow equilibration of oxygen concentration profiles with instantaneous production and consumption of oxygen. To confirm this, we developed a mathematical simulation of oxygen dynamics that included diffusion, photosynthesis, and respiration. The simulation further indicated that (1) net oxygen evolution is light limited is and confined to the upper few millimeters of the mat, (2) below 5–7 mm, respiration balanced photosynthesis, (3) below 17 mm, respiration and photosynthesis approached zero, even though organic carbon and dissolved oxygen were present, and (4) photosynthesis deep into the mat was dependent on high light transmission through the gelatinous matrix. These conclusions are consistent with current understanding of mat growth dynamics and point to approaches for long-term analysis of microbial mat productivity.1 aHawes, Ian1 aGiles, H.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/estimating-photosynthetic-activity-microbial-mats-ice-covered-antarctic-lake-using-automated01873nas a2200241 4500008004100000022001400041245005200055210005100107260001200158300001400170490000700184520122300191100001401414700001501428700002001443700002101463700001501484700001401499700001601513700002001529700001501549856006701564 2014 eng d a1084-545300aForum: Climate Change and Environmental History0 aForum Climate Change and Environmental History c04/2014 a281 - 3640 v193 a

This Forum explores global climate change, one of this century's most prominent environmental issues. Authors answer two critical questions: (1) How does the study of climate history enrich the field of environmental history more broadly? (2) How can environmental historians contribute to present-day understandings of and responses to global climate change? This introductory essay (and the Forum more generally) contribute to both environmental history research and climate change discussions by grappling with several key issues including the agency of nonhuman nature and environmental determinism, environmental governance, climate as a cultural construction, the history of environmental ideas and discourse, environmental narratives, the commodification of nature, and the politicization of the natural and life sciences. This essay also shows how the study of climate history provides methodological and practical tools for environmental historians. It analyzes the role of interdisciplinary sources and archives, scale, the place of science in environmental history scholarship, and the relevance of environmental histories for present-day policymaking and public discussions about climate change.

1 aCarey, M.1 aGarone, P.1 aHowkins, Adrian1 aEndfield, G., H.1 aCulver, L.1 aWhite, S.1 aJohnson, S.1 aFleming, J., R.1 aGarone, P. uhttp://envhis.oxfordjournals.org/cgi/doi/10.1093/envhis/emu00402215nas a2200205 4500008004100000245009200041210006900133260004000202490001000242520158200252653001501834653001001849653001301859653002401872653001601896653001601912100002201928700002101950856003801971 2014 eng d00aGeophysics, Water Balance, and History of Thick Perennial Ice Covers on Antarctic Lakes0 aGeophysics Water Balance and History of Thick Perennial Ice Cove aChicago, ILbUniversity of Illinois0 vPh.D.3 a

Antarctic lakes are studied as sentinels of future change, for paleolimnological records contained in the sediments, and as habitats for the simple food webs that can exist in inhospitable environments. Understanding how lakes are formed and are sustained in response to landscape and climate conditions is critical in addressing the aforementioned research themes. This thesis is governed by the overarching hypothesis that an understanding of hydrologic and sediment transport processes associated with lake ice formation and preservation can be used to reveal past climatic changes, and further our awareness of current changes in climate and water balance in the McMurdo Dry Valleys of Antarctica. The first chapter focuses on water loss from closed basin lakes in Taylor Valley, Antarctica, and presents updated estimates of sublimation and ablation rates from long-term empirical measurements. The second and third chapters address the formation of Lake Vida, Antarctica. The former investigates the accretion of a 27 m ice cover, and considers the origin of thick sediment layers in the ice cover, and the latter uses two geophysical methods to quantify the extent and volume of the brine network in the subsurface beneath the lake. The results presented herein advance the study of hydrogeology in continuous permafrost, provide additional evidence for fluctuating climate states in the McMurdo Dry Valleys throughout the mid to late Holocene, and provide a case study for the preservation of water in a cold, desert environment analogous to neighboring planets.

10aAntarctica10abrine10alake ice10aMcMurdo Dry Valleys10apolar lakes10asublimation1 aDugan, Hilary, A.1 aDoran, Peter, T. uhttp://hdl.handle.net/10027/1940700633nas a2200193 4500008004100000245011600041210006900157260001200226300001400238490000700252100002200259700001800281700002000299700001400319700002600333700001600359700002100375856004300396 2014 eng d00aGlobal-scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties0 aGlobalscale patterns of assemblage structure of soil nematodes i c01/2014 a968 - 9780 v231 aNielsen, Uffe, N.1 aAyres, Edward1 aWall, Diana, H.1 aLi, Grace1 aBardgett, Richard, D.1 aWu, Tiehang1 aGarey, James, R. uhttp://doi.wiley.com/10.1111/geb.1217702874nas a2200133 4500008004100000245008500041210006900126260004000195490001000235520241400245100002202659700002102681856003802702 2014 eng d00aHydrological and Biogeochemical Modeling of Taylor Valley Lakes, East Antarctica0 aHydrological and Biogeochemical Modeling of Taylor Valley Lakes  aChicago, ILbUniversity of Illinois0 vPh.D.3 a

Taylor Valley, McMurdo Dry Valleys, East Antarctica contains three perennially ice-covered lakes located in closed basins. The lakes respond to climatic changes on seasonal and decadal scales due to their existence on a very narrow climatic spectrum. The climate has to be sufficiently warm during the austral summer to induce glacial melt yet cold enough to maintain the ice covers year round. This thesis is focused on better understanding and constraining the sensitivity of past and present lakes to changes in climatic forcings. Melt water generation for large proglacial lakes, that existed during the Last Glacial Maximum, is attributed to strong westerly winds that increase surface air temperature above freezing, prolonging the melt season. The high frequency of westerly winds during the Last Glacial Maximum, based on the ice core record from Taylor Dome, is responsible for generation of enough glacial melt to sustain large proglacial lakes during this time period, suggesting that summer surface air temperatures were as warm as present day. Contemporary lakes are much smaller, however, the effect of strong westerly winds on modern lakes is equally profound. Strong winds are responsible for aeolian sediment deposition on the surface of the ice covers. The deposited sediment, on the other hand, absorbs more solar radiation and preferentially decreases the ice thickness around it. The localized ice thinning allows a greater amount of light penetration into the water column, which is negatively correlated with chlorophyll-a concentration. This negative correlation does not indicate changes in biomass; rather, it is a result of the short-term photo-adaptation of phytoplankton to the light intensity by increasing/decreasing light harvesting antenna size. The ice thicknesses in Taylor Valley lakes have been fluctuating since the first measurements were obtained. A one-dimensional physics-based ice thickness model was developed capable of reproducing 16 years of ice thickness trends for two different lakes. The model is based on surface radiative fluxes while considering heat fluxes from the water column. Deep lakes with well-developed temperature maximum can facilitate or hinder ice thickness growth/decay due to the heat flux from the underlying water column. This finding suggests that not all perennially ice-covered lakes can be used as a proxy for climatic changes.

1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttp://hdl.handle.net/10027/1890901695nas a2200181 4500008004100000022001400041245013500055210006900190260001200259300001400271490000700285520107500292100002101367700001601388700002401404700002001428856006501448 2014 eng d a0954-102000aHyperspectral measurements of wet, dry and saline soils from the McMurdo Dry Valleys: soil moisture properties from remote sensing0 aHyperspectral measurements of wet dry and saline soils from the  c10/2014 a565 - 5720 v263 a

Soil moisture is a spatially heterogeneous quantity in the McMurdo Dry Valleys of Antarctica that exerts a large influence on the biological community and on the thermal state of Dry Valleys permafrost. The goal of this project was to determine whether hyperspectral remote sensing techniques could be used to determine soil moisture conditions in the Dry Valleys. We measured the spectral reflectance factors of wetted soil samples from the Dry Valleys under natural light conditions and related diagnostic spectral features to surface layer soil moisture content. Diagnostic water absorption features in the spectra at 1.4 µm and 1.9 µm were present in all samples, including samples doped with high concentrations of chloride salts. The depth of the 1.4 µm absorption is shown to increase linearly with increasing gravimetric water content. These results suggest that airborne hyperspectral imaging of the Dry Valleys could generate soil moisture maps of this environment over large spatial areas using non-invasive remote-sensing techniques.

1 aLevy, Joseph, S.1 aNolin, Anne1 aFountain, Andrew, G1 aHead, James, W. uhttp://www.journals.cambridge.org/abstract_S095410201300097702542nas a2200181 4500008004100000022001300041245006800054210006300122260001200185300001200197490000800209520181900217100002402036700002102060700002502081700002402106856023002130 2014 eng d a0169555X00aThe McMurdo Dry Valleys: A landscape on the threshold of change0 aMcMurdo Dry Valleys A landscape on the threshold of change c11/2014 a25 - 350 v2253 a

Field observations of coastal and lowland regions in the McMurdo Dry Valleys suggest they are on the threshold of rapid topographic change, in contrast to the high elevation upland landscape that represents some of the lowest rates of surface change on Earth. A number of landscapes have undergone dramatic and unprecedented landscape changes over the past decade including, the Wright Lower Glacier (Wright Valley) — ablated several tens of meters, the Garwood River (Garwood Valley) has incised > 3 m into massive ice permafrost, smaller streams in Taylor Valley (Crescent, Lawson, and Lost Seal Streams) have experienced extensive down-cutting and/or bank undercutting, and Canada Glacier (Taylor Valley) has formed sheer, > 4 meter deep canyons. The commonality between all these landscape changes appears to be sediment on ice acting as a catalyst for melting, including ice-cement permafrost thaw. We attribute these changes to increasing solar radiation over the past decade despite no significant trend in summer air temperature. To infer possible future landscape changes in the McMurdo Dry Valleys, due to anticipated climate warming, we map ‘at risk’ landscapes defined as those with buried massive ice in relative warm regions of the valleys. Results show that large regions of the valley bottoms are ‘at risk’. Changes in surface topography will trigger important responses in hydrology, geochemistry, and biological community structure and function.

1 aFountain, Andrew, G1 aLevy, Joseph, S.1 aGooseff, Michael, N.1 aVan Horn, David, J. uhttp://linkinghub.elsevier.com/retrieve/pii/S0169555X14001780http://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/xmlhttp://api.elsevier.com/content/article/PII:S0169555X14001780?httpAccept=text/plain00428nas a2200109 4500008004100000245009200041210006900133260001200202100001600214700002300230856006500253 2014 eng d00aMicrobial biomass and respiration responses to nitrogen fertilization in a polar desert0 aMicrobial biomass and respiration responses to nitrogen fertiliz c01/20141 aBall, Becky1 aVirginia, Ross, A. uhttp://link.springer.com/article/10.1007%2Fs00300-014-1459-000531nas a2200121 4500008004100000245013000041210006900171260001200240100002800252700002100280700003000301856007800331 2014 eng d00aModular community structure suggests metabolic plasticity during the transition to polar night in ice-covered Antarctic lakes0 aModular community structure suggests metabolic plasticity during c10/20131 aVick-Majors, Trista, J.1 aPriscu, John, C.1 aAmaral-Zettler, Linda, A. uhttp://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej2013190a.html01831nas a2200157 4500008004100000245009400041210006900135260001200204300001200216490000700228520126700235100001501502700002401517700001401541856011801555 2014 eng d00aNear-Surface Internal Melting - a Substantial Mass Loss on Antarctic Dry Valley Glaciers.0 aNearSurface Internal Melting a Substantial Mass Loss on Antarcti c04/2014 a361-3740 v603 aThe McMurdo Dry Valleys, southern Victoria Land, East Antarctica, are a polar desert, and melt from glacial ice is the primary source of water to streams, lakes and associated ecosystems. Previous work found that to adequately model glacier ablation and subsurface ice temperatures with a surface energy-balance model required including the transmission of solar radiation into the ice. Here we investigate the contribution of subsurface melt to the mass balance of (and runoff from) Dry Valley glaciers by including a drainage process in the model and applying the model to three glacier sites using 13years of hourly meteorological data. Model results for the smooth glacier surfaces common to many glaciers in the Dry Valleys showed that sublimation was typically the largest component of surface lowering, with rare episodes of surface melting, consistent with anecdotal field observations. Results also showed extensive internal melting 5-15 cm below the ice surface, the drainage of which accounted for 50% of summer ablation. This is consistent with field observations of subsurface streams and formation of a weathering crust. We identify an annual cycle of weathering crust formation in summer and its removal during the 10 months of winter sublimation.1 aHoffman, M1 aFountain, Andrew, G1 aListon, G uhttps://mcm.lternet.edu/content/near-surface-internal-melting-substantial-mass-loss-antarctic-dry-valley-glaciers03712nas a2200157 4500008004100000245021300041210006900254260001200323300001600335490000800351520308500359100002203444700002103466700002103487856004603508 2014 eng d00aThe permanent ice cover of Lake Bonney, Antarctica: The influence of thickness and sediment distribution on photosynthetically available radiation and chlorophyll-a distribution in the underlying water column0 apermanent ice cover of Lake Bonney Antarctica The influence of t c09/2014 a1879 - 18910 v1193 a

The thick permanent ice cover on the lakes of the McMurdo Dry Valleys, Antarctica, inhibits spatial lake sampling due to logistical constraints of penetrating the ice cover. To date most sampling of these lakes has been made at only a few sites with the assumption that there is a spatial homogeneity of the physical and biogeochemical properties of the ice cover and the water column at any given depth. To test this underlying assumption, an autonomous underwater vehicle (AUV) was deployed in Lake Bonney, Taylor Valley. Measurements were obtained over the course of 2 years in a 100 × 100 m horizontal sampling grid (at a 0.2 m vertical resolution). Additionally, the AUV measured the ice thickness (in water equivalent) and collected images looking up through the ice, which were used to quantify sediment distribution on the surface and within the ice. Satellite imagery was used to map sediment distribution on the surface of the ice. We present results of the spatial investigation of the sediment distribution on the ice cover and its effects on biological processes, with particular emphasis on photosynthetically active radiation (PAR). The surface sediment is a secondary controller of the ice cover thickness, which in turn controls the depth-integrated PAR in the water column. Our data revealed that depth-integrated PAR was negatively correlated with depth-integrated chlorophyll-a (r = 0.88, p < 0.001, n = 83), which appears to be related to short-term photoadaptation of phytoplanktonic communities to spatial and temporal variation in PAR within the water column.

1 aObryk, Maciek, K.1 aDoran, Peter, T.1 aPriscu, John, C. uhttp://doi.wiley.com/10.1002/2014JG00267200468nas a2200145 4500008004100000245005400041210005400095260001200149300001400161490000700175100002100182700002800203700001900231856007200250 2014 eng d00aPolar and alpine microbiology in a changing world0 aPolar and alpine microbiology in a changing world c08/2014 a209 - 2100 v891 aPriscu, John, C.1 aLaybourn-Parry, Johanna1 aHäggblom, Max uhttp://onlinelibrary.wiley.com/doi/10.1111/1574-6941.12371/abstract00623nas a2200169 4500008004100000245009600041210006900137260001200206300001200218490000700230100002100237700001800258700002100276700002200297700001700319856011700336 2014 eng d00aRadiocarbon abundance and reservoir effects in lakes of the McMurdo Dry Valleys, Antarctica0 aRadiocarbon abundance and reservoir effects in lakes of the McMu c05/2014 a811-8260 v591 aDoran, Peter, T.1 aKenig, Fabien1 aKnoepfle, Lawson1 aMikucki, Jill, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/radiocarbon-abundance-and-reservoir-effects-lakes-mcmurdo-dry-valleys-antarctica02909nas a2200193 4500008004100000245012700041210006900168260001200237300001600249490000700265520221300272100002502485700002002510700002302530700002502553700002402578700002202602856009102624 2014 eng d00aSoil animal responses to moisture availability are largely scale, not ecosystem dependent: insight from a cross-site study0 aSoil animal responses to moisture availability are largely scale c08/2014 a2631 - 26430 v203 a

Climate change will result in reduced soil water availability in much of the world either due to changes in precipitation or increased temperature and evapotranspiration. How communities of mites and nematodes may respond to changes in moisture availability is not well known, yet these organisms play important roles in decomposition and nutrient cycling processes. We determined how communities of these organisms respond to changes in moisture availability and whether common patterns occur along fine-scale gradients of soil moisture within four individual ecosystem types (mesic, xeric and arid grasslands and a polar desert) located in the western United States and Antarctica, as well as across a cross-ecosystem moisture gradient (CEMG) of all four ecosystems considered together. An elevation transect of three sampling plots was monitored within each ecosystem and soil samples were collected from these plots and from existing experimental precipitation manipulations within each ecosystem once in fall of 2009 and three times each in 2010 and 2011. Mites and nematodes were sorted to trophic groups and analyzed to determine community responses to changes in soil moisture availability. We found that while both mites and nematodes increased with available soil moisture across the CEMG, within individual ecosystems, increases in soil moisture resulted in decreases to nematode communities at all but the arid grassland ecosystem; mites showed no responses at any ecosystem. In addition, we found changes in proportional abundances of mite and nematode trophic groups as soil moisture increased within individual ecosystems, which may result in shifts within soil food webs with important consequences for ecosystem functioning. We suggest that communities of soil animals at local scales may respond predictably to changes in moisture availability regardless of ecosystem type but that additional factors, such as climate variability, vegetation composition, and soil properties may influence this relationship over larger scales.

1 aSylvain, Zachary, A.1 aWall, Diana, H.1 aCherwin, Karie, L.1 aPeters, Debra, P. C.1 aReichmann, Lara, G.1 aSala, Osvaldo, E. uhttp://doi.wiley.com/10.1111/gcb.2014.20.issue-8http://doi.wiley.com/10.1111/gcb.1252202505nas a2200193 4500008004100000245011800041210006900159260001200228300001400240490000700254520178100261100002402042700001502066700002402081700002502105700002202130700003302152856012602185 2014 eng d00aSoil microbial responses to increased moisture and organic resources along a salinity gradient in a polar desert.0 aSoil microbial responses to increased moisture and organic resou c05/2014 a3034-30430 v803 aMicrobial communities in extreme environments often have low diversity and specialized physiologies suggesting a limited resistance to change. The McMurdo Dry Valleys (MDV) are a microbially dominated, extreme ecosystem currently undergoing climate change-induced disturbances, including the melting of massive buried ice, cutting through of permafrost by streams, and warming events. These processes are increasing moisture across the landscape, altering conditions for soil communities by mobilizing nutrients and salts and stimulating autotrophic carbon inputs to soils. The goal of this study was to determine the effects of resource addition (water/organic matter) on the composition and function of microbial communities in the MDV along a natural salinity gradient representing an additional gradient of stress in an already extreme environment. Soil respiration and the activity of carbon-acquiring extracellular enzymes increased significantly (P < 0.05) with the addition of resources at the low- and moderate-salinity sites but not the high-salinity site. The bacterial community composition was altered, with an increase in Proteobacteria and Firmicutes with water and organic matter additions at the low- and moderate-salinity sites and a near dominance of Firmicutes at the high-salinity site. Principal coordinate analyses of all samples using a phylogenetically informed distance matrix (UniFrac) demonstrated discrete clustering among sites (analysis of similarity [ANOSIM], P < 0.05 and R > 0.40) and among most treatments within sites. The results from this experimental work suggest that microbial communities in this environment will undergo rapid change in response to the altered resources resulting from climate change impacts occurring in this region.1 aVan Horn, David, J.1 aOkie, J.G.1 aBuelow, Heather, N.1 aGooseff, Michael, N.1 aBarrett, John, E.1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/soil-microbial-responses-increased-moisture-and-organic-resources-along-salinity-gradient03560nas a2200397 4500008004100000022001400041245005200055210004800107260001200155300001400167490000700181520243500188100001802623700002202641700001902663700002502682700001902707700002002726700002202746700002102768700002402789700002102813700002302834700002702857700002302884700002802907700001702935700001902952700002202971700002002993700002103013700002503034700002603059700002003085856005703105 2014 eng d a0012-961500aThe spatial structure of Antarctic biodiversity0 aspatial structure of Antarctic biodiversity c05/2014 a203 - 2440 v843 a

Patterns of environmental spatial structure lie at the heart of the most fundamental and familiar patterns of diversity on Earth. Antarctica contains some of the strongest environmental gradients on the planet and therefore provides an ideal study ground to test hypotheses on the relevance of environmental variability for biodiversity. To answer the pivotal question, “How does spatial variation in physical and biological environmental properties across the Antarctic drive biodiversity?” we have synthesized current knowledge on environmental variability across terrestrial, freshwater, and marine Antarctic biomes and related this to the observed biotic patterns. The most important physical driver of Antarctic terrestrial communities is the availability of liquid water, itself driven by solar irradiance intensity. Patterns of biota distribution are further strongly influenced by the historical development of any given location or region, and by geographical barriers. In freshwater ecosystems, free water is also crucial, with further important influences from salinity, nutrient availability, oxygenation, and characteristics of ice cover and extent. In the marine biome there does not appear to be one major driving force, with the exception of the oceanographic boundary of the Polar Front. At smaller spatial scales, ice cover, ice scour, and salinity gradients are clearly important determinants of diversity at habitat and community level. Stochastic and extreme events remain an important driving force in all environments, particularly in the context of local extinction and colonization or recolonization, as well as that of temporal environmental variability. Our synthesis demonstrates that the Antarctic continent and surrounding oceans provide an ideal study ground to develop new biogeographical models, including life history and physiological traits, and to address questions regarding biological responses to environmental variability and change.

 

1 aConvey, Peter1 aChown, Steven, L.1 aClarke, Andrew1 aBarnes, David, K. A.1 aBokhorst, Stef1 aCummings, Vonda1 aDucklow, Hugh, W.1 aFrati, Francesco1 aGreen, T., G. Allan1 aGordon, Shulamit1 aGriffiths, Huw, J.1 aHoward-Williams, Clive1 aHuiskes, Ad, H. L.1 aLaybourn-Parry, Johanna1 aLyons, Berry1 aMcMinn, Andrew1 aMorley, Simon, A.1 aPeck, Lloyd, S.1 aQuesada, Antonio1 aRobinson, Sharon, A.1 aSchiaparelli, Stefano1 aWall, Diana, H. uhttp://www.esajournals.org/doi/abs/10.1890/12-2216.102923nas a2200229 4500008004100000245012800041210006900169260001200238490000600250520215100256100001602407700002602423700002002449700002402469700002202493700001802515700002402533700001702557700002302574700001902597856007702616 2014 eng d00aSpring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes0 aSpring thaw ionic pulses boost nutrient availability and microbi c12/20140 v53 a

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

1 aTelling, J.1 aAnesio, Alexandre, M.1 aTranter, Martyn1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aHawkings, Jon1 aSingh, Virendra, B.1 aKaur, Preeti1 aMusilova, Michaela1 aWadham, J., L. uhttp://journal.frontiersin.org/article/10.3389/fmicb.2014.00694/abstract00634nas a2200181 4500008004100000245007700041210006900118260001200187490000600199100002100205700002400226700002300250700002000273700001900293700002400312700002000336856009600356 2013 eng d00aAccelerated thermokarst formation in the McMurdo Dry Valleys, Antarctica0 aAccelerated thermokarst formation in the McMurdo Dry Valleys Ant c07/20130 v31 aLevy, Joseph, S.1 aFountain, Andrew, G1 aDickson, James, L.1 aHead, James, W.1 aOkal, Marianne1 aMarchant, David, R.1 aWatters, Jaclyn uhttp://www.nature.com/srep/2013/130724/srep02269/full/srep02269.html?WT.ec_id=SREP-2013073002237nas a2200337 4500008004100000024003300041245010300074210006900177260001200246300001300258490000700271520126700278100001301545700001701558700001901575700001401594700002001608700001801628700001801646700001301664700001701677700001401694700002001708700001801728700001401746700002101760700001801781700002001799700001701819856006301836 2013 eng d ahdl: 10013 / epic.42531.d00100aAntarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA), a new SCAR-biology programme0 aAntarctic Thresholds Ecosystem Resilience and Adaptation AnTERA  c10/2013 a147-150.0 v823 a

Stresses on Antarctic ecosystems result from environmental change, including extreme events, and from (other) human impacts. Consequently, Antarctic habitats are changing, some at a rapid pace while others are relatively stable. A cascade of responses from molecular through organismic to the community level are expected. The differences in biological complexity and evolutionary histories between both polar regions and the rest of the planet suggest that stresses on polar ecosystem function may have fundamentally different outcomes from those at lower latitudes. Polar ecosystem processes are therefore key to informing wider ecological debate about the nature of stability and potential changes across the biosphere. The main goal of AnT-ERA is to facilitate the science required to examine changes in biological processes in Antarctic and sub-Antarctic marine-, freshwater and terrestrial ecosystems. Tolerance limits, as well as thresholds, resistance and resilience to environmental change will be determined. AnT-ERA is classified into three overlapping themes, which represent three levels of biological organisation: (1) molecular and physiological performance, (2) population processes and species traits, (3) ecosystem function and services.

1 aGutt, J.1 aAdams, Byron1 aBracegirdle, T1 aCowan, D.1 aCummings, Vonda1 adi Prisco, G.1 aGradinger, R.1 aIsla, E.1 aMcIntyre, T.1 aMurphy, E1 aPeck, Lloyd, S.1 aSchloss, I.R.1 aSmith, C.1 aSuckling, C., C.1 aTakahashi, A.1 aWall, Diana, H.1 aXavier, J.C. uhttp://epic.awi.de/34238/1/Polarforschung_82-2_147-150.pdf03970nas a2200217 4500008004100000245011000041210007200151260004000223490001000263520322300273653001503496653001903511653001903530653002403549653003003573653003703603653001603640100001703656700001703673856006203690 2013 eng d00aThe application of stable isotopes, δ11B, δ18O, and δD, in geochemical and hydrological investigations0 aapplication of stable isotopes δ11B δ18O and δD in geochemical a aColumbus, OHbOhio State University0 vPh.D.3 a

My dissertation research utilizes stable isotopes as tracers of water and solute sources to study specific geochemical (solute origin) and hydrological (glacier meltwater source across a season comparing water contributions from hyporheic zone and/or glacier melt and residence time of precipitation within a managed water supply) problems within McMurdo Dry Valleys (MCM), Antarctica, and Central Ohio, USA. In Chapter II, δ11B isotopic and dissolved B measurements are used to infer the origin of B within MCM aquatic system. Boron stable isotopic values span the range of +12.3‰ to +51.4‰, varying from glacier meltwater streams to the hypolimnion of a highly evaporated hypersaline lake. These data demonstrate that the major sources of B are chemical weathering of alumniosilicates within the stream channels, and a marine source, either currently introduced by marine-derived aerosols or from ancient seawater. In-lake processes create a more positive δ11B through adsorption or mineral precipitation. The glacier meltwater streams, Lakes Fryxell, Hoare, and upper waters of Lake Joyce display a mixture of these two sources, with Lake Joyce bottom waters primarily of marine origin. Lakes Bonney and Vanda and Blood Falls brine are interpreted as having a marine-like source changed by in-lake processes to result in a more positive δ11B, while Don Juan Pond displays a more terrestrial influence. In Chapter III, δ18O and δD are used to trace water source variation via hyporheic zone or glacier melt within two MCM streams over an entire melt season. The isotopic variation of these streams was more negative at the beginning of the season and more positive later. D-excess measurements were used to infer mixing between hyporheic storage and glacier meltwater. It was supported that Von Guerard Stream has a large, widespread hyporheic zone that changes with time and discharge amounts. The chemistry of Andersen Creek also displayed hyporheic zone influence at certain times of the year. This work adds important new information on the role of hyperheic zone-stream interactions, and supports the short term, more physically based, descriptions of hyporheic dynamics explained in the past decade. Chapter IV describes water flow and travel time within a human managed watershed-reservoir system by measuring the δ18O and δD of the precipitation source to the reservoirs and finally to the distribution system, the tap. Generally, the tap waters experienced little lag time in the managed system, having a residence time of about two months. Tap and reservoir waters preserved the precipitation signal with the reservoir morphology acting as an important control. These water supply reservoirs functioned more like a river system with a faster throughput of water and larger variations in chemical parameters. Other water supply reservoirs have a greater capacity with a larger amount of water supply usage through a more lacustrine environment, which displays more constant solute concentrations and longer flow-through times. This work provides a basic understanding of a regional water supply system in central Ohio, reservoir isotopic dynamics, and Ohio precipitation sources.

10aAntarctica10aboron isotopes10ahyporheic zone10aMcMurdo Dry Valleys10aOhio precipitation source10aoxygen-18 and deuterium isotopes10asaline lake1 aLeslie, D.L.1 aLyons, Berry u http://rave.ohiolink.edu/etdc/view?acc_num=osu138600003702257nas a2200133 4500008004100000245011700041210006900158260004000227490000900267520175200276100002102028700002502049856004902074 2013 eng d00aAre the Dry Valleys getting wetter? A preliminary assessment of wetness across the McMurdo Dry Valleys landscape0 aAre the Dry Valleys getting wetter A preliminary assessment of w bPennsylvania State Universityc20130 vM.S.3 a

Liquid water is scarce across the landscape of the McMurdo Dry Valleys (MDV), Antarctica and is associated with soils that are adjacent to streams and lakes, during the annual thaw season. However, seeps, water tracks, and wet patches have been observed at several other locations as well. The source of water for these is likely generated by a combination of infiltration from melting snowpacks, melting of pore ice at the ice table beneath the water tracks, and melting of buried segregation ice formed during winter freezing. We are using high resolution (<1m pixel) remote sensing data gathered several times per week in the MDV region to determine the spatial and temporal distribution of wet soils. We assess the spatial consistency with which these wet soils occur for the 2008-2009 to 2011-2012 austral summers with complete coverage and partial coverage for 2003-2004 and 2006-2007 austral summers using a land cover classification. We also quantify the soil moisture of wetted soils using an artificial neural network (ANN). The ANN utilizes field radiometer data to retrieve estimates of surface moisture based on the spectral measurements and soil moisture samples collected during the 2010-2011 field season. The remote sensing based analyses of the wetted soils have shown the magnitude to vary greatly and how topography and regional microclimates influence the wetted soils in the MDV. The 2010-2011 austral summer provided the most wetted soil area, 10.21 km2, and 2008- 2009 covered the least, 5.38 km2. The ANN soil moisture distribution in the MDV shows values ranging from 0.36 % to over 19 %. We suggest that wet soils are a significant component of this cold desert land system and ecosystem.

1 aLangford, Z., L.1 aGooseff, Michael, N. uhttps://etda.libraries.psu.edu/catalog/1736407866nas a2200205 4500008004100000022001400041245011200055210006900167260001200236300001400248490000700262520715200269100001907421700001907440700001807459700002707477700001807504700002107522856011707543 2013 eng d a1380-616500aCarbon Sequestration and Release from Antarctic Lakes: Lake Vida and West Lake Bonney (McMurdo Dry Valleys)0 aCarbon Sequestration and Release from Antarctic Lakes Lake Vida  c03/2013 a135 - 1450 v193 a

Perennial ice covers on many Antarctic lakes have resulted in high lake inorganic carbon contents. The objective of this paper was to evaluate and compare the brine and CO2 chemistries of Lake Vida (Victoria Valley) and West Lake Bonney (Taylor Valley), two lakes of the McMurdo Dry Valleys (East Antarctica), and their potential consequences during global warming. An existing geochemical model (FREZCHEM-15) was used to convert measured molarity into molality needed for the FREZCHEM model, and this model added a new algorithm that converts measured DIC into carbonate alkalinity needed for the FREZCHEM model. While quite extensive geochemical information exists for ice-covered Taylor Valley lakes, such as West Lake Bonney, only limited information exists for the recently sampled brine of >25 m ice-thick Lake Vida. Lake Vida brine had a model-calculated pCO2 = 0.60 bars at the field pH (6.20); West Lake Bonney had a model-calculated pCO2 = 5.23 bars at the field pH (5.46). Despite the high degree of atmospheric CO2supersaturation in West Lake Bonney, it remains significantly undersaturated with the gas hydrate, CO2·6H2O, unless these gas hydrates are deep in the sediment layer or are metastable having formed under colder temperatures or greater pressures. Because of lower temperatures, Lake Vida could start forming CO2·6H2O at lower pCO2 values than West Lake Bonney; but both lakes are significantly undersaturated with the gas hydrate, CO2·6H2O. For both lakes, simulation of global warming from current subzero temperatures (−13.4 °C in Lake Vida and −4.7 °C in West Lake Bonney) to 10 °C has shown that a major loss of solution-phase carbon as CO2 gases and carbonate minerals occurred when the temperatures rose above 0 °C and perennial ice covers would disappear. How important these Antarctic CO2 sources will be for future global warming remains to be seen. But a recent paper has shown that methane increased in atmospheric concentration due to deglaciation about 10,000 years ago. So, CO2 release from ice lakes might contribute to atmospheric gases in the future.

1 aMarion, G., M.1 aMurray, A., E.1 aWagner, Bernd1 aFritsen, Christian, H.1 aKenig, Fabien1 aDoran, Peter, T. uhttp://link.springer.com/10.1007/s10498-012-9184-1http://link.springer.com/content/pdf/10.1007/s10498-012-9184-100663nas a2200193 4500008004100000245008400041210006900125260001200194300001200206490000700218100001700225700001700242700001700259700001900276700002400295700001900319700002400338856010700362 2013 eng d00aThe carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica0 acarbon stable isotope biogeochemistry of streams Taylor Valley A c05/2013 a26 - 360 v321 aLyons, Berry1 aLeslie, D.L.1 aHarmon, R.S.1 aNeumann, Klaus1 aWelch, Kathleen, A.1 aBisson, K., M.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/carbon-stable-isotope-biogeochemistry-streams-taylor-valley-antarctica02340nas a2200241 4500008004100000245013800041210006900179260001200248300001100260490000600271520148800277100002301765700002401788700002301812700001901835700002001854700002201874700001901896700001701915700001801932700002701950856012101977 2013 eng d00aCharacterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica0 aCharacterization of fulvic acid fractions of dissolved organic m c12/2013 a0450150 v83 aDissolved humic material (HDOM) is ubiquitous to all natural waters and its source material influences its chemical structure, reactivity, and bioavailability. While terrestrially derived HDOM reference materials distributed by the International Humic Substances Society (IHSS) have been readily available to engineering and scientific communities, a microbially derived reference HDOM was not, despite the well-characterized differences in the chemistry and reactivity of HDOM derived from terrestrial versus microbial sources. To address this gap, we collected a microbial reference fulvic acid from Pony Lake (PLFA) for distribution through the IHSS. Pony Lake is a saline coastal pond on Ross Island, Antarctica, where the landscape is devoid of terrestrial plants. Sample collection occurred over a 17-day period in the summer season at Pony Lake. During this time, the dissolved organic carbon (DOC) concentrations increased nearly two-fold, and the fulvic acid fraction (collected using the XAD-8 method) accounted for 14.6% of the DOC. During the re-concentration and desalting procedures we isolated two other chemically distinct fulvic acid fractions: (1) PLFA-2, which was high in carbohydrates and (2) PLFA-CER, which was high in nitrogen. The chemical characteristics (elemental analysis, optical characterization with UV–vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.1 aCawley, Kaelin, M.1 aMcKnight, Diane, M.1 aMiller, Penney, L.1 aCory, Rose, M.1 aFimmen, Ryan, L1 aGuerard, Jennifer1 aDieser, Markus1 aJaros, Chris1 aChin, Yu-Ping1 aForeman, Christine, M. uhttps://mcm.lternet.edu/content/characterization-fulvic-acid-fractions-dissolved-organic-matter-during-ice-out-hyper00663nas a2200157 4500008004100000245019300041210006900234260001200303300001200315490000700327100002600334700002700360700002300387700002400410856007100434 2013 eng d00aCharacterization of IHSS Pony Lake fulvic acid dissolved organic matter by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and fluorescence spectroscopy0 aCharacterization of IHSS Pony Lake fulvic acid dissolved organic c12/2013 a19 - 280 v651 aD’Andrilli, Juliana1 aForeman, Christine, M.1 aMarshall, Alan, G.1 aMcKnight, Diane, M. uhttp://www.sciencedirect.com/science/article/pii/S014663801300216700625nas a2200145 4500008004100000245013000041210006900171260001100240490000600251100002300257700002000280700002100300700002400321856013400345 2013 eng d00aCORRIGENDUM: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth’s most saline lake and implications for Mars0 aCORRIGENDUM Don Juan Pond Antarctica Nearsurface CaCl2brine feed c3/20130 v31 aDickson, James, L.1 aHead, James, W.1 aLevy, Joseph, S.1 aMarchant, David, R. uhttps://mcm.lternet.edu/content/corrigendum-don-juan-pond-antarctica-near-surface-cacl2-brine-feeding-earth%E2%80%99s-most-saline00502nas a2200133 4500008004100000245007800041210006900119260000900188300001400197490000700211100002600218700002100244856010300265 2013 eng d00aDistribution of Siliceous-Walled Algae in Taylor Valley, Antarctica Lakes0 aDistribution of SiliceousWalled Algae in Taylor Valley Antarctic c2013 a688 - 6990 v041 aWarnock, Jonathan, P.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/distribution-siliceous-walled-algae-taylor-valley-antarctica-lakes00735nas a2200181 4500008004100000245015100041210006900192260001200261300001400273490000700287100002300294700002000317700002400337700002400361700002400385700001700409856012700426 2013 eng d00aDo Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica?0 aDo Cryoconite Holes have the Potential to be Significant Sources c11/2013 a440 - 4540 v451 aBagshaw, Elizabeth1 aTranter, Martyn1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aBasagic, Hassan, J.1 aLyons, Berry uhttps://mcm.lternet.edu/content/do-cryoconite-holes-have-potential-be-significant-sources-c-n-and-p-downstream-depauperate00577nas a2200145 4500008004100000245011500041210006900156260001200225490000600237100002300243700002000266700002100286700002400307856010000331 2013 eng d00aDon Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth's most saline lake and implications for Mars0 aDon Juan Pond Antarctica Nearsurface CaCl2brine feeding Earths m c01/20130 v31 aDickson, James, L.1 aHead, James, W.1 aLevy, Joseph, S.1 aMarchant, David, R. uhttp://www.nature.com/srep/2013/130130/srep01166/full/srep01166.html?WT.ec_id=SREP-704-2013020100652nas a2200181 4500008004100000245007600041210006900117260001200186300001100198490000600209100002100215700002500236700002400261700003300285700002500318700002200343856010500365 2013 eng d00aEnvironmental controls over bacterial communities in polar desert soils0 aEnvironmental controls over bacterial communities in polar deser c10/2013 aart1270 v41 aGeyer, Kevin, M.1 aAltrichter, Adam, E.1 aVan Horn, David, J.1 aTakacs-Vesbach, Cristina, D.1 aGooseff, Michael, N.1 aBarrett, John, E. uhttps://mcm.lternet.edu/content/environmental-controls-over-bacterial-communities-polar-desert-soils00588nas a2200169 4500008004100000245008700041210006900128260001200197300001100209490000600220100002100226700002300247700002400270700002400294700002000318856008000338 2013 eng d00aEnvironmental factors influencing diatom communities in Antarctic cryoconite holes0 aEnvironmental factors influencing diatom communities in Antarcti c12/2013 a0450060 v81 aStanish, Lee, F.1 aBagshaw, Elizabeth1 aMcKnight, Diane, M.1 aFountain, Andrew, G1 aTranter, Martyn uhttp://iopscience.iop.org/1748-9326/8/4/045006/pdf/1748-9326_8_4_045006.pdf00764nas a2200205 4500008004100000245015000041210006900191260001200260300001100272490000600283100002400289700001800313700002200331700002500353700002500378700002100403700002200424700003300446856007900479 2013 eng d00aFactors Controlling Soil Microbial Biomass and Bacterial Diversity and Community Composition in a Cold Desert Ecosystem: Role of Geographic Scale0 aFactors Controlling Soil Microbial Biomass and Bacterial Diversi c06/2013 ae661030 v81 aVan Horn, David, J.1 aVan Horn, Lee1 aBarrett, John, E.1 aGooseff, Michael, N.1 aAltrichter, Adam, E.1 aGeyer, Kevin, M.1 aZeglin, Lydia, H.1 aTakacs-Vesbach, Cristina, D. uhttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.006610300566nas a2200133 4500008004100000245013000041210006900171260001200240300001400252490000700266100002200273700002000295856011700315 2013 eng d00aThe future of soil invertebrate communities in polar regions: different climate change responses in the Arctic and Antarctic?0 afuture of soil invertebrate communities in polar regions differe c03/2013 a409 - 4190 v161 aNielsen, Uffe, N.1 aWall, Diana, H. uhttp://onlinelibrary.wiley.com/doi/10.1111/ele.12058/abstract;jsessionid=2591020317030CE8FCDC37FE39B4F0B2.f01t0400638nas a2200169 4500008004100000245013200041210006900173260001200242300001600254490000800270100002100278700002400299700002100323700002400344700001700368856008300385 2013 eng d00aGarwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys0 aGarwood Valley Antarctica A new record of Last Glacial Maximum t c09/2013 a1484 - 15020 v1251 aLevy, Joseph, S.1 aFountain, Andrew, G1 aO'Connor, J., E.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract00495nas a2200121 4500008004100000245009100041210006900132260001200201300001400213490000700227100002100234856011800255 2013 eng d00aHow big are the McMurdo Dry Valleys? Estimating ice-free area using Landsat image data0 aHow big are the McMurdo Dry Valleys Estimating icefree area usin c02/2013 a119 - 1200 v251 aLevy, Joseph, S. uhttps://mcm.lternet.edu/content/how-big-are-mcmurdo-dry-valleys-estimating-ice-free-area-using-landsat-image-data00579nas a2200157 4500008004100000245012400041210006900165260001200234300001600246490000700262100001600269700002500285700002500310700002400335856006200359 2013 eng d00aThe influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream0 ainfluence of stream thermal regimes and preferential flow paths  c09/2013 a5552 - 55690 v491 aCozzetto, K1 aBencala, Kenneth, E.1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttp://onlinelibrary.wiley.com/doi/10.1002/wrcr.20410/pdf00501nas a2200133 4500008004100000245007300041210006900114260001200183490000700195100002200202700002200224700002100246856010000267 2013 eng d00aLake ice ablation rates from permanently ice-covered Antarctic lakes0 aLake ice ablation rates from permanently icecovered Antarctic la c01/20130 v591 aDugan, Hilary, A.1 aObryk, Maciek, K.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/lake-ice-ablation-rates-permanently-ice-covered-antarctic-lakes00533nas a2200157 4500008004100000245009000041210006900131260001300200300001000213490000700223100002500230700001700255700002600272700002000298856005700318 2013 eng d00aThe Life Cycle of the Antarctic Nematode Plectus murrayi Under Laboratory Conditions.0 aLife Cycle of the Antarctic Nematode Plectus murrayi Under Labor c2013 Mar a39-420 v451 aTomasel, Cecilia, M.1 aAdams, Byron1 aTomasel, Fernando, G.1 aWall, Diana, H. uhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625130/00643nas a2200169 4500008004100000245010200041210006900143260001200212300001100224490000600235100002000241700002300261700002100284700001900305700002200324856012700346 2013 eng d00aLocal and regional influences over soil microbial metacommunities in the Transantarctic Mountains0 aLocal and regional influences over soil microbial metacommunitie c11/2013 aart1360 v41 aSokol, Eric, R.1 aHerbold, Craig, W.1 aLee, Charles, K.1 aCary, Craig, S1 aBarrett, John, E. uhttps://mcm.lternet.edu/content/local-and-regional-influences-over-soil-microbial-metacommunities-transantarctic-mountains02033nas a2200229 4500008004100000245011500041210006900156260001200225300001100237490000600248520129700254100002701551700001901578700002101597700002901618700002001647700002001667700002301687700001801710700002401728856005101752 2013 eng d00aMicrobial growth under humic-free conditions in a supraglacial stream system on the Cotton Glacier, Antarctica0 aMicrobial growth under humicfree conditions in a supraglacial st c09/2013 a0350220 v83 aDuring the austral summers of 2004 and 2009, we sampled a supraglacial stream on the Cotton Glacier, Antarctica. The stream dissolved organic matter (DOM) was low (44–48 μM C) and lacked detectable humic fluorescence signatures. Analysis of the excitation emissions matrices (EEMs) indicated that amino-acid fluorophores dominated, consistent with DOM of microbial origin, with little humic-like fluorescence. In most aquatic ecosystems, humic DOM attenuates harmful UV radiation and its absence may represent an additional stressor influencing the microbial community. Nonetheless, the stream contained an active microbial assemblage with bacterial cell abundances from 2.94 × 104 to 4.97 × 105 cells ml−1, and bacterial production ranging from 58.8 to 293.2 ng C l−1 d−1. Chlorophyll-a concentrations ranged from 0.3 to 0.53 μg l−1 indicating that algal phototrophs were the probable source of the DOM. Microbial isolates produced a rainbow of pigment colors, suggesting adaptation to stress, and were similar to those from other cryogenic systems (Proteobacteria and Bacteroidetes lineages). Supraglacial streams provide an example of contemporary microbial processes on the glacier surface and a natural laboratory for studying microbial adaptation to the absence of humics.1 aForeman, Christine, M.1 aCory, Rose, M.1 aMorris, Cindy, E1 aSanClements, Michael, D.1 aSmith, Heidi, J1 aLisle, John, T.1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttp://iopscience.iop.org/1748-9326/8/3/03502200572nas a2200145 4500008004100000245015400041210006900195260001200264300001400276490000700290100001900297700002100316700001800337856007100355 2013 eng d00aMicro-hole and multigrain quartz luminescence dating of Paleodeltas at Lake Fryxell, McMurdo Dry Valleys (Antarctica), and relevance for lake history0 aMicrohole and multigrain quartz luminescence dating of Paleodelt c12/2013 a119 - 1340 v181 aBerger, G., W.1 aDoran, Peter, T.1 aThomsen, K.J. uhttp://www.sciencedirect.com/science/article/pii/S187110141300042300803nas a2200217 4500008004100000245011600041210006900157260001200226300001400238490000700252100001900259700002700278700001700305700002000322700002400342700002800366700002300394700001800417700002400435856012600459 2013 eng d00aPhysicochemical and biological dynamics in a coastal Antarctic lake as it transitions from frozen to open water0 aPhysicochemical and biological dynamics in a coastal Antarctic l c12/2013 a663–6750 v251 aDieser, Markus1 aForeman, Christine, M.1 aJaros, Chris1 aLisle, John, T.1 aGreenwood, Mark, C.1 aLaybourn-Parry, Johanna1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/physicochemical-and-biological-dynamics-coastal-antarctic-lake-it-transitions-frozen-open05193nas a2200229 4500008004100000245009300041210006900134260004000203490000900243520447100252653002304723653001504746653001304761653002204774653000904796653001704805653002704822653002404849100002404873700002604897856004004923 2013 eng d00aResource Legacies and Priming Regulate Microbial Communities in Antarctica's Dry Valleys0 aResource Legacies and Priming Regulate Microbial Communities in  aProvo, UTbBrigham Young University0 vM.S.3 a

Multiple mechanisms control bacterial community structure but two in particular, the "legacy" of past environmental conditions, and the "priming" of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. Further, to investigate the ecological significance of priming, we conducted a series of stable isotope probing experiments (i.e., 18O-DNA SIP with 18O-labeled water, 13C-DNA SIP with 13C-labeled mannitol, 15N-DNA with 15N- NH4NO3, and a combined C and N SIP) and characterized the responding (i.e., isotopically labeled) and seed bank (i.e., unlabeled) bacterial communities. We performed each of the SIPs in soil microcosms corresponding to a single resource manipulation (e.g., 13C-labeled mannitol in C addition soils). We hypothesized that all long-term additions of nutrients and water will lead to a distinct bacterial community—a legacy effect due to the nutrient and water impoverished state of Antarctica soils. We also hypothesized that the stronger the legacy effects demonstrated by a specific community the more adapted or primed bacterial species will be to take advantage of the resource and respond. As hypothesized, resource additions created distinct bacterial legacy but to different degrees among the treatments. The extent of the resource legacy effects was greatest in the CN, intermediate in water and N, and lowest in C communities relative to the control communities, suggesting that C induced changes in communities were intensified by tandem N additions and that water alone created a more distinct legacy than water and C additions combined. Contrary to our hypothesis, the stronger the legacy effects, the less adapted or primed the community was to take advantage of resource additions. For example, the CN treatment that induced the greatest effect on bacterial communities had the lowest number of species (20.9%) in common between the responding and seed bank communities. This inverse relationship may be due to only two species (i.e., Arthrobacter, Actinobacteria and Massilia, Betaproteobacteria) really being primed to take advantage of CN and these species constituting over 75% of the seed bank community. Water, N, and C additions had similar levels of priming with 38.4%, 41.4%, and 36.3% of the responding species being present in the seed bank community, respectively. But of these three treatments, only the priming with water resulted in a unique responding community, suggesting that water, a universal bacterial resource, was enough to prime bacteria. Furthermore, water generates the most diverse responding community of all the resources with stemming from all of the fourteen dominant phyla. We did find patterns of ecological coherence among the responders, especially in the major responders (i.e., responders that increased in relative recovery by at least ten-fold). These responders were predominantly found in only three phyla (i.e., Actinobacteria, Bacteriodetes, and Gammaproteobacteria) regardless of resource addition. Alternatively minor responders (i.e., responders that increased in relative recovery at least two-fold) were contained in fourteen different phyla with specific taxa stimulated by CN (i.e., Betaproteobacteria) and N and water (i.e., Deltaproteobacteria). Further, resource additions elicited responses from 37% of bacterial species with species specializing on a specific resource (e.g., Chloroflexi) or being a generalist (e.g., Planctomycetes and Gammaproteobacteria). Our results offer the first direct links between legacy and priming effects on bacterial community composition and demonstrate that these mechanisms are not always complimentary leading to the formation of similar communities but may both be essential to maintain the high levels of bacterial diversity. Further, all resources produced elicited responders that were either specialists of generalists demonstrating that even bacteria in the extreme environment of Antarctica respond to pulses of resources.

10a454 pyrosequencing10aAntarctica10abacteria10amicrobial ecology10asoil10asoil ecology10astable isotope probing10atarget metagenomics1 aSaurey, Sabrina, D.1 aAanderud, Zachary, T. uhttp://hdl.lib.byu.edu/1877/etd622900637nas a2200169 4500008004100000245013500041210006900176260001200245300001400257490000600271100002100277700002500298700002500323700002200348700003300370856006400403 2013 eng d00aSeasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica0 aSeasonal controls on snow distribution and aerial ablation at th c09/2013 a917 - 9310 v71 aEveland, Jeffery1 aGooseff, Michael, N.1 aLampkin, Derrick, J.1 aBarrett, John, E.1 aTakacs-Vesbach, Cristina, D. uhttp://www.the-cryosphere.net/7/917/2013/tc-7-917-2013.html00493nas a2200145 4500008004100000245007100041210006900112260001200181300001400193490000700207100002500214700002200239700002100261856006500282 2013 eng d00aShallow groundwater systems in a polar desert, McMurdo Dry Valleys0 aShallow groundwater systems in a polar desert McMurdo Dry Valley c02/2013 a171 - 1830 v211 aGooseff, Michael, N.1 aBarrett, John, E.1 aLevy, Joseph, S. uhttp://link.springer.com/article/10.1007%2Fs10040-012-0926-300619nas a2200169 4500008004100000245011800041210006900159260001200228300001600240490000700256100002100263700002500284700002500309700002200334700003300356856006000389 2013 eng d00aSpatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica0 aSpatial and temporal patterns of snow accumulation and aerial ab c09/2013 a2864 - 28750 v271 aEveland, Jeffery1 aGooseff, Michael, N.1 aLampkin, Derrick, J.1 aBarrett, John, E.1 aTakacs-Vesbach, Cristina, D. uhttp://onlinelibrary.wiley.com/doi/10.1002/hyp.9407/pdf00488nas a2200145 4500008004100000245007700041210006900118260001200187300001200199490000700211100002100218700001700239700001700256856006900273 2013 eng d00aUnderstanding Terrestrial Ecosystem Response to Antarctic Climate Change0 aUnderstanding Terrestrial Ecosystem Response to Antarctic Climat c01/2013 a33 - 330 v941 aLevy, Joseph, S.1 aLyons, Berry1 aAdams, Byron uhttp://onlinelibrary.wiley.com/doi/10.1002/2013EO030009/abstract00730nas a2200193 4500008004100000245009900041210006900140300001100209100002100220700002400241700002500265700002200290700002200312700002400334700001700358700002200375700002000397856011900417 2013 eng d00aWater track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica0 aWater track modification of soil ecosystems in the Lake Hoare ba a1 - 101 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aBarrett, John, E.1 aVantreese, Robert1 aWelch, Kathleen, A.1 aLyons, Berry1 aNielsen, Uffe, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/water-track-modification-soil-ecosystems-lake-hoare-basin-taylor-valley-antarctica00646nas a2200193 4500008004100000245007700041210006900118260001100187300001400198490001200212100002100224700002100245700002400266700002400290700002000314700002300334700002400357856007100381 2012 eng d00aAeolian flux of biotic and abiotic material in Taylor Valley, Antarctica0 aAeolian flux of biotic and abiotic material in Taylor Valley Ant c6/2012 a102 - 1110 v155-1561 aŠabacká, Marie1 aPriscu, John, C.1 aBasagic, Hassan, J.1 aFountain, Andrew, G1 aWall, Diana, H.1 aVirginia, Ross, A.1 aGreenwood, Mark, C. uhttp://www.sciencedirect.com/science/article/pii/S0169555X1100622200753nas a2200193 4500008004100000245014000041210006900181260001200250300000800262490000700270100002100277700002300298700001700321700002500338700002400363700002400387700002200411856012600433 2012 eng d00aAntarctic Tardigrada: a first step in understanding molecular operational taxonomic units (MOTUs) and biogeography of cryptic meiofauna0 aAntarctic Tardigrada a first step in understanding molecular ope c12/2012 a5260 v261 aCzechowski, Paul1 aSands, Chester, J.1 aAdams, Byron1 aD'Haese, Cyrille, A.1 aGibson, John, A. E.1 aMcInnes, Sandra, J.1 aStevens, Mark, I. uhttps://mcm.lternet.edu/content/antarctic-tardigrada-first-step-understanding-molecular-operational-taxonomic-units-motus02734nas a2200229 4500008004100000245012900041210006900170260001600239300001100255490000600266520197000272100002402242700002202266700001902288700001602307700002202323700002002345700001702365700002102382700002402403856007702427 2012 eng d00aAt Limits of Life: Multidisciplinary Insights Reveal Environmental Constraints on Biotic Diversity in Continental Antarctica0 aAt Limits of Life Multidisciplinary Insights Reveal Environmenta cJul-09-2013 ae445780 v73 a

Multitrophic communities that maintain the functionality of the extreme Antarctic terrestrial ecosystems, while the simplest of any natural community, are still challenging our knowledge about the limits to life on earth. In this study, we describe and interpret the linkage between the diversity of different trophic level communities to the geological morphology and soil geochemistry in the remote Transantarctic Mountains (Darwin Mountains, 80°S). We examined the distribution and diversity of biota (bacteria, cyanobacteria, lichens, algae, invertebrates) with respect to elevation, age of glacial drift sheets, and soil physicochemistry. Results showed an abiotic spatial gradient with respect to the diversity of the organisms across different trophic levels. More complex communities, in terms of trophic level diversity, were related to the weakly developed younger drifts (Hatherton and Britannia) with higher soil C/N ratio and lower total soluble salts content (thus lower conductivity). Our results indicate that an increase of ion concentration from younger to older drift regions drives a succession of complex to more simple communities, in terms of number of trophic levels and diversity within each group of organisms analysed. This study revealed that integrating diversity across multi-trophic levels of biotic communities with abiotic spatial heterogeneity and geological history is fundamental to understand environmental constraints influencing biological distribution in Antarctic soil ecosystems.

 
1 aMagalhaes, Catarina1 aStevens, Mark, I.1 aCary, Craig, S1 aBall, Becky1 aStorey, Bryan, C.1 aWall, Diana, H.1 aTürk, Roman1 aRuprecht, Ulrike1 ade Bello, Francesco uhttp://journals.plos.org/plosone/article?id=10.1371/journal.pone.004457800656nas a2200181 4500008004100000245009100041210006900132260001200201100002100213700002200234700002300256700002100279700002000300700002400320700002500344700002400369856008100393 2012 eng d00aBacteria and diatom co-occurrence patterns in microbial mats from polar desert streams0 aBacteria and diatom cooccurrence patterns in microbial mats from c10/20121 aStanish, Lee, F.1 aO'Neill, Sean, P.1 aGonzález, Antonio1 aLegg, Teresa, M.1 aKnelman, Joseph1 aMcKnight, Diane, M.1 aSpaulding, Sarah, A.1 aNemergut, Diana, R. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2012.02872.x/abstract03100nas a2200157 4500008004100000022001400041245011100055210006900166260001200235300001200247490000700259520257200266100002802838700002102866856005502887 2012 eng d a0948-305500aBacterioplankton productivity in lakes of the Taylor Valley, Antarctica, during the polar night transition0 aBacterioplankton productivity in lakes of the Taylor Valley Anta c12/2013 a77 - 900 v683 a

Research on the lakes of the McMurdo Dry Valleys, Antarctica, is typically conducted during the period of 24 h sunlight (October to January) when logistical support is readily available. As part of the International Polar Year initiative, we obtained logistical support to study microbial dynamics in the permanently ice-covered lakes of the Taylor Valley during the transition from 24 h of sunlight to the complete darkness of the polar night (mid-April). Our study focused on the perennially ice-covered lakes Fryxell (FRX), East Lobe Bonney (ELB), and West Lobe Bonney (WLB), all of which are chemically stratified and have food webs dominated by microorganisms. Depth-integrated bacterioplankton productivity (BP; leucine incorporation [Leu] and thymidine incorporation [TdR]) in the lakes ranged from 1.2 to 3.4 mg C m−2 d−1. Overall, summer was characterized by relatively high rates of BP and photoautotrophic primary productivity. Rapid decreases in photosynthetically active radiation marked a subsequent transition period, which was characterized by variable cell counts and decreasing Leu:TdR ratios (ratios >1 signify a physiological shift from growth to maintenance mode). Finally, cell counts decreased and Leu:TdR increased by as much as 280% during the fall, revealing a distinct change in the physiological state of the bacterioplankton as light-mediated primary productivity ceased. Our data reveal that the shift in physiological state may result from a switch from contemporary phytoplankton-excreted carbon to other sources of dissolved organic carbon, which can support the bacterioplankton populations through the winter.

1 aVick-Majors, Trista, J.1 aPriscu, John, C. uhttp://www.int-res.com/abstracts/ame/v68/n1/p77-9004191nas a2200445 4500008004100000022001400041245005900055210005900114260001600173300001400189490000800203520302300211100002203234700001603256700001903272700001503291700001803306700002003324700001503344700001903359700001603378700001303394700001503407700001803422700001303440700002203453700001503475700001503490700002303505700001303528700001903541700001703560700001503577700001703592700001803609700002003627700001603647700002003663856006203683 2012 eng d a0036-807500aChallenges to the Future Conservation of the Antarctic0 aChallenges to the Future Conservation of the Antarctic cJan-07-2013 a158 - 1590 v3373 a

The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globe's largest commons (1), is under substantial pressure. Concerns have been raised about increased stress on Antarctic systems from global environmental change and growing interest in the region's resources (23). Although policy-makers may recognize these challenges, failure to respond in a timely way can have substantial negative consequences. We provide a horizon scan, a systematic means for identifying emerging trends and assisting decision-makers in identifying policies that address future challenges (23). Previous analyses of conservation threats in the Antarctic have been restricted to matters for which available evidence is compelling (4). We reconsider these concerns because they might escalate quickly, judging from recent rapid environmental change in parts of Antarctica and increasing human interest in the region (see the map). We then focus on a more distant time horizon.

1 aChown, Steven, L.1 aLee, J., E.1 aHughes, K., A.1 aBarnes, J.1 aBarrett, P.J.1 aBergstrom, D.M.1 aConvey, P.1 aCowan, Don, A.1 aCrosbie, K.1 aDyer, G.1 aFrenot, Y.1 aGrant, S., M.1 aHerr, D.1 aKennicutt, M., C.1 aLamers, M.1 aMurray, A.1 aPossingham, H., P.1 aReid, K.1 aRiddle, M., J.1 aRyan, P., G.1 aSanson, L.1 aShaw, J., D.1 aSparrow, M.D.1 aSummerhayes, C.1 aTerauds, A.1 aWall, Diana, H. uhttp://www.sciencemag.org/cgi/doi/10.1126/science.122282100624nas a2200169 4500008004100000245011500041210006900156260001200225300001600237490000700253100002500260700002100285700002100306700002200327700002500349856008000374 2012 eng d00aChemical analysis of ice vein microenvironments: II. Analysis of glacial samples from Greenland and Antarctica0 aChemical analysis of ice vein microenvironments II Analysis of g c12/2012 a1109 - 11180 v581 aBarletta, Robert, E.1 aPriscu, John, C.1 aMader, Heidy, M.1 aJones, Warren, L.1 aRoe, Christopher, H. uhttp://www.montana.edu/priscu/DOCS/Publications/BarlettaEtAl2012IceVein.pdf00683nas a2200205 4500008004100000245009900041210006900140260001200209100001700221700002300238700001700261700002200278700002100300700002600321700001700347700002200364700002000386700002200406856004900428 2012 eng d00aCross-biome metagenomic analyses of soil microbial communities and their functional attributes0 aCrossbiome metagenomic analyses of soil microbial communities an c11/20121 aFierer, Noah1 aLeff, Jonathan, W.1 aAdams, Byron1 aNielsen, Uffe, N.1 aBates, Scott, T.1 aLauber, Christian, L.1 aOwens, Sarah1 aGilbert, Jack, A.1 aWall, Diana, H.1 aCaporaso, Gregory uwww.pnas.org/cgi/doi/10.1073/pnas.121521011000532nas a2200145 4500008004100000245009700041210006900138260001200207300001400219490000700233100002700240700002100267700002100288856007700309 2012 eng d00aCyanobacterial diversity across landscape units in a polar desert: Taylor Valley, Antarctica0 aCyanobacterial diversity across landscape units in a polar deser c11/2012 a268 - 2780 v821 aMichaud, Alexander, B.1 aŠabacká, Marie1 aPriscu, John, C. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01297.x/full00624nas a2200181 4500008004100000245009000041210006900131260001200200300001400212490000700226100002400233700002300257700002600280700002800306700002300334700002200357856006300379 2012 eng d00aThe Disappearing Cryosphere: Impacts and Ecosystem Responses to Rapid Cryosphere Loss0 aDisappearing Cryosphere Impacts and Ecosystem Responses to Rapid c04/2012 a405 - 4150 v621 aFountain, Andrew, G1 aCampbell, John, L.1 aSchuur, Edward, A. G.1 aStammerjohn, Sharon, E.1 aWilliams, Mark, W.1 aDucklow, Hugh, W. uhttp://bioscience.oxfordjournals.org/content/62/4/405.full00561nas a2200157 4500008004100000245012400041210006900165260001200234300001400246490000700260100001800267700002000285700002100305700002900326856004800355 2012 eng d00aDiversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition0 aDiversity and Expression of RubisCO Genes in a Perennially IceCo c04/2012 a4358-43660 v781 aKong, Weidong1 aReam, David, C.1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttp://aem.asm.org/content/78/12/4358.short00640nas a2200193 4500008004100000245010100041210006900142260001200211300001000223490000600233100002200239700002000261700001700281700002300298700001600321700002500337700002400362856006000386 2012 eng d00aThe ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem0 aecology of pulse events insights from an extreme climatic event  c02/2012 aart170 v31 aNielsen, Uffe, N.1 aWall, Diana, H.1 aAdams, Byron1 aVirginia, Ross, A.1 aBall, Becky1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttp://www.esajournals.org/doi/abs/10.1890/ES11-00325.100583nas a2200169 4500008004100000245008400041210006900125260001200194300001400206490000700220100001800227700002100245700002000266700002100286700002900307856007700336 2012 eng d00aEvidence of form II RubisCO ( cbbM) in a perennially ice-covered Antarctic lake0 aEvidence of form II RubisCO cbbM in a perennially icecovered Ant c11/2012 a491 - 5000 v821 aKong, Weidong1 aDolhi, Jenna, M.1 aChiuchiolo, Amy1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01431.x/full00743nas a2200205 4500008004100000245013500041210006900176260001200245300001600257490000700273100002100280700002200301700002500323700002400348700002200372700002000394700002400414700002400438856007500462 2012 eng d00aExtreme streams: flow intermittency as a control on diatom communities in meltwater streams in the McMurdo Dry Valleys, Antarctica0 aExtreme streams flow intermittency as a control on diatom commun c08/2012 a1405 - 14190 v691 aStanish, Lee, F.1 aKohler, Tyler, J.1 aEsposito, Rhea, M.M.1 aSimmons, Breana, L.1 aNielsen, Uffe, N.1 aWall, Diana, H.1 aNemergut, Diana, R.1 aMcKnight, Diane, M. uhttp://www.nrcresearchpress.com/doi/abs/10.1139/f2012-022#.UH2NlWcnq9g00619nas a2200193 4500008004100000245006400041210005800105260001100163300001100174490000700185100001700192700002400209700002900233700001700262700002400279700001600303700002100319856008500340 2012 eng d00aThe geochemistry of upland ponds, Taylor Valley, Antarctica0 ageochemistry of upland ponds Taylor Valley Antarctica c2/2012 a3 - 140 v241 aLyons, Berry1 aWelch, Kathleen, A.1 aGardner, Christopher, B.1 aJaros, Chris1 aMoorhead, Daryl, L.1 aKnoepfle, J1 aDoran, Peter, T. uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=848335100514nas a2200145 4500008004100000245006300041210005600104260001200160490000700172100002100179700002400200700002400224700001700248856010300265 2012 eng d00aHypersaline “wet patches” in Taylor Valley, Antarctica0 aHypersaline wet patches in Taylor Valley Antarctica c03/20120 v391 aLevy, Joseph, S.1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/hypersaline-%E2%80%9Cwet-patches%E2%80%9D-taylor-valley-antarctica00350nas a2200121 4500008004100000245003400041210003400075260001200109300001400121490000700135100002000142856006600162 2012 eng d00aLeaving scientific footprints0 aLeaving scientific footprints c11/2012 a502 - 5030 v101 aWall, Diana, H. uhttps://mcm.lternet.edu/content/leaving-scientific-footprints00548nas a2200133 4500008004100000245010500041210006900146260001200215300001400227490001200241100001600253700002300269856012200292 2012 eng d00aMeltwater seep patches increase heterogeneity of soil geochemistry and therefore habitat suitability0 aMeltwater seep patches increase heterogeneity of soil geochemist c11/2012 a652 - 6600 v189-1901 aBall, Becky1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/meltwater-seep-patches-increase-heterogeneity-soil-geochemistry-and-therefore-habitat00684nas a2200193 4500008004100000245011200041210006900153260001200222300001400234490000700248100001800255700002200273700002100295700002100316700002800337700002000365700002800385856007700413 2012 eng d00aMicrobial dynamics and flagellate grazing during transition to winter in Lakes Hoare and Bonney, Antarctica0 aMicrobial dynamics and flagellate grazing during transition to w c11/2012 a449 - 4580 v821 aThurman, Jill1 aParry, Jacqueline1 aHill, Philip, J.1 aPriscu, John, C.1 aVick-Majors, Trista, J.1 aChiuchiolo, Amy1 aLaybourn-Parry, Johanna uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01423.x/full01017nas a2200337 4500008004100000022001400041245007500055210006900130260001200199300001800211490000800229100001900237700001800256700002700274700002700301700002300328700002000351700001900371700002400390700002500414700001700439700001800456700002100474700002700495700002400522700001800546700001900564700001900583700002100602856005600623 2012 eng d a0027-842400aMicrobial life at -13  C in the brine of an ice-sealed Antarctic lake0 aMicrobial life at 13 C in the brine of an icesealed Antarctic la c12/2012 a20626 - 206310 v1091 aMurray, A., E.1 aKenig, Fabien1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aCawley, Kaelin, M.1 aEdwards, R., L.1 aKuhn, Emanuele1 aMcKnight, Diane, M.1 aOstrom, Nathaniel, E1 aPeng, Vivian1 aPonce, Adrian1 aPriscu, John, C.1 aSamarkin, Vladimir, A.1 aTownsend, Ashley, T1 aWagh, Protima1 aYoung, Seth, A1 aYung, Pung, To1 aDoran, Peter, T. uhttp://www.pnas.org/cgi/doi/10.1073/pnas.120860710902199nas a2200205 4500008004100000245013600041210006900177260003400246490000900280520151100289653001401800653001901814653001201833653001401845653002501859653001101884100002401895700002501919856004901944 2012 eng d00aModeling nitrate concentrations in an Antarctic glacial meltwater stream under fluctuating hydrologic conditions and nitrate inputs0 aModeling nitrate concentrations in an Antarctic glacial meltwate bPennsylvania State University0 vM.S.3 a

The McMurdo Dry Valleys comprise a unique polar desert ecosystem in Victoria Land, Antarctica. The hydrologic system in the Dry Valleys is often characterized as being simplified compared to temperate watersheds, due to the ability to identify physical boundaries and nutrient sources and sinks. We seek to characterize the evolution of streamflow, solutes, and nutrients along a glacial meltwater stream in the McMurdo Dry Valleys, and to understand the role of different sources and sinks under varying hydrologic conditions. The study presented here includes streamflow routing, solute modeling, and nitrate concentration modeling in Von Guerard stream, a stream with abundant algal coverage in the McMurdo Dry Valleys region of Antarctica. The streamflow model is a solution to the kinematic wave routing problem. Solute modeling addresses advection, dispersion, as well as hyporheic zone inputs, which are controlled by weathering and hyporheic exchange. Lastly, the nitrate model builds on the solute model with the addition of a gross primary production (GPP) component. Results indicate that the hyporheic source of nitrate is controlling due to rapid exchange with the main channel. GPP impacts are small due to light-saturated conditions for a majority of the season, but provide a consistent sink for nitrate. The role of advective and dispersive transport is highly dependent on flow conditions, with advective transport controlling at high flows and dispersive controlling at low flows.

10ahydrology10ahyporheic zone10anitrate10anutrients10aprimary productivity10astream1 aBernzott, Emily, D.1 aGooseff, Michael, N. uhttps://etda.libraries.psu.edu/catalog/1531600621nas a2200181 4500008004100000245010500041210006900146260001200215300001200227490000700239100002000246700002400266700001900290700001700309700002100326700002100347856007100368 2012 eng d00aPerchlorate and chlorate biogeochemistry in ice-covered lakes of the McMurdo Dry Valleys, Antarctica0 aPerchlorate and chlorate biogeochemistry in icecovered lakes of  c12/2012 a19 - 300 v981 aJackson, Andrew1 aDavila, Alfonso, F.1 aEstrada, Nubia1 aLyons, Berry1 aCoates, John, D.1 aPriscu, John, C. uhttp://www.sciencedirect.com/science/article/pii/S001670371200511X01724nam a2200385 4500008004100000020002200041245011900063210006900182260005100251300001400302490000900316520052100325100002500846700002200871700001900893700002500912700002700937700002000964700002300984700002101007700002101028700001801049700001901067700001901086700001901105700002201124700001401146700002001160700002101180700002101201700002001222700001901242700001901261856005801280 2012 eng d a978-3-642-33179-400aPoisson Reconstruction of Extreme Submersed Environments: The ENDURANCE Exploration of an Under-Ice Antarctic Lake0 aPoisson Reconstruction of Extreme Submersed Environments The END aBerlin, HeidelbergbSpringer Berlin Heidelberg a394 - 4030 v74313 a

We evaluate the use of Poisson reconstruction to generate a 3D bathymetric model of West Lake Bonney, Antarctica. The source sonar dataset has been collected by the ENDURANCE autonomous ve- hicle in the course of two Antarctic summer missions. The reconstruction workflow involved processing 200 million datapoints to generate a high resolution model of the lake bottom, Narrows region and underwater glacier face. A novel and flexible toolset has been developed to automate the processing of the Bonney data.

1 aFebretti, Alessandro1 aRichmond, Kristof1 aGulati, Shilpa1 aFlesher, Christopher1 aHogan, Bartholomew, P.1 aJohnson, Andrew1 aStone, William, C.1 aPriscu, John, C.1 aDoran, Peter, T.1 aBebis, George1 aBoyle, Richard1 aParvin, Bahram1 aKoracin, Darko1 aFowlkes, Charless1 aWang, Sen1 aChoi, Min-Hyung1 aMantler, Stephan1 aSchulze, Jürgen1 aAcevedo, Daniel1 aMueller, Klaus1 aPapka, Michael uhttp://www.springerlink.com/content/hg97w43588229087/02772nas a2200169 4500008004100000245009200041210006900133260001200202490000800214520222300222100002302445700001502468700001502483700002402498700001502522856006502537 2012 eng d00aSeismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica0 aSeismic multiplet response triggered by melt at Blood Falls Tayl c07/20120 v1173 a

Meltwater input often triggers a seismic response from glaciers and ice sheets. It is difficult, however, to measure melt production on glaciers directly, while subglacial water storage is not directly observable. Therefore, we document temporal changes in seismicity from a dry-based polar glacier (Taylor Glacier, Antarctica) during a melt season using a synthesis of seismic observation and melt modeling. We record icequakes using a dense six-receiver network of three-component geophones and compare this with melt input generated from a calibrated surface energy balance model. In the absence of modeled surface melt, we find that seismicity is well-described by a diurnal signal composed of microseismic events in lake and glacial ice. During melt events, the diurnal signal is suppressed and seismicity is instead characterized by large glacial icequakes. We perform network-based correlation and clustering analyses of seismic record sections and determine that 18% of melt-season icequakes are repetitive (multiplets). The epicentral locations for these multiplets suggest that they are triggered by meltwater produced near a brine seep known as Blood Falls. Our observations of the correspondingp-wave first motions are consistent with volumetric source mechanisms. We suggest that surface melt enables a persistent pathway through this cold ice to an englacial fracture system that is responsible for brine release episodes from the Blood Falls seep. The scalar moments for these events suggest that the volumetric increase at the source region can be explained by melt input.

1 aCarmichael, J., D.1 aPettit, E.1 aHoffman, M1 aFountain, Andrew, G1 aHallet, B. uhttp://onlinelibrary.wiley.com/doi/10.1029/2011JF002221/full03506nas a2200133 4500008004100000245006900041210006700110260004000177490000900217520305100226100002103277700002503298856004903323 2012 eng d00aSnow dynamics in a polar desert, McMurdo Dry Valleys, Antarctica0 aSnow dynamics in a polar desert McMurdo Dry Valleys Antarctica bPennsylvania State Universityc20120 vM.S.3 a

Snow in the McMurdo Dry Valleys is rare source of moisture for subnivian soils (beneath snow) in a cold desert ecosystem. While sublimation dominates the ablation process, measurable increases in soil moisture are expected to provide more favorable conditions for subnivian soil communities. In addition, snow cover insulates the underlying soil from temperature extremes. Quantifying the spatial distribution and ablation patterns of seasonal snow is necessary to understand these dynamics. Annual snowfall varies spatially ranging from 3 to 50 mm of snow water equivalent, with greater amounts occurring at the coast. Despite receiving very little precipitation, significant amounts of snow can accumulate (via aeolian redistribution) in topographic lees at the valley bottoms, forming thousands of discontinuous patches (typically 1-100 m2 in area). These patches have the potential to act as fertility islands, controlling the landscape distribution of microbial communities, and biogeochemical cycling.

High resolution imagery acquired during the 2009-2010 and 2010-2011 austral summers was used to quantify the distribution of snow across Taylor and Wright Valleys. An object-based classification was used to extract snow-covered area from the imagery. Coupled with topographic parameters, unique distribution patterns were characterized for 5 regions within the neighboring valleys. Time lapses of snow distribution during each season in each region provide insight into spatially characterizing the aerial ablation rates (change in area of landscape covered by snow) across the valleys. The distribution of snow-covered area during the 2009-2010 austral summer is used as a baseline for seasonal comparison. The surrounding regions of Lake Fryxell, Lake Hoare, Lake Bonney, Lake Brownworth, and Lake Vanda exhibited losses of snow-covered area of 9.61 km2 (-93%), 1.63 km2 (-72%), 1.07 km2 (-97%), 2.60 km2 (-82%), and 0.25 km2 (- 96%) respectively, as measured from peak accumulation in October to mid-January during the 2009-2010 season. Differences in aerial ablation rates within and across local regions suggest that both topographic variation and regional microclimates influence the ablation of seasonal snow cover. Elevation has shown to be the strongest control over aerial ablation. Fifteen 1 km2 plots (3 in each region) were selected to assess the prevalence of snow cover at smaller scales. Results confirm that snow patches form in the same locations each year with some minor deviations observed. Stable isotopes from snow patches also provide insights into temporal and spatial processes associated with ablation. At the snow patch scale, neighboring patches often exhibit considerable differences in aerial ablation rates, presumably controlled by snow depth. This highlights the importance of both the landscape and snow patch scales in assessing the effects of snow cover on biogeochemical cycling and microbial communities.

1 aEveland, Jeffery1 aGooseff, Michael, N. uhttps://etda.libraries.psu.edu/catalog/1268000474nas a2200133 4500008004100000245010000041210006900141260002700210490000900237100001200246700002000258700001700278856004500295 2012 eng d00aTaylor’s ‘missing’ lake: Integrating history into LTER research in the McMurdo Dry Valley0 aTaylor s missing lake Integrating history into LTER research in  aAlbuquerquebLTER News0 v20131 aKhan, A1 aHowkins, Adrian1 aLyons, Berry uhttp://news.lternet.edu/Article2568.html00626nas a2200181 4500008004100000245012300041210006900164260001100233300001200244490000700256100001600263700002000279700001200299700001700311700002200328700002300350856007100373 2012 eng d00aThawing permafrost alters nematode populations and soil habitat characteristics in an Antarctic polar desert ecosystem0 aThawing permafrost alters nematode populations and soil habitat  c3/2012 a75 - 810 v551 aSmith, T.E.1 aWall, Diana, H.1 aHogg, I1 aAdams, Byron1 aNielsen, Uffe, N.1 aVirginia, Ross, A. uhttp://www.sciencedirect.com/science/article/pii/S003140561100115602476nas a2200145 4500008004100000245007200041210006900113260004800182300000800230490001000238520198300248100002102231700002102252856005702273 2012 eng d00aWind as an ecological factor in the McMurdo Dry Valleys, Antarctica0 aWind as an ecological factor in the McMurdo Dry Valleys Antarcti aBozeman, MTbMontana State Universityc2012 a2010 vPh.D.3 a

The aim of this work was to investigate the role of wind on the ecology of the McMurdo Dry Valleys in Antarctica (MDV), one of the coldest and driest deserts on Earth. The MDV landscape consists of a mosaic of permanently ice-covered lakes, ephemeral streams, exposed soils, and glaciers, all of which contain habitats dominated by microorganisms. Data on wind-driven flux of sediments and associated organic matter were collected using passive aeolian traps and dynamic mass erosion particle counters to investigate the timing, direction and magnitude of aeolian sediment transport. Combination of genomic techniques and phenotypical fingerprinting (pigment analysis) was used to examine microbial diversity over a wide variety of wind-eroded habitats across the MDV landscape to elucidate the role of wind dispersal on the contemporary distribution of microorganisms across the MDVs. Sediment entrainment occurs predominantly within 20 cm of the ground surface and has character of saltation bursts that occupy <3% of the total time within a year. The high-energy winter föhn winds uplift sediments in the upper parts of the MDVs and transport them down-valley where they are deposited onto the surface of perennially ice-covered lakes and surrounding soils. The sediment that enters the water column of the lakes does not provide a significant source of organic carbon for bacterioplankton communities compared to the in situ production by phytoplankton but can be a source of new microbial propagules. The aeolian material is low in organic matter (<1% dw) but is composed of a relatively large numbers of cyanobacterial taxa (~20 OTUs) that can be found in all other MDV habitats. In conclusion, wind distributes microorganisms across the MDV landscape but local environment selects for specific taxa. Predicted climate warming will increase the importance of wind transport, which will affect nutrient cycling and connectivity among MDV ecosystem components.

1 aŠabacká, Marie1 aPriscu, John, C. uhttps://scholarworks.montana.edu/xmlui/handle/1/217100682nas a2200169 4500008004100000245014300041210006900184260001200253300001400265490000700279100001800286700001800304700001900322700002400341700002400365856012300389 2011 eng d00a15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: Evidence for a hydantoin derivative0 a15N and 13C 14N NMR investigation of the major nitrogencontainin c12/2011 a775 - 7800 v491 aFang, Xiaowen1 aMao, Jingdong1 aCory, Rose, M.1 aMcKnight, Diane, M.1 aSchmidt-Rohr, Klaus uhttps://mcm.lternet.edu/content/15n-and-13c14n-nmr-investigation-major-nitrogen-containing-segment-aquatic-fulvic-acid00530nas a2200157 4500008004100000245008700041210006900128260001200197300001600209490000700225100002200232700002000254700001700274700002300291856005800314 2011 eng d00aAntarctic nematode communities: observed and predicted responses to climate change0 aAntarctic nematode communities observed and predicted responses  c11/2011 a1701 - 17110 v341 aNielsen, Uffe, N.1 aWall, Diana, H.1 aAdams, Byron1 aVirginia, Ross, A. uhttp://www.springerlink.com/content/v588t5671p1w1323/00655nas a2200181 4500008004100000245012000041210006900161260001100230300001400241490000700255100002200262700002300284700002200307700002500329700002800354700003300382856005800415 2011 eng d00aBacterial Community Structure Along Moisture Gradients in the Parafluvial Sediments of Two Ephemeral Desert Streams0 aBacterial Community Structure Along Moisture Gradients in the Pa c4/2011 a543 - 5560 v611 aZeglin, Lydia, H.1 aDahm, Clifford, N.1 aBarrett, John, E.1 aGooseff, Michael, N.1 aFitpatrick, Shannon, K.1 aTakacs-Vesbach, Cristina, D. uhttp://www.springerlink.com/content/r83j53334v5n505w/00722nas a2200193 4500008004100000245012800041210006900169260001200238300001400250490000700264100002300271700001900294700001500313700002000328700001600348700002400364700001600388856012400404 2011 eng d00aDetermination of Dissolved Oxygen in the Cryosphere: A Comprehensive Laboratory and Field Evaluation of Fiber Optic Sensors0 aDetermination of Dissolved Oxygen in the Cryosphere A Comprehens c01/2011 a700 - 7050 v451 aBagshaw, Elizabeth1 aWadham, J., L.1 aMowlem, M.1 aTranter, Martyn1 aEveness, J.1 aFountain, Andrew, G1 aTelling, J. uhttps://mcm.lternet.edu/content/determination-dissolved-oxygen-cryosphere-comprehensive-laboratory-and-field-evaluation00571nas a2200157 4500008004100000245011700041210006900158260001200227300001400239490000700253100002600260700002600286700002200312700002100334856005800355 2011 eng d00aA diatom record of environmental change in Fryxell Basin, Taylor Valley, Antarctica, late Pleistocene to present0 adiatom record of environmental change in Fryxell Basin Taylor Va c08/2011 a257 - 2720 v461 aKonfirst, Matthew, A.1 aSjunneskog, Charlotte1 aScherer, Reed, P.1 aDoran, Peter, T. uhttp://www.springerlink.com/content/y3483576u8220081/03418nas a2200217 4500008004100000245009200041210006900133260004000202490001000242520270900252653001502961653002402976653002203000653001203022653001903034653002403053653001203077100002103089700002403110856006603134 2011 eng d00aEcological controls on stream diatom communities in the McMurdo Dry Valleys, Antarctica0 aEcological controls on stream diatom communities in the McMurdo  aBoulder, CObUniversity of Colorado0 vPh.D.3 a

 

Diatoms are vital primary producers in aquatic ecosystems and useful indicators of environmental change. In climatically sensitive polar areas, diatoms have been used as beacons of climate change, allowing us to monitor physical, chemical, and biological changes. This research aims to improve our understanding of diatom ecology in the pristine and dynamic McMurdo Dry Valleys of Antarctica, where diatoms reside in stream microbial mats. These results aid in understanding how changes in hydrologic regime will affect stream microbial communities, biodiversity, and ecosystem function in a changing environment.

Relationships between hydrologic regime and diatom community composition were investigated using long-term data. Diatom communities were structured by stream physical features, and streams with more similar hydrologic characteristics had more similar communities. Variation in diatom community composition was best explained by hydrologic regime. Small diatoms increased in relative abundances with increasing streamflow, suggesting a role of diatom size in structuring communities. Overall, diatom communities were resistant to flood and drought-like conditions, suggesting an adaptation to frequent disturbances.

The importance of hydrologic regime on drift activity was investigated during three 24- hour experiments. Diel variations in drift could be attributed to diurnal flow peaks. Biomass and diatom cell densities followed a clockwise pattern with stream discharge and support the dominant role of hydraulic processes. The quality of source material differed between seasons and throughout the day. Drifting diatom communities were dominated by Fistulifera pelliculosa, which is rarely found in stream mats and suggests a different source. Modeling results suggest that the less firmly anchored marginal mats contribute more to the drift than channel mats in low- flow seasons, while the channel mats become more important during high-flow seasons.

The relationships between diatom and bacterial assemblages in microbial mats were assessed based on phylogenetic and functional relatedness in five Dry Valley streams. Significant relationships between diatom and bacterial communities were found, and co-occurrence analysis identified numerous correlations between individual diatom and bacterial taxa. A consistency in metabolic lifestyles of correlated taxa suggests that the relationships are ecologically relevant. Diatom and bacterial diversity showed opposite patterns, which indicate differences in environmental drivers of diversity for bacteria and eukaryotes.

 

10aAntarctica10abiological sciences10acommunity ecology10adiatoms10aearth sciences10aMcMurdo Dry Valleys10astreams1 aStanish, Lee, F.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/915694114?accountid=1450300566nas a2200133 4500008004100000245008000041210006900121260006700190300001200257490000800269100002100277700002500298856010900323 2011 eng d00aEnvironmental Protection and Stewardship of Subglacial Aquatic Environments0 aEnvironmental Protection and Stewardship of Subglacial Aquatic E aBaltimorebAmerican Geophysical Union, Washington, DCc03/2011 a149-1570 v1921 aDoran, Peter, T.1 aVincent, Warwick, F. uhttps://mcm.lternet.edu/content/environmental-protection-and-stewardship-subglacial-aquatic-environments00484nam a2200121 4500008004100000020001800041245006800059210006700127260003300194100001800227700002100245856009600266 2011 eng d a0-309-21087-900aFrontiers in Understanding Climate Change and Polar Ecosystems0 aFrontiers in Understanding Climate Change and Polar Ecosystems bThe National Academies Press1 aGrebmeier, J.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/frontiers-understanding-climate-change-and-polar-ecosystems00443nas a2200145 4500008004100000022001400041245005700055210005700112260001200169300001600181490000700197100001800204700002000222856005500242 2011 eng d a0722-406000aGlobal change and Antarctic terrestrial biodiversity0 aGlobal change and Antarctic terrestrial biodiversity c11/2011 a1625 - 16270 v341 aHogg, Ian, D.1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-011-1108-900636nas a2200169 4500008004100000245009700041210006900138260001200207300001600219490000700235100002300242700002000265700001900285700002400304700001500328856012300343 2011 eng d00aHigh-resolution monitoring reveals dissolved oxygen dynamics in an Antarctic cryoconite hole0 aHighresolution monitoring reveals dissolved oxygen dynamics in a c08/2011 a2868 - 28770 v251 aBagshaw, Elizabeth1 aTranter, Martyn1 aWadham, J., L.1 aFountain, Andrew, G1 aMowlem, M. uhttps://mcm.lternet.edu/content/high-resolution-monitoring-reveals-dissolved-oxygen-dynamics-antarctic-cryoconite-hole00641nas a2200181 4500008004100000245011500041210006900156260001100225300001400236490000700250100001800257700002100275700002100296700001800317700001900335700002000354856008500374 2011 eng d00aThe Holocene environmental history of Lake Hoare, Taylor Valley, Antarctica, reconstructed from sediment cores0 aHolocene environmental history of Lake Hoare Taylor Valley Antar c6/2011 a307 - 3190 v231 aWagner, Bernd1 aOrtlepp, Sabrina1 aDoran, Peter, T.1 aKenig, Fabien1 aMelles, Martin1 aBurkemper, Andy uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=827537403517nas a2200349 4500008004100000245015900041210006900200260003400269490000900303520243200312653001502744653002002759653002402779653001402803653002802817653001702845653001302862653001402875653001402889653001302903653002402916653002002940653001402960653001702974653002102991653002103012653001503033653002003048100002503068700002503093856004903118 2011 eng d00aHydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica0 aHydrologic controls of nutrient fluxes in glacial meltwater stre bPennsylvania State University0 vM.S.3 a

In the McMurdo Dry Valleys of Antarctica, glaciers are hydrologically linked to closed-basin lakes at the valley floor by glacial meltwater streams. Streams flow through porous, well-defined channels with extensive chemically active hyporheic zones. Temporally varying dynamics of meltwater generation and sub-stream thaw depth are thought to control the potential for the hyporheic zone and benthic communities to influence transport of nutrients and dissolved ions downstream. Using the McMurdo LTER database, patterns in stream discharge, electrical conductivity (both with 15-minute sampling intervals), and solute chemistry (weekly sampling intervals) were examined on eight MDV streams from 1990-2008. Discharge and electrical conductivity values were highly variable among streams. Discharge values were highly dependent upon glacial source area, but meteorological and topographical complexities create large variability at all time scales. The longer streams were found to have much higher electrical conductivity values than the shorter streams, suggesting that there are more opportunities for hyporheic weathering reactions along longer stream reaches. Weekly sampled water solutes from each stream's entire record were plotted against the discharge recorded at the time when the sample was taken. Silicate concentrations displayed a decreasing logarithmic relationship, while nutrient concentrations had no apparent relationship. This suggests that with the exception to bioreactive solutes, the majority of hyporheic interactions could possibly be characterized by electrical conductivity and discharge. To attain information on in-stream nutrient dynamics and nutrient fluxes, glacial source water at the upper reach of Green Creek and stream outlet water at the lower reach of Green Creek were sampled hourly for two separate diel periods during the 2008-09 austral summer. Both dates were in late January under two distinct flow conditions (~0.5 L/s and ~10 L/s). Under low flow conditions, nutrient cycling was found to be uptake dominated. High flow conditions showed both uptake and regeneration with much higher nutrient loads, but as in the low flow conditions, no apparent temporal trends were found. Nutrient concentrations could not be predicted using the two parameters of discharge and electrical conductivity with in-stream nutrient dynamics likely too complicated at the sub-daily scale.

10aAntarctica10abiogeochemistry10achemical weathering10adischarge10aelectrical conductivity10aglacial melt10aglaciers10ahydrology10ahyporheic10aMCM LTER10aMcMurdo Dry Valleys10anutrient fluxes10anutrients10apolar desert10asolute chemistry10astream chemistry10astreamflow10awater chemistry1 aWeaver, Mitchell, R.1 aGooseff, Michael, N. uhttps://etda.libraries.psu.edu/catalog/1156800494nas a2200145 4500008004100000245008600041210006900127260001200196300001400208490000700222100002100229700002400250700002400274856005000298 2011 eng d00aHydrologic processes influence diatom community composition in Dry Valley streams0 aHydrologic processes influence diatom community composition in D c12/2011 a1057-10730 v301 aStanish, Lee, F.1 aNemergut, Diana, R.1 aMcKnight, Diane, M. uhttp://www.jnabs.org/doi/abs/10.1899/11-008.100581nas a2200169 4500008004100000245008600041210006900127260001200196300001400208490000600222100002500228700002400253700002100277700002400298700001700322856007200339 2011 eng d00aHydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica0 aHydrological Connectivity of the Landscape of the McMurdo Dry Va c09/2011 a666 - 6810 v51 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1749-8198.2011.00445.x00609nas a2200169 4500008004100000022001400041245010500055210006900160260001200229490002400241100001600265700002200281700002500303700002300328700002000351856006800371 2011 eng d a0800-039500aImplications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert0 aImplications of meltwater pulse events for soil biology and biog c12/20110 v30812810303525113401 aBall, Becky1 aBarrett, John, E.1 aGooseff, Michael, N.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://www.polarresearch.net/index.php/polar/article/view/1455500651nas a2200205 4500008004100000022001400041245007900055210006900134260001200203300000800215490000700223100002000230700001700250700002200267700001800289700002700307700002100334700002500355856006500380 2011 eng d a0954-102000aLong-term ecosystem networks to record change: an international imperative0 aLongterm ecosystem networks to record change an international im c06/2011 a2090 v231 aWall, Diana, H.1 aLyons, Berry1 aChown, Steven, L.1 aConvey, Peter1 aHoward-Williams, Clive1 aQuesada, Antonio1 aVincent, Warwick, F. uhttp://www.journals.cambridge.org/abstract_S095410201100031900324nas a2200121 4500008004100000245003000041210002900071250001400100260001400114490000900128100002000137856004500157 2011 eng d00aMCM IV: Getting Connected0 aMCM IV Getting Connected aFall 2011 bLTER News0 v20131 aHowkins, Adrian uhttp://news.lternet.edu/Article2316.html00668nas a2200205 4500008004100000022001400041245010700055210006900162260001200231300001600243490000700259100001900266700001600285700001800301700002400319700002000343700002400363700002000387856005500407 2011 eng d a0722-406000aMicroclimate impacts of passive warming methods in Antarctica: implications for climate change studies0 aMicroclimate impacts of passive warming methods in Antarctica im c10/2011 a1421 - 14350 v341 aBokhorst, Stef1 aHuiskes, Ad1 aConvey, Peter1 aSinclair, Brent, J.1 aLebouvier, Marc1 aVan de Vijver, Bart1 aWall, Diana, H. uhttp://link.springer.com/10.1007/s00300-011-0997-y00518nas a2200133 4500008004100000020001800041245007000059210006900129260003600198300001200234100002500246700001700271856009600288 2011 eng d a978184593687700aMolecular analysis of desiccation survival in Antarctic nematodes0 aMolecular analysis of desiccation survival in Antarctic nematode aWallingfordbCABI International a205-2321 aAdhikari, Bishwo, N.1 aAdams, Byron uhttps://mcm.lternet.edu/content/molecular-analysis-desiccation-survival-antarctic-nematodes00627nam a2200145 4500008004100000245012700041210006900168260002200237300001400259100002500273700001700298700001800315700002000333856012800353 2011 eng d00aMolecular and physiological basis of nematode survival: Molecular analyses of desiccation survival in Antarctic nematodes.0 aMolecular and physiological basis of nematode survival Molecular aWallingfordbCABI a205 - 2321 aAdhikari, Bishwo, N.1 aAdams, Byron1 aPerry, R., N.1 aWharton, D., A. uhttps://mcm.lternet.edu/content/molecular-and-physiological-basis-nematode-survival-molecular-analyses-desiccation-survival00597nas a2200169 4500008004100000245007600041210006900117260001200186300001800198490000800216100001600224700001800240700002600258700002000284700002100304856010200325 2011 eng d00aMolecular study of worldwide distribution and diversity of soil animals0 aMolecular study of worldwide distribution and diversity of soil  c10/2011 a17720 - 177250 v1081 aWu, Tiehang1 aAyres, Edward1 aBardgett, Richard, D.1 aWall, Diana, H.1 aGarey, James, R. uhttps://mcm.lternet.edu/content/molecular-study-worldwide-distribution-and-diversity-soil-animals00632nas a2200181 4500008004100000245008400041210006900125260001100194300001400205490000700219100002200226700002000248700001400268700001700282700001700299700002300316856011100339 2011 eng d00aNematode communities of Byers Peninsula, Livingston Island, maritime Antarctica0 aNematode communities of Byers Peninsula Livingston Island mariti c8/2011 a349 - 3570 v231 aNielsen, Uffe, N.1 aWall, Diana, H.1 aLi, Grace1 aToro, Manuel1 aAdams, Byron1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematode-communities-byers-peninsula-livingston-island-maritime-antarctica00623nas a2200181 4500008004100000245010000041210006900141260001100210300001600221490000600237100002100243700002100264700001800285700002000303700002100323700002900344856006800373 2011 eng d00aProtist diversity in a permanently ice-covered Antarctic Lake during the polar night transition0 aProtist diversity in a permanently icecovered Antarctic Lake dur c9/2011 a1559 - 15640 v51 aBielewicz, Scott1 aBell, Elanor, R.1 aKong, Weidong1 aFriedberg, Iddo1 aPriscu, John, C.1 aMorgan-Kiss, Rachael, M. uhttp://www.nature.com/ismej/journal/v5/n9/abs/ismej201123a.html02193nas a2200145 4500008004100000245014200041210006900183260004000252300000800292490001000300520162300310100002401933700002401957856006601981 2011 eng d00aRemoval of benthic algae in swift-flowing streams: The significance of spatial and temporal variation in shear stress and bed disturbance0 aRemoval of benthic algae in swiftflowing streams The significanc aBoulder, CObUniversity of Colorado a2630 vPh.D.3 a

 

In this thesis I investigate the role of spatial and temporal dynamics of flow, bed shear stress, and bed disturbance on the removal of benthic algal and the consequences for our understanding of the dynamics of stream ecosystems and the transport of organic matter in fluvial systems. I use data obtained from two specific case studies where benthic algal mats are key components in the overall system dynamics. The first case study investigates spatial and temporal variations in particular organic matter transport derived from the removal of benthic algae in a stream in the McMurdo Dry Valleys of Antarctica. The second case study uses a combination of field observations and analysis, one and two dimensional hydraulic modeling, and laboratory flume studies to investigate the controls on the removal of the stalk forming diatom Didymosphenia geminata. The results show that benthic algae growing in swift-flowing streams are well adapted to this environment. Hence the removal of organic material due to elevated shear stress alone is limited and effective control of nuisance blooms of benthic algae such as D. geminata requires flood events sufficiently high enough to results in wide spread disturbance of the stream substrate. These flow requirements are similar to the requirements for channel maintenance flows and could therefore be considered for inclusion in the operating rules for dams in order to maintain the diversity of stream ecosystems and functioning water supply infrastructure.

 

1 aCullis, James, D.S.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/916604693?accountid=1450300608nas a2200133 4500008004100000245016200041210006900203260000900272490000700281100001300288700002400301700002100325856012800346 2011 eng d00aSimulating unsteady flow, anabranching, and hyporheic dynamics in a glacial meltwater stream using a coupled surface water routing and groundwater flow model0 aSimulating unsteady flow anabranching and hyporheic dynamics in  c20110 v471 aKoch, J.1 aMcKnight, Diane, M.1 aNeupauer, R., M. uhttps://mcm.lternet.edu/content/simulating-unsteady-flow-anabranching-and-hyporheic-dynamics-glacial-meltwater-stream-using00519nas a2200121 4500008004100000245009200041210006900133260004900202300000800251490001000259100001500269856011300284 2011 eng d00aSpatial and Temporal Variability of Glacier Melt in the McMurdo Dry Valleys, Antarctica0 aSpatial and Temporal Variability of Glacier Melt in the McMurdo  aPortlandbPortland State Universityc01/2011 a2960 vPh.D.1 aHoffman, M uhttps://mcm.lternet.edu/content/spatial-and-temporal-variability-glacier-melt-mcmurdo-dry-valleys-antarctica00685nam a2200193 4500008004100000020002200041245010600063210006900169260003600238300001400274490000800288100001900296700002500315700002400340700002300364700002600387700002000413856005800433 2011 eng d a978-94-007-1363-500aSpectral Methods to Advance Understanding of Dissolved Organic Carbon Dynamics in Forested Catchments0 aSpectral Methods to Advance Understanding of Dissolved Organic C aDordrechtbSpringer Netherlands a117 - 1350 v2161 aCory, Rose, M.1 aBoyer, Elizabeth, W.1 aMcKnight, Diane, M.1 aLevia, Delphis, F.1 aCarlyle-Moses, Darryl1 aTanaka, Tadashi uhttp://www.springerlink.com/content/lv9365ml54192m29/00630nas a2200169 4500008004100000245013600041210006900177260001200246300001400258490000800272100002100280700002400301700002500325700002400350700001700374856006900391 2011 eng d00aWater tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem0 aWater tracks and permafrost in Taylor Valley Antarctica Extensiv c11/2011 a2295-23110 v1231 aLevy, Joseph, S.1 aFountain, Andrew, G1 aGooseff, Michael, N.1 aWelch, Kathleen, A.1 aLyons, Berry uhttp://bulletin.geoscienceworld.org/content/123/11-12/2295.short00776nas a2200229 4500008004100000245011100041210006900152260001200221300001400233490000700247100002700254700001900281700002000300700001900320700002800339700002000367700001700387700002300404700001800427700002400445856007700469 2011 eng d00aWhen a habitat freezes solid: microorganisms over-winter within the ice column of a coastal Antarctic lake0 aWhen a habitat freezes solid microorganisms overwinter within th c06/2011 a401 - 4120 v761 aForeman, Christine, M.1 aDieser, Markus1 aGreenwood, Mark1 aCory, Rose, M.1 aLaybourn-Parry, Johanna1 aLisle, John, T.1 aJaros, Chris1 aMiller, Penney, L.1 aChin, Yu-Ping1 aMcKnight, Diane, M. uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2011.01061.x/full00655nas a2200193 4500008004100000245008400041210006900125260001100194300001400205490000600219100002700225700002500252700002500277700002500302700002100327700002700348700002300375856006300398 2010 eng d00aAbiotic nitrous oxide emission from the hypersaline Don Juan Pond in Antarctica0 aAbiotic nitrous oxide emission from the hypersaline Don Juan Pon c5/2010 a341 - 3440 v31 aSamarkin, Vladimir, A.1 aMadigan, Michael, T.1 aBowles, Marshall, W.1 aCasciotti, Karen, L.1 aPriscu, John, C.1 aMcKay, Christopher, P.1 aJoye, Samantha, B. uhttp://www.nature.com/ngeo/journal/v3/n5/full/ngeo847.html05611nas a2200229 4500008004100000245006100041210006000102260004000162490000900202520491500211653002205126653001505148653000905163653002605172653001705198653002405215653002405239653001505263100002505278700001705303856006105320 2010 eng d00aAeolian sediments of the McMurdo Dry Valleys, Antarctica0 aAeolian sediments of the McMurdo Dry Valleys Antarctica aColumbus, OHbOhio State University0 vM.S.3 a

The role of dust has become a topic of increasing interest in the interface between climate and geological/ecological sciences. Dust emitted from major sources, the majority of which are desert regions in the Northern Hemisphere, is transported via suspension in global wind systems and incorporated into the biogeochemical cycles of the ecosystems where it is ultimately deposited. While emissions within the McMurdo Dry Valleys (MDV) region of Antarctica are small compared to other source regions, the redistribution of new, reactive material by wind may be important to sustaining life in the ecosystem.


The interaction of the dry, warm foehn winds and the cool, moist coastal breezes “recycles” soil particles throughout the landscape. The bulk of sediment movement occurs during foehn events in the winter that redistribute material throughout the MDV. To understand the source and transfer of this material samples were collected early in the austral summer (November 2008) prior to the initiation of extensive ice melt from glacial and lake surfaces, aeolian landforms, and elevated sediment traps. These were preserved and processed for grain size distribution and major element composition at the sand and silt particle sizes. Major elemental oxide analysis indicated that the silt and sand size particles are of different composition: SiO2 values for silt range from 50 to 59% by weight and for sand range from 59 to 74%. When compared to the elemental oxide composition four rock types present in the MDV, the composition of the silt indicates a mixing influenced mostly by the igneous rock types (Ferrar Dolerite and McMurdo Volcanic basanite) and sand a mixing influenced largely by the sedimentary rocks (Beacon Sandstone and the metasedimentary Basement Complex). This could imply a local source of the aeolian material that is corroborated by low CIA values at both particle sizes (44-57%) indicating low degrees of chemical weathering. In addition, comparison of 87Sr/86Sr and 143Nd/144Nd to values published for the major MDV rock types and ice core dust to values analyzed in 3 silt size glacier sample and one bulk glacier sample also indicates a local source of sediments and that it is not likely to be transferred inland.


During the melt season, the aeolian material is actively solubilized where it interacts with water, releasing solutes and vital bioavailable nutrients throughout the aquatic system. Differences in the chemistry of supra- and proglacial streams as well as lake surface waters may be derived from the deposition and dissolution of these aeolian sediments. To simulate these conditions, a two-step leaching method using deionized water to represent glacial melt in field conditions was employed and leachates analyzed for major ion and nutrient constituents. Leachates represent a small degree (<0.7%) of dissolution of major elements, and are solubilized to a greater extent from samples closer to the coast or with increased silt content. The composition of the leachates reflects the dissolution of the major salts found in the MDV. Leach 1 (cold water) indicates that Na- and Cl-bearing salt phases are dissolved to a greater extent than seen in Leach 2 (freeze-thaw). Conversely, Leach 2 compositions indicate that carbonate mineral dissolution and Mg-bearing silicate weathering are proceeding to a greater extent than in Leach 1.


Inorganic N:P ratios follow the same patterns of nutrient limitations based on the Redfield Ratio found by Priscu (1995) in the terminal lakes of the Taylor Valley: N-limited in the Fryxell and Hoare basins (east) and P-limited in the Bonney basin (west). This is also consistent with the age of the tills in the area, as found by Gudding (2003). The concentration of soluble Fe in the leachates is about the same as soluble inorganic P, and thus is not a limiting nutrient in the leachates. Comparison of total dissolved N and P to their inorganic counterparts reveals increased organic nutrients in the glacier and lake leachates that may indicate the influence of biota. Nutrient fluxes based on known sediment fluxes from elevated sediment traps deployed throughout the MDV and the composition of these leachates range from 0.34-330 g a-1 for N, 0.02-8.3 g a-1 for P, and 0.03-8.6 g a-1 for Fe. These are at least two orders of magnitude less than calculated loads from streams to the lakes in the Taylor Valley and, thus, should be considered underestimations or minima.


This work provides the first investigation into the composition and source of aeolian transported materials in the MDV, as well of what is potentially solubilized from it during the austral summer melt season. In addition, it will contribute to the understanding of the interplay between aeolian and aquatic processes in the MDV and further the understanding of this unique ecosystem.

10aaeolian transport10aAntarctica10adust10aexperimental leaching10ageochemistry10aMcMurdo Dry Valleys10asediment provenance10aweathering1 aDeuerling, Kelly, M.1 aLyons, Berry uhttp://rave.ohiolink.edu/etdc/view?acc_num=osu129052486200618nas a2200169 4500008004100000245011400041210006900155260001200224300001800236490000800254100002100262700002300283700002400306700002100330700002600351856007100377 2010 eng d00aAntarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation0 aAntarctic lakes suggest millennial reorganizations of Southern H c12/2010 a21355 - 213590 v1071 aHall, Brenda, L.1 aDenton, George, H.1 aFountain, Andrew, G1 aHendy, Chris, H.1 aHenderson, Gideon, M. uhttp://www.pnas.org/content/107/50/21355.full.pdf#page=1&view=FitH00722nas a2200193 4500008004100000020001800041245008800059210006900147260004200216300001400258100002500272700002400297700001700321700001700338700002100355700001700376700002400393856011100417 2010 eng d a978052188919300aAntarctic McMurdo Dry Valley stream ecosystems as analog to fluvial systems on Mars0 aAntarctic McMurdo Dry Valley stream ecosystems as analog to fluv aCambridgebCambridge University Press a139 - 1591 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aCarr, M., H.1 aBaeseman, J.1 aDoran, Peter, T.1 aLyons, Berry1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/antarctic-mcmurdo-dry-valley-stream-ecosystems-analog-fluvial-systems-mars00639nas a2200169 4500008004100000245009600041210006900137260001200206300002800218490000900246100002500255700002500280700001000305700002000315700001700335856011700352 2010 eng d00aThe Antarctic Nematode Plectus murrayi: An Emerging Model to Study Multiple Stress Survival0 aAntarctic Nematode Plectus murrayi An Emerging Model to Study Mu c11/2010 apdb.emo142 - pdb.emo1420 v20101 aAdhikari, Bishwo, N.1 aTomasel, Cecilia, M.1 aLi, G1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/antarctic-nematode-plectus-murrayi-emerging-model-study-multiple-stress-survival02548nas a2200145 4500008004100000245011900041210006900160260004800229300000700277490000900284520200300293100002802296700002102324856005702345 2010 eng d00aBacterioplakton dynamics in stratified lakes of the Taylor Valley, Antarctica during the transition to polar night0 aBacterioplakton dynamics in stratified lakes of the Taylor Valle aBozeman, MTbMontana State Universityc2010 a830 vM.S.3 a

Limnological research on the lakes of the McMurdo Dry Valleys (MCM), Antarctica, is typically carried out during the austral spring-summer (October January) when logistical support is readily available; the current study marks the first sampling effort during the summer-fall transition (January-April). Sampling during the darkness of winter is logistically difficult and expensive, and my study is an important step towards understanding the year-round ecology of the dry valley lakes. Bacterial productivity, measured as protein synthesis and DNA replication, and bacterial cell numbers were measured 10-12 times between October 2007 and April 2008 in Lakes Fryxell (FRX) and the east and west lobes of Lake Bonney (ELB and WLB). Lake Fryxell was the most productive (bacterial) lake on average by an order of magnitude (average = 1.24 mg C m -²d -¹; range = 0.00 to 3.29 mg C m -²d -¹), and also contained the greatest bacterial biomass (~10 ⁶ cells ml -¹) by 1 to 3 orders of magnitude. If bacterial production were directly linked to organic carbon supplied by photosynthetic primary production, a decrease in bacterial production would be expected during the sunset; however, no statistically significant change in bacterial production (a=0.05) was observed during the summer-fall transition. A distinct decoupling of bacterial protein production and DNA replication was detected in FRX and ELB of the lakes as the season progressed, and was present in WLB throughout the season, indicating either a shift towards a lower growth-rate in response to decreasing light or nutrient supply, or a mechanism for dealing with the perennially low temperatures, low light, and nutrient poor conditions in the lakes. Overall, it appears that bacterial communities remain active during the darkness of winter, when the lakes enter a period of "net heterotrophy", which cannot be sustained unless the carbon balance of the TV lakes is reset by climatic events.

1 aVick-Majors, Trista, J.1 aPriscu, John, C. uhttps://scholarworks.montana.edu/xmlui/handle/1/247700620nas a2200205 4500008004100000245005400041210005300095260000900148490000700157100001900164700002000183700001600203700001900219700002100238700001700259700001400276700001300290700002600303856008500329 2010 eng d00aBiogeochemical weathering under ice: Size matters0 aBiogeochemical weathering under ice Size matters c20100 v241 aWadham, J., L.1 aTranter, Martyn1 aSkidmore, M1 aHodson, A., J.1 aPriscu, John, C.1 aLyons, Berry1 aSharp, M.1 aWynn, P.1 aJackson, Margaret, S. uhttps://mcm.lternet.edu/content/biogeochemical-weathering-under-ice-size-matters00601nas a2200145 4500008004100000245009600041210006900137260004200206300001200248100002000260700002300280700002400303700001500327856011300342 2010 eng d00aThe biogeochemistry and hydrology of Dry Valley glaciers: is there life on Martian ice now?0 abiogeochemistry and hydrology of Dry Valley glaciers is there li aCambridgebCambridge University Press a195-2201 aTranter, Martyn1 aBagshaw, Elizabeth1 aFountain, Andrew, G1 aForman, C. uhttps://mcm.lternet.edu/content/biogeochemistry-and-hydrology-dry-valley-glaciers-there-life-martian-ice-now00534nas a2200169 4500008004100000245005300041210005300094260001200147300003200159490000900191100002500200700002500225700001000250700002000260700001700280856006700297 2010 eng d00aCulturing the Antarctic Nematode Plectus murrayi0 aCulturing the Antarctic Nematode Plectus murrayi c11/2010 apdb.prot5522 - pdb.prot55220 v20101 aAdhikari, Bishwo, N.1 aTomasel, Cecilia, M.1 aLi, G1 aWall, Diana, H.1 aAdams, Byron uhttp://cshprotocols.cshlp.org/content/2010/11/pdb.emo142.short00861nas a2200253 4500008004100000245013000041210006900171260001200240300001400252490000800266100001300274700002600287700001500313700001400328700002200342700001500364700001500379700001500394700001400409700001600423700002100439700002100460856012600481 2010 eng d00aDesign and deployment of a four-degrees-of-freedom hovering autonomous underwater vehicle for sub-ice exploration and mapping0 aDesign and deployment of a fourdegreesoffreedom hovering autonom c11/2010 a341 - 3610 v2241 aStone, W1 aHogan, Bartholomew, P1 aFlesher, C1 aGulati, S1 aRichmond, Kristof1 aMurarka, A1 aKuhlman, G1 aIdharan, M1 aSiegel, V1 aPrice, R, M1 aDoran, Peter, T.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/design-and-deployment-four-degrees-freedom-hovering-autonomous-underwater-vehicle-sub-ice00711nas a2200181 4500008004100000020001800041245009200059210006900151250000600220260003100226100002500257700002400282700001500306700002400321700001900345700002100364856014400385 2010 eng d a978052150996100aDiatoms as indicators of environmental change in Antarctic and subantarctic freshwaters0 aDiatoms as indicators of environmental change in Antarctic and s a2 bCambridge University Press1 aSpaulding, Sarah, A.1 aVan de Vijver, Bart1 aHodgson, D1 aMcKnight, Diane, M.1 aVerleyen, Elie1 aStanish, Lee, F. uhttp://www.cambridge.org/us/academic/subjects/life-sciences/plant-science/diatoms-applications-environmental-and-earth-sciences-2nd-edition00667nas a2200169 4500008004100000245011600041210006900157260001200226300001400238490000700252100002300259700002000282700001900302700002400321700002400345856012800369 2010 eng d00aDynamic behaviour of supraglacial lakes on cold polar glaciers: Canada Glacier, McMurdo Dry Valleys, Antarctica0 aDynamic behaviour of supraglacial lakes on cold polar glaciers C c06/2010 a366 - 3680 v561 aBagshaw, Elizabeth1 aTranter, Martyn1 aWadham, J., L.1 aFountain, Andrew, G1 aBasagic, Hassan, J. uhttps://mcm.lternet.edu/content/dynamic-behaviour-supraglacial-lakes-cold-polar-glaciers-canada-glacier-mcmurdo-dry-valleys00571nas a2200145 4500008004100000245009100041210006900132260001500201300001200216100001700228700002400245700002100269700002400290856011100314 2010 eng d00aA dynamic physical model for soil temperature and water in Taylor Valley, Antarctica.0 adynamic physical model for soil temperature and water in Taylor  c05/13/2010 a419-4341 aHunt, H., W.1 aFountain, Andrew, G1 aDoran, Peter, T.1 aBasagic, Hassan, J. uhttps://mcm.lternet.edu/content/dynamic-physical-model-soil-temperature-and-water-taylor-valley-antarctica00568nas a2200169 4500008004100000245009500041210006900136260001200205300001000217490000600227100001900233700002300252700002400275700002200299700002300321856005400344 2010 eng d00aEffect of instrument-specific response on the analysis of fulvic acid fluorescence spectra0 aEffect of instrumentspecific response on the analysis of fulvic  c07/2010 a67-780 v81 aCory, Rose, M.1 aMiller, Mathew, P.1 aMcKnight, Diane, M.1 aGuerard, Jennifer1 aMiller, Penney, L. uhttp://www.aslo.org/lomethods/free/2010/0067.html00587nas a2200145 4500008004100000245011100041210006900152260001200221300001600233490000800249100002500257700002000282700001700302856012200319 2010 eng d00aEffect of slow desiccation and freezing on gene transcription and stress survival of an Antarctic nematode0 aEffect of slow desiccation and freezing on gene transcription an c06/2010 a1803 - 18120 v2131 aAdhikari, Bishwo, N.1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/effect-slow-desiccation-and-freezing-gene-transcription-and-stress-survival-antarctic02203nas a2200217 4500008004100000245008900041210006900130260001200199300001100211490000800222520155200230653001501782653002601797653002301823653002101846653001801867100001301885700002401898700001701922856004601939 2010 eng d00aEffect of unsteady flow on nitrate loss in an oligotrophic, glacial meltwater stream0 aEffect of unsteady flow on nitrate loss in an oligotrophic glaci c03/2010 aG010010 v1153 a

The McMurdo Dry Valleys of Antarctica are among the coldest, driest ecosystems on Earth. During the austral summer, glacial meltwater supports cyanobacterial mat communities in some streams, but they are not ubiquitous. We conducted a nitrate (NO3-) enrichment tracer injection in Huey Creek to quantify NO3- loss in a Dry Valley stream where algal mats would not obscure hyporheic microbial processes. Unsteady streamflow led to diel variability in the tracer concentration and in surface/subsurface water and solute exchange. Subsequently, concentrations of NO3-, nitrite (NO2-), ammonium (NH4+), and dissolved organic carbon (DOC) varied significantly during the injection, with a net loss of NO3-, NO2-, and DOC, and production of nitrous oxide. These mass changes within a reach were often coincident with high streamflows. Reactivity also coincided with the highest DOC concentrations, suggesting that DOC is the primary limitation to heterotrophic microbial activity in the stream. Together, streamflow and DOC availability create the hot spots and hot moments that dominate NO3- reactivity and removal in this polar desert ecosystem. The combination of spatially and temporally variable hyporheic dynamics and solute availability underscore the limitations of common nutrient uptake metrics and transient storage models when unsteady flow conditions exist.

10aAntarctica10ahot spots/hot moments10ahyporheic exchange10anitrogen cycling10aunsteady flow1 aKoch, J.1 aMcKnight, Diane, M.1 aBaeseman, J. uhttp://doi.wiley.com/10.1029/2009JG00103000528nas a2200121 4500008004100000245010100041210006900142260003000211490000900241100001300250700002400263856011900287 2010 eng d00aAn Energy Balance Model of Melt-water Production for Polar Glaciers in Taylor Valley, Antarctica0 aEnergy Balance Model of Meltwater Production for Polar Glaciers  bPortland State University0 vM.S.1 aEbnet, J1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/energy-balance-model-melt-water-production-polar-glaciers-taylor-valley-antarctica00756nas a2200205 4500008004100000245011700041210006900158260001100227300001400238490000700252100001800259700002200277700002000299700001700319700002200336700002400358700002300382700002400405856012100429 2010 eng d00aExperimentally increased snow accumulation alters soil moisture and animal community structure in a polar desert0 aExperimentally increased snow accumulation alters soil moisture  c7/2010 a897 - 9070 v331 aAyres, Edward1 aNkem, Johnson, N.1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aSimmons, Breana, L.1 aVirginia, Ross, A.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/experimentally-increased-snow-accumulation-alters-soil-moisture-and-animal-community00641nas a2200181 4500008004100000020001800041245006900059210006900128260003100197300001200228490000600240100003300246700002200279700002500301700002200326700002100348856009000369 2010 eng d a978052188919300aFactors promoting microbial diversity in the McMurdo Dry Valleys0 aFactors promoting microbial diversity in the McMurdo Dry Valleys bCambridge University Press a221-2570 v51 aTakacs-Vesbach, Cristina, D.1 aZeglin, Lydia, H.1 aGooseff, Michael, N.1 aBarrett, John, E.1 aPriscu, John, C. uhttp://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258&cid=CBO9780511712258A01503656nas a2200337 4500008004100000245005700041210005600098260004900154490001000203520257600213653001802789653002302807653003202830653003002862653001602892653002402908653003402932653002402966653002402990653002003014653005103034653002403085653001803109653002003127653003003147653002403177653003003201100002503231700001703256856004503273 2010 eng d00aGenomic analysis of nematode-environment interaction0 aGenomic analysis of nematodeenvironment interaction aProvo, UTbBrigham Young Universityc08/20100 vPh.D.3 a

The natural environments of organisms present a multitude of biotic and abiotic challenges that require both short-term ecological and long-term evolutionary responses. Though most environmental response studies have focused on effects at the ecosystem, community and organismal levels, the ultimate controls of these responses are located in the genome of the organism. Soil nematodes are highly responsive to, and display a wide variety of responses to changing environmental conditions, making them ideal models for the study of organismal interactions with their environment. In an attempt to examine responses to environmental stress (desiccation and freezing), genomic level analyses of gene expression during anhydrobiosis of the Antarctic nematode Plectus murrayi was undertaken. An EST library representative of the desiccation induced transcripts was established and the transcripts differentially expressed during desiccation stress were identified. The expressed genome of P. murrayi showed that desiccation survival in nematodes involves differential expression of a suite of genes from diverse functional areas, and constitutive expression of a number of stress related genes. My study also revealed that exposure to slow desiccation and freezing plays an important role in the transcription of stress related genes, improves desiccation and freezing survival of nematodes. Deterioration of traits essential for biological control has been recognized in diverse biological control agents including insect pathogenic nematodes. I studied the genetic mechanisms behind such deterioration using expression profiling. My results showed that trait deterioration of insect pathogenic nematode induces substantial overall changes in the nematode transcriptome and exhibits a general pattern of metabolic shift causing massive changes in metabolic and other processes. Finally, through field observations and molecular laboratory experiments the validity of the growth rate hypothesis in natural populations of Antarctic nematodes was tested. My results indicated that elemental stoichiometry influences evolutionary adaptations in gene expression and genome evolution. My study, in addition to providing immediate insight into the mechanisms by which multicellular animals respond to their environment, is transformative in its potential to inform other fundamental ecological and evolutionary questions, such as the evolution of life-history patterns and the relationship between community structure and ecological function in ecosystems.

10aanhydrobiosis10aAntarctic nematode10acomparative transcriptomics10acomplementary DNA library10adesiccation10afunctional analysis10aHeterorhabditis bacteriophora10aMcMurdo Dry Valleys10amicroarray analysis10aPlectus murrayi10aquantative real-time polymerase chain reaction10aScottnema lindsayae10astoichiometry10astress survival10asubtractive hybridization10atrait deterioration10atranscriptional profiling1 aAdhikari, Bishwo, N.1 aAdams, Byron uhttps://scholarsarchive.byu.edu/etd/257803183nas a2200229 4500008004100000245011200041210006900153260004600222300000800268490001000276520245700286653001102743653001502754653001902769653001302788653001302801653001502814653003702829100001302866700002402879856005002903 2010 eng d00aHydrologic and biogeochemical implications of flooding in two catchments underlain by continuous permafrost0 aHydrologic and biogeochemical implications of flooding in two ca aBoulder, CObUniversity of Coloradoc2010 a2060 vPh.D.3 a

Flooding is a critical driver of ecosystem productivity. By rapidly increasing stream stage and velocity, floods mix water and solutes from the stream, hyporheic zone, and floodplains/riparian areas. Such mixing may spur biogeochemical activity. In catchments underlain by permafrost, flooding is more common due to both the potential for rapid ice melting and minimal storage potential in frozen soils. High latitude environments are often underlain by permafrost and are also areas of biogeochemical interest, due to large stores of carbon (C) and nitrogen (N), and the potential for rapid cycling. The increased complexity in groundwater/surface water hydrology during floods requires rigorous hydrologic analysis before biogeochemical trends can be correctly interpreted. This research aims to accurately quantify the hydrology and biogeochemical cycling of C and N in two high-latitude catchments utilizing stream tracer additions, synoptic sampling, and surface water (sw), groundwater (gw), and coupled sw/gw flow models.

Two catchments, in Alaska and Antarctica represent very different ecosystems, both characterized by continuous permafrost and shallow aquifers. In Antarctica, coupled surface water/groundwater flow modeling and tracer additions identify sources of DOC (dissolved organic carbon) and locations of denitrification. Mass balance calculations identify heightened water/sediment interactions at high flows, and increased C and N uptake when solutes return to the stream during low flows. In Alaska, discharge correlates to DOC and nitrate concentrations, indicating leaching and flushing of organic material from the hillslope during high discharge, with a greater potential for microbial processing of this organic material during low flows. Multiple tracer additions demonstrate a seasonal trend, with the greatest C and N uptake early in the summer, potentially related to shallower flowpaths.

Differences between discharge, flooding, and C and N cycling in these two catchments indicate the importance of stream size and morphology. Using tracer dilution and major ion and uranium isotope chemistry, we identify preferential flow near and beneath the stream, indicating erosion of the stream bed via soil piping and thermokarsting. We propose that channel evolution will lead to decreased stream/catchment interactions and subsequently decreased C and N uptake potential in these high-latitude catchments.

10acarbon10acatchments10aearth sciences10aflooding10anitrogen10apermafrost10asurface-groundwater interactions1 aKoch, J.1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/83900886502518nas a2200205 4500008004100000245010700041210006900148260003400217490000700251520182600258653002502084653003402109653002402143653002702167653002202194653001102216100002502227700002202252856003802274 2010 eng d00aLandscape history and contemporary environmental drivers of microbial community structure and function0 aLandscape history and contemporary environmental drivers of micr aBlacksburg, VAbVirginia Tech0 vMS3 a

Recent work in microbial ecology has focused on elucidating controls over biogeographic patterns and connecting microbial community composition to ecosystem function. My objective was to investigate the relative influences of landscape legacies and contemporary environmental factors on the distribution of soil microbial communities and their contribution to ecosystem processes across a glacial till sequence in Taylor Valley, Antarctica. Within each till unit, I sampled from dry areas and areas with visible evidence of recent surface water movement generated by seasonal melting of ephemeral snow packs and hillslope ground ice. Using T-RFLP 16S rRNA gene profiles of microbial communities, I analyzed the contribution of till and environmental factors to community similarity, and assessed the functional potential of the microbial community using extracellular enzyme activity assays. Microbial communities were influenced by geochemical differences among both tills and local environments, but especially organized by variables associated with water availability as the first axis of an NMDS ordination was strongly related to shifts in soil moisture content. CCA revealed that tills explained only 3.4% of the variability in community similarity among sites, while geochemical variables explained 18.5%. Extracellular enzyme activity was correlated with relevant geochemical variables reflecting the influence of nutrient limitation on microbial activity. In addition, enzyme activity was related to changes in community similarity, particularly in wet environments with a partial Mantel correlation of 0.32. These results demonstrate how landscape history and environmental conditions can shape the functional potential of a microbial community mediated through shifts in microbial community composition.

10acommunity similarity10aextracellular enzyme activity10aMcMurdo Dry Valleys10amicrobial biogeography10asoil geochemistry10aT-RFLP1 aAltrichter, Adam, E.1 aBarrett, John, E. uhttp://hdl.handle.net/10919/3188300672nas a2200157 4500008004100000245016900041210006900210260001200279300001400291490000700305100002700312700001200339700002400351700001700375856012200392 2010 eng d00aLatitudinal distribution and mitochondrial DNA (COI) variability of Stereotydeus spp. (Acari: Prostigmata) in Victoria Land and the central Transantarctic Mountains0 aLatitudinal distribution and mitochondrial DNA COI variability o c12/2010 a749 - 7560 v221 aDemetras, Nicholas, J.1 aHogg, I1 aBanks, Jonathan, C.1 aAdams, Byron uhttps://mcm.lternet.edu/content/latitudinal-distribution-and-mitochondrial-dna-coi-variability-stereotydeus-spp-acari00667nas a2200169 4500008004100000020001800041245012500059210006900184260004200253300001300295490000600308100002200314700001300336700002500349700003300374856009000407 2010 eng d a978052188919300aThe legacy of aqueous environments on soils of the McMurdo Dry Valleys: contexts for future exploration of martian soils0 alegacy of aqueous environments on soils of the McMurdo Dry Valle aCambridgebCambridge University Press a78 - 1090 v51 aBarrett, John, E.1 aPoage, M1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D. uhttp://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258&cid=CBO9780511712258A01000763nam a2200241 4500008004100000020001800041245005800059210005800117260004300175300000800218490000600226653002200232100002100254700001700275700002400292700002400316700002500340700003300365700002200398700002000420700001800440856006300458 2010 eng d a978051171225800aLife in Antarctic Deserts and Other Cold Environments0 aLife in Antarctic Deserts and Other Cold Environments aCambridgebCambridge University Press. a3070 v510aPlanetary Science1 aDoran, Peter, T.1 aLyons, Berry1 aMcKnight, Diane, M.1 aMcKnight, Diane, M.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D.1 aMikucki, Jill, A.1 aTranter, Martyn1 aSun, Henry, J uhttp://ebooks.cambridge.org/ebook.jsf?bid=CBO978051171225800474nas a2200109 4500008004100000245008300041210006900124260002700193100001400220700002400234856010600258 2010 eng d00aMicrobial interactions with dissolved organic matter in saline natural waters0 aMicrobial interactions with dissolved organic matter in saline n bUniversity of Colorado1 aCawley, K1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/microbial-interactions-dissolved-organic-matter-saline-natural-waters00662nas a2200181 4500008004100000245013300041210006900174260001200243300001400255490000800269100002400277700002200301700002000323700002100343700001800364700002700382856007100409 2010 eng d00aNew insights into the origin and evolution of Lake Vida, McMurdo Dry Valleys, Antarctica — A noble gas study in ice and brines0 aNew insights into the origin and evolution of Lake Vida McMurdo  c01/2010 a112 - 1220 v2891 aMalone, Jessica, L.1 aCastro, Clara, M.1 aHall, Chris, M.1 aDoran, Peter, T.1 aKenig, Fabien1 aMcKay, Christopher, P. uhttp://www.sciencedirect.com/science/article/pii/S0012821X0900633500684nas a2200169 4500008004100000245012300041210006900164260001100233300001400244490000700258100002800265700002400293700002900317700002100346700001800367856012900385 2010 eng d00aOrigin and tentative identification of tri to pentaunsaturated ketones in sediments from Lake Fryxell, East Antarctica0 aOrigin and tentative identification of tri to pentaunsaturated k c4/2010 a386 - 3970 v411 aJaraula, Caroline, M.B.1 aBrassell, Simon, C.1 aMorgan-Kiss, Rachael, M.1 aDoran, Peter, T.1 aKenig, Fabien uhttps://mcm.lternet.edu/content/origin-and-tentative-identification-tri-pentaunsaturated-ketones-sediments-lake-fryxell-east00643nas a2200169 4500008004100000245011300041210006900154260001200223300001400235490000700249100001800256700002100274700001800295700002100313700001900334856012000353 2010 eng d00aPalaeoenvironmental implications derived from a piston core from east lobe Bonney, Taylor Valley, Antarctica0 aPalaeoenvironmental implications derived from a piston core from c10/2010 a522 - 5300 v221 aWagner, Bernd1 aOrtlepp, Sabrina1 aKenig, Fabien1 aDoran, Peter, T.1 aMelles, Martin uhttps://mcm.lternet.edu/content/palaeoenvironmental-implications-derived-piston-core-east-lobe-bonney-taylor-valley00627nas a2200145 4500008004100000245010900041210006900150100001700219700001700236700002800253700002900281700002100310700002400331856012600355 2010 eng d00aPhysiochemical properties influencing biomass abundance and primary production in Lake Hoare, Antarctica0 aPhysiochemical properties influencing biomass abundance and prim1 aHerbei, Radu1 aLyons, Berry1 aLaybourn-Parry, Johanna1 aGardner, Christopher, B.1 aPriscu, John, C.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/physiochemical-properties-influencing-biomass-abundance-and-primary-production-lake-hoare00649nas a2200169 4500008004100000020001800041245010800059210006900167260004200236300001400278100002200292700001700314700001500331700002200346700002100368856009000389 2010 eng d a978052188919300aSaline lakes and ponds in the McMurdo Dry Valleys: ecological analogs to martian paleolake environments0 aSaline lakes and ponds in the McMurdo Dry Valleys ecological ana aCambridgebCambridge University Press a160 - 1941 aMikucki, Jill, A.1 aLyons, Berry1 aHawes, Ian1 aLanoil, Brian, D.1 aDoran, Peter, T. uhttp://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258&cid=CBO9780511712258A01300461nas a2200133 4500008004100000245005900041210005900100300001000159490000700169100002300176700002200199700002100221856008500242 2010 eng d00aSediment Melt Dynamics in Permanent Antarctic Lake Ice0 aSediment Melt Dynamics in Permanent Antarctic Lake Ice a57-660 v421 aJepsen, Steven, M.1 aAdams, Edward, E.1 aPriscu, John, C. uhttp://mcmlter.lternet.edu/reports/lakes/JepsenEtAl2010SedimentMeltMigration.pdf00598nas a2200145 4500008004100000245012800041210006900169260001200238300001400250490000600264100001900270700002100289700001800310856012400328 2010 eng d00aSingle-grain and multigrain luminescence dating of on-ice and lake-bottom deposits at Lake Hoare, Taylor Valley, Antarctica0 aSinglegrain and multigrain luminescence dating of onice and lake c12/2010 a679 - 6900 v51 aBerger, G., W.1 aDoran, Peter, T.1 aThomsen, K.J. uhttps://mcm.lternet.edu/content/single-grain-and-multigrain-luminescence-dating-ice-and-lake-bottom-deposits-lake-hoare01745nas a2200193 4500008004100000245004900041210004700090260001200137300001200149490000700161520118900168653001101357100002401368700002201392700002101414700002401435700002001459856007201479 2010 eng d00aSnow in the McMurdo Dry Valleys, Antarctica.0 aSnow in the McMurdo Dry Valleys Antarctica c04/2010 a633-6420 v303 a

Snowfall was measured at 11 sites in the McMurdo Dry Valleys to determine its magnitude, its temporal changes, and spatial patterns. Annual values ranged from 3 to 50 mm water equivalent with the highest values nearest the coast and decreasing inland. A particularly strong spatial gradient exists in Taylor Valley, probably resulting from local uplift conditions at the coastal margin and valley topography that limits migration inland. More snow occurs in winter near the coast, whereas inland no seasonal pattern is discernable. This may be due, again, to local uplift conditions, which are common in winter. We find no influence of the distance to the sea ice edge. Katabatic winds play an important role in transporting snow to the valley bottoms and essentially double the precipitation. That much of the snow accumulation sublimates prior to making a hydrologic contribution underscores the notion that the McMurdo Dry Valleys are indeed an extreme polar desert. Copyright © 2009 Royal Meteorological Society

10aBiggie1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aMonaghan, Andrew1 aBasagic, Hassan, J.1 aBromwich, David uhttps://mcm.lternet.edu/content/snow-mcmurdo-dry-valleys-antarctica00685nas a2200193 4500008004100000245010500041210006900146260001200215300001400227490000700241100002400248700001700272700001900289700002900308700002500337700002400362700002100386856008400407 2010 eng d00aSpatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica0 aSpatial variations in the geochemistry of glacial meltwater stre c12/2010 a662 - 6720 v221 aWelch, Kathleen, A.1 aLyons, Berry1 aWhisner, Carla1 aGardner, Christopher, B.1 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aPriscu, John, C. uhttp://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf00839nas a2200217 4500008004100000020002200041245013600063210007100199260003300270300001400303100001400317700002200331700001500353700002600368700001500394700002200409700002100431700001300452700002100465856013500486 2010 eng d a978-1-4244-5038-100aToward autonomous scientific exploration of ice-covered lakes—Field experiments with the ENDURANCE AUV in an Antarctic Dry Valley0 aToward autonomous scientific exploration of icecovered lakes—Fie aAnchorage, AKbIEEEc05/2010 a308 - 3151 aGulati, S1 aRichmond, Kristof1 aFlesher, C1 aHogan, Bartholomew, P1 aMurarka, A1 aKuhlmann, Gregory1 aSridharan, Mohan1 aStone, W1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/toward-autonomous-scientific-exploration-ice-covered-lakes%E2%80%94field-experiments-endurance-auv01928nas a2200169 4500008004100000245010300041210006900144260001200213300001400225490000700239520131500246100001901561700002001580700002101600700002701621856011001648 2010 eng d00aViable microbes in ice: application of molecular assays to McMurdo Dry Valley lake ice communities0 aViable microbes in ice application of molecular assays to McMurd c10/2010 a470 - 4760 v223 a

The permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) to examine membrane integrity of prokaryotes in these extreme environments. PMA selectively penetrates cells with compromised membranes and modifies their DNA resulting in the suppression of PCR amplification. Our results based on analysis of 16S rRNA genes demonstrate that despite the hostile conditions of the Dry Valleys, the permanent ice covers of the lakes support a ‘potentially viable’ microbial community. The level of membrane integrity, as well as diversity, was higher in samples where sediment was entrapped in the ice cover. Pronounced differences in the fraction of cells with intact and compromised cell membranes were found for Lake Fryxell and east lobe of Lake Bonney, both expressed in differences in DGGE banding patterns and qPCR signal reductions. Limitations in the ability to distinguish between intact or compromised cells occurred in samples from Lake Hoare and west lobe of Lake Bonney due to low DNA template concentrations recovered from the samples.

1 aDieser, Markus1 aNocker, Andreas1 aPriscu, John, C.1 aForeman, Christine, M. uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7909836&fileId=S095410201000040400918nas a2200325 4500008004100000245006400041210006300105300001200168490000700180100001700187700001600204700001400220700001600234700001500250700001400265700002500279700001500304700001300319700002000332700002600352700001600378700001700394700001900411700001300430700001500443700001200458700001500470700001500485856009200500 2009 eng d00aAccelerate Synthesis in Ecology and Environmental Sciences.0 aAccelerate Synthesis in Ecology and Environmental Sciences a699-7010 v591 aCarpenter, S1 aLundberg, P1 aMangel, M1 aMerchant, N1 aMurdoch, W1 aPalmer, M1 aPeters, Debra, P. C.1 aPickett, S1 aSmith, K1 aWall, Diana, H.1 aZimmerman, Maggie, K.1 aArmbrust, E1 aArzberger, E1 aChapin, F., S.1 aElser, J1 aHackett, E1 aIves, A1 aKareiva, P1 aLeibold, M uhttps://mcm.lternet.edu/content/accelerate-synthesis-ecology-and-environmental-sciences00627nas a2200157 4500008004100000245011700041210006900158300001400227490000700241100001500248700001800263700002100281700002100302700002400323856012200347 2009 eng d00aComposition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica0 aComposition and Biodegradation of a Synthetic Oil Spilled on the a2708-27130 v431 aJaraula, C1 aKenig, Fabien1 aDoran, Peter, T.1 aPriscu, John, C.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/composition-and-biodegradation-synthetic-oil-spilled-perennial-ice-cover-lake-fryxell01755nas a2200241 4500008004100000245006900041210006500110260001200175300001200187490000800199520109500207653001101302100002201313700001501335700001601350700001501366700001601381700001401397700001301411700002101424700001101445856005701456 2009 eng d00aA Contemporary Microbially Maintained Subglacial Ferrous "Ocean"0 aContemporary Microbially Maintained Subglacial Ferrous Ocean c04/2009 a397-4000 v3243 a

An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5′-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic. Coupled biogeochemical processes below the glacier enable subglacial microbes to grow in extended isolation, demonstrating how analogous organic-starved systems, such as Neoproterozoic oceans, accumulated Fe(II) despite the presence of an active sulfur cycle.

10aBiggie1 aMikucki, Jill, A.1 aPearson, A1 aJohnston, D1 aTurchyn, A1 aFarquhar, J1 aSchrag, D1 aAnbar, A1 aPriscu, John, C.1 aLee, P uhttp://www.sciencemag.org/content/324/5925/397.short03833nas a2200217 4500008004100000245017200041210006900213260004600282300000800328490001000336520305700346653001503403653001903418653002103437653002503458653001903483653002303502100001603525700002403541856005003565 2009 eng d00aControls on stream and hyporheic temperatures, Taylor Valley, Antarctica and large-scale climate influences on interannual flow variation in the Onyx River, Antarctica0 aControls on stream and hyporheic temperatures Taylor Valley Anta aBoulder, CObUniversity of Coloradoc2009 a3170 vPh.D.3 a

The McMurdo Dry Valleys comprise the largest ice-free polar desert on the continent of Antarctica. My Ph.D. research investigated summertime glacial meltwater streams flowing through this region. This work is presented in Chapters 2 through 6 of my thesis. Chapters 2-5 present the work I have done related to hyporheic processes while Chapter 6 focuses on the hydroclimatological investigations I have carried out.

More specifically, Chapter 2 addresses the question: what are the dominant processes controlling dry valley stream temperatures? In particular, this investigation quantified the role of hyporheic exchange. The study found that in the Dry Valleys, exchange acted to decrease stream temperatures, accounting for 6–21% of cooling.

Chapter 3 discusses a follow up tracer study to investigate whether the comparatively large daily changes in dry valley stream temperatures (6-9°C) affect hyporheic processes, for instance through viscosity effects. Results showed that the hyporheic zone volume and exchange coefficient were lower during the warmer, afternoon stream/streambed temperature regime than during the cooler, morning one. A temperature-induced feedback mechanism that increases subsurface flow path preferentiality is proposed as a possible explanation for the reduction in hyporheic volume under warmer conditions. The tracer results also suggested a “Swiss Cheese” type conceptual model of the hyporheic zone in which flow takes place along paths weaving their way through isolated areas.

Chapter 4 presents work done to elucidate individual hyporheic flow path lengths and residence times. A streambed injection revealed some long (over 100 m) paths that were also fast, having subsurface travel times on par with the surface water. Hyporheic pipeflow is proposed as an explanation.

In Chapter 5 research is presented showing that nitrate and phosphate concentrations at specific locations in the hyporheic zone increase with the decreasing connectivity of that location to the stream.

Finally, Chapter 6 describes the large-scale climate conditions that prevailed during December and January during the highest and lowest flow summers of the Onyx River record, the longest flow record for Antarctica. Climate variables and regions in the Southern Hemisphere that had a statistically significant linear correlation to Onyx River flows were also identified. The highest flow summer on record, 2001-2, was found to have some unusual climate features when compared to the other high flow summers. It stands out as having an anomalous wind pattern that would have increased katabatic winds in the valleys, raising air temperatures and possibly depositing sediment on the glaciers, decreasing their albedo. It is also characterized by anomalously high incoming shortwave radiation. We postulate that those high levels may have been due in part to the unusually low concentrations of radiation absorbing stratospheric ozone prevalent over the valleys that particular summer.

10aAntarctica10aearth sciences10ahydroclimatology10ahyporheic flow paths10ahyporheic zone10astream temperature1 aCozzetto, K1 aMcKnight, Diane, M. uhttps://search.proquest.com/docview/30486636600495nas a2200145 4500008004100000245010200041210006900143260001200212300000700224490000700231100002500238700002000263700001700283856004900300 2009 eng d00aDesiccation survival in an Antarctic nematode: molecular analysis using expressed sequenced tags.0 aDesiccation survival in an Antarctic nematode molecular analysis c09/2009 a690 v101 aAdhikari, Bishwo, N.1 aWall, Diana, H.1 aAdams, Byron uhttp://www.biomedcentral.com/1471-2164/10/6900675nas a2200193 4500008004100000245008100041210006900122260001200191300000700203490000600210100002400216700002700240700002400267700002000291700001700311700002200328700002200350856010900372 2009 eng d00aEnvironmental DNA sequencing primers for eutardigrades and bdelloid rotifers0 aEnvironmental DNA sequencing primers for eutardigrades and bdell c11/2009 a250 v91 aRobeson, Michael, S1 aCostello, Elizabeth, K1 aFreeman, Kristen, R1 aWhiting, Jeremy1 aAdams, Byron1 aMartin, Andrew, P1 aSchmidt, Steve, K uhttps://mcm.lternet.edu/content/environmental-dna-sequencing-primers-eutardigrades-and-bdelloid-rotifers00419nas a2200133 4500008004100000245005700041210005700098260000900155300000700164490000700171100002100178700002600199856006000225 2009 eng d00aExamining the Scientific Consensus on Climate Change0 aExamining the Scientific Consensus on Climate Change c2009 a220 v901 aDoran, Peter, T.1 aZimmerman, Maggie, K. uhttp://www.agu.org/pubs/crossref/2009/2009EO030002.shtm00683nas a2200169 4500008004100000245011900041210006900160300001400229490000700243100001700250700002500267700002200292700002200314700003300336700001600369856012800385 2009 eng d00aHydrologic characteristics of lake- and stream-side riparian wetted margins in the McMurdo Dry Valleys, Antarctica0 aHydrologic characteristics of lake and streamside riparian wette a1255-12670 v231 aNorthcott, M1 aGooseff, Michael, N.1 aBarrett, John, E.1 aZeglin, Lydia, H.1 aTakacs-Vesbach, Cristina, D.1 aHumphrey, J uhttps://mcm.lternet.edu/content/hydrologic-characteristics-lake-and-stream-side-riparian-wetted-margins-mcmurdo-dry-valleys00622nas a2200157 4500008004100000245010300041210006900144300001400213490000700227100001600234700002300250700002200273700002400295700002000319856012500339 2009 eng d00aInteractions between physical and biotic factors influence CO_2 flux in Antarctic dry valley soils0 aInteractions between physical and biotic factors influence CO2 f a1510-15170 v411 aBall, Becky1 aVirginia, Ross, A.1 aBarrett, John, E.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/interactions-between-physical-and-biotic-factors-influence-co2-flux-antarctic-dry-valley01451nas a2200481 4500008004100000245006900041210006900110260001200179300001600191490001400207100002200221700002200243700002200265700002500287700002400312700002600336700001800362700001800380700002100398700002200419700002800441700001700469700001800486700002200504700002000526700002300546700002400569700002100593700001900614700002200633700001800655700002500673700001800698700002600716700002500742700002100767700002000788700002300808700002700831700002700858700002600885856005800911 2009 eng d00aLakes and reservoirs as regulators of carbon cycling and climate0 aLakes and reservoirs as regulators of carbon cycling and climate c11/2009 a2298–23140 v54 part 21 aTranvik, Lars, J.1 aDowning, John, A.1 aCotner, James, B.1 aLoiselle, Steven, A.1 aStriegl, Robert, G.1 aBallatore, Thomas, J.1 aDillon, Peter1 aFinlay, Kerri1 aFortino, Kenneth1 aKnoll, Lesley, B.1 aKortelainen, Pirkko, L.1 aKutser, Tiit1 aLarsen, Soren1 aLaurion, Isabelle1 aLeech, Dina, M.1 aMcCallister, Leigh1 aMcKnight, Diane, M.1 aMelack, John, M.1 aOverholt, Erin1 aPorter, Jason, A.1 aPrairie, Yves1 aRenwick, William, H.1 aRoland, Fabio1 aSherman, Bradford, S.1 aSchindler, David, W.1 aSobek, Sebastian1 aTremblay, Alain1 aVanni, Michael, J.1 aVerschoor, Antonie, M.1 avon Wachenfeldt, Eddie1 aWeyhenmeyer, Gesa, A. uhttp://aslo.org/lo/toc/vol_54/issue_6_part_2/2298.pdf00380nas a2200133 4500008004100000245002400041210002400065260002700089300001200116100002100128700002700149700001700176856005300193 2009 eng d00aLakes of Antarctica0 aLakes of Antarctica aOxfordbElsevier Press a555-5661 aPriscu, John, C.1 aForeman, Christine, M.1 aLikens, G.E. uhttps://mcm.lternet.edu/content/lakes-antarctica00686nas a2200157 4500008004100000245015700041210006900198300001200267490000700279100002200286700001800308700002200326700002500348700003300373856012200406 2009 eng d00aLandscape Distribution of Microbial Activity in the McMurdo Dry Valleys: Linked Biotic Processes, Hydrology, and Geochemistry in a Cold Desert Ecosystem0 aLandscape Distribution of Microbial Activity in the McMurdo Dry  a562-5730 v121 aZeglin, Lydia, H.1 aSinsabaugh, R1 aBarrett, John, E.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/landscape-distribution-microbial-activity-mcmurdo-dry-valleys-linked-biotic-processes00654nas a2200169 4500008004100000245010800041210006900149300001400218490000700232100002400239700002000263700001700283700001800300700002200318700002300340856012100363 2009 eng d00aLong-term experimental warming reduces soil nematode populations in the McMurdo Dry Valleys, Antarctica0 aLongterm experimental warming reduces soil nematode populations  a2052-20600 v411 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron1 aAyres, Edward1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/long-term-experimental-warming-reduces-soil-nematode-populations-mcmurdo-dry-valleys00718nas a2200241 4500008004100000245007300041210006900114300001200183490000600195100001500201700001300216700001800229700002000247700001600267700001300283700001200296700001400308700001500322700001500337700001300352700001300365856009800378 2009 eng d00aManaging for ocean biodiversity to sustain marine ecosystem services0 aManaging for ocean biodiversity to sustain marine ecosystem serv a204-2110 v71 aPalumbi, S1 aNorse, E1 aStachowicz, J1 aWall, Diana, H.1 aSandifer, P1 aAllan, J1 aBeck, M1 aFautin, D1 aFogerty, M1 aHalpern, B1 aIncze, L1 aLeong, J uhttps://mcm.lternet.edu/content/managing-ocean-biodiversity-sustain-marine-ecosystem-services00480nas a2200109 4500008004100000245008700041210006900128260003000197100001600227700001700243856011000260 2009 eng d00aThe Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-basin Lakes0 aMinor Alkaline Earth Element and Alkali Metal Behavior in Closed bThe Ohio State University1 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/minor-alkaline-earth-element-and-alkali-metal-behavior-closed-basin-lakes00633nas a2200157 4500008004100000245012400041210006900165300001200234100001000246700001800256700001000274700002600284700002000310700002100330856012400351 2009 eng d00aMolecular profiling of soil animal diversity in natural ecosystems: incongruence of molecular and morphological results0 aMolecular profiling of soil animal diversity in natural ecosyste a849-8571 aWu, T1 aAyres, Edward1 aLi, G1 aBardgett, Richard, D.1 aWall, Diana, H.1 aGarey, James, R. uhttps://mcm.lternet.edu/content/molecular-profiling-soil-animal-diversity-natural-ecosystems-incongruence-molecular-and00641nas a2200157 4500008004100000245014100041210006900182300001200251490000800263100001600271700002100287700001800308700001700326700001700343856012300360 2009 eng d00aParticulate organic and dissolved inorganic carbon stable isotopic compositions in Taylor Valley lakes, Antarctica: the effect of legacy0 aParticulate organic and dissolved inorganic carbon stable isotop a139-1560 v6321 aKnoepfle, J1 aDoran, Peter, T.1 aKenig, Fabien1 aLyons, Berry1 aGalchenko, V uhttps://mcm.lternet.edu/content/particulate-organic-and-dissolved-inorganic-carbon-stable-isotopic-compositions-taylor00514nas a2200133 4500008004100000245008400041210006900125260000900194300000800203490000700211100002100218700002600239856011500265 2009 eng d00aReply to Comments on “Examining the Scientific Consensus on Climate Change”0 aReply to Comments on Examining the Scientific Consensus on Clima c2009 a2330 v901 aDoran, Peter, T.1 aZimmerman, Maggie, K. uhttps://mcm.lternet.edu/content/reply-comments-%E2%80%9Cexamining-scientific-consensus-climate-change%E2%80%9D00399nas a2200109 4500008004100000245006100041210005500102300001200157100002300169700001700192856008000209 2009 eng d00aThe saline lakes of the McMurdo Dry Valleys, Antarctica,0 asaline lakes of the McMurdo Dry Valleys Antarctica a321-3481 aGreen, William, J.1 aLyons, Berry uhttps://mcm.lternet.edu/content/saline-lakes-mcmurdo-dry-valleys-antarctica00579nas a2200133 4500008004100000245011000041210006900151300001400220490000700234100002200241700002500263700003300288856012400321 2009 eng d00aSpatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems.0 aSpatial variation in soil activelayer geochemistry across hydrol a2349-23580 v131 aBarrett, John, E.1 aGooseff, Michael, N.1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/spatial-variation-soil-active-layer-geochemistry-across-hydrologic-margins-polar-desert00835nas a2200289 4500008004100000245006600041210006500107490000700172100002300179700002000202700001600222700001600238700001700254700001400271700001200285700001200297700001700309700001600326700001900342700001400361700001300375700002200388700001500410700001500425700001900440856008600459 2009 eng d00aState of the Antarctic and the Southern Ocean climate system,0 aState of the Antarctic and the Southern Ocean climate system0 v471 aMayewski, Paul, A.1 aBromwich, David1 aCampbell, H1 aHamilton, G1 aLyons, Berry1 aMaasch, K1 aAoki, S1 aXiao, C1 avan Ommen, T1 aMeredith, M1 aSummerhayes, C1 aTurner, J1 aWorby, A1 aBarrett, John, E.1 aCasassa, G1 aBertler, N1 aBracegirdle, T uhttps://mcm.lternet.edu/content/state-antarctic-and-southern-ocean-climate-system00629nas a2200169 4500008004100000245008900041210006900130300001400199490000700213100002400220700002000244700001700264700001800281700002200299700002300321856011500344 2009 eng d00aTerrestrial mesofauna in above- and below-ground habitats: Taylor Valley, Antarctica0 aTerrestrial mesofauna in above and belowground habitats Taylor V a1549-15580 v321 aSimmons, Breana, L.1 aWall, Diana, H.1 aAdams, Byron1 aAyres, Edward1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/terrestrial-mesofauna-above-and-below-ground-habitats-taylor-valley-antarctica00606nas a2200145 4500008004100000245011600041210006900157300001000226490000700236100001300243700002500256700002200281700003300303856012400336 2009 eng d00aThermal Characterisation of Active Layer Across a Soil Moisture Gradient in the McMurdo Dry Valleys, Antarctica0 aThermal Characterisation of Active Layer Across a Soil Moisture  a27-390 v201 aIkard, S1 aGooseff, Michael, N.1 aBarrett, John, E.1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/thermal-characterisation-active-layer-across-soil-moisture-gradient-mcmurdo-dry-valleys00440nas a2200145 4500008004100000245004600041210004400087260001200131300001400143490000800157100002300165700002000188700001700208856006900225 2009 eng d00aWhere's the ecology in molecular ecology?0 aWheres the ecology in molecular ecology c05/2009 a1601-16090 v1181 aJohnson, Jerry, B.1 aPeat, Scott, M.1 aAdams, Byron uhttps://mcm.lternet.edu/content/wheres-ecology-molecular-ecology00572nas a2200157 4500008004100000245006300041210006000104260003600164100002100200700001600221700001700237700001600254700002500270700002700295856009200322 2008 eng d00aAntarctic subglacial water: origin, evolution, and ecology0 aAntarctic subglacial water origin evolution and ecology aOxfordbOxford University Press1 aPriscu, John, C.1 aTulaczyk, S1 aStudinger, M1 aKenicutt, M1 aChristner, Brent, C.1 aForeman, Christine, M. uhttps://mcm.lternet.edu/content/antarctic-subglacial-water-origin-evolution-and-ecology00526nas a2200169 4500008004100000245004000041210004000081260003000121300001000151100002500161700001600186700002100202700002000223700002700243700001700270856006900287 2008 eng d00aBacteria in Subglacial Environments0 aBacteria in Subglacial Environments aNew YorkbSpringer Verlag a51-711 aChristner, Brent, C.1 aSkidmore, M1 aPriscu, John, C.1 aTranter, Martyn1 aForeman, Christine, M.1 aMargesin, R. uhttps://mcm.lternet.edu/content/bacteria-subglacial-environments00464nas a2200157 4500008004100000245004100041210004100082300001200123490000700135100001600142700002000158700002600178700002100204700002800225856005300253 2008 eng d00aBacteriophage in polar inland waters0 aBacteriophage in polar inland waters a167-1750 v121 aSawstrom, C1 aLisle, John, T.1 aAnesio, Alexandre, M.1 aPriscu, John, C.1 aLaybourn-Parry, Johanna u/reports/lakes/SawstromEtAl2008Bacteriophage.pdf00512nas a2200133 4500008004100000245006300041210006200104260003600166100001700202700001400219700002500233700002800258856009200286 2008 eng d00aBiogeochemical processes in high-latitude lakes and rivers0 aBiogeochemical processes in highlatitude lakes and rivers aOxfordbOxford University Press1 aLyons, Berry1 aFinlay, J1 aVincent, Warwick, F.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/biogeochemical-processes-high-latitude-lakes-and-rivers00481nas a2200109 4500008004100000245008500041210006900126260003000195100002300225700002000248856010300268 2008 eng d00aThe Biogeochemistry of Cryoconite Holes on Glaciers in Taylor Valley, Antarctica0 aBiogeochemistry of Cryoconite Holes on Glaciers in Taylor Valley bUniversity of Bristol, UK1 aBagshaw, Elizabeth1 aTranter, Martyn uhttps://mcm.lternet.edu/content/biogeochemistry-cryoconite-holes-glaciers-taylor-valley-antarctica00528nas a2200109 4500008004100000245011900041210006900160260003000229100001400259700002000273856012500293 2008 eng d00aA comparison of anhydrobiosis in nematodes of the McMurdo Dry Valleys, Antarctica and Short Grass Steppe, Colorado0 acomparison of anhydrobiosis in nematodes of the McMurdo Dry Vall bColorado School of Mines,1 aSeaver, K1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/comparison-anhydrobiosis-nematodes-mcmurdo-dry-valleys-antarctica-and-short-grass-steppe00606nas a2200145 4500008004100000245011900041210006900160300001400229490000700243100002200250700002300272700002000295700001700315856012800332 2008 eng d00aDecline in a dominant invertebrate species contributes to altered carbon cycling in a low-diversity soil ecosystem0 aDecline in a dominant invertebrate species contributes to altere a1734-17440 v141 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aAdams, Byron uhttps://mcm.lternet.edu/content/decline-dominant-invertebrate-species-contributes-altered-carbon-cycling-low-diversity-soil02709nas a2200241 4500008004100000245010000041210006900141260001200210300001400222490000700236520190500243100001802148700002202166700002002188700001702208700002202225700001302247700002402260700002202284700002402306700002302330856011402353 2008 eng d00aEffects of Human Trampling on Populations of Soil Fauna in the McMurdo Dry Valleys, Antarctica.0 aEffects of Human Trampling on Populations of Soil Fauna in the M c12/2008 a1544-15510 v223 a

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO2 fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

1 aAyres, Edward1 aNkem, Johnson, N.1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aBroos, E1 aParsons, Andrew, N.1 aPowers, Laura, E.1 aSimmons, Breana, L.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/effects-human-trampling-populations-soil-fauna-mcmurdo-dry-valleys-antarctica00639nas a2200169 4500008004100000245009800041210006900139300001200208490000600220100002100226700002700247700001900274700001800293700002700311700001200338856011900350 2008 eng d00aEntry approach into pristine ice-sealed lakes - Lake Vida, East Antarctica, a model ecosystem0 aEntry approach into pristine icesealed lakes Lake Vida East Anta a542-5470 v61 aDoran, Peter, T.1 aFritsen, Christian, H.1 aMurray, A., E.1 aKenig, Fabien1 aMcKay, Christopher, P.1 aKyne, J uhttps://mcm.lternet.edu/content/entry-approach-pristine-ice-sealed-lakes-lake-vida-east-antarctica-model-ecosystem00522nas a2200121 4500008004100000245009800041210006900139260003000208490001000238100001900248700001700267856011600284 2008 eng d00aThe geochemistry of glacier snow and melt: The Oregon Cascades and Taylor Valley, Antarctica.0 ageochemistry of glacier snow and melt The Oregon Cascades and Ta bThe Ohio State University0 vPh.D.1 aFortner, Sarah1 aLyons, Berry uhttps://mcm.lternet.edu/content/geochemistry-glacier-snow-and-melt-oregon-cascades-and-taylor-valley-antarctica02787nas a2200241 4500008004100000245002300041210002300064250000600087300001000093490000700103520220500110653001102315653001702326100001402343700002602357700002002383700002402403700001402427700002102441700002802462700001502490856004002505 2008 eng d00aGlacial ecosystems0 aGlacial ecosystems a1 a41-670 v783 a
There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must now consider ice masses as ecosystem habitats in their own right and address their diversity, functional potential, and activity as part of alpine and polar environments. Although such research is already underway, its fragmentary nature provides little basis for developing modern concepts of glacier ecology. This paper therefore provides a much-needed framework for development by reviewing the physical, biogeochemical, and microbiological characteristics of microbial habitats that have been identified within glaciers and ice sheets. Two key glacial ecosystems emerge, one inhabiting the glacier surface (the supraglacial ecosystem) and one at the ice-bed interface (the subglacial ecosystem). The supraglacial ecosystem is characterized by a diverse consortium of microbes (usually bacteria, algae, phytoflagellates, fungi, viruses and occasional rotifers, tardigrades, and diatoms) within the snowpack, supraglacial streams, and melt pools (cryoconite holes). The subglacial system is dominated by aerobic/anaerobic bacteria and most probably viruses in basal ice/till mixtures and subglacial lakes. A third, so-called englacial ecosystem is also described, but it is demonstrated that conditions within glacier ice are sufficient to make metabolic activity and its impact upon nutrient dynamics negligible at the glacier scale.
 
Consideration of the surface and internal heat balances of the glacier show that all glacial ecosystems are sensitive to climate change, although at different timescales. Thus, while rapid, melt-driven habitat changes lead to melt-out, resuscitation, and redistribution of microorganisms in many supraglacial ecosystems, much slower climatic and glacial mass-balance processes effect such changes in the subglacial ecosystem. Paradoxically, it is shown that these forces have brought about net refreezing and the onset of cryostasis in the subglacial ecosystems of many Arctic glaciers subject to thinning in recent decades.
10aBiggie10asnow ecology1 aHodson, A1 aAnesio, Alexandre, M.1 aTranter, Martyn1 aFountain, Andrew, G1 aOsborn, M1 aPriscu, John, C.1 aLaybourn-Parry, Johanna1 aSattler, B uhttp://dx.doi.org/10.1890/07-0187.101642nas a2200541 4500008004100000245010100041210006900142260001200211300001400223490000700237100002000244700002300264700002100287700002300308700002900331700002300360700002200383700002400405700001700429700002000446700002100466700002600487700002000513700002200533700002400555700002400579700001900603700002200622700002200644700002100666700001700687700002200704700002300726700001500749700001900764700002100783700002100804700002400825700002200849700002300871700002600894700002300920700001900943700002900962700001500991700001701006856007701023 2008 eng d00aGlobal decomposition experiment shows soil animal impacts on decomposition are climate dependent0 aGlobal decomposition experiment shows soil animal impacts on dec c11/2008 a2661-26770 v141 aWall, Diana, H.1 aBradford, Mark, A.1 aStJohn, Mark, G.1 aTrofymow, John, A.1 aBehan-Pelletier, Valerie1 aBignell, David, E.1 aDangerfield, Mark1 aParton, William, J.1 aRusek, Josef1 aVoigt, Winfried1 aWolters, Volkmar1 aGardel, Holley, Zadeh1 aAyuke, Fred, O.1 aBashford, Richard1 aBeljakova, Olga, I.1 aBohlen, Patrick, J.1 aBrauman, Alain1 aFlemming, Stephen1 aHenschel, Joh, R.1 aJohnson, Dan, L.1 aJones, Hefin1 aKovarova, Marcela1 aKranabetter, Marty1 aKutny, Les1 aLin, Kuo-Chuan1 aMaryati, Mohamed1 aMasse, Dominique1 aPokarzhevsk, Andrei1 aRahman, Homathevi1 aSabara, Millor, G.1 aSalamon, Joerg-Alfred1 aSwift, Michael, J.1 aVarela, Amanda1 aVasconcelos, Heraldo, L.1 aWhite, Don1 aZou, Xiaming uhttp://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2008.01672.x/full00521nas a2200157 4500008004100000245003800041210003600079260003600115100002400151700002500175700002500200700001600225700002500241700002800266856006900294 2008 eng d00aHigh-latitude rivers and streams.0 aHighlatitude rivers and streams aOxfordbOxford University Press1 aMcKnight, Diane, M.1 aGooseff, Michael, N.1 aVincent, Warwick, F.1 aPeterson, B1 aVincent, Warwick, F.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/high-latitude-rivers-and-streams00775nas a2200217 4500008004100000245010100041210006900142260001500211300001200226490000700238653002100245653001200266100002100278700002700299700002400326700002200350700002400372700001700396700002200413856012200435 2008 eng d00aHydrologic response to extreme warm and cold summers in the McMurdo Dry Valleys, East Antarctica0 aHydrologic response to extreme warm and cold summers in the McMu c05/16/2008 a499-5090 v2010aClimate Response10astreams1 aDoran, Peter, T.1 aMcKay, Christopher, P.1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aMcKnight, Diane, M.1 aJaros, Chris1 aBarrett, John, E. uhttps://mcm.lternet.edu/content/hydrologic-response-extreme-warm-and-cold-summers-mcmurdo-dry-valleys-east-antarctica00481nas a2200145 4500008004100000245003600041210003500077260003600112100001500148700002700163700002400190700002500214700002800239856006800267 2008 eng d00aIce-based freshwater ecosystems0 aIcebased freshwater ecosystems aOxfordbOxford University Press1 aHawes, Ian1 aHoward-Williams, Clive1 aFountain, Andrew, G1 aVincent, Warwick, F.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/ice-based-freshwater-ecosystems00591nas a2200157 4500008004100000245009700041210006900138260001200207300001200219490000700231100001300238700002200251700002300273700002000296856011700316 2008 eng d00aThe influence of soil geochemistry on nematode distribution, McMurdo Dry Valleys, Antarctica0 ainfluence of soil geochemistry on nematode distribution McMurdo  c02/2008 a119-1280 v401 aPoage, M1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/influence-soil-geochemistry-nematode-distribution-mcmurdo-dry-valleys-antarctica00672nas a2200193 4500008004100000245008200041210006900123300001400192490000700206100002500213700002500238700002400263700001700287700001600304700001600320700002100336700001700357856010400374 2008 eng d00aInland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica0 aInland diatoms from the McMurdo Dry Valleys and James Ross Islan a1378-13920 v121 aEsposito, Rhea, M.M.1 aSpaulding, Sarah, A.1 aMcKnight, Diane, M.1 aDe Vijver, B1 aKopalova, K1 aLubinski, D1 aHall, Brenda, L.1 aWhittaker, T uhttps://mcm.lternet.edu/content/inland-diatoms-mcmurdo-dry-valleys-and-james-ross-island-antarctica00401nas a2200109 4500008004100000245005900041210005700100490000800157100002400165700002000189856008200209 2008 eng d00aIntroduction - The Biogeochemistry of Cryoconite Holes0 aIntroduction The Biogeochemistry of Cryoconite Holes0 v1131 aFountain, Andrew, G1 aTranter, Martyn uhttps://mcm.lternet.edu/content/introduction-biogeochemistry-cryoconite-holes00397nas a2200121 4500008004100000245005100041210005100092300001400143490000700157100001600164700001700180856007800197 2008 eng d00aMercury Deposition in a Polar Desert Ecosystem0 aMercury Deposition in a Polar Desert Ecosystem a4710-47160 v421 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/mercury-deposition-polar-desert-ecosystem00626nas a2200181 4500008004100000245008300041210006900124300001400193490000700207100002000214700001600234700001400250700001100264700002200275700002000297700001900317856010800336 2008 eng d00aMicrobial community composition in soils of Northern Victoria Land, Antarctica0 aMicrobial community composition in soils of Northern Victoria La a1713-17240 v101 aNiederberger, T1 aMcDonald, i1 aHacker, A1 aSoo, R1 aBarrett, John, E.1 aWall, Diana, H.1 aCary, Craig, S uhttps://mcm.lternet.edu/content/microbial-community-composition-soils-northern-victoria-land-antarctica00539nas a2200121 4500008004100000245009500041210006900136260002900205490001000234100002200244700003300266856011800299 2008 eng d00aMicrobial diversity and function at aquatic- terrestrial interfaces in desert ecosystems.0 aMicrobial diversity and function at aquatic terrestrial interfac bUniversity of New Mexico0 vPh.D.1 aZeglin, Lydia, H.1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/microbial-diversity-and-function-aquatic-terrestrial-interfaces-desert-ecosystems00528nas a2200145 4500008004100000245005900041210005900100260003600159100001500195700002100210700001700231700002500248700002800273856008100301 2008 eng d00aOrigin and geomorphology of lakes in the polar regions0 aOrigin and geomorphology of lakes in the polar regions aOxfordbOxford University Press1 aPienitz, R1 aDoran, Peter, T.1 aLamoureuz, S1 aVincent, Warwick, F.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/origin-and-geomorphology-lakes-polar-regions00595nas a2200169 4500008004100000245008100041210006900122260001200191300001400203490000700217653002100224653001400245100002200259700002300281700002000304856010100324 2008 eng d00aPersistent effects of a discrete climate event on a polar desert ecosystem0 aPersistent effects of a discrete climate event on a polar desert c06/2008 a2249-22610 v1410aClimate Response10anematodes1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/persistent-effects-discrete-climate-event-polar-desert-ecosystem00475nas a2200097 4500008004100000245012300041210006900164490000600233100002100239856011700260 2008 eng d00aPlankton Dynamics in the McMurdo Dry Valley Lakes During the Transition to Polar Night - A Project Contributing to EBA0 aPlankton Dynamics in the McMurdo Dry Valley Lakes During the Tra0 v21 aPriscu, John, C. uhttps://mcm.lternet.edu/content/plankton-dynamics-mcmurdo-dry-valley-lakes-during-transition-polar-night-project00556nas a2200121 4500008004100000245011000041210006900151260003600220490000900256100002600265700002100291856012200312 2008 eng d00aProvenance of organic matter in Taylor Valley, Antarctica lakes: Scanning Electron Microscopy of sediment0 aProvenance of organic matter in Taylor Valley Antarctica lakes S bUniversity of Illinois, Chicago0 vM.S.1 aWarnock, Jonathan, P.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/provenance-organic-matter-taylor-valley-antarctica-lakes-scanning-electron-microscopy00685nas a2200205 4500008004100000245010300041210006900144260000900213490000700222100002300229700002300252700002900275700001500304700002300319700002100342700001500363700001500378700002500393856006100418 2008 eng d00aReply to comment by K. Gajewski on “Abrupt environmental change in Canada's northernmost lake”0 aReply to comment by K Gajewski on Abrupt environmental change in c20080 v351 aAntoniades, Dermot1 aCrawley, Catherine1 aDouglas, Marianne, S. V.1 aPienitz, R1 aAndersen, Dale, T.1 aDoran, Peter, T.1 aHawes, Ian1 aPollard, W1 aVincent, Warwick, F. uhttp://www.agu.org/pubs/crossref/2008/2007GL032889.shtml00475nas a2200145 4500008004100000245005700041210005700098300001000155490000800165100001500173700002200188700001300210700002300223856008300246 2008 eng d00aSoil phosphorus cycling in an Antarctic polar desert0 aSoil phosphorus cycling in an Antarctic polar desert a21-320 v1441 aBate, Brad1 aBarrett, John, E.1 aPoage, M1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-phosphorus-cycling-antarctic-polar-desert00645nas a2200157 4500008004100000245012900041210006900170300001200239490000800251100001500259700001800274700002100292700002100313700002400334856012900358 2008 eng d00aSPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica0 aSPMEGCMS study of the natural attenuation of aviation diesel spi a250-2620 v4071 aJaraula, C1 aKenig, Fabien1 aDoran, Peter, T.1 aPriscu, John, C.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/spme-gcms-study-natural-attenuation-aviation-diesel-spilled-perennial-ice-cover-lake-fryxell00949nas a2200349 4500008004100000245005900041210005800100300001400158490000700172100001800179700001300197700001500210700001400225700001500239700001400254700001400268700001600282700003300298700001500331700001900346700001400365700001100379700002200390700001700412700001300429700001500442700001600457700001600473700001400489700001200503856008400515 2008 eng d00aStoichiometry of soil enzyme activity at global scale.0 aStoichiometry of soil enzyme activity at global scale a1252-12640 v111 aSinsabaugh, R1 aGallo, M1 aGartner, T1 aHobbie, S1 aHolland, K1 aKeeler, B1 aPowers, J1 aStursova, M1 aTakacs-Vesbach, Cristina, D.1 aWaldrop, M1 aWallenstein, M1 aLauber, M1 aZak, D1 aZeglin, Lydia, H.1 aWeintraub, M1 aAhmed, B1 aAllison, S1 aCrenshaw, C1 aContosta, A1 aCusack, D1 aFrey, S uhttps://mcm.lternet.edu/content/stoichiometry-soil-enzyme-activity-global-scale00658nas a2200181 4500008004100000245013600041210006900177300001400246490000700260100002100267700002500288700001900313700002400332700002000356700002500376700001700401856005800418 2008 eng d00aSupersaturated N2O in a perennially ice-covered Antarctic lake: Molecular and stable isotopic evidence for a biogeochemical relict.0 aSupersaturated N2O in a perennially icecovered Antarctic lake Mo a2439-24500 v531 aPriscu, John, C.1 aChristner, Brent, C.1 aDore, John, E.1 aWestley, Marian, B.1 aPopp, Brian, N.1 aCasciotti, Karen, L.1 aLyons, Berry uhttp://brent.xner.net/pdf/Priscu_etal2008_ELB-N2O.pdf00503nas a2200121 4500008004100000245009100041210006900132490000800201100001500209700002400224700001400248856011900262 2008 eng d00aSurface energy balance and melt thresholds over 11 years at Taylor Glacier, Antarctica0 aSurface energy balance and melt thresholds over 11 years at Tayl0 v1131 aHoffman, M1 aFountain, Andrew, G1 aListon, G uhttps://mcm.lternet.edu/content/surface-energy-balance-and-melt-thresholds-over-11-years-taylor-glacier-antarctica00620nas a2200145 4500008004100000245012900041210006900170300001100239490000800250100002400258700002200282700002000304700002300324856012700347 2008 eng d00aTemporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica0 aTemporal variations in physical and chemical features of cryocon aG01S920 v1131 aFountain, Andrew, G1 aNylen, Thomas, H.1 aTranter, Martyn1 aBagshaw, Elizabeth uhttps://mcm.lternet.edu/content/temporal-variations-physical-and-chemical-features-cryoconite-holes-canada-glacier-mcmurdo00530nas a2200121 4500008004100000245011000041210006900151300001400220490000700234100002200241700002100263856012400284 2007 eng d00aBacterial diversity associated with Blood Falls, A subglacial outflow from the Taylor Glacier, Antarctica0 aBacterial diversity associated with Blood Falls A subglacial out a4029-40390 v731 aMikucki, Jill, A.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/bacterial-diversity-associated-blood-falls-subglacial-outflow-taylor-glacier-antarctica00637nas a2200169 4500008004100000245009400041210006900135300001100204490000800215100002300223700002000246700002400266700002400290700002400314700001700338856011200355 2007 eng d00aThe biogeochemical evolution of cryoconite holes on glaciers in Taylor Valley, Antarctica0 abiogeochemical evolution of cryoconite holes on glaciers in Tayl aG04S350 v1131 aBagshaw, Elizabeth1 aTranter, Martyn1 aFountain, Andrew, G1 aWelch, Kathleen, A.1 aBasagic, Hassan, J.1 aLyons, Berry uhttps://mcm.lternet.edu/content/biogeochemical-evolution-cryoconite-holes-glaciers-taylor-valley-antarctica03147nas a2200241 4500008004100000245006800041210006800109260001200177300001400189490000800203520239000211653001102601100002202612700002302634700001702657700002402674700002102698700002402719700002002743700002402763700002102787856009702808 2007 eng d00aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems0 aBiogeochemical stoichiometry of Antarctic Dry Valley ecosystems c02/2007 aG01010+120 v1123 a

Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–106 years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aLyons, Berry1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aFountain, Andrew, G1 aWall, Diana, H.1 aMoorhead, Daryl, L.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/biogeochemical-stoichiometry-antarctic-dry-valley-ecosystems00701nas a2200193 4500008004100000245009100041210006900132300001200201490000600213100002500219700002200244700002700266700001500293700002200308700002200330700001200352700003300364856011000397 2007 eng d00aControls on the spatial dimensions of wetted hydrologic margins of two antarctic lakes0 aControls on the spatial dimensions of wetted hydrologic margins  a841-8480 v61 aGooseff, Michael, N.1 aBarrett, John, E.1 aNorthcott, Melissa, L.1 aBate, Brad1 aHill, Kenneth, R.1 aZeglin, Lydia, H.1 aBobb, M1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/controls-spatial-dimensions-wetted-hydrologic-margins-two-antarctic-lakes00499nas a2200121 4500008004100000245007700041210006900118260003100187490000900218100002400227700002300251856010300274 2007 eng d00aEcotoxicity and microbial biogeochemistry of Fluoride in Antarctic soils0 aEcotoxicity and microbial biogeochemistry of Fluoride in Antarct bDartmouth Collegec07/20070 vB.S.1 aCollins, Pamela, M.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/ecotoxicity-and-microbial-biogeochemistry-fluoride-antarctic-soils01239nas a2200157 4500008004100000245010700041210006900148260001200217300001400229490000800243520072000251653001100971653000900982100002000991856007001011 2007 eng d00aGlobal Change tipping points: Above- and below-ground biotic interactions in a low diversity ecosystem0 aGlobal Change tipping points Above and belowground biotic intera c12/2007 a2291-23060 v3623 a

Low diversity ecosystems are expected to be more vulnerable to global changes although they have received less attention than high diversity ecosystems. Addressing the present state of the Antarctic Dry Valley region by focusing on the potential global changes that may alter the coupling of above- and below-ground species and ecosystem processes is a realistic and critical need that has value beyond the Antarctic community. Presented here are suggested implications of global change on the Dry Valley terrestrial systems and how these effects might be manifested in the future.

10aBiggie10asoil1 aWall, Diana, H. uhttp://rstb.royalsocietypublishing.org/content/362/1488/2291.full00380nas a2200109 4500008004100000245004700041210004400088260003300132100002000165700002900185856005600214 2007 eng d00aHidden Assets: Biodiversity Below-Surface.0 aHidden Assets Biodiversity BelowSurface bUNESCO-SCOPE Policy Brief #51 aWall, Diana, H.1 aBehan-Pelletier, Valerie uhttp://www.icsu-scope.org/unesco/USPB05_SOIL_En.pdf00541nas a2200121 4500008004100000245010000041210006900141260003600210490000900246100002000255700002100275856012300296 2007 eng d00aLacustrine History of Lake Hoare, McMurdo Dry Valleys, Antarctica, Based on Long Sediment Cores0 aLacustrine History of Lake Hoare McMurdo Dry Valleys Antarctica  bUniversity of Illinois, Chicago0 vM.S.1 aBurkemper, Andy1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/lacustrine-history-lake-hoare-mcmurdo-dry-valleys-antarctica-based-long-sediment-cores00539nas a2200145 4500008004100000245008300041210006900124300001200193490000700205100001200212700002000224700002000244700002300264856010600287 2007 eng d00aA mathematical model for variation in water-retention curves among sandy soils0 amathematical model for variation in waterretention curves among  a427-4360 v191 aHunt, H1 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/mathematical-model-variation-water-retention-curves-among-sandy-soils00503nas a2200097 4500008004100000245013700041210006900178300001000247100002400257856012400281 2007 eng d00aMesoscale dynamics of ephemeral wetlands in the Antarctic Dry Valleys: Implications to production and distribution of organic matter0 aMesoscale dynamics of ephemeral wetlands in the Antarctic Dry Va a87-951 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/mesoscale-dynamics-ephemeral-wetlands-antarctic-dry-valleys-implications-production-and00558nas a2200145 4500008004100000245008500041210006900126490000800195100002700203700001500230700002200245700001800267700002100285856010600306 2007 eng d00aMetabolic activity and diversity of cryoconites in the Taylor Valley, Antarctica0 aMetabolic activity and diversity of cryoconites in the Taylor Va0 v1121 aForeman, Christine, M.1 aSattler, B1 aMikucki, Jill, A.1 aPorazinska, D1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/metabolic-activity-and-diversity-cryoconites-taylor-valley-antarctica00476nas a2200121 4500008004100000245007900041210006900120260002900189490000900218100001300227700002100240856009300261 2007 eng d00aMicrobial Processes in the Moats of Lakes in the Taylor Valley, Antarctica0 aMicrobial Processes in the Moats of Lakes in the Taylor Valley A bMontana State University0 vM.S.1 aMoore, J1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/microbial-processes-moats-lakes-taylor-valley-antarctica00393nas a2200121 4500008004100000245004600041210004600087490000700133100001700140700002400157700001500181856007500196 2007 eng d00aOrganic carbon in Antarctic precipitation0 aOrganic carbon in Antarctic precipitation0 v341 aLyons, Berry1 aWelch, Kathleen, A.1 aDoggett, J uhttps://mcm.lternet.edu/content/organic-carbon-antarctic-precipitation00763nas a2200205 4500008004100000245013200041210006900173260001200242300001200254490000700266100002400273700002000297700002400317700002000341700001600361700002400377700001700401700001900418856012000437 2007 eng d00aReactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment0 aReactivation of a cryptobiotic stream ecosystem in the McMurdo D c09/2007 a186-2040 v891 aMcKnight, Diane, M.1 aTate, Cathy, M.1 aAndrews, Edmund, D.1 aNiyogi, Dev, K.1 aCozzetto, K1 aWelch, Kathleen, A.1 aLyons, Berry1 aCapone, D., G. uhttps://mcm.lternet.edu/content/reactivation-cryptobiotic-stream-ecosystem-mcmurdo-dry-valleys-antarctica-long-term00491nas a2200121 4500008004100000245008300041210006900124260002200193490000900215100001500224700002300239856010700262 2007 eng d00aSoil organic matter sources and quality in the McMurdo Dry Valleys, Antarctica0 aSoil organic matter sources and quality in the McMurdo Dry Valle bDartmouth College0 vM.S.1 aBate, Brad1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-organic-matter-sources-and-quality-mcmurdo-dry-valleys-antarctica00599nas a2200181 4500008004100000245009400041210006900135260001200204300001200216490000800228653002100236100001400257700002000271700002400291700001700315700002400332856006100356 2007 eng d00aSolute and isotope geochemistry of subsurface ice melt seeps in Taylor Valley, Antarctica0 aSolute and isotope geochemistry of subsurface ice melt seeps in  c01/2007 a548-5550 v11910aClimate Response1 aHarris, K1 aCarey, Anne, E.1 aWelch, Kathleen, A.1 aLyons, Berry1 aFountain, Andrew, G uhttp://gsabulletin.gsapubs.org/content/119/5-6/548.short00625nas a2200169 4500008004100000245010600041210006900147300001200216490000700228100001700235700002000252700001300272700001500285700001500300700001200315856012800327 2007 eng d00aThe southernmost worm, Scottnema lindsayae (Nematoda): diversity, dispersal and ecological stability.0 asouthernmost worm Scottnema lindsayae Nematoda diversity dispers a809-8150 v301 aAdams, Byron1 aWall, Diana, H.1 aGozel, U1 aDillman, A1 aChaston, J1 aHogg, I uhttps://mcm.lternet.edu/content/southernmost-worm-scottnema-lindsayae-nematoda-diversity-dispersal-and-ecological-stability00592nas a2200121 4500008004100000245015900041210006900200260002900269490000900298100001300307700002500320856012500345 2007 eng d00aSpatial and Temporal Active Layer Thermal Dynamics from Temperature Time Series Analysis: Case Studies from Lake Fryxell, McMurdo Dry Valleys, Antarctica.0 aSpatial and Temporal Active Layer Thermal Dynamics from Temperat bColorado School of Mines0 vM.S.1 aIkard, S1 aGooseff, Michael, N. uhttps://mcm.lternet.edu/content/spatial-and-temporal-active-layer-thermal-dynamics-temperature-time-series-analysis-case00498nas a2200121 4500008004100000245007800041210006900119260003600188490000900224100002100233700002100254856010100275 2007 eng d00aStable Carbon Isotope Analyses of Sediments from Lake Fryxell, Antarctica0 aStable Carbon Isotope Analyses of Sediments from Lake Fryxell An bUniversity of Illinois, Chicago0 vM.S.1 aMoore-Topinka, N1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/stable-carbon-isotope-analyses-sediments-lake-fryxell-antarctica00704nas a2200169 4500008004100000245010300041210006900144260005400213100002500267700002400292700002100316700001700337700001700354700001900371700002700390856011700417 2007 eng d00aTrends in discharge and flow season timing of the Onyx River, Wright Valley, Antarctica since 19690 aTrends in discharge and flow season timing of the Onyx River Wri bU.S. Geological Survey Open-File Report 2007-10471 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aDoran, Peter, T.1 aLyons, Berry1 aCooper, Alan1 aRaymond, Carol1 aTeam, ISAES, Editorial uhttps://mcm.lternet.edu/content/trends-discharge-and-flow-season-timing-onyx-river-wright-valley-antarctica-196900578nas a2200133 4500008004100000245011000041210006900151100001800220700002000238700001700258700002200275700002300297856012400320 2007 eng d00aUnique similarity of faunal communities across aquatic terrestrial interfaces in a polar desert ecosystem0 aUnique similarity of faunal communities across aquatic terrestri1 aAyres, Edward1 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/unique-similarity-faunal-communities-across-aquatic-terrestrial-interfaces-polar-desert00449nas a2200121 4500008004100000245006100041210006100102260003000163490000900193100001700202700002500219856008300244 2007 eng d00aWETTED MARGIN HYDROLOGY OF THE DRY VALLEYS OF ANTARCTICA0 aWETTED MARGIN HYDROLOGY OF THE DRY VALLEYS OF ANTARCTICA bColorado School of Mines,0 vM.S.1 aNorthcott, M1 aGooseff, Michael, N. uhttps://mcm.lternet.edu/content/wetted-margin-hydrology-dry-valleys-antarctica02534nas a2200193 4500008004100000245009700041210006900138260001200207300001200219490000700231520185500238653001102093100002902104700002102133700001402154700002502168700002402193856012302217 2006 eng d00aAdaptation and acclimation of photosynthetic microorganisms to permanently cold environments0 aAdaptation and acclimation of photosynthetic microorganisms to p c03/2006 a222-2520 v703 a

Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.

10aBiggie1 aMorgan-Kiss, Rachael, M.1 aPriscu, John, C.1 aPocock, T1 aGudynaite-Savitch, L1 aHuner, Norman, P.A. uhttps://mcm.lternet.edu/content/adaptation-and-acclimation-photosynthetic-microorganisms-permanently-cold-environments00754nas a2200205 4500008004100000245012400041210006900165300001200234490000700246100001600253700001500269700002400284700001700308700002300325700001300348700002200361700001500383700002400398856012600422 2006 eng d00aThe aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis0 aaeolian flux of calcium chloride and nitrate to the McMurdo Dry  a497-5050 v181 aWitherow, R1 aBertler, N1 aWelch, Kathleen, A.1 aLyons, Berry1 aMayewski, Paul, A.1 aSneed, S1 aNylen, Thomas, H.1 aHandley, M1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/aeolian-flux-calcium-chloride-and-nitrate-mcmurdo-dry-valleys-landscape-evidence-snow-pit01738nas a2200229 4500008004100000245008300041210006900124260001200193300001100205490000700216520101800223653001101241100002501252700001201277700002401289700001101313700001301324700002501337700002101362700001601383856010901399 2006 eng d00aAntarctic Climate Cooling and Response of Diatoms in Glacial Meltwater Streams0 aAntarctic Climate Cooling and Response of Diatoms in Glacial Mel c04/2006 aL074060 v333 a

To understand biotic responses to an Antarctic cooling trend, we analyzed diatom samples from glacial meltwater streams in the McMurdo Dry Valleys, the largest ice-free area in Antarctica. Diatoms are abundant in these streams, and 24 of 40 species have only been found in the Antarctic. The percentage of these Antarctic diatom species increased with decreasing annual stream flow and increasing harshness of the stream habitat. The species diversity of assemblages reached a maximum when the Antarctic species accounted for 40–60% of relative diatom abundance. Decreased solar radiation and air-temperatures reduce annual stream flow, raising the dominance of these Antarctic species to levels above 60%. Thus, cooling favors the Antarctic species, and lowers diatom species diversity in this region.

10aBiggie1 aEsposito, Rhea, M.M.1 aHorn, S1 aMcKnight, Diane, M.1 aCox, M1 aGrant, M1 aSpaulding, Sarah, A.1 aDoran, Peter, T.1 aCozzetto, K uhttps://mcm.lternet.edu/content/antarctic-climate-cooling-and-response-diatoms-glacial-meltwater-streams00563nas a2200169 4500008004100000245004600041210004600087260003400133100001700167700002800184700002400212700002100236700002000257700001800277700002000295856007800315 2006 eng d00aAntarctic lake systems and climate change0 aAntarctic lake systems and climate change aDordrecht, The NetherlandsbS1 aLyons, Berry1 aLaybourn-Parry, Johanna1 aWelch, Kathleen, A.1 aPriscu, John, C.1 aBergstrom, D.M.1 aConvey, Peter1 aHuiskes, A.H.L. uhttps://mcm.lternet.edu/content/antarctic-lake-systems-and-climate-change00429nas a2200145 4500008004100000245003300041210003200074260003000106300001200136490000600148100002200154700002300176700002000199856006400219 2006 eng d00aBiogeochemistry, terrestrial0 aBiogeochemistry terrestrial aNew YorkbRoutledge Press a154-1550 v11 aBarrett, John, E.1 aVirginia, Ross, A.1 aRiffenburgh, B. uhttps://mcm.lternet.edu/content/biogeochemistry-terrestrial00665nas a2200217 4500008004100000245008000041210006900121300001400190490000700204100001200211700002000223700001900243700001400262700001500276700001600291700001700307700001600324700002100340700001500361856007100376 2006 eng d00aBiotic interactions in Antarctic terrestrial ecosystems: Are they a factor?0 aBiotic interactions in Antarctic terrestrial ecosystems Are they a3035-30400 v381 aHogg, I1 aWall, Diana, H.1 aCary, Craig, S1 aConvey, K1 aNewsham, K1 aODonnell, G1 aAdams, Byron1 aAislabie, J1 aFrati, Francesco1 aStevens, M uhttp://www.sciencedirect.com/science/article/pii/S003807170600217300757nas a2200181 4500008004100000245010900041210006900150300001200219490000700231100002200238700002300260700002000283700001900303700001700322700001400339700001600353856020600369 2006 eng d00aCo-variation in soil biodiversity and biogeochemistry in Northern and Southern Victoria Land, Antarctica0 aCovariation in soil biodiversity and biogeochemistry in Northern a535-5480 v181 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aCary, Craig, S1 aAdams, Byron1 aHacker, A1 aAislabie, J uhttps://www.cambridge.org/core/journals/antarctic-science/article/covariation-in-soil-biodiversity-and-biogeochemistry-in-northern-and-southern-victoria-land-antarctica/C3514C28DB75F3A19DB5F266D4B1B56E00891nas a2200325 4500008004100000245005400041210005400095300001400149490000700163100001700170700001500187700001800202700001200220700002100232700001200253700001500265700001700280700001500297700001500312700001500327700002600342700001800368700002000386700001600406700001600422700001600438700001900454700001600473856007600489 2006 eng d00aDiversity and distribution of Victoria Land biota0 aDiversity and distribution of Victoria Land biota a3003-30180 v381 aAdams, Byron1 aConnell, L1 aConvey, Peter1 aFell, J1 aFrati, Francesco1 aHogg, I1 aNewsham, K1 aO'Donnell, A1 aRussell, N1 aSeppelt, R1 aStevens, M1 aBardgett, Richard, D.1 aAyres, Edward1 aWall, Diana, H.1 aAislabie, J1 aBamforth, S1 aBargagli, R1 aCary, Craig, S1 aCavacini, P uhttps://www.sciencedirect.com/science/article/abs/pii/S003807170600221500600nas a2200145 4500008004100000245011900041210006900160300001200229490000700241100001500248700002400263700001500287700002700302856012500329 2006 eng d00aEnvironmental factors associated with deep chlorophyll maxima in dry valley lakes, South Victoria Land, Antarctica0 aEnvironmental factors associated with deep chlorophyll maxima in a179-1890 v381 aBurnett, L1 aMoorhead, Daryl, L.1 aHawes, Ian1 aHoward-Williams, Clive uhttps://mcm.lternet.edu/content/environmental-factors-associated-deep-chlorophyll-maxima-dry-valley-lakes-south-victoria00609nas a2200145 4500008004100000245012000041210006900161300001200230490000700242100001600249700002400265700002200289700002400311856012800335 2006 eng d00aExperimental investigations into processes controlling stream and hyporheic temperatures, Fryxell Basin, Antarctica0 aExperimental investigations into processes controlling stream an a130-1530 v291 aCozzetto, K1 aMcKnight, Diane, M.1 aNylen, Thomas, H.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/experimental-investigations-processes-controlling-stream-and-hyporheic-temperatures-fryxell00439nas a2200133 4500008004100000245005000041210005000091300001200141490000700153100002300160700002200183700002100205856007900226 2006 eng d00aFuel movement between grain boundaries in ice0 aFuel movement between grain boundaries in ice a158-1650 v451 aJepsen, Steven, M.1 aAdams, Edward, E.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/fuel-movement-between-grain-boundaries-ice00655nas a2200181 4500008004100000245011400041210006900155300000800224490000800232100001400240700001400254700002100268700001800289700001400307700001400321700001300335856012500348 2006 eng d00aGlacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, Southern Victoria Land, Antarctica0 aGlacial and postglacial sedimentation in the Fryxell basin Taylo a3200 v3411 aWagner, B1 aMelles, M1 aDoran, Peter, T.1 aKenig, Fabien1 aForman, S1 aPierau, R1 aAllan, P uhttps://mcm.lternet.edu/content/glacial-and-postglacial-sedimentation-fryxell-basin-taylor-valley-southern-victoria-land00551nas a2200145 4500008004100000245008500041210006900126300000800195490000700203100002400210700002200234700001600256700002000272856011300292 2006 eng d00aGlacier mass balances (1993-2001) Taylor Valley, McMurdo Dry Valleys, Antarctica0 aGlacier mass balances 19932001 Taylor Valley McMurdo Dry Valleys a4510 v521 aFountain, Andrew, G1 aNylen, Thomas, H.1 aMacClune, K1 aDana, Gayle, L. uhttps://mcm.lternet.edu/content/glacier-mass-balances-1993-2001-taylor-valley-mcmurdo-dry-valleys-antarctica00331nam a2200121 4500008004100000020001900041245001800060210001400078260004000092300000700132100002400139856004600163 2006 eng d a978-097234227800aThe Lost Seal0 aLost Seal aLafayettebMoonlight Publishing LLC a401 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/lost-seal00592nas a2200145 4500008004100000245010200041210006900143490000700212100002700219700001600246700001700262700002300279700002100302856012300323 2006 eng d00aMeasuring ecosystem response in a rapidly changing environment: the Latitudinal Gradient Project0 aMeasuring ecosystem response in a rapidly changing environment t0 v101 aHoward-Williams, Clive1 aPeterson, D1 aLyons, Berry1 aCattaneo-Vietti, R1 aGordon, Shulamit uhttps://mcm.lternet.edu/content/measuring-ecosystem-response-rapidly-changing-environment-latitudinal-gradient-project00612nas a2200145 4500008004100000245011000041210006900151260003400220300001100254100001300265700001700278700002200295700002300317856012600340 2006 eng d00aPedogenic carbonate distribution within glacial till in Taylor Valley, Southern Victoria Land, Antarctica0 aPedogenic carbonate distribution within glacial till in Taylor V bGeological Society of America a89-1031 aFoley, K1 aLyons, Berry1 aBarrett, John, E.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/pedogenic-carbonate-distribution-within-glacial-till-taylor-valley-southern-victoria-land00554nas a2200169 4500008004100000245006300041210006200104300001200166490000700178100001500185700001600200700002200216700002000238700002300258700001500281856008800296 2006 eng d00aPhosphorus fractions in soils of Taylor Valley, Antarctica0 aPhosphorus fractions in soils of Taylor Valley Antarctica a806-8150 v701 aBlecker, S1 aIppolito, J1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aNorvell, K uhttps://mcm.lternet.edu/content/phosphorus-fractions-soils-taylor-valley-antarctica00487nas a2200109 4500008004100000245009400041210006900135260003000204100001400234700001700248856011200265 2006 eng d00aA Qualitative Approach to Understanding the Rate of Weathering, Taylor Valley, Antarctica0 aQualitative Approach to Understanding the Rate of Weathering Tay bThe Ohio State University1 aMiller, E1 aLyons, Berry uhttps://mcm.lternet.edu/content/qualitative-approach-understanding-rate-weathering-taylor-valley-antarctica00583nas a2200157 4500008004100000245008700041210006900128300001200197490000700209100002200216700002300238700002200261700002000283700001000303856011200313 2006 eng d00aSalt tolerance and survival thresholds for two species of Antarctic soil nematodes0 aSalt tolerance and survival thresholds for two species of Antarc a643-6510 v291 aNkem, Johnson, N.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aWall, Diana, H.1 aLi, G uhttps://mcm.lternet.edu/content/salt-tolerance-and-survival-thresholds-two-species-antarctic-soil-nematodes00556nas a2200145 4500008004100000245008200041210006900123300001200192490000800204100001500212700002400227700002300251700002800274856010800302 2006 eng d00aSimulating energy flow through a pelagic food web in Lake Fryxell, Antarctica0 aSimulating energy flow through a pelagic food web in Lake Fryxel a457-4720 v1921 aMcKenna, K1 aMoorhead, Daryl, L.1 aRoberts, Emily, C.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/simulating-energy-flow-through-pelagic-food-web-lake-fryxell-antarctica00531nas a2200145 4500008004100000245007100041210006900112300001400181490000700195100002200202700002300224700002400247700002000271856009400291 2006 eng d00aSoil carbon turnover model for the McMurdo Dry Valleys, Antarctica0 aSoil carbon turnover model for the McMurdo Dry Valleys Antarctic a3065-30820 v381 aBarrett, John, E.1 aVirginia, Ross, A.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/soil-carbon-turnover-model-mcmurdo-dry-valleys-antarctica00506nas a2200121 4500008004100000245008900041210006900130260002200199490000900221100001500230700002300245856011600268 2006 eng d00aSoil nitrogen cycling in cold desert (McMurdo Dry Valleys) and hot desert ecosystems0 aSoil nitrogen cycling in cold desert McMurdo Dry Valleys and hot bDartmouth College0 vM.S.1 aStucker, A1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-nitrogen-cycling-cold-desert-mcmurdo-dry-valleys-and-hot-desert-ecosystems00585nas a2200133 4500008004100000245012400041210006900165300001000234490000700244100002400251700002300275700002400298856012900322 2006 eng d00aSpatial and temporal active layer dynamics along three glacial meltwater streams in the McMurdo Dry Valleys, Antarctica0 aSpatial and temporal active layer dynamics along three glacial m a42-530 v381 aConovitz, Peter, A.1 aMacDonald, Lee, H.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/spatial-and-temporal-active-layer-dynamics-along-three-glacial-meltwater-streams-mcmurdo-dry00492nas a2200121 4500008004100000245007700041210006900118260002900187490000900216100001200225700003300237856010000270 2006 eng d00aSpatial Patterns of Bacterial Diversity in Cold Desert Riparian Zones.0 aSpatial Patterns of Bacterial Diversity in Cold Desert Riparian  bUniversity of New Mexico0 vB.S.1 aBobb, M1 aTakacs-Vesbach, Cristina, D. uhttps://mcm.lternet.edu/content/spatial-patterns-bacterial-diversity-cold-desert-riparian-zones00687nas a2200181 4500008004100000245010500041210006900146260001200215300001000227490000700237100002500244700001700269700002400286700002200310700002400332700002100356856012800377 2006 eng d00aA stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica0 astable isotopic investigation of a polar desert hydrologic syste c02/2006 a60-710 v381 aGooseff, Michael, N.1 aLyons, Berry1 aMcKnight, Diane, M.1 aVaughn, Bruce, H.1 aFountain, Andrew, G1 aDowling, Carolyn uhttps://mcm.lternet.edu/content/stable-isotopic-investigation-polar-desert-hydrologic-system-mcmurdo-dry-valleys-antarctica00563nas a2200145 4500008004100000245009200041210006900133300001400202490000700216100002000223700001700243700002200260700002000282856011500302 2006 eng d00aA synthesis of soil biodiversity and ecosystem functioning in Victoria Land, Antarctica0 asynthesis of soil biodiversity and ecosystem functioning in Vict a3001-30020 v381 aWall, Diana, H.1 aAdams, Byron1 aBarrett, John, E.1 aHopkins, D., W. uhttps://mcm.lternet.edu/content/synthesis-soil-biodiversity-and-ecosystem-functioning-victoria-land-antarctica00812nas a2200265 4500008004100000245006500041210006400106300001400170490000700184100002200191700002200213700001500235700001600250700002000266700001900286700002300305700002000328700001600348700001600364700001600380700001600396700001700412700002400429856009300453 2006 eng d00aTerrestrial ecosystem processes of Victoria Land, Antarctica0 aTerrestrial ecosystem processes of Victoria Land Antarctica a3019-30340 v381 aBarrett, John, E.1 aNkem, Johnson, N.1 aSletten, R1 aSteltzer, H1 aWall, Diana, H.1 aWallenstein, M1 aVirginia, Ross, A.1 aHopkins, D., W.1 aAislabie, J1 aBargagli, R1 aBockheim, J1 aCampbell, I1 aLyons, Berry1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/terrestrial-ecosystem-processes-victoria-land-antarctica02560nas a2200205 4500008004100000245008000041210006900121300001200190490000700202520193000209653001102139100002202150700002002172700002302192700002202215700001302237700001802250700001702268856006902285 2006 eng d00aWind dispersal of soil invertebrates in the McMurdo Dry Valleys, Antarctica0 aWind dispersal of soil invertebrates in the McMurdo Dry Valleys  a346-3520 v293 a

Dispersal of soil organisms is crucial for their spatial distribution and adaptation to the prevailing conditions of the Antarctic Dry Valleys. This study investigated the possibility of wind dispersal of soil invertebrates within the dry valleys. Soil invertebrates were evaluated in (1) pockets of transported sediments to lake ice and glacier surfaces, (2) wind-transported dust particles in collection pans (Bundt pans) 100 cm above the soil surface, and (3) sediments transported closer to the surface (<50 cm) and collected in open top chambers (OTCs). Invertebrates were extracted and identified. Nematodes were identified to species and classified according to life stage and sex. Three species of nematodes were recovered and Scottnema lindsayae was the most dominant. There were more juveniles (∼71%) in the transported sediments than adults (29%). Tardigrades and rotifers were more abundant in sediments on lake and glacier surfaces while nematodes were more abundant in the dry sediment collections of Bundt pans and OTCs. The abundance of immobile (dead) nematodes in the Bundt pans and OTCs was three times greater than active (live) nematodes. Anhydrobiosis constitutes a survival mechanism that allows wind dispersal of nematodes in the McMurdo Dry Valleys. Our results show that soil invertebrates are dispersed by wind in the Dry Valleys and are viable in ice communities on lake surfaces and glaciers.

10aBiggie1 aNkem, Johnson, N.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aBarrett, John, E.1 aBroos, E1 aPorazinska, D1 aAdams, Byron uhttp://link.springer.com/content/pdf/10.1007%2Fs00300-005-0061-x00497nas a2200121 4500008004100000245008100041210006900122260001200191300001200203490000700215100002000222856013300242 2005 eng d00aBiodiversity and ecosystem functioning in terrestrial habitats of Antarctica0 aBiodiversity and ecosystem functioning in terrestrial habitats o c07/2005 a523-5310 v171 aWall, Diana, H. uhttp://journals.cambridge.org/download.php?file=%2FANS%2FANS17_04%2FS0954102005002944a.pdf&code=f0bfb3b7eb4345bde6bbfbf916a408e100559nas a2200157 4500008004100000245008000041210006900121490000700190100001300197700001400210700001500224700001500239700002100254700001700275856010900292 2005 eng d00aBiogeological Raman spectroscopic studies of Antarctic lacustrine sediments0 aBiogeological Raman spectroscopic studies of Antarctic lacustrin0 v611 aMoody, C1 aVillar, S1 aEdwards, H1 aHodgson, D1 aDoran, Peter, T.1 aBishop, J.L. uhttps://mcm.lternet.edu/content/biogeological-raman-spectroscopic-studies-antarctic-lacustrine-sediments00648nas a2200157 4500008004100000245012800041210006900169300001000238490000700248100002000255700002400275700001700299700002200316700002400338856012800362 2005 eng d00aThe chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer0 achemical composition of runoff from Canada Glacier Antarctica im a15-190 v401 aTranter, Martyn1 aFountain, Andrew, G1 aLyons, Berry1 aNylen, Thomas, H.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/chemical-composition-runoff-canada-glacier-antarctica-implications-glacier-hydrology-during00884nas a2200265 4500008004100000245007800041210007000119300001100189490000700200653002500207100002100232700001900253700002700272700002700299700002400326700002100350700001700371700001300388700002400401700002400425700002400449700002300473700002000496856010200516 2005 eng d00aComment on ``El Niño suppresses Antarctic warming'' by N. Bertler et al.0 aComment on El Niño suppresses Antarctic warming by N Bertler et  aL077060 v3210aTropical meteorology1 aDoran, Peter, T.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N.1 aPriscu, John, C.1 aLyons, Berry1 aWalsh, J1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/comment-el-ni%C3%B1o-suppresses-antarctic-warming-n-bertler-et-al00509nas a2200121 4500008004100000245009600041210006900137490000700206100002400213700001700237700001500254856011800269 2005 eng d00aContributions of Benthic Microbial Mats to Net Primary Production in Lake Hoare, Antarctica0 aContributions of Benthic Microbial Mats to Net Primary Productio0 v171 aMoorhead, Daryl, L.1 aSchmeling, S1 aHawes, Ian uhttps://mcm.lternet.edu/content/contributions-benthic-microbial-mats-net-primary-production-lake-hoare-antarctica00618nas a2200181 4500008004100000245006900041210006800110300000900178490000700187100001700194700002100211700002400232700001400256700002300270700002100293700002400314856009800338 2005 eng d00aDating water and solute additions to ice-covered Antarctic lakes0 aDating water and solute additions to icecovered Antarctic lakes aA7200 v691 aLyons, Berry1 aDowling, Carolyn1 aWelch, Kathleen, A.1 aSnyder, G1 aPoreda, Robert, J.1 aDoran, Peter, T.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/dating-water-and-solute-additions-ice-covered-antarctic-lakes00528nas a2200109 4500008004100000245014300041210006900184260002700253490000900280100001400289856011500303 2005 eng d00aDetermining the role of chemical weathering reactions and hyporheic exchange on silicate concentrations in Dry Valley streams, Antarctica.0 aDetermining the role of chemical weathering reactions and hyporh bUniversity of Colorado0 vM.S.1 aJoslin, J uhttps://mcm.lternet.edu/content/determining-role-chemical-weathering-reactions-and-hyporheic-exchange-silicate00612nas a2200169 4500008004100000245007600041210006900117260003100186300000900217100002000226700001500246700001700261700002600278700001800304700002000322856010000342 2005 eng d00aDeveloping new perspectives from advances in soil biodiversity research0 aDeveloping new perspectives from advances in soil biodiversity r bCambridge University Press a3-301 aWall, Diana, H.1 aFritter, A1 aPaul, E., A.1 aBardgett, Richard, D.1 aUsher, M., B.1 aHopkins, D., W. uhttps://mcm.lternet.edu/content/developing-new-perspectives-advances-soil-biodiversity-research00519nas a2200133 4500008004100000245008900041210006900130300001200199490000700211100001600218700002000234700002300254856010800277 2005 eng d00aDistribution and diversity of soil protozoa in the McMurdo Dry Valleys of Antarctica0 aDistribution and diversity of soil protozoa in the McMurdo Dry V a756-7620 v281 aBamforth, S1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/distribution-and-diversity-soil-protozoa-mcmurdo-dry-valleys-antarctica00340nas a2200109 4500008004100000245003300041210003000074300001200104490000700116100002100123856008600144 2005 eng d00aAn Ecosystem of Superlatives0 aEcosystem of Superlatives a804-8060 v551 aPriscu, John, C. uhttp://www.jstor.org/stable/10.1641/0006-3568%282005%29055%5B0804:AEOS%5D2.0.CO;200646nas a2200157 4500008004100000245013500041210006900176300001200245490000700257100001900264700002000283700002400303700001700327700002400344856012000368 2005 eng d00aThe Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters0 aGeochemistry of Supraglacial Streams of Canada Glacier Taylor Va a391-4120 v111 aFortner, Sarah1 aTranter, Martyn1 aFountain, Andrew, G1 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/geochemistry-supraglacial-streams-canada-glacier-taylor-valley-antarctica-and-their00549nas a2200157 4500008004100000245009600041210006900137300001200206490000800218100002500226700002200251700002700273700001400300700002100314856005600335 2005 eng d00aGlacial ice cores: a model system for developing extraterrestrial decontamination protocols0 aGlacial ice cores a model system for developing extraterrestrial a572-5840 v1741 aChristner, Brent, C.1 aMikucki, Jill, A.1 aForeman, Christine, M.1 aDenson, J1 aPriscu, John, C. u/reports/lakes/ChristnerEtAl2005Decontamination.pdf00711nas a2200205 4500008004100000245008900041210006900130300001200199490000700211100001700218700002400235700002000259700002000279700002300299700002400322700002100346700001400367700001500381856010900396 2005 eng d00aGroundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event0 aGroundwater seeps in Taylor Valley Antarctica An example of a su a200-2060 v401 aLyons, Berry1 aWelch, Kathleen, A.1 aCarey, Anne, E.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aFountain, Andrew, G1 aDoran, Peter, T.1 aCsatho, B1 aTremper, C uhttps://mcm.lternet.edu/content/groundwater-seeps-taylor-valley-antarctica-example-subsurface-melt-event00681nas a2200181 4500008004100000245012100041210006900162300001200231490000700243100001700250700002400267700001400291700001400305700001400319700001900333700002300352856012400375 2005 eng d00aHalogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution0 aHalogen geochemistry of the McMurdo Dry Valleys Lakes Antarctica a305-3230 v691 aLyons, Berry1 aWelch, Kathleen, A.1 aSnyder, G1 aOlesik, J1 aGraham, E1 aMarion, G., M.1 aPoreda, Robert, J. uhttps://mcm.lternet.edu/content/halogen-geochemistry-mcmurdo-dry-valleys-lakes-antarctica-clues-origin-solutes-and-lake00520nas a2200157 4500008004100000245009400041210006900135260001200204300001000216490000700226653002100233100001300254700002400267700002200291856004900313 2005 eng d00aAn index model of stream flow at below freezing-temperatures in Taylor Valley, Antarctica0 aindex model of stream flow at below freezingtemperatures in Tayl c01/2005 a76-820 v4010aClimate Response1 aEbnet, A1 aFountain, Andrew, G1 aNylen, Thomas, H. uhttp://dx.doi.org/10.3189/17275640578181351900476nas a2200133 4500008004100000245006400041210006400105300001000169490000700179100002000186700002000206700002300226856009300249 2005 eng d00aInvertebrate diversity in Taylor Valley soils and sediments0 aInvertebrate diversity in Taylor Valley soils and sediments a13-160 v331 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/invertebrate-diversity-taylor-valley-soils-and-sediments00443nas a2200121 4500008004100000245005800041210005800099260003600157490001000193100001400203700002100217856008300238 2005 eng d00aLacustrine Biogeochemistry of the McMurdo Dry Valleys0 aLacustrine Biogeochemistry of the McMurdo Dry Valleys bUniversity of Illinois, Chicago0 vPh.D.1 aLawson, J1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/lacustrine-biogeochemistry-mcmurdo-dry-valleys02329nas a2200181 4500008004100000245009400041210006900135260004900204300000800253490000900261520166100270100002201931700001701953700002001970700002001990700002702010856011002037 2005 eng d00aMathematical Modeling of a Hydrocarbon Spill on the Ice Cover of Lake Fryxell, Antarctica0 aMathematical Modeling of a Hydrocarbon Spill on the Ice Cover of aColumbusbThe Ohio State Universityc06/2005 a1140 vM.S.3 a

Numerous perennially ice-covered lakes exist in the McMurdo Dry Valleys region of Antarctica. Ice cover melting on these lakes and meltwater infiltration are important processes affecting the ecology of these lakes. The three lakes in Taylor Valley, Lakes Bonney, Fryxell and Hoare, have been investigated since 1993 as part of the McMurdo Dry Valleys Long Term Ecological Research (MCM LTER) site. A Bell 212 helicopter flying in support of the National Science Foundation's Antarctic Research Program crashed on the frozen surface of Lake Fryxell on January 17, 2003. This resulted in the release of approximately 731 Liters (193 gallons) of diesel fuel and amounts of engine oil and hydraulic fluid. Two physically based models are developed that simulate heat, meltwater flow and solute transport. The first is a transient, one-dimensional, thermodynamic model, which can predict the temperature distribution in the ice cover, melting rate at the surface and at the bottom of ice cover, and ice thickness. The second model simulates unsaturated flow and solute transport and is used to estimate water content distribution and solute transport through the ice cover. The validation of heat transport model was accomplished by comparing model results with the original measurements of ice temperature at various depth in Lake Fryxell. Because of lack of the field data, validation of the unsaturated flow and solute transport model couldn't been accomplished, instead of model validation, programming code has been verified by comparing results with results generated by the HYDRUS 1D software, developed by U.S. Salinity Laboratory, USDA.

1 aKarnovic, Marinko1 aLyons, Berry1 aCarey, Anne, E.1 aBair, Scott, E.1 avan der Veen, Cornelis uhttps://mcm.lternet.edu/content/mathematical-modeling-hydrocarbon-spill-ice-cover-lake-fryxell-antarctica00509nas a2200121 4500008004100000245009200041210006900133260003000202490000900232100001600241700001700257856011300274 2005 eng d00aMercury Concentrations in Snow and the Modern Mercury Flux to Taylor Valley, Antarctica0 aMercury Concentrations in Snow and the Modern Mercury Flux to Ta bThe Ohio State University0 vM.S.1 aWitherow, R1 aLyons, Berry uhttps://mcm.lternet.edu/content/mercury-concentrations-snow-and-modern-mercury-flux-taylor-valley-antarctica00454nas a2200121 4500008004100000245006100041210006100102260002900163490001000192100002200202700002100224856008700245 2005 eng d00aMicrobial Ecology of an Antarctic Subglacial Environment0 aMicrobial Ecology of an Antarctic Subglacial Environment bMontana State University0 vPh.D.1 aMikucki, Jill, A.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/microbial-ecology-antarctic-subglacial-environment00569nas a2200133 4500008004100000245012200041210006900163300000800232490000700240100001600247700002400263700002200287856012600309 2005 eng d00aThe origin of channels on lower Taylor Glacier, McMurdo Dry Valleys Antarctica and their implication for water runoff0 aorigin of channels on lower Taylor Glacier McMurdo Dry Valleys A a1-70 v401 aJohnston, R1 aFountain, Andrew, G1 aNylen, Thomas, H. uhttps://mcm.lternet.edu/content/origin-channels-lower-taylor-glacier-mcmurdo-dry-valleys-antarctica-and-their-implication00539nas a2200121 4500008004100000245011000041210006900151260003000220490000900250100001300259700001700272856012800289 2005 eng d00aPedogenic Carbonate Distribution within Glacial Till in Taylor Valley, Southern Victoria Land, Antarctica0 aPedogenic Carbonate Distribution within Glacial Till in Taylor V bThe Ohio State University0 vM.S.1 aFoley, K1 aLyons, Berry uhttps://mcm.lternet.edu/content/pedogenic-carbonate-distribution-within-glacial-till-taylor-valley-southern-victoria-land-000755nas a2200217 4500008004100000245008700041210006900128260003100197300001000228100002100238700002200259700002000281700002700301700001900328700002000347700002000367700002200387700001900409700001700428856009200445 2005 eng d00aPerennial Antarctic lake ice: A refuge for cyanobacteria in an extreme environment0 aPerennial Antarctic lake ice A refuge for cyanobacteria in an ex bPrinceton University Press a22-491 aPriscu, John, C.1 aAdams, Edward, E.1 aPaerl, Hans, W.1 aFritsen, Christian, H.1 aDore, John, E.1 aLisle, John, T.1 aWolf, Craig, F.1 aMikucki, Jill, A.1 aRogers, S., O.1 aCastello, J. uhttp://www.montana.edu/lkbonney/DOCS/Publications/PriscuEtAl2005CyanobacteriaRefuge.pdf00677nas a2200181 4500008004100000245009700041210006900138300001000207490000600217100002000223700002400243700002700267700001700294700002100311700001600332700002400348856012300372 2005 eng d00aPerturbation of hydrochemical conditions in natural microcosms entombed within Antarctic ice0 aPerturbation of hydrochemical conditions in natural microcosms e a22-230 v61 aTranter, Martyn1 aFountain, Andrew, G1 aFritsen, Christian, H.1 aLyons, Berry1 aPriscu, John, C.1 aStratham, P1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/perturbation-hydrochemical-conditions-natural-microcosms-entombed-within-antarctic-ice00662nas a2200193 4500008004100000245008500041210006900126260004000195300001200235100002700247700002300274700001500297700001600312700002100328700002700349700002100376700002000397856005100417 2005 eng d00aPolar lakes, streams, and springs as analogs for the hydrological cycle on Mars.0 aPolar lakes streams and springs as analogs for the hydrological  aBerlin, HeidelbergbSpringer Verlag a219-2331 aMcKay, Christopher, P.1 aAndersen, Dale, T.1 aPollard, W1 aHeldmann, J1 aDoran, Peter, T.1 aFritsen, Christian, H.1 aPriscu, John, C.1 aTokano, Tetsuya u/reports/lakes/McKayEtAl2005StreamsSprings.pdf00875nas a2200361 4500008004100000245001800041210001800059260001700077300001200094100001900106700001500125700001500140700002300155700001300178700001300191700001900204700001500223700001400238700002000252700001500272700001400287700001700301700001800318700001900336700001400355700002200369700001400391700001500405700001500420700001600435700001200451856005000463 2005 eng d00aPolar Systems0 aPolar Systems bIsland Press a717-7431 aChapin, F., S.1 aMcGuire, A1 aNuttall, M1 aVirginia, Ross, A.1 aYoung, O1 aZimov, S1 aChristensen, T1 aGodduhn, A1 aMurphy, E1 aWall, Diana, H.1 aZockler, C1 aBerman, M1 aCallaghan, T1 aConvey, Peter1 aCrepin, A., S.1 aDanell, K1 aDucklow, Hugh, W.1 aForbes, B1 aKofinas, G1 aHassan, R.1 aScholes, R.1 aAsh, N. uhttps://mcm.lternet.edu/content/polar-systems02635nas a2200181 4500008004100000245007200041210006900113260001200182300001200194490000700206520208100213653001102294100002202305700002302327700002402350700002002374856005902394 2005 eng d00aPotential soil organic matter turnover in Taylor Valley, Antarctica0 aPotential soil organic matter turnover in Taylor Valley Antarcti c02/2005 a108-1170 v373 a

Antarctic Dry Valley ecosystems are among the most inhospitable soil ecosystems on earth with simple food webs and nearly undetectable fluxes of carbon (C) and nitrogen (N). Due to the lack of vascular plants, soil organic matter concentrations are extremely low, and it is unclear how much of the contemporary soil C budget is actively cycling or a legacy of paleolake production and sedimentation. While recent work indicates multiple sources of organic matter for dry valley soils, the composition and kinetics of organic pools remain poorly characterized. We examined soil organic matter pools and potential C and N turnover in soils from within six sites located across three hydrological basins of Taylor Valley, Antarctica that differed in surface age, microclimate and proximity to legacy (paleolake) sources of organic matter. We estimated potential C and N mineralization, and rate kinetics using gas exchange and repeated leaching techniques during 90-d incubations of surface soils collected from valley basin and valley slope positions in three basins of Taylor Valley. Soil organic C content was negatively correlated with the ages of underlying tills, supporting previous descriptions of legacy organic matter. Carbon and N mineralization generally followed 1st order kinetics and were well described by exponential models. Labile pools of C (90 d) were 10% of the total organic C in the upper 5 cm of the soil profile. Labile N was 50% of the total N in surface soils of Taylor Valley. These results show that a large proportion of soil C and particularly N are mineralizable under suitable conditions and suggest that a kinetically defined labile pool of organic matter is potentially active in the field during brief intervals of favorable microclimate. Climate variation changing the duration of these conditions may have potentially large effects on the small pools of C and N in these soils.

10aBiggie1 aBarrett, John, E.1 aVirginia, Ross, A.1 aParsons, Andrew, N.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/e653225425230175/00700nas a2200169 4500008004100000245014000041210006900181260001200250300001200262490000700274100002500281700002500306700002300331700002300354700002400377856012900401 2005 eng d00aSensitivity analysis of conservative and reactive stream transient storage models applied to field data from multiple-reach experiments0 aSensitivity analysis of conservative and reactive stream transie c05/2005 a479-4920 v281 aGooseff, Michael, N.1 aBencala, Kenneth, E.1 aScott, Durelle, T.1 aRunkel, Robert, L.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/sensitivity-analysis-conservative-and-reactive-stream-transient-storage-models-applied-field00648nas a2200181 4500008004100000245008700041210006900128300001200197490000800209100002000217700001800237700002900255700001400284700002200298700001600320700002100336856010900357 2005 eng d00aSoils, freshwater and marine sediments: the need for integrative landscape science0 aSoils freshwater and marine sediments the need for integrative l a302-3070 v3041 aWall, Diana, H.1 aAyres, Edward1 aBehan-Pelletier, Valerie1 aCovich, A1 aSnelgrove, P.V.R.1 aBrowman, H.1 aStergiou, K., I. uhttps://mcm.lternet.edu/content/soils-freshwater-and-marine-sediments-need-integrative-landscape-science00479nas a2200121 4500008004100000245007400041210006900115260003000184490000900214100001300223700002400236856009700260 2005 eng d00aA temperature-index model of stream flow in Taylor Valley, Antarctica0 atemperatureindex model of stream flow in Taylor Valley Antarctic bPortland State University0 vM.S.1 aEbnet, A1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/temperature-index-model-stream-flow-taylor-valley-antarctica00468nas a2200157 4500008004100000245002900041210002900070260003100099100001500130700002400145700002100169700001500190700002900205700001500234856006100249 2004 eng d00aAntarctic Paleolimnology0 aAntarctic Paleolimnology bKluwer Academic Publishers1 aHodgson, D1 aGibson, John, A. E.1 aDoran, Peter, T.1 aPienitz, R1 aDouglas, Marianne, S. V.1 aSmol, J.P. uhttps://mcm.lternet.edu/content/antarctic-paleolimnology00655nas a2200169 4500008004100000245010600041210006900147300001000216490000700226100001800233700002400251700002200275700002000297700002300317700002000340856012500360 2004 eng d00aThe Biodiversity and Biogeochemistry of Cryoconite Holes from McMurdo Dry Valley Glaciers, Antarctica0 aBiodiversity and Biogeochemistry of Cryoconite Holes from McMurd a84-910 v361 aPorazinska, D1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aTranter, Martyn1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/biodiversity-and-biogeochemistry-cryoconite-holes-mcmurdo-dry-valley-glaciers-antarctica00566nas a2200157 4500008004100000245007700041210006900118260001200187300001200199490000700211100002400218700002400242700002000266700001800286856010400304 2004 eng d00aCan warming induce advances of polar glaciers, Taylor Valley, Antarctica0 aCan warming induce advances of polar glaciers Taylor Valley Anta c12/2004 a556-5640 v501 aFountain, Andrew, G1 aNeumann, Thomas, A.1 aGlenn, Paul, L.1 aChinn, Trevor uhttps://mcm.lternet.edu/content/can-warming-induce-advances-polar-glaciers-taylor-valley-antarctica00642nas a2200145 4500008004100000245014700041210006900188490000700257100001900264700001700283700002100300700002500321700002400346856012600370 2004 eng d00aThe Carbon Isotopic Composition of Dissolved Inorganic Carbon in Perennially Ice-Covered Antarctica Lakes: Searching for a Biogenic Signature.0 aCarbon Isotopic Composition of Dissolved Inorganic Carbon in Per0 v391 aNeumann, Klaus1 aLyons, Berry1 aPriscu, John, C.1 aDesMarais, David, J.1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/carbon-isotopic-composition-dissolved-inorganic-carbon-perennially-ice-covered-antarctica00636nas a2200169 4500008004100000245010400041210006900145300000900214490000700223100001400230700002400244700002700268700001900295700001500314700001300329856012400342 2004 eng d00aChanges in fulvic acid redox state through the oxycline of a permanently ice-covered Antarctic lake0 aChanges in fulvic acid redox state through the oxycline of a per a1-200 v661 aFulton, J1 aMcKnight, Diane, M.1 aForeman, Christine, M.1 aCory, Rose, M.1 aStedmon, C1 aBlunt, E uhttps://mcm.lternet.edu/content/changes-fulvic-acid-redox-state-through-oxycline-permanently-ice-covered-antarctic-lake00523nas a2200121 4500008004100000245009800041210006900139490000800208100002200216700002400238700002100262856011800283 2004 eng d00aClimatology of Katabatic Winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica0 aClimatology of Katabatic Winds in the McMurdo Dry Valleys Southe0 v1091 aNylen, Thomas, H.1 aFountain, Andrew, G1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/climatology-katabatic-winds-mcmurdo-dry-valleys-southern-victoria-land-antarctica00572nas a2200157 4500008004100000245008100041210006900122300001000191490000700201100002400208700002000232700002200252700001300274700002100287856010600308 2004 eng d00aCryoconite holes on polar glaciers and their importance for meltwater runoff0 aCryoconite holes on polar glaciers and their importance for melt a25-450 v501 aFountain, Andrew, G1 aTranter, Martyn1 aNylen, Thomas, H.1 aBooth, D1 aLewis, Karen, J. uhttps://mcm.lternet.edu/content/cryoconite-holes-polar-glaciers-and-their-importance-meltwater-runoff00630nas a2200157 4500008004100000245011600041210006900157260001200226300001400238490000700252100002500259700002400284700002300308700001900331856012200350 2004 eng d00aDenitrification and hydrologic transient storage in a glacial meltwater stream, McMurdo Dry Valleys, Antarctica0 aDenitrification and hydrologic transient storage in a glacial me c09/2004 a1884-18950 v491 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aRunkel, Robert, L.1 aDuff, John, H. uhttps://mcm.lternet.edu/content/denitrification-and-hydrologic-transient-storage-glacial-meltwater-stream-mcmurdo-dry00811nas a2200301 4500008004100000245004900041210004700090300001200137490000600149100001300155700001300168700001900181700001700200700001200217700001200229700001200241700002300253700002000276700001400296700002300310700002500333700001200358700001500370700001500385700001400400700001600414856007900430 2004 eng d00aDetritus, trophic dynamics and biodiversity.0 aDetritus trophic dynamics and biodiversity a584-6000 v71 aMoore, J1 aMorin, P1 aNadelhoffer, K1 aRosemound, A1 aPost, D1 aSabo, J1 aScow, K1 aVanni, Michael, J.1 aWall, Diana, H.1 aBerlow, E1 aColeman, David, C.1 aDe Ruiter, Peter, C.1 aDong, Q1 aHasting, A1 aJohnson, N1 aMcCann, K1 aMelville, K uhttps://mcm.lternet.edu/content/detritus-trophic-dynamics-and-biodiversity00477nas a2200121 4500008004100000245007200041210006900113260003000182490000900212100001600221700002400237856009400261 2004 eng d00aDevelopment of large supraglacial channels in the polar environment0 aDevelopment of large supraglacial channels in the polar environm bPortland State University0 vM.S.1 aJohnston, R1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/development-large-supraglacial-channels-polar-environment00670nas a2200157 4500008004100000245014600041210006900187300001200256490000700268100002300275700002100298700002000319700001700339700002800356856012800384 2004 eng d00aThe distribution of microplankton in the McMurdo dry valley lakes, Antarctica: Response to ecosystem legacy or present-day climate controls?0 adistribution of microplankton in the McMurdo dry valley lakes An a238-2490 v271 aRoberts, Emily, C.1 aPriscu, John, C.1 aWolf, Craig, F.1 aLyons, Berry1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/distribution-microplankton-mcmurdo-dry-valley-lakes-antarctica-response-ecosystem-legacy-or00394nas a2200121 4500008004100000245002600041210002500067260003800092100002100130700002500151700001900176856007700195 2004 eng d00aEarth's Icy Biosphere0 aEarths Icy Biosphere bAmerican Society for Microbiology1 aPriscu, John, C.1 aChristner, Brent, C.1 aBull, Alan, T. uhttp://mcm.lternet.edu/reports/lakes/PriscuChristner2004IcyBiosphere.pdf00578nas a2200169 4500008004100000245006700041210006600108300001400174490000800188100001400196700002600210700001800236700001400254700002200268700002000290856009800310 2004 eng d00aEcological linkages between aboveground and belowground biota.0 aEcological linkages between aboveground and belowground biota a1629-16330 v3041 aWardle, D1 aBardgett, Richard, D.1 aKlironomos, J1 aSetala, H1 avan der Putten, W1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/ecological-linkages-between-aboveground-and-belowground-biota00627nas a2200169 4500008004100000245010400041210006900145300001400214490000700228100001100235700002100246700001900267700001500286700001500301700001400316856012700330 2004 eng d00aElevated levels of dimethylated-sulfur compounds in Lake Bonney, a poorly ventilated Antarctic lake0 aElevated levels of dimethylatedsulfur compounds in Lake Bonney a a1044-10550 v491 aLee, P1 aPriscu, John, C.1 aDiTullio, G, R1 aRiseman, S1 aTursich, N1 aDeMora, S uhttps://mcm.lternet.edu/content/elevated-levels-dimethylated-sulfur-compounds-lake-bonney-poorly-ventilated-antarctic-lake00673nas a2200169 4500008004100000245013000041210006900171260001200240300001000252490000700262100002400269700002000293700002200313700002100335700002300356856012400379 2004 eng d00aEvolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the McMurdo Dry Valleys, Antarctica0 aEvolution of cryoconite holes and their contribution to meltwate c01/2004 a35-450 v501 aFountain, Andrew, G1 aTranter, Martyn1 aNylen, Thomas, H.1 aLewis, Karen, J.1 aMueller, Derek, R. uhttps://mcm.lternet.edu/content/evolution-cryoconite-holes-and-their-contribution-meltwater-runoff-glaciers-mcmurdo-dry00667nas a2200181 4500008004100000245009000041210006900131300001200200490000700212100002000219700002400239700002700263700001700290700002100307700001500328700002400343856011800367 2004 eng d00aExtreme hydrochemical conditions in natural microcosms entombed within Antarctic ice.0 aExtreme hydrochemical conditions in natural microcosms entombed  a379-3870 v181 aTranter, Martyn1 aFountain, Andrew, G1 aFritsen, Christian, H.1 aLyons, Berry1 aPriscu, John, C.1 aStathan, P1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/extreme-hydrochemical-conditions-natural-microcosms-entombed-within-antarctic-ice00594nas a2200193 4500008004100000245005000041210005000091260003100141100001200172700001400184700001300198700001400211700002100225700001600246700001500262700002900277700001500306856007900321 2004 eng d00aGeochronology of high latitude lake sediments0 aGeochronology of high latitude lake sediments bKluwer Academic Publishers1 aWolf, A1 aMiller, G1 aOlsen, C1 aForman, S1 aDoran, Peter, T.1 aHolmgren, S1 aPienitz, R1 aDouglas, Marianne, S. V.1 aSmol, J.P. uhttps://mcm.lternet.edu/content/geochronology-high-latitude-lake-sediments00629nas a2200157 4500008004100000245011500041210006900156300001200225490000700237100002200244700002700266700001500293700001700308700002100325856012500346 2004 eng d00aGeomicrobiology of Blood Fall: An iron-rich saline discharge at the terminus of the Taylor Glacier, Antarctica0 aGeomicrobiology of Blood Fall An ironrich saline discharge at th a199-2000 v101 aMikucki, Jill, A.1 aForeman, Christine, M.1 aSattler, B1 aLyons, Berry1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/geomicrobiology-blood-fall-iron-rich-saline-discharge-terminus-taylor-glacier-antarctica00455nas a2200121 4500008004100000245007100041210006900112300001000181490000700191100002300198700001500221856009700236 2004 eng d00aGradient analysis of cryoconite ecosystems from two Polar glaciers0 aGradient analysis of cryoconite ecosystems from two Polar glacie a66-740 v271 aMueller, Derek, R.1 aPollard, W uhttps://mcm.lternet.edu/content/gradient-analysis-cryoconite-ecosystems-two-polar-glaciers-000667nas a2200169 4500008004100000245013500041210006900176300001400245490000700259100001400266700001600280700001700296700002100313700001100334700002400345856012800369 2004 eng d00aIdentification of a psychrophilic green alga from Lake Bonney, Antarctica: Chlamydomonas raudensis ETTL. (UWO 241) (Chlorophyceae)0 aIdentification of a psychrophilic green alga from Lake Bonney An a1138-11480 v401 aPocock, T1 aLachance, M1 aProschold, T1 aPriscu, John, C.1 aKim, S1 aHuner, Norman, P.A. uhttps://mcm.lternet.edu/content/identification-psychrophilic-green-alga-lake-bonney-antarctica-chlamydomonas-raudensis-ettl00555nas a2200121 4500008004100000245014000041210006900181300001200250490000700262100001400269700002400283856012600307 2004 eng d00aThe impact of anhydrobiosis on the persistence of Scottnema lindsyae (Nematoda): a modeling analysis of population stability thresholds0 aimpact of anhydrobiosis on the persistence of Scottnema lindsyae a507-5120 v271 aWeicht, T1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/impact-anhydrobiosis-persistence-scottnema-lindsyae-nematoda-modeling-analysis-population00616nas a2200169 4500008004100000245014100041210006900182260001200251300001200263490000700275653002100282653001800303100002700321700001200348700002100360856006500381 2004 eng d00aImpact of episodic warming events on the physical, chemical and biological relationships of lakes in the McMurdo Dry Valleys, Antarctica0 aImpact of episodic warming events on the physical chemical and b c09/2004 a239-2680 v1010aClimate Response10astoichiometry1 aForeman, Christine, M.1 aWolf, C1 aPriscu, John, C. uhttp://link.springer.com/article/10.1007%2Fs10498-004-2261-300681nas a2200157 4500008004100000245015800041210006900199300001200268490000700280100002400287700002300311700001900334700002000353700002400373856012600397 2004 eng d00aInorganic nitrogen and phosphorus dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities0 aInorganic nitrogen and phosphorus dynamics of Antarctic glacial  a171-1880 v231 aMcKnight, Diane, M.1 aRunkel, Robert, L.1 aDuff, John, H.1 aTate, Cathy, M.1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/inorganic-nitrogen-and-phosphorus-dynamics-antarctic-glacial-meltwater-streams-controlled00526nas a2200133 4500008004100000245008200041210006900123300001200192490000700204100002300211700002100234700002800255856010900283 2004 eng d00aMicroplankton dynamics in a perennially ice-covered Antarctic lake-Lake Hoare0 aMicroplankton dynamics in a perennially icecovered Antarctic lak a238-2490 v271 aRoberts, Emily, C.1 aPriscu, John, C.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/microplankton-dynamics-perennially-ice-covered-antarctic-lake-lake-hoare00626nas a2200145 4500008004100000245012200041210006900163260001700232100002000249700002600269700001400295700002200309700002000331856012900351 2004 eng d00aThe need for understanding how biodiversity and ecosystem functioning affect ecosystem services in soil and sediments0 aneed for understanding how biodiversity and ecosystem functionin bIsland Press1 aWall, Diana, H.1 aBardgett, Richard, D.1 aCovich, A1 aSnelgrove, P.V.R.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/need-understanding-how-biodiversity-and-ecosystem-functioning-affect-ecosystem-services-soil00538nas a2200121 4500008004100000245011800041210006900159300001200228490000700240100002000247700002100267856012800288 2004 eng d00aThe Occurrence of Lysogenic Bacteria and Microbial Aggregates in the Lakes of the McMurdo Dry Valleys, Antarctica0 aOccurrence of Lysogenic Bacteria and Microbial Aggregates in the a427-4390 v471 aLisle, John, T.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/occurrence-lysogenic-bacteria-and-microbial-aggregates-lakes-mcmurdo-dry-valleys-antarctica00791nas a2200217 4500008004100000020002200041245008200063210006900145260005900214300001200273100002100285700002100306700001700327700001400344700002300358700002300381700001500404700002900419700001500448856011000463 2004 eng d a978-1-4020-2125-100aPaleolimnology of extreme cold terrestrial and extraterrestrial environments.0 aPaleolimnology of extreme cold terrestrial and extraterrestrial  aDordrecht, The NetherlandsbKluwer Academic Publishers a475-5071 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aPowell, R1 aPoreda, Robert, J.1 aAndersen, Dale, T.1 aPienitz, R1 aDouglas, Marianne, S. V.1 aSmol, J.P. uhttps://mcm.lternet.edu/content/paleolimnology-extreme-cold-terrestrial-and-extraterrestrial-environments00602nas a2200193 4500008004100000245004700041210004600088260003100134300001200165100002100177700002100198700001700219700001400236700002300250700001500273700002900288700001500317856007600332 2004 eng d00aPaleolimnology of Ice-covered Environments0 aPaleolimnology of Icecovered Environments bKluwer Academic Publishers a475-5071 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aPowell, R1 aPoreda, Robert, J.1 aPienitz, R1 aDouglas, Marianne, S. V.1 aSmol, John uhttps://mcm.lternet.edu/content/paleolimnology-ice-covered-environments00568nas a2200133 4500008004100000245010500041210006900146300001200215490000700227100002500234700002400259700002300283856012800306 2004 eng d00aReach-scale cation exchange controls on major ion chemistry of an Antarctic glacial meltwater stream0 aReachscale cation exchange controls on major ion chemistry of an a221-2380 v101 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aRunkel, Robert, L. uhttps://mcm.lternet.edu/content/reach-scale-cation-exchange-controls-major-ion-chemistry-antarctic-glacial-meltwater-stream00504nas a2200145 4500008004100000245006100041210006100102300001200163490000600175100002400181700002200205700002000227700002300247856008800270 2004 eng d00aSoil carbon dioxide flux from Antarctic Dry Valley soils0 aSoil carbon dioxide flux from Antarctic Dry Valley soils a286-2950 v71 aParsons, Andrew, N.1 aBarrett, John, E.1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-carbon-dioxide-flux-antarctic-dry-valley-soils00433nas a2200121 4500008004100000245005800041210005700099260002200156490000900178100001500187700002300202856008600225 2004 eng d00aSoil phosphorus dynamics in Taylor Valley, Antarctica0 aSoil phosphorus dynamics in Taylor Valley Antarctica bDartmouth College0 vB.S.1 aBate, Brad1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/soil-phosphorus-dynamics-taylor-valley-antarctica00661nas a2200157 4500008004100000245015000041210006900191300001200260490000700272100001400279700002100293700001800314700002500332700002100357856012500378 2004 eng d00aStable carbon and nitrogen isotopic compositions of benthic and pelagic organic matter in four polar lakes of the McMurdo Dry Valleys, Antarctica0 aStable carbon and nitrogen isotopic compositions of benthic and  a269-3010 v101 aLawson, J1 aDoran, Peter, T.1 aKenig, Fabien1 aDesMarais, David, J.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/stable-carbon-and-nitrogen-isotopic-compositions-benthic-and-pelagic-organic-matter-four00424nam a2200097 4500008004100000245007400041210006900115100002000184700002000204856010200224 2004 eng d00aSustaining Biodiversity and Ecosystem Services in Soil and Sediments.0 aSustaining Biodiversity and Ecosystem Services in Soil and Sedim1 aWall, Diana, H.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/sustaining-biodiversity-and-ecosystem-services-soil-and-sediments00726nas a2200205 4500008004100000245011200041210006900153300000900222490000700231100001100238700002200249700002700271700002100298700001900319700001500338700001400353700002000367700001400387856011900401 2004 eng d00aThermodynamic constraints on microbially mediated processes in lakes of the McMurdo Dry Valleys, Antarctica0 aThermodynamic constraints on microbially mediated processes in l a1-170 v211 aLee, P1 aMikucki, Jill, A.1 aForeman, Christine, M.1 aPriscu, John, C.1 aDiTullio, G, R1 aRiseman, S1 aDeMora, S1 aWolf, Craig, F.1 aKester, L uhttps://mcm.lternet.edu/content/thermodynamic-constraints-microbially-mediated-processes-lakes-mcmurdo-dry-valleys00681nas a2200205 4500008004100000245009300041210006900134300001200203490000600215100001600221700001700237700001500254700001500269700001300284700001200297700001400309700001300323700002000336856011900356 2004 eng d00aTrophic interactions in a changing world: modelling aboveground-belowground interactions0 aTrophic interactions in a changing world modelling abovegroundbe a515-5280 v51 aSchroter, D1 aBrussaard, L1 aDe Deyn, G1 aProveda, K1 aBrown, V1 aBerg, M1 aWardle, D1 aMoore, J1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/trophic-interactions-changing-world-modelling-aboveground-belowground-interactions00662nas a2200157 4500008004100000245014000041210006900181260001700250300001200267100002000279700002600299700001400325700002200339700002000361856012300381 2004 eng d00aUnderstanding the functions of biodiversity in soils and sediments will enhance global ecosystem sustainability and societal well-being0 aUnderstanding the functions of biodiversity in soils and sedimen bIsland Press a249-2541 aWall, Diana, H.1 aBardgett, Richard, D.1 aCovich, A1 aSnelgrove, P.V.R.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/understanding-functions-biodiversity-soils-and-sediments-will-enhance-global-ecosystem02593nas a2200181 4500008004100000245009500041210006900136300001400205490000700219520193100226100002202157700002302179700002002202700002402222700002202246700002402268856011902292 2004 eng d00aVariation in biogeochemistry and soil biodiversity across spatial scales in a polar desert0 aVariation in biogeochemistry and soil biodiversity across spatia a3105-31180 v853 a
Desert ecosystems are characterized by distinct spatial patterning in soil
biogeochemistry and biodiversity. In the Antarctic Dry Valleys, soil polygons are prominent
features of the landscape and may be key units for scaling local ecological information to
the greater region. We examined polygon soils in each of the three basins of Taylor Valley,
Antarctica. Our objectives were to characterize variability in soil biogeochemistry and
biodiversity at local to regional scales, and to test the influence of soil properties upon
invertebrate communities. We found that soil biogeochemical properties and biodiversity
vary over multiple spatial scales from fine (,10 m) to broad (.10 km) scales. Differences
in biogeochemistry were most pronounced at broad scales among the major lake basins of
Taylor Valley corresponding to differences in geology and microclimate, while variation
in invertebrate biodiversity and abundance occurred at landscape scales of 10–500 m, and
within individual soil polygons. Variation in biogeochemistry and invertebrate communities
across these scales reflects the influence of physical processes and landscape development
over ecosystem structure in the dry valleys. The development of soil polygons influences
the spatial patterning of soil properties such as soil organic matter, salinity, moisture, and
invertebrate habitat suitability. Nematode abundance and life history data indicate that
polygon interiors are more suitable habitats than soils in the troughs at the edges of polygons.
These data suggest that physical processes (i.e., polygon development) and biogeochemistry
are important influences on the spatial variability of biotic communities in dry valley soil
ecosystems.
1 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aParsons, Andrew, N.1 aPowers, Laura, E.1 aBurkins, Melody, B. uhttps://mcm.lternet.edu/content/variation-biogeochemistry-and-soil-biodiversity-across-spatial-scales-polar-desert00957nas a2200301 4500008004100000020001800041245008800059210006900147260001700216300001200233100001400245700001600259700002900275700001400304700001700318700002600335700001800361700001500379700001500394700002200409700002100431700001700452700001800469700001700487700002000504700002000524856011100544 2004 eng d a1-55963-760-900aVulnerability to global change of ecosystem goods and services driven by soil biota0 aVulnerability to global change of ecosystem goods and services d bIsland Press a101-1361 aWardle, D1 aBrown, V.K.1 aBehan-Pelletier, Valerie1 aJohn, St.1 aWojtowicz, T1 aBardgett, Richard, D.1 aBrown, G., G.1 aIneson, P.1 aLavelle, P1 avan der Putten, W1 aAnderson, J., M.1 aBrussaard, L1 aHunt, William1 aPaul, E., A.1 aWall, Diana, H.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/vulnerability-global-change-ecosystem-goods-and-services-driven-soil-biota00536nas a2200157 4500008004100000245006700041210006600108300001200174490000600186100001200192700002400204700001700228700002100245700002400266856008800290 2003 eng d00aBiochemistry of Si in the McMurdo Dry Valley lakes, Antarctica0 aBiochemistry of Si in the McMurdo Dry Valley lakes Antarctica a737-7490 v11 aPugh, H1 aWelch, Kathleen, A.1 aLyons, Berry1 aPriscu, John, C.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/biochemistry-si-mcmurdo-dry-valley-lakes-antarctica00702nas a2200181 4500008004100000020001500041245009900056210006900155260004300224300001200267653002100279100002400300700001700324700001800341700001900359700001800378856012400396 2003 eng d a019515059700aCentury to millennial scale climate change and ecosystem response in Taylor Valley, Antarctica0 aCentury to millennial scale climate change and ecosystem respons aNew York CitybOxford University Press a319-34010aClimate Response1 aFountain, Andrew, G1 aLyons, Berry1 aGreenland, D.1 aGoodin, D., G.1 aSmith, R., C. uhttps://mcm.lternet.edu/content/century-millennial-scale-climate-change-and-ecosystem-response-taylor-valley-antarctica00679nas a2200169 4500008004100000245011200041210006900153260001700222100002400239700001900263700001700282700002400299700002700323700001700350700001500367856012700382 2003 eng d00aChemistry and lake dynamics of the Taylor Valley lakes, Antarctica: The importance of long-term monitoring.0 aChemistry and lake dynamics of the Taylor Valley lakes Antarctic bCaxton Press1 aWelch, Kathleen, A.1 aNeumann, Klaus1 aLyons, Berry1 aMcKnight, Diane, M.1 aHoward-Williams, Clive1 aDavidson, W.1 aBroady, P. uhttps://mcm.lternet.edu/content/chemistry-and-lake-dynamics-taylor-valley-lakes-antarctica-importance-long-term-monitoring00558nas a2200145 4500008004100000245007900041210006900120300001400189490000700203100002500210700002400235700002300259700002200282856010800304 2003 eng d00aDetermining long time-scale hyporheic zone flow paths in Antarctic streams0 aDetermining long timescale hyporheic zone flow paths in Antarcti a1691-17100 v171 aGooseff, Michael, N.1 aMcKnight, Diane, M.1 aRunkel, Robert, L.1 aVaughn, Bruce, H. uhttps://mcm.lternet.edu/content/determining-long-time-scale-hyporheic-zone-flow-paths-antarctic-streams00482nas a2200121 4500008004100000245007500041210006900116260003600185490000900221100001300230700002100243856009600264 2003 eng d00aDistribution of 210Pb and 137Cs in the McMurdo Dry Valleys, Antarctica0 aDistribution of 210Pb and 137Cs in the McMurdo Dry Valleys Antar bUniversity of Illinois, Chicago0 vM.S.1 aOlsen, C1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/distribution-210pb-and-137cs-mcmurdo-dry-valleys-antarctica00567nas a2200169 4500008004100000245009200041210006900133260001200202300001000214490000800224100002100232700002700253700002700280700002100307700002200328856004700350 2003 eng d00aFormation and character of an ancient 19 m ice cover and underlying trapped brine in an0 aFormation and character of an ancient 19 m ice cover and underly c01/2003 a26-310 v1001 aDoran, Peter, T.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aPriscu, John, C.1 aAdams, Edward, E. uhttp://www.pnas.org/content/100/1/26.short00733nas a2200193 4500008004100000245014900041210006900190300001200259490000600271100001500277700002100292700001900313700001400332700001400346700001900360700001500379700002100394856012400415 2003 eng d00aFourier-transform raman spectroscopic studies of organic and inorganic chemical components in stromatolitic cores from Antarctic lake sediments0 aFouriertransform raman spectroscopic studies of organic and inor a325-3310 v11 aEdwards, H1 aWynn-Williams, D1 aEllis-Evans, J1 aNewton, E1 aLittle, S1 ade Oliveira, L1 aHodgson, D1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/fourier-transform-raman-spectroscopic-studies-organic-and-inorganic-chemical-components00548nas a2200145 4500008004100000245009000041210006900131300000900200490000800209100002100217700002400238700001400262700001600276856011000292 2003 eng d00aGlaciers of the McMurdo Dry Valleys: terrestrial analog for Martian polar sublimation0 aGlaciers of the McMurdo Dry Valleys terrestrial analog for Marti a50310 v1081 aLewis, Karen, J.1 aFountain, Andrew, G1 aKargel, J1 aMacAyeal, D uhttps://mcm.lternet.edu/content/glaciers-mcmurdo-dry-valleys-terrestrial-analog-martian-polar-sublimation00584nas a2200181 4500008004100000245006300041210006000104300001000164100001500174700001600189700002000205700001300225700001600238700001800254700002500272700001400297856009100311 2003 eng d00aLong-term perspectives on biodiversity-ecosystem function.0 aLongterm perspectives on biodiversityecosystem function a89-981 aSymstad, A1 aIII, Chapin1 aWall, Diana, H.1 aGross, K1 aHuenneke, L1 aMittelbach, G1 aPeters, Debra, P. 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Review in the SCAR VIII International Biology Symposium Proceedings0 aPolar Limnology the past the present and the future Review in th1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/polar-limnology-past-present-and-future-review-scar-viii-international-biology-symposium00491nas a2200121 4500008004100000245008000041210006900121260002900190490000900219100001400228700002100242856010600263 2003 eng d00aSpatial and temporal variations of phytoplankton populations in Lake Bonney0 aSpatial and temporal variations of phytoplankton populations in  bMontana State University0 vM.S.1 aTurish, N1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/spatial-and-temporal-variations-phytoplankton-populations-lake-bonney00722nas a2200193 4500008004100000245015200041210006900193300001200262490000600274100001700280700001800297700001400315700001400329700001400343700001200357700002400369700001400393856012100407 2003 eng d00aStrontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate0 aStrontium isotopic signatures of the streams and lakes of Taylor a875-8950 v81 aLyons, Berry1 aNezat, C., A.1 aBenson, L1 aBullen, T1 aGraham, E1 aKidd, J1 aWelch, Kathleen, A.1 aThomas, J uhttps://mcm.lternet.edu/content/strontium-isotopic-signatures-streams-and-lakes-taylor-valley-southern-victoria-land00682nas a2200169 4500008004100000245012300041210006900164300001200233490000700245100001700252700002400269700002400293700002000317700002200337700002400359856012900383 2003 eng d00aSurface glaciochemistry of Taylor Valley, southern Victoria Land, Antarctica and its relationship to stream chemistry.0 aSurface glaciochemistry of Taylor Valley southern Victoria Land  a115-1300 v171 aLyons, Berry1 aWelch, Kathleen, A.1 aFountain, Andrew, G1 aDana, Gayle, L.1 aVaughn, Bruce, H.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/surface-glaciochemistry-taylor-valley-southern-victoria-land-antarctica-and-its-relationship00890nas a2200277 4500008004100000245006500041210006500106260001200171300001200183490000800195653002100203100002100224700002100245700001700266700002000283700002400303700002400327700002400351700002300375700002000398700001900418700002700437700002700464700002400491856009700515 2002 eng d00aAntarctic climate cooling and terrestrial ecosystem response0 aAntarctic climate cooling and terrestrial ecosystem response c01/2002 a517-5200 v41510aClimate Response1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aWalsh, John, E.1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N. uhttps://mcm.lternet.edu/content/antarctic-climate-cooling-and-terrestrial-ecosystem-response00529nas a2200121 4500008004100000245010400041210006900145300001400214490000700228100001600235700002800251856012800279 2002 eng d00aThe balance between photosynthesis and grazing in Antarctic mixotrophic cryptophytes during summer0 abalance between photosynthesis and grazing in Antarctic mixotrop a2060-20700 v471 aMarshall, W1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/balance-between-photosynthesis-and-grazing-antarctic-mixotrophic-cryptophytes-during-summer00431nas a2200121 4500008004100000245006200041210005800103260003000161490000900191100001200200700001700212856008000229 2002 eng d00aThe biogeochemistry of Si in the McMurdo Dry Valley Lakes0 abiogeochemistry of Si in the McMurdo Dry Valley Lakes bThe Ohio State University0 vB.S.1 aPugh, H1 aLyons, Berry uhttps://mcm.lternet.edu/content/biogeochemistry-si-mcmurdo-dry-valley-lakes00539nas a2200121 4500008004100000245011500041210006900156260003000225490000900255100001200264700001700276856012400293 2002 eng d00aThe chemical evolution of Canada Glacier melt: supraglacial and proglacial waters in Taylor Valley, Antarctica0 achemical evolution of Canada Glacier melt supraglacial and progl bThe Ohio State University0 vM.S.1 aTegt, S1 aLyons, Berry uhttps://mcm.lternet.edu/content/chemical-evolution-canada-glacier-melt-supraglacial-and-proglacial-waters-taylor-valley00517nas a2200121 4500008004100000245009300041210006900134260002700203490000900230100001700239700002400256856011500280 2002 eng d00aClimatic controls on interannual variation in streamflow in Fryxell Basin, Taylor Valley0 aClimatic controls on interannual variation in streamflow in Fryx bUniversity of Colorado0 vM.S.1 aJaros, Chris1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/climatic-controls-interannual-variation-streamflow-fryxell-basin-taylor-valley00614nas a2200157 4500008004100000245010900041210006900150300001400219490000700233100001500240700002400255700001200279700001500291700002500306856012500331 2002 eng d00aDirect observation of aluminosilicate weathering in the hyporheic zone of an Antarctic Dry Valley stream0 aDirect observation of aluminosilicate weathering in the hyporhei a1335-13470 v661 aMaurice, P1 aMcKnight, Diane, M.1 aLeff, L1 aFulghun, J1 aGooseff, Michael, N. uhttps://mcm.lternet.edu/content/direct-observation-aluminosilicate-weathering-hyporheic-zone-antarctic-dry-valley-stream00625nas a2200145 4500008004100000245013200041210006900173300001200242490000700254100002400261700002000285700002300305700002400328856012700352 2002 eng d00aDistribution and life cycle of Scottnema lindsayae (Nematoda) in Antarctic soils: A modeling analysis of tempaerature responses0 aDistribution and life cycle of Scottnema lindsayae Nematoda in A a118-1250 v251 aMoorhead, Daryl, L.1 aWall, Diana, H.1 aVirginia, Ross, A.1 aParsons, Andrew, N. uhttps://mcm.lternet.edu/content/distribution-and-life-cycle-scottnema-lindsayae-nematoda-antarctic-soils-modeling-analysis00548nas a2200169 4500008004100000245005100041210005000092260004700142300001200189100001500201700001300216700002100229700001700250700001400267700001500281856008200296 2002 eng d00aExtremophiles: ice ecosystems and biodiversity0 aExtremophiles ice ecosystems and biodiversity aOxfordbUNESCO Publishing-Eolss Publishers a573-5981 aPsenner, R1 aFelip, M1 aPriscu, John, C.1 aWagenbach, D1 aWillie, A1 aSattler, B uhttps://mcm.lternet.edu/content/extremophiles-ice-ecosystems-and-biodiversity00499nas a2200121 4500008004100000245008700041210006900128490000600197100002000203700002000223700002300243856011100266 2002 eng d00aField and microcosm studies of decomposition and soil biota in a cold dessert soil0 aField and microcosm studies of decomposition and soil biota in a0 v51 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/field-and-microcosm-studies-decomposition-and-soil-biota-cold-dessert-soil00460nas a2200109 4500008004100000245009300041210006900134300001200203490000700215100001700222856011100239 2002 eng d00aFlux of eolian sediment in the Mcmurdo Dry Valleys, Antarctica: a preliminary assessment0 aFlux of eolian sediment in the Mcmurdo Dry Valleys Antarctica a  a318-3230 v341 aLancaster, N uhttps://mcm.lternet.edu/content/flux-eolian-sediment-mcmurdo-dry-valleys-antarctica-preliminary-assessment00470nas a2200121 4500008004100000245006800041210006800109260002700177490000900204100001700213700002400230856009400254 2002 eng d00aInterannual variation in phytoplankton dynamics in Lake Fryxell0 aInterannual variation in phytoplankton dynamics in Lake Fryxell bUniversity of Colorado0 vM.S.1 aVan Matre, E1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/interannual-variation-phytoplankton-dynamics-lake-fryxell00481nas a2200133 4500008004100000245006800041210006600109300001200175490000700187100001800194700002000212700002300232856009200255 2002 eng d00aInvertebrates in ornithogenic soils at Ross Island, Antarctica.0 aInvertebrates in ornithogenic soils at Ross Island Antarctica a569-5740 v251 aPorazinska, D1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/invertebrates-ornithogenic-soils-ross-island-antarctica00543nas a2200121 4500008004100000245011700041210006900158260002900227490000900256100001400265700002100279856012100300 2002 eng d00aLinkages between soils and lake ice sediments biogeochemistry: Taylor Valley, southern Victoria Land, Antarctica0 aLinkages between soils and lake ice sediments biogeochemistry Ta bMontana State University0 vM.S.1 aKonley, S1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/linkages-between-soils-and-lake-ice-sediments-biogeochemistry-taylor-valley-southern00452nas a2200121 4500008004100000245007700041210006900118300001000187490000600197100001200203700002000215856009500235 2002 eng d00aModeling the effects of loss of soil biodiversity on ecosystem function0 aModeling the effects of loss of soil biodiversity on ecosystem f a32-490 v81 aHunt, H1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/modeling-effects-loss-soil-biodiversity-ecosystem-function00578nas a2200133 4500008004100000245012500041210006900166300001200235490000700247100001800254700002000272700002300292856012900315 2002 eng d00aPopulation age structure of nematodes in the Antarctic Dry Valleys: perspectives on time, space, and habitat suitability0 aPopulation age structure of nematodes in the Antarctic Dry Valle a159-1680 v341 aPorazinska, D1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/population-age-structure-nematodes-antarctic-dry-valleys-perspectives-time-space-and-habitat00772nas a2200253 4500008004100000245004700041210004700088300001200135490000800147100002000155700001900175700002700194700002700221700002400248700002100272700002100293700001700314700002400331700002400355700002400379700002300403700002000426856007200446 2002 eng d00aRecent Temperature Trends in the Antarctic0 aRecent Temperature Trends in the Antarctic a291-2920 v4181 aWalsh, John, E.1 aClow, Gary, D.1 aFritsen, Christian, H.1 aMcKay, Christopher, P.1 aParsons, Andrew, N.1 aDoran, Peter, T.1 aPriscu, John, C.1 aLyons, Berry1 aFountain, Andrew, G1 aMcKnight, Diane, M.1 aMoorhead, Daryl, L.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/recent-temperature-trends-antarctic00540nas a2200145 4500008004100000245007900041210006900120300001400189490000700203100002000210700001300230700002400243700002400267856010300291 2002 eng d00aSatellite-Derived Indices of Stream Discharge in Taylor Valley,Antarctica.0 aSatelliteDerived Indices of Stream Discharge in Taylor ValleyAnt a1603-16160 v161 aDana, Gayle, L.1 aDavis, R1 aFountain, Andrew, G1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/satellite-derived-indices-stream-discharge-taylor-valleyantarctica00760nas a2200229 4500008004100000245012700041210006900168260001200237300001000249490000700259653001100266100002500277700002200302700002100324700002400345700001700369700002400386700001800410700002300428700002000451856005900471 2002 eng d00aSnow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica0 aSnow patch influence on soil biogeochemical processes and invert c02/2003 a91-990 v3510aBiggie1 aGooseff, Michael, N.1 aBarrett, John, E.1 aDoran, Peter, T.1 aFountain, Andrew, G1 aLyons, Berry1 aParsons, Andrew, N.1 aPorazinska, D1 aVirginia, Ross, A.1 aWall, Diana, H. uhttp://instaar.metapress.com/content/r086455ju7213711/00357nas a2200109 4500008004100000245004300041210004300084300001200127490000800139100002800147856007200175 2002 eng d00aSurvival mechanisms in Antarctic lakes0 aSurvival mechanisms in Antarctic lakes a863-8690 v3571 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/survival-mechanisms-antarctic-lakes00582nas a2200145 4500008004100000245011800041210006900159300001200228490000700240100001400247700002400261700001200285700001200297856012700309 2002 eng d00aSynthetic aperture radar detection of the snowline on Commonwealth and Howard Glaciers, Taylor Valley, Antarctica0 aSynthetic aperture radar detection of the snowline on Commonweal a177-1830 v341 aBardel, P1 aFountain, Andrew, G1 aHall, D1 aKwok, R uhttps://mcm.lternet.edu/content/synthetic-aperture-radar-detection-snowline-commonwealth-and-howard-glaciers-taylor-valley00561nas a2200133 4500008004100000245011000041210006900151300001200220490000600232100002200238700002300260700002000283856012400303 2002 eng d00aTrends in resin and KCl-extractable soil nitrogen across landscape gradients in Taylor Valley, Antarctica0 aTrends in resin and KClextractable soil nitrogen across landscap a289-2990 v51 aBarrett, John, E.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/trends-resin-and-kcl-extractable-soil-nitrogen-across-landscape-gradients-taylor-valley03551nas a2200217 4500008004100000245009000041210006900131260001200200300001400212490000800226520282700234653001103061100002103072700002703093700001903120700002003139700002403159700002203183700001703205856011103222 2002 eng d00aValley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-20000 aValley floor climate observations from the McMurdo Dry Valleys A c12/2002 a4772-47840 v1073 a

Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from −14.8°C to −30.0°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2 = 0.992) of increasing potential temperature with distance from the coast (0.09°C km−1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites.

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a519529A model for nematode locomotion in soil a705-7160 v31 aHunt, H1 aWall, Diana, H.1 aDeCrappeo, N1 aBrenner, J uhttps://mcm.lternet.edu/content/519-529a-model-nematode-locomotion-soil00512nas a2200121 4500008004100000245010700041210006900148300000900217490000700226100001500233700001800248856012400266 2001 eng d00aAbsorption and utilization of low irradiance by cyanobacterial mats in two ice-covered Antarctic lakes0 aAbsorption and utilization of low irradiance by cyanobacterial m a5-150 v371 aHawes, Ian1 aSchwartz, A-M uhttps://mcm.lternet.edu/content/absorption-and-utilization-low-irradiance-cyanobacterial-mats-two-ice-covered-antarctic00506nas a2200157 4500008004100000245007600041210006900117260001200186300001400198490000700212653001100219100003300230700002100263700002400284856004000308 2001 eng d00aBacterial dissolved organic carbon demand in antarctic dry valley lakes0 aBacterial dissolved organic carbon demand in antarctic dry valle c07/2001 a1189-11940 v4610aBiggie1 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aSchmeling, J1 aSchwartz, A uhttps://mcm.lternet.edu/content/benthic-primary-production-two-perennially-ice-covered-antarctic-lakes-comparisons-annual00607nas a2200133 4500008004100000245015900041210006900200300001200269490000600281100002000287700001700307700002200324856012700346 2001 eng d00aBiodiversity in critical transition zones between terrestrial freshwater and marine soils and sediments: processes, linkages, and management implications.0 aBiodiversity in critical transition zones between terrestrial fr a418-4200 v41 aWall, Diana, H.1 aPalmer, M.A.1 aSnelgrove, P.V.R. uhttps://mcm.lternet.edu/content/biodiversity-critical-transition-zones-between-terrestrial-freshwater-and-marine-soils-and00510nas a2200133 4500008004100000245008300041210006900124300001400193490000800207100001800215700001700233700002400250856010200274 2001 eng d00aChemical weathering in streams of a polar desert (Taylor Valley, Antarctica).0 aChemical weathering in streams of a polar desert Taylor Valley A a1401-14080 v1131 aNezat, C., A.1 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/chemical-weathering-streams-polar-desert-taylor-valley-antarctica00540nas a2200145 4500008004100000245008500041210006900126300001000195490000700205100001900212700001700231700002100248700001500269856011000284 2001 eng d00aCO2 concentrations in perennially ice-covered lakes of Taylor Valley, Antarctica0 aCO2 concentrations in perennially icecovered lakes of Taylor Val a27-500 v561 aNeumann, Klaus1 aLyons, Berry1 aPriscu, John, C.1 aDonahoe, R uhttps://mcm.lternet.edu/content/co2-concentrations-perennially-ice-covered-lakes-taylor-valley-antarctica00571nas a2200133 4500008004100000245012300041210006900164300000900233490000700242100001800249700002000267700002300287856012700310 2001 eng d00aDetermining habitat suitability for soil invertebrates in an extreme environment: The McMurdo Dry Valleys, Antarctica.0 aDetermining habitat suitability for soil invertebrates in an ext a9-170 v131 aCourtright, E1 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/determining-habitat-suitability-soil-invertebrates-extreme-environment-mcmurdo-dry-valleys00531nas a2200121 4500008004100000245009500041210006900136260003000205490001000235100002100245700002400266856011900290 2001 eng d00aEnergy balance of a rough glacier surface, Canada Glacier, McMurdo Dry Valleys, Antarctica0 aEnergy balance of a rough glacier surface Canada Glacier McMurdo bPortland State University0 vPh.D.1 aLewis, Karen, J.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/energy-balance-rough-glacier-surface-canada-glacier-mcmurdo-dry-valleys-antarctica00572nas a2200145 4500008004100000245009000041210006900131300001200200490000800212100002300220700002500243700001500268700002700283856011600310 2001 eng d00aGlacial cryoconite ecosystems: a bipolar comparison of algal communities and habitats0 aGlacial cryoconite ecosystems a bipolar comparison of algal comm a173-1970 v1231 aMueller, Derek, R.1 aVincent, Warwick, F.1 aPollard, W1 aFritsen, Christian, H. uhttps://mcm.lternet.edu/content/glacial-cryoconite-ecosystems-bipolar-comparison-algal-communities-and-habitats00534nas a2200121 4500008004100000245010800041210006900149260002700218490000900245100001300254700002400267856012100291 2001 eng d00aThe influence of mixotroph growth on DOM chemistry in Pony Lake, a eutrophic coastal pond in Antarctica0 ainfluence of mixotroph growth on DOM chemistry in Pony Lake a eu bUniversity of Colorado0 vM.S.1 aBrown, A1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/influence-mixotroph-growth-dom-chemistry-pony-lake-eutrophic-coastal-pond-antarctica00756nas a2200193 4500008004100000245013700041210006900178490000600247100002600253700002100279700002900300700001700329700002300346700001300369700001600382700001500398700002000413856012900433 2001 eng d00aThe influence of soil biodiversity on hydrological pathways and the transfer of materials between terrestrial and aquatic ecosystems0 ainfluence of soil biodiversity on hydrological pathways and the 0 v41 aBardgett, Richard, D.1 aAnderson, J., M.1 aBehan-Pelletier, Valerie1 aBrussaard, L1 aColeman, David, C.1 aEttma, C1 aMoldenke, A1 aSchimel, J1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/influence-soil-biodiversity-hydrological-pathways-and-transfer-materials-between-terrestrial00462nas a2200121 4500008004100000245007200041210006900113300001200182490000700194100001900201700002100220856009900241 2001 eng d00aLuminescence zeroing tests in Lake Hoare, Taylor Valley, Antarctica0 aLuminescence zeroing tests in Lake Hoare Taylor Valley Antarctic a519-5290 v251 aBerger, G., W.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/luminescence-zeroing-tests-lake-hoare-taylor-valley-antarctica00774nas a2200193 4500008004100000245014400041210006900185300001200254490000700266100001700273700002400290700002100314700002800335700002400363700002400387700002100411700002000432856012800452 2001 eng d00aThe McMurdo Dry Valleys Long-Term Ecological Research Program: new understanding of the biogeochemistry of the Dry Valley lakes: a review.0 aMcMurdo Dry Valleys LongTerm Ecological Research Program new und a202-2170 v251 aLyons, Berry1 aWelch, Kathleen, A.1 aPriscu, John, C.1 aLaybourn-Parry, Johanna1 aMoorhead, Daryl, L.1 aMcKnight, Diane, M.1 aDoran, Peter, T.1 aTranter, Martyn uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-long-term-ecological-research-program-new-understanding-biogeochemistry00770nas a2200193 4500008004100000245019000041210006900231300001400300490000700314100002300321700001500344700001400359700002100373700001600394700001300410700001500423700001700438856012100455 2001 eng d00aMineralogical and geochemical analyses of Antarctic lake sediments: A study of reflectanceand Mossbauer spectroscopy and C, N and S isotopes with applications for remote sensing on Mars0 aMineralogical and geochemical analyses of Antarctic lake sedimen a2875-28970 v651 aBishop, Janice, L.1 aLougear, A1 aNewton, J1 aDoran, Peter, T.1 aFroeschl, H1 aKrner, W1 aKoeberl, C1 aTrautwein, A uhttps://mcm.lternet.edu/content/mineralogical-and-geochemical-analyses-antarctic-lake-sediments-study-reflectanceand03621nas a2200133 4500008004100000245010500041210006900146260002700215490001000242520306700252100002503319700002403344856011903368 2001 eng d00aModeling hyporheic exchange influences on biogeochemical processes in dry valley streams, Antarctica0 aModeling hyporheic exchange influences on biogeochemical process bUniversity of Colorado0 vPh.D.3 a

The ephemeral streams of the Dry Valleys of Antarctica provide habitat to benthic algal mats, and greatly control the quantity and quality of glacial melt water that enters closed basin Dry Valley lakes. Dry Valley watersheds are composed of streambeds and adjacent hyporheic zones. Hydrologic exchange of water and solutes between the stream and the hyporheic zone has the overall effect of increasing residence time in the stream/hyporheic system. Biogeochemical reactions (e.g. chemical weathering, nutrient assimilation) occur both in the water column and in the hyporheic zone. Field experiments and solute transport modeling were employed to elucidate the effects of rapid hyporheic exchange on biogeochemical cycling in Antarctic streams. The results presented here show that (1) large portions of the wetted zone that surrounds each stream is a hyporheic zone, and that stream water exchanges into and out of extended portions of this zone on the order of weeks, (2) the rapid exchange of stream water between the water column and the hyporheic zone controls the rate of weathering in streambed sediments, and (3) denitrification in streams is limited by the conversion of NO2 to N2O, while the conversion of NO3 to NO2 occurs very quickly.

1 aGooseff, Michael, N.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/modeling-hyporheic-exchange-influences-biogeochemical-processes-dry-valley-streams00556nas a2200133 4500008004100000245010600041210006900147300001200216490000600228100002400234700002300258700002000281856012100301 2001 eng d00aOrganic carbon cycling in Taylor Valley, Antarctica: Quantifying soil reservoirs and soil respiration0 aOrganic carbon cycling in Taylor Valley Antarctica Quantifying s a113-1250 v71 aBurkins, Melody, B.1 aVirginia, Ross, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/organic-carbon-cycling-taylor-valley-antarctica-quantifying-soil-reservoirs-and-soil00561nas a2200133 4500008004100000245011900041210006900160260001200229300001400241490000700255100001900262700002100281856012500302 2001 eng d00aPhytoplankton phosphorus deficiency and alkaline phosphatase activity in the McMurdo Dry Valley lakes, Antarctica.0 aPhytoplankton phosphorus deficiency and alkaline phosphatase act c09/2001 a1331-13460 v461 aDore, John, E.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/phytoplankton-phosphorus-deficiency-and-alkaline-phosphatase-activity-mcmurdo-dry-valley00492nas a2200121 4500008004100000245008000041210006900121260002700190490000900217100002100226700002400247856009900271 2001 eng d00aRegrowth of cyanobacterial mats in Greek Creek and the impact of ecotourism0 aRegrowth of cyanobacterial mats in Greek Creek and the impact of bUniversity of Colorado0 vM.S.1 aChatfield, Ethan1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/regrowth-cyanobacterial-mats-greek-creek-and-impact-ecotourism00661nas a2200145 4500008004100000245017000041210006900211300001200280490000700292653002100299100001900320700002400339700002400363856012800387 2001 eng d00aRetrospective simulation of lake level rise in Lake Bonney based on recent 21-year record: indication of recent climate change in the McMurdo Dry Valleys, Antarctica0 aRetrospective simulation of lake level rise in Lake Bonney based a477-4920 v2510aClimate Response1 aBomblies, Arne1 aMcKnight, Diane, M.1 aAndrews, Edmund, D. uhttps://mcm.lternet.edu/content/retrospective-simulation-lake-level-rise-lake-bonney-based-recent-21-year-record-indication00551nas a2200121 4500008004100000245011800041210006900159260002500228490000900253100001700262700002400279856012600303 2001 eng d00aSensitivity of carbon dynamics to changing light availability of benthic microbial mats in Lake Hoare, Antarctica0 aSensitivity of carbon dynamics to changing light availability of bUniversity of Toledo0 vM.S.1 aSchmeling, J1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/sensitivity-carbon-dynamics-changing-light-availability-benthic-microbial-mats-lake-hoare00477nas a2200169 4500008004100000245002200041210002200063260003000085300001000115100002000125700002000145700002400165700001900189700002200208700002300230856005400253 2001 eng d00aSoil Biodiversity0 aSoil Biodiversity aNew YorkbSpringer Verlag a47-821 aWall, Diana, H.1 aAdams, Gina, A.1 aParsons, Andrew, N.1 aChapin, F., S.1 aSala, Osvaldo, E.1 aHuber-Sannwald, E. uhttps://mcm.lternet.edu/content/soil-biodiversity00706nas a2200169 4500008004100000245014800041210006900189300001000258490000700268100002400275700002500299700002500324700002100349700001800370700002300388856012500411 2001 eng d00aSpectrofluorometric characterization of aquatic fulvic acid for determination of precursor organic material and general structural properties.0 aSpectrofluorometric characterization of aquatic fulvic acid for  a38-480 v461 aMcKnight, Diane, M.1 aBoyer, Elizabeth, W.1 aWesterhoff, Paul, K.1 aDoran, Peter, T.1 aKulbe, Thomas1 aAndersen, Dale, T. uhttps://mcm.lternet.edu/content/spectrofluorometric-characterization-aquatic-fulvic-acid-determination-precursor-organic00434nas a2200121 4500008004100000245005500041210005500096260003000151490000900181100001400190700002400204856008400228 2001 eng d00aSynthetic aperture radar imagery of polar glaciers0 aSynthetic aperture radar imagery of polar glaciers bPortland State University0 vM.S.1 aBardel, P1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/synthetic-aperture-radar-imagery-polar-glaciers00553nas a2200121 4500008004100000245010800041210006900149260002700218490000900245100002400254700002400278856012900302 2000 eng d00aActive layer dynamics and hyporheic zone storage in three streams in the McMurdo Dy Valleys, Antarctica0 aActive layer dynamics and hyporheic zone storage in three stream bUniversity of Colorado0 vM.S.1 aConovitz, Peter, A.1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/active-layer-dynamics-and-hyporheic-zone-storage-three-streams-mcmurdo-dy-valleys-antarctica00532nas a2200121 4500008004100000245011300041210006900154300001400223490000700237100002000244700002000264856012600284 2000 eng d00aBiodiversity above and below the surface of soils and sediments: linkages and implications for global change0 aBiodiversity above and below the surface of soils and sediments  a1043-10480 v501 aAdams, Gina, A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/biodiversity-above-and-below-surface-soils-and-sediments-linkages-and-implications-global00868nas a2200229 4500008004100000245013400041210006900175260002800244300001200272100002400284700001700308700002400325700001700349700002400366700002200390700002100412700002700433700001800460700001900478700001800497856012300515 2000 eng d00aClimate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica0 aClimate and hydrologic variations and implications for lake and  bOxford University Press a174-1951 aWelch, Kathleen, A.1 aLyons, Berry1 aMcKnight, Diane, M.1 aJaros, Chris1 aFountain, Andrew, G1 aNylen, Thomas, H.1 aDoran, Peter, T.1 aHoward-Williams, Clive1 aGreenland, D.1 aGoodin, D., G.1 aSmith, R., C. uhttps://mcm.lternet.edu/content/climate-and-hydrologic-variations-and-implications-lake-and-stream-ecological-response00578nas a2200133 4500008004100000245011300041210006900154300001200223490000700235100002400242700002100266700002800287856012900315 2000 eng d00aDistribution and phylogeny of bacterial communities associated with mineral particles in Antarctic lake ice.0 aDistribution and phylogeny of bacterial communities associated w a197-2020 v391 aGordon, Douglas, A.1 aPriscu, John, C.1 aGiovannoni, Stephen, J. uhttps://mcm.lternet.edu/content/distribution-and-phylogeny-bacterial-communities-associated-mineral-particles-antarctic-lake00550nas a2200133 4500008004100000245010500041210006900146300001200215490000700227100002700234700001200261700002100273856012200294 2000 eng d00aDistribution of organic carbon and nitrogen in surface soils in the McMurdo Dry Valleys, Antarctica.0 aDistribution of organic carbon and nitrogen in surface soils in  a121-1280 v231 aFritsen, Christian, H.1 aGrue, A1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/distribution-organic-carbon-and-nitrogen-surface-soils-mcmurdo-dry-valleys-antarctica00520nas a2200121 4500008004100000245010100041210006900142260002500211490000900236100001500245700002400260856011400284 2000 eng d00aDynamics of the deep chlorophyll maximum within the lakes of the McMurdo Dry Valleys, Antarctica0 aDynamics of the deep chlorophyll maximum within the lakes of the bUniversity of Toledo0 vM.S.1 aBurnett, L1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/dynamics-deep-chlorophyll-maximum-within-lakes-mcmurdo-dry-valleys-antarctica00602nas a2200169 4500008004100000245007200041210006900113260003000182300001200212100002400224700001600248700002200264700001500286700001400301700001600315856010100331 2000 eng d00aExperimental Approaches to Investigate Belowground Animal Diversity0 aExperimental Approaches to Investigate Belowground Animal Divers aNew YorkbSpringer Verlag a318-3291 aFreckman, Diana, W.1 aReichman, O1 aSala, Osvaldo, E.1 aJackson, R1 aMooney, H1 aHowarth, R. uhttps://mcm.lternet.edu/content/experimental-approaches-investigate-belowground-animal-diversity00674nas a2200157 4500008004100000245016800041210006900209300001400278490000700292100001700299700001800316700002400334700001700358700002100375856012000396 2000 eng d00aFossil fuel burning in Taylor Valley, southern Victoria Land, Antarctica: estimating the role of scientific activities on carbon and nitrogen reservoirs and fluxes0 aFossil fuel burning in Taylor Valley southern Victoria Land Anta a1659-16620 v341 aLyons, Berry1 aNezat, C., A.1 aWelch, Kathleen, A.1 aKottmeier, S1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/fossil-fuel-burning-taylor-valley-southern-victoria-land-antarctica-estimating-role00870nas a2200325 4500008004100000245005200041210005200093300001400145490000800159100002200167700001400189700001500203700001300218700001400231700001800245700001200263700001300275700001400288700001500302700002000317700001900337700001500356700001400371700001800385700001300403700002100416700001600437700001500453856007600468 2000 eng d00aGlobal biodiversity scenarios for the year 21000 aGlobal biodiversity scenarios for the year 2100 a1770-17740 v2871 aSala, Osvaldo, E.1 aKinzig, A1 aLeemans, R1 aLodge, D1 aMooney, H1 aOesterheld, M1 aPoff, N1 aSykes, M1 aWalker, B1 aWalkder, M1 aWall, Diana, H.1 aChapin, F., S.1 aArmesto, J1 aBerlow, E1 aBloomfield, J1 aDirzo, R1 aHuber-Sanwald, E1 aHuenneke, L1 aJackson, R uhttps://mcm.lternet.edu/content/global-biodiversity-scenarios-year-210001013nas a2200313 4500008004100000245014800041210006900189300001400258490000700272100001500279700001400294700001700308700002200325700001300347700001400360700001400374700002200388700001400410700001600424700001400440700001500454700002300469700001500492700002200507700001600529700001700545700002000562856011700582 2000 eng d00aGlobal change effects on above and below ground biodiversity in terrestrial ecosystems: interactions and implications for ecosystem functioning0 aGlobal change effects on above and below ground biodiversity in  a1089-10990 v501 aWolters, V1 aWardle, D1 aBrussaard, L1 aDangerfield, Mark1 aBrown, V1 aGiller, K1 aHooper, D1 aSala, Osvaldo, E.1 aTiedje, J1 avan Veen, J1 aSilver, W1 aBignell, D1 aColeman, David, C.1 aLavelle, P1 avan der Putten, W1 aDeRuiter, P1 aRusek, Josef1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/global-change-effects-above-and-below-ground-biodiversity-terrestrial-ecosystems00667nas a2200169 4500008004100000245011600041210006900157300001200226490000700238100001700245700002400262700002100286700002100307700001900328700002400347856012600371 2000 eng d00aThe importance of landscape position and legacy: The evolution of the Taylor Valley Lake District, Antarctica.0 aimportance of landscape position and legacy The evolution of the a355-3670 v431 aLyons, Berry1 aFountain, Andrew, G1 aDoran, Peter, T.1 aPriscu, John, C.1 aNeumann, Klaus1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/importance-landscape-position-and-legacy-evolution-taylor-valley-lake-district-antarctica00932nas a2200289 4500008004100000245012200041210006900163300001400232490000700246100001400253700001500267700002200282700001600304700001700320700001400337700001400351700001500365700001500380700001300395700001700408700002200425700002000447700001400467700002300481700001400504856012400518 2000 eng d00aInteractions between above and belowground biodiversity in terrestrial ecosystems: patterns, mechanisms and feedbacks0 aInteractions between above and belowground biodiversity in terre a1049-10610 v501 aHooper, D1 aLavelle, P1 avan der Putten, W1 aDeRuiter, P1 aRusek, Josef1 aSilver, W1 aTiedje, J1 aWolters, V1 aBignell, D1 aBrown, V1 aBrussaard, L1 aDangerfield, Mark1 aWall, Diana, H.1 aWardle, D1 aColeman, David, C.1 aGiller, K uhttps://mcm.lternet.edu/content/interactions-between-above-and-belowground-biodiversity-terrestrial-ecosystems-patterns00388nas a2200133 4500008004100000245003300041210002900074260003100103300000800134100002000142700002400162700001400186856005400200 2000 eng d00aThe Lions of the Dry Valleys0 aLions of the Dry Valleys bLonely Planet Publications a3131 aWall, Diana, H.1 aParsons, Andrew, N.1 aRubin, J. uhttps://mcm.lternet.edu/content/lions-dry-valleys00606nas a2200157 4500008004100000245008300041210006900124260001700193100002800210700002300238700002100261700002700282700001700309700001500326856010700341 2000 eng d00aMixotrophy as a survival strategy among planktonic protozoa in Antarctic lakes0 aMixotrophy as a survival strategy among planktonic protozoa in A bCaxton Press1 aLaybourn-Parry, Johanna1 aRoberts, Emily, C.1 aBell, Elanor, R.1 aHoward-Williams, Clive1 aDavidson, W.1 aBroady, P. uhttps://mcm.lternet.edu/content/mixotrophy-survival-strategy-among-planktonic-protozoa-antarctic-lakes00610nas a2200157 4500008004100000245005700041210005500098260011100153300001200264100001800276700001400294700002000308700002000328700002100348856008300369 2000 eng d00aNematodes - Pervading The Earth and Linking All Life0 aNematodes Pervading The Earth and Linking All Life bCommittee for the Second Forum on Biodiversity, National Academy of Sciences and National Research Council a176-1911 aBaldwin, J.G.1 aNadler, S1 aWall, Diana, H.1 aWilliams, Tania1 aRaven, Peter, H. uhttps://mcm.lternet.edu/content/nematodes-pervading-earth-and-linking-all-life00624nas a2200169 4500008004100000245009900041210006900140300001200209490000800221100001800229700002000247700002300267700001200290700001400302700001400316856012400330 2000 eng d00aNuclear and mitochondrial DNA sequence diversity in the Antarctic nematode Scottnema lindsayae0 aNuclear and mitochondrial DNA sequence diversity in the Antarcti a143-1530 v3221 aCourtright, E1 aWall, Diana, H.1 aVirginia, Ross, A.1 aVida, J1 aFrisse, L1 aThomas, W uhttps://mcm.lternet.edu/content/nuclear-and-mitochondrial-dna-sequence-diversity-antarctic-nematode-scottnema-lindsayae00594nas a2200157 4500008004100000245009500041210006900136300001400205490000700219653001100226100002400237700002300261700002200284700002000306856011000326 2000 eng d00aThe Origin of Soil Organic Matter in Taylor Valley, Antarctica: A Legacy of Climate Change0 aOrigin of Soil Organic Matter in Taylor Valley Antarctica A Lega a2377-23910 v8110alegacy1 aBurkins, Melody, B.1 aVirginia, Ross, A.1 aChamberlain, Page1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/origin-soil-organic-matter-taylor-valley-antarctica-legacy-climate-change00632nas a2200181 4500008004100000245008800041210006900129260001200198300001200210490000700222653001100229653001100240100002400251700001800275700001900293700002300312856011500335 2000 eng d00aPhytoplankton dynamics in a stably stratified Antarctic lake during winter darkness0 aPhytoplankton dynamics in a stably stratified Antarctic lake dur c10/2000 a852-8610 v3610aBiggie10awinter1 aMcKnight, Diane, M.1 aHowes, B., L.1 aTaylor, C., D.1 aGoehringer, D., D. uhttps://mcm.lternet.edu/content/phytoplankton-dynamics-stably-stratified-antarctic-lake-during-winter-darkness00433nas a2200133 4500008004100000245004600041210004600087300001200133490000700145100002800152700002100180700002300201856007500224 2000 eng d00aProtozoan growth rates in Antarctic lakes0 aProtozoan growth rates in Antarctic lakes a445-4510 v231 aLaybourn-Parry, Johanna1 aBell, Elanor, R.1 aRoberts, Emily, C. uhttps://mcm.lternet.edu/content/protozoan-growth-rates-antarctic-lakes00594nas a2200193 4500008004100000245004800041210004800089260002500137300001200162100002000174700001600194700001500210700001600225700001600241700001900257700002000276700002400296856008000320 2000 eng d00aSoil Biodiversity and Ecosystem Functioning0 aSoil Biodiversity and Ecosystem Functioning aHeidelbergbSpringer a283-2901 aWall, Diana, H.1 aLynch, J.M.1 aBalazs, E.1 aGalante, E.1 aLynch, J.M.1 aSchepers, J.S.1 aToutant, Werner1 aWerry, P.A., Th. J. uhttps://mcm.lternet.edu/content/soil-biodiversity-and-ecosystem-functioning00374nas a2200145 4500008004100000245002200041210002200063260001900085300001200104490000600116100001800122700002000140700001400160856005400174 2000 eng d00aSoil Conservation0 aSoil Conservation bAcademic Press a315-3260 v51 aPorazinska, D1 aWall, Diana, H.1 aLevin, S. uhttps://mcm.lternet.edu/content/soil-conservation00609nas a2200181 4500008004100000245009000041210006900131260001200200300001200212490000700224653001100231653001300242100002300255700002800278700002400306700001600330856008100346 2000 eng d00aStratification and dynamics of microbial loop communities in Lake Fryxell, Antarctica0 aStratification and dynamics of microbial loop communities in Lak c12/2001 a649-6610 v4410aBiggie10aprotozoa1 aRoberts, Emily, C.1 aLaybourn-Parry, Johanna1 aMcKnight, Diane, M.1 aNovarino, G uhttp://onlinelibrary.wiley.com/doi/10.1046/j.1365-2427.2000.00612.x/abstract00562nas a2200169 4500008004100000245007600041210006900117260001200186300001200198490000700210653001100217653002400228100002000252700002000272700002300292856007700315 2000 eng d00aThe use of anhydrobiosis by soil nematodes in the Antarctic Dry Valleys0 ause of anhydrobiosis by soil nematodes in the Antarctic Dry Vall c08/2000 a460-4670 v1410aBiggie10asurvival strategies1 aTreonis, Amy, M1 aWall, Diana, H.1 aVirginia, Ross, A. uhttp://onlinelibrary.wiley.com/doi/10.1046/j.1365-2435.2000.00442.x/full00602nas a2200157 4500008004100000245010300041210006900144300001200213490000800225100001700233700002400250700001500274700001500289700001500304856012500319 2000 eng d00aUV radiation and potential biological effects beneath the perennial ice cover of an antarctic lake0 aUV radiation and potential biological effects beneath the perenn a155-1650 v4271 aKepner, R.L.1 aWharton, Robert, A.1 aCollier, R1 aCockell, C1 aJeffrey, W uhttps://mcm.lternet.edu/content/uv-radiation-and-potential-biological-effects-beneath-perennial-ice-cover-antarctic-lake00522nas a2200157 4500008004100000245005500041210005300096260003100149300001000180653001100190100002100201700001700222700001800239700002200257856008500279 1999 eng d00aArctic and Antarctic lakes: contrast or continuum?0 aArctic and Antarctic lakes contrast or continuum bUniversity of Ottawa Press a59-6810aBiggie1 aDoran, Peter, T.1 aAdams, Peter1 aEcclestone, M1 aLewkowicz, A., G. uhttps://mcm.lternet.edu/content/arctic-and-antarctic-lakes-contrast-or-continuum00332nas a2200097 4500008004100000245004300041210004300084300001200127100002000139856007500159 1999 eng d00aBiodiversity and Ecosystem Functioning0 aBiodiversity and Ecosystem Functioning a107-1081 aWall, Diana, H. uhttps://mcm.lternet.edu/content/biodiversity-and-ecosystem-functioning00481nas a2200121 4500008004100000245007000041210006900111260003800180490001000218100001900228700001700247856009500264 1999 eng d00aCarbon dynamics in lakes and streams of Taylor Valley, Antarctica0 aCarbon dynamics in lakes and streams of Taylor Valley Antarctica bUniversity of Alabama, Tuscaloosa0 vPh.D.1 aNeumann, Klaus1 aLyons, Berry uhttps://mcm.lternet.edu/content/carbon-dynamics-lakes-and-streams-taylor-valley-antarctica00607nas a2200157 4500008004100000245007100041210006900112100002100181700002000202700003300222700002700255700002800282700002300310700001800333856009800351 1999 eng d00aCarbon transformations in a perennially ice-covered Antarctic lake0 aCarbon transformations in a perennially icecovered Antarctic lak1 aPriscu, John, C.1 aWolf, Craig, F.1 aTakacs-Vesbach, Cristina, D.1 aFritsen, Christian, H.1 aLaybourn-Parry, Johanna1 aRoberts, Emily, C.1 aSattl, Birgit uhttps://mcm.lternet.edu/content/carbon-transformations-perennially-ice-covered-antarctic-lake00557nas a2200133 4500008004100000245011000041210006900151300001200220490000700232100001700239700002400256700001900280856012400299 1999 eng d00aChlorine-36 in the waters of the McMurdo Dry Valley lakes, southern Victoria Land, Antarctica: revisited0 aChlorine36 in the waters of the McMurdo Dry Valley lakes souther a185-1910 v621 aLyons, Berry1 aWelch, Kathleen, A.1 aSharma, Pankaj uhttps://mcm.lternet.edu/content/chlorine-36-waters-mcmurdo-dry-valley-lakes-southern-victoria-land-antarctica-revisited00570nas a2200133 4500008004100000245013100041210006900172300001200241490000700253100001700260700001600277700002400293856011900317 1999 eng d00aCiliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates0 aCiliated protozoa of two antarctic lakes analysis by quantitativ a285-2940 v211 aKepner, R.L.1 aCoats, D.W.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/ciliated-protozoa-two-antarctic-lakes-analysis-quantitative-protargol-staining-and00459nas a2200121 4500008004100000245007100041210006900112300001200181490000700193100002000200700002300220856009400243 1999 eng d00aControls on soil biodiversity: insight s from extreme environments0 aControls on soil biodiversity insight s from extreme environment a137-1500 v131 aWall, Diana, H.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/controls-soil-biodiversity-insight-s-extreme-environments00684nas a2200205 4500008004100000245008100041210006900122260001200191300001200203490000800215653001400223100002100237700001900258700001700277700002400294700002100318700001600339700001700355856010600372 1999 eng d00aDating quaternary lacustrine sediments in the McMurdo Dry Valleys Antarctica0 aDating quaternary lacustrine sediments in the McMurdo Dry Valley c03/1999 a223-2390 v14710asediments1 aDoran, Peter, T.1 aBerger, G., W.1 aLyons, Berry1 aWharton, Robert, A.1 aDavisson, M., L.1 aSouthon, J.1 aDibb, J., E. uhttps://mcm.lternet.edu/content/dating-quaternary-lacustrine-sediments-mcmurdo-dry-valleys-antarctica00554nas a2200109 4500008004100000245012600041210006900167260004800236490000900284100002500293856012600318 1999 eng d00aDiatoms of the McMurdo Dry Valleys, Antarctica: A taxonomic appraisal including a detailed study of the genus Hantzschia.0 aDiatoms of the McMurdo Dry Valleys Antarctica A taxonomic apprai aAnn Arbor, MichiganbUniversity of Michigan0 vM.S.1 aAlger, Alexander, S. uhttps://mcm.lternet.edu/content/diatoms-mcmurdo-dry-valleys-antarctica-taxonomic-appraisal-including-detailed-study-genus00574nas a2200133 4500008004100000245012300041210006900164300001200233490000800245100002100253700002100274700001900295856012600314 1999 eng d00aThe distribution and relative abundance of ammonium-oxidizing bacteria in lakes of the McMurdo Dry Valleys, Antarctica0 adistribution and relative abundance of ammoniumoxidizing bacteri a113-1300 v4011 aVoytek, Mary, A.1 aPriscu, John, C.1 aWard, Bess, B. 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v2861 aPriscu, John, C.1 aAdams, Edward, E.1 aLyons, Berry1 aVoytek, Mary, A.1 aMogk, David, W.1 aBrown, Robert, L.1 aMcKay, Christopher, P.1 aTakacs-Vesbach, Cristina, D.1 aWelch, Kathleen, A.1 aWolf, Craig, F.1 aKirshtein, Julie, D.1 aAvci, Recep uhttps://mcm.lternet.edu/content/geomicrobiology-sub-glacial-ice-above-vostok-station00489nas a2200121 4500008004100000245008700041210006900128490000700197100001700204700001300221700002400234856010900258 1999 eng d00aHistory of McMurdo Dry Valley Lakes, Antarctica, from stable chlorine isotope data0 aHistory of McMurdo Dry Valley Lakes Antarctica from stable chlor0 v271 aLyons, Berry1 aFrape, S1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/history-mcmurdo-dry-valley-lakes-antarctica-stable-chlorine-isotope-data00401nas a2200097 4500008004100000245007500041210006900116300001200185490000700197856009900204 1999 eng d00aHow soils structure communities in the McMurdo Dry Valleys, Antarctica0 aHow soils structure communities in the 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4500008004100000245016300041210006900204300001200273490000700285100002700292700002100319856012700340 1999 eng d00aSeasonal change in the optical properties of the permanent ice cover on Lake Bonney, Antarctica: Consequences for lake productivity and phytoplankton dynamics0 aSeasonal change in the optical properties of the permanent ice c a447-4540 v441 aFritsen, Christian, H.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/seasonal-change-optical-properties-permanent-ice-cover-lake-bonney-antarctica-consequences00404nas a2200133 4500008004100000245003600041210003500077260003000112300001200142100002000154700001700174700001500191856006400206 1999 eng d00aSoil Biodiversity: life in soil0 aSoil Biodiversity life in soil bColumbia University Press a124-1281 aWall, Diana, H.1 aCracraft, J.1 aGriffo, F. uhttps://mcm.lternet.edu/content/soil-biodiversity-life-soil00536nas a2200193 4500008004100000245002300041210002300064260003800087300001200125100002300137700001600160700001400176700002000190700002000210700001800230700002300248700001600271856005500287 1999 eng d00aSoil invertebrates0 aSoil invertebrates aNew YorkbOxford University Press a349-3771 aColeman, David, C.1 aBlair, J.M.1 aElliot, E1 aWall, Diana, H.1 aRobertson, G.P.1 aBledsoe, C.S.1 aColeman, David, C.1 aSollins, P. uhttps://mcm.lternet.edu/content/soil-invertebrates00467nas a2200097 4500008004100000245011800041210006900159300000900228490000700237856012500244 1999 eng d00aSpatial and climatic variations and its control on glacier equilibrium line altitude in Taylor Valley, Antarctica0 aSpatial and climatic variations and its control on glacier equil a1-100 v22 uhttps://mcm.lternet.edu/content/spatial-and-climatic-variations-and-its-control-glacier-equilibrium-line-altitude-taylor00546nas a2200133 4500008004100000245007600041210006900117260003900186100002000225700002300245700002000268700002100288856010300309 1999 eng d00aThe world beneath our feet: Soil biodiversity and ecosystem functioning0 aworld beneath our feet Soil biodiversity and ecosystem functioni bNational Academy of Sciences Press1 aWall, Diana, H.1 aVirginia, Ross, A.1 aWilliams, Tania1 aRaven, Peter, H. uhttps://mcm.lternet.edu/content/world-beneath-our-feet-soil-biodiversity-and-ecosystem-functioning00670nas a2200133 4500008004100000245021900041210006900260300001200329490000700341100002100348700001900369700002100388856012700409 1998 eng d00aThe Abundance of Ammonium-Oxidizing Bacteria in Lake Bonney, Antarctica Determined by Immunofluorescence, PCR and In Situ Hybridization, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica0 aAbundance of AmmoniumOxidizing Bacteria in Lake Bonney Antarctic a217-2280 v721 aVoytek, Mary, A.1 aWard, Bess, B.1 aPriscu, John, C. 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John, C. uhttps://mcm.lternet.edu/content/bacterioplankton-dynamics-mcmurdo-dry-valley-lakes-antarctica-production-and-biomass-loss00492nas a2200121 4500008004100000245007500041210006900116260003800185490001000223100001800233700001700251856010200268 1998 eng d00aChemical Weathering in Taylor Valley, Antarctica: Quantity and Quality0 aChemical Weathering in Taylor Valley Antarctica Quantity and Qua bUniversity of Alabama, Tuscaloosa0 vPh.D.1 aNezat, C., A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/chemical-weathering-taylor-valley-antarctica-quantity-and-quality00499nas a2200121 4500008004100000245007100041210006900112260004900181490000900230100001900239700002400258856009500282 1998 eng d00aClimatic controls on streamflow generation from Antarctic glaciers0 aClimatic controls on streamflow generation from Antarctic glacie aBoulder, CObUniversity of Colorado Boulder0 vM.S.1 aBomblies, Arne1 aMcKnight, Diane, M. 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McMurdo Dry Valleys, Antarctica0 aPhotosynthetic characteristics of cyanobacteria in permanent ice a216-2180 v311 aFritsen, Christian, H.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/photosynthetic-characteristics-cyanobacteria-permanent-ice-covers-lakes-mcmurdo-dry-valleys00556nas a2200121 4500008004100000245013500041210006900176300001200245490000700257100002300264700002100287856012600308 1998 eng d00aPhysical Limnology of the McMurdo Dry Valleys Lakes, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica0 aPhysical Limnology of the McMurdo Dry Valleys Lakes in Ecosystem a153-1870 v721 aSpigel, Robert, H.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/physical-limnology-mcmurdo-dry-valleys-lakes-ecosystem-processes-polar-desert-mcmurdo-dry00548nas a2200121 4500008004100000245012600041210006900167300001200236490000700248100002500255700002100280856012500301 1998 eng d00aPigment Analysis of the Distribution, Succession, and Fate of Phytoplankton in 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Ecology in Lakes of the Dr a255-2670 v721 aJames, Mark, R.1 aHall, Julie, A.1 aLaybourn-Parry, Johanna uhttps://mcm.lternet.edu/content/protozooplankton-and-microzooplankton-ecology-lakes-dry-valleys-southern-victoria-land00540nas a2200121 4500008004100000245011400041210006900155300001200224490000700236100003300243700002100276856012100297 1998 eng d00aThe role of phytoplankton extracellular release in bacterioplankton growth of Taylor Valley Lakes, Antarctica0 arole of phytoplankton extracellular release in bacterioplankton  a211-2120 v311 aTakacs-Vesbach, Cristina, D.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/role-phytoplankton-extracellular-release-bacterioplankton-growth-taylor-valley-lakes00492nas a2200109 4500008004100000245010400041210006900145300001200214490000700226100002200233856012700255 1998 eng d00aScience and Environmental Management in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica0 aScience and Environmental Management in the McMurdo Dry Valleys  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Iain, B.1 aClaridge, Graeme, G.C.1 aCampbell, David, I.1 aBalks, Megan, R. uhttps://mcm.lternet.edu/content/soil-environment-mcmurdo-dry-valleys-antarctica00452nas a2200133 4500008004100000245005900041210005800100300001000158490000700168100002000175700002400195700001600219856008300235 1998 eng d00aSolar Radiation in the McMurdo Dry Valleys, Antarctica0 aSolar Radiation in the McMurdo Dry Valleys Antarctica a39-640 v721 aDana, Gayle, L.1 aWharton, Robert, A.1 aDubayah, R. uhttps://mcm.lternet.edu/content/solar-radiation-mcmurdo-dry-valleys-antarctica00569nas a2200121 4500008004100000245013800041210006900179260002600248490000900274100001300283700002400296856012700320 1998 eng d00aSpatial-temporal patterns of primary production in phytoplankton communities of Taylor Valley lakes, Antartica: A modelling synthesis0 aSpatialtemporal patterns of primary production in phytoplankton  bTexas Tech University0 vM.S.1 aDavis, W1 aMoorhead, Daryl, L. uhttps://mcm.lternet.edu/content/spatial-temporal-patterns-primary-production-phytoplankton-communities-taylor-valley-lakes00640nas a2200157 4500008004100000245011400041210006900155300001200224490000700236100002400243700002600267700002100293700002300314700002400337856012100361 1998 eng d00aStructure and composition of the photochemical apparatus of the Antarctic green alga Chlamydomonas subcaudata0 aStructure and composition of the photochemical apparatus of the  a303-3140 v561 aMorgan, Rachael, M.1 aIvanov, Alexander, G.1 aPriscu, John, C.1 aMaxwell, Denis, P.1 aHuner, Norman, P.A. uhttps://mcm.lternet.edu/content/structure-and-composition-photochemical-apparatus-antarctic-green-alga-chlamydomonas00560nas a2200133 4500008004100000245010400041210006900145300001200214490000700226100002100233700002400254700002000278856012800298 1998 eng d00aSurface energy balance and meltwater production for a Dry Valley glacier, Taylor Valley, Antarctica0 aSurface energy balance and meltwater production for a Dry Valley a603-6090 v271 aLewis, Karen, J.1 aFountain, Andrew, G1 aDana, Gayle, L. uhttps://mcm.lternet.edu/content/surface-energy-balance-and-meltwater-production-dry-valley-glacier-taylor-valley-antarctica00672nas a2200181 4500008004100000245007800041210006900119260005900188300001000247100002000257700001300277700002400290700002400314700001900338700001600357700001600373856010100389 1998 eng d00aA Temperature area index of stream discharge in Taylor Valley, Antarctica0 aTemperature area index of stream discharge in Taylor Valley Anta bNational Water Research Institute , Environment Canada a29-391 aDana, Gayle, L.1 aDavis, R1 aFountain, Andrew, G1 aWharton, Robert, A.1 aPietroniro, A.1 aGranger, R.1 aPultz, T.J. uhttps://mcm.lternet.edu/content/temperature-area-index-stream-discharge-taylor-valley-antarctica00564nas a2200157 4500008004100000245007000041210006900111300001200180490000700192100002500199700001600224700002200240700002700262700002100289856009600310 1998 eng d00aTransparency of Antarctic ice-covered lakes to solar UV radiation0 aTransparency of Antarctic icecovered lakes to solar UV radiation a618-6240 v431 aVincent, Warwick, F.1 aRae, Rowena1 aLaurion, Isabelle1 aHoward-Williams, Clive1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/transparency-antarctic-ice-covered-lakes-solar-uv-radiation00397nas a2200145 4500008004100000245003100041210003100072300001400103490000700117653001100124100001700135700002400152700001500176856006000191 1998 eng d00aViruses in antarctic lakes0 aViruses in antarctic lakes a1754-17610 v4310aBiggie1 aKepner, R.L.1 aWharton, Robert, A.1 aSuttle, C. uhttps://mcm.lternet.edu/content/viruses-antarctic-lakes00597nas a2200169 4500008004100000245007200041210006700113260002900180300001200209100001700221700002400238700001700262700001700279700002700296700001500323856008900338 1997 eng d00aThe abundance of planktonic virus-like particles in Antarctic lakes0 aabundance of planktonic viruslike particles in Antarctic lakes aRotterdambBalkema Press a241-2501 aKepner, R.L.1 aWharton, Robert, A.1 aGalchenko, V1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/abundance-planktonic-virus-particles-antarctic-lakes00625nas a2200205 4500008004100000245005100041210005100092300001200143490000700155100001700162700002900179700002300208700001600231700001500247700001800262700001600280700002400296700001900320856008000339 1997 eng d00aBiodiversity and Ecosystem Functioning in Soil0 aBiodiversity and Ecosystem Functioning in Soil a563-5700 v261 aBrussaard, L1 aBehan-Pelletier, Valerie1 aBignell, David, E.1 aBrown, V.K.1 aDidden, W.1 aFolgarait, P.1 aFragoso, C.1 aFreckman, Diana, W.1 aGupt, V.V.S.R. uhttps://mcm.lternet.edu/content/biodiversity-and-ecosystem-functioning-soil00499nas a2200109 4500008004100000245011300041210006900154300001200223490000600235100002100241856012700262 1997 eng d00aThe Biogeochemistry of Nitrous Oxide in Permanently Ice-Covered Lakes of the McMurdo Dry Valleys, Antarctica0 aBiogeochemistry of Nitrous Oxide in Permanently IceCovered Lakes a301-3150 v31 aPriscu, John, C. uhttps://mcm.lternet.edu/content/biogeochemistry-nitrous-oxide-permanently-ice-covered-lakes-mcmurdo-dry-valleys-antarctica00510nas a2200121 4500008004100000245009700041210006900138300001000207490000700217100002400224700002000248856012000268 1997 eng d00aCanada Stream: a glacial meltwater stream in Taylor Valley, South Victoria Land, Antarctica0 aCanada Stream a glacial meltwater stream in Taylor Valley South  a14-170 v161 aMcKnight, Diane, M.1 aTate, Cathy, M. uhttps://mcm.lternet.edu/content/canada-stream-glacial-meltwater-stream-taylor-valley-south-victoria-land-antarctica00531nas a2200145 4500008004100000245007300041210006900114300000800183490000700191100002400198700002300222700002400245700002200269856009400291 1997 eng d00aCarbon cycling in soils of the McMurdo Dry Valley region, Antarctica0 aCarbon cycling in soils of the McMurdo Dry Valley region Antarct a2300 v781 aBurkins, Melody, B.1 aVirginia, Ross, A.1 aFreckman, Diana, W.1 aChamberlain, Page uhttps://mcm.lternet.edu/content/carbon-cycling-soils-mcmurdo-dry-valley-region-antarctica00661nas a2200169 4500008004100000245009900041210006900140260002900209300001200238100002400250700001700274700002400291700001700315700002700332700001500359856011700374 1997 eng d00aCarbon dynamics of aquatic microbial mats in the Antarctic dry valleys: A modelling synthesis0 aCarbon dynamics of aquatic microbial mats in the Antarctic dry v bBalkema Press, Rotterdam a181-1961 aMoorhead, Daryl, L.1 aDavis, Shane1 aWharton, Robert, A.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/carbon-dynamics-aquatic-microbial-mats-antarctic-dry-valleys-modelling-synthesis00811nas a2200217 4500008004100000245012400041210006900165260002900234300001200263100001700275700002400292700001800316700001400334700002300348700001900371700002400390700001700414700002700431700001500458856012000473 1997 eng d00aChemical weathering rates and reactions in the Lake Fryxell Basin, Taylor Valley : Comparison to temperate river basins0 aChemical weathering rates and reactions in the Lake Fryxell Basi bBalkema Press, Rotterdam a147-1541 aLyons, Berry1 aWelch, Kathleen, A.1 aNezat, C., A.1 aCrick, K.1 aToxey, Jeffrey, K.1 aMastrine, J.A.1 aMcKnight, Diane, M.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/chemical-weathering-rates-and-reactions-lake-fryxell-basin-taylor-valley-comparison00670nas a2200181 4500008004100000245009200041210006900133260002900202300001200231100001700243700002200260700002300282700002100305700001700326700002700343700001500370856010300385 1997 eng d00aClimate history of the McMurdo Dry Valleys since the last glacial maximum: A synthesis0 aClimate history of the McMurdo Dry Valleys since the last glacia bBalkema Press, Rotterdam a155-1621 aLyons, Berry1 aBartek, Louis, R.1 aMayewski, Paul, A.1 aDoran, Peter, T.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/climate-history-mcmurdo-dry-valleys-last-glacial-maximum-synthesis00524nas a2200121 4500008004100000245010600041210006900147300001000216490000800226100001900234700002100253856012800274 1997 eng d00aDetection and Characterization of Denitrifying Bacteria from a Permanently Ice-Covered Antarctic Lake0 aDetection and Characterization of Denitrifying Bacteria from a P a57-680 v3471 aWard, Bess, B.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/detection-and-characterization-denitrifying-bacteria-permanently-ice-covered-antarctic-lake00602nas a2200145 4500008004100000245009900041210006900140260003900209300001200248100001400260700001900274700001700293700002400310856012200334 1997 eng d00aDetermination of rare earth elements in Antarctic lakes and streams of varying ionic strengths0 aDetermination of rare earth elements in Antarctic lakes and stre aLondonbRoyal Society of Chemistry a253-2621 aGraham, E1 aRamsey, L., A.1 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/determination-rare-earth-elements-antarctic-lakes-and-streams-varying-ionic-strengths00640nas a2200145 4500008004100000245015200041210006900193300001200262490000700274100002500281700002400306700001900330700002100349856012400370 1997 eng d00aDiatoms in sediments of perennially ice-covered Lake Hoare, and implications for interpreting lake history in the McMurdo Dry Valleys of Antarctica0 aDiatoms in sediments of perennially icecovered Lake Hoare and im a403-4200 v171 aSpaulding, Sarah, A.1 aMcKnight, Diane, M.1 aStoermer, E.F.1 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/diatoms-sediments-perennially-ice-covered-lake-hoare-and-implications-interpreting-lake00801nas a2200217 4500008004100000245015200041210006900193260002700262300001100289490000700300100002500307700002400332700002500356700002000381700002100401700002400422700002000446700002400466700001600490856007700506 1997 eng d00aEcological processes in a cold desert ecosystem: the abundance and species distribution of algal mats in glacial meltwater streams in Taylor Valley0 aEcological processes in a cold desert ecosystem the abundance an bUniversity of Colorado a108 pp0 v511 aAlger, Alexander, S.1 aMcKnight, Diane, M.1 aSpaulding, Sarah, A.1 aTate, Cathy, M.1 aShupe, Gordon, H1 aWelch, Kathleen, A.1 aEdwards, R., L.1 aAndrews, Edmund, D.1 aHouse, H.R. uhttp://instaar.colorado.edu/other/download/OP51-ECOLOGICAL-PROCESSES.pdf00578nas a2200133 4500008004100000245011900041210006900160300001400229490000700243100002400250700002000274700002400294856012600318 1997 eng d00aImpact of Light Regimes on Productivity Patterns of Benthic Microbial Mats in an Antarctic Lake: A Modeling Study0 aImpact of Light Regimes on Productivity Patterns of Benthic Micr a1561-15690 v421 aMoorhead, Daryl, L.1 aWolf, Craig, F.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/impact-light-regimes-productivity-patterns-benthic-microbial-mats-antarctic-lake-modeling00594nas a2200169 4500008004100000245007400041210006900115300001200184490000700196100002400203700002000227700001700247700001800264700001700282700002200299856010300321 1997 eng d00aLinking biodiversity and ecosystem functioning of soils and sediments0 aLinking biodiversity and ecosystem functioning of soils and sedi a556-5620 v261 aFreckman, Diana, W.1 aBlackburn, T.H.1 aBrussaard, L1 aHutchings, P.1 aPalmer, M.A.1 aSnelgrove, P.V.R. uhttps://mcm.lternet.edu/content/linking-biodiversity-and-ecosystem-functioning-soils-and-sediments00369nas a2200121 4500008004100000245004000041210004000081300001400121490000700135100001700142700002400159856006400183 1997 eng d00aLithium in waters of a polar desert0 aLithium in waters of a polar desert a4309-43190 v611 aLyons, Berry1 aWelch, Kathleen, A. uhttps://mcm.lternet.edu/content/lithium-waters-polar-desert00518nas a2200121 4500008004100000245009600041210006900137300001200206490000700218100002400225700002300249856012400272 1997 eng d00aLow-diversity Antarctic soil nematode communities: distribution and response to disturbance0 aLowdiversity Antarctic soil nematode communities distribution an a363-3690 v781 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/low-diversity-antarctic-soil-nematode-communities-distribution-and-response-disturbance00387nas a2200073 4500008004100000245009500041210006900136856010800205 1997 eng d00aThe measurement of reactive silicate in saline-hypersaline lakes: examples of the problem0 ameasurement of reactive silicate in salinehypersaline lakes exam uhttps://mcm.lternet.edu/content/measurement-reactive-silicate-saline-hypersaline-lakes-examples-problem00462nas a2200145 4500008004100000245004200041210003800083260002900121300001200150100002800162700001700190700002700207700001500234856006700249 1997 eng d00aThe microbial loop in Antarctic lakes0 amicrobial loop in Antarctic lakes aRotterdambBalkema Press a231-2401 aLaybourn-Parry, Johanna1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/microbial-loop-antarctic-lakes00675nas a2200169 4500008004100000245011500041210006900156300001000225490000700235100002800242700002000270700002400290700002100314700002500335700001900360856012600379 1997 eng d00aThe microbial plankton of Lake Fryxell, southern Victoria Land, Antarctica during the summers of 1992 and 19940 amicrobial plankton of Lake Fryxell southern Victoria Land Antarc a54-610 v171 aLaybourn-Parry, Johanna1 aJames, Mark, R.1 aMcKnight, Diane, M.1 aPriscu, John, C.1 aSpaulding, Sarah, A.1 aShiel, Russell uhttps://mcm.lternet.edu/content/microbial-plankton-lake-fryxell-southern-victoria-land-antarctica-during-summers-1992-and00806nas a2200253 4500008004100000245008400041210006900125260001200194300001000206490000600216100001900222700001800241700002400259700001800283700001400301700001600315700001700331700001400348700001800362700002400380700001600404700002300420856010900443 1997 eng d00aOpen-top Designs for Manipulating Field Temperature in High-Latitude Ecosystems0 aOpentop Designs for Manipulating Field Temperature in HighLatitu c12/1997 a20-320 v31 aMarion, G., M.1 aHenry, G.H.R.1 aFreckman, Diana, W.1 aJohnstone, J.1 aJones, G.1 aJones, M.H.1 aLevesque, E.1 aMolau, U.1 aMØLGAARD, P.1 aParsons, Andrew, N.1 aSvoboda, J.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/open-top-designs-manipulating-field-temperature-high-latitude-ecosystems00516nas a2200133 4500008004100000245008200041210006900123260001100192300001200203100002000215700001700235700002400252856010600276 1997 eng d00aSatellite-derived surface temperatures in the McMurdo Dry Valleys, Antarctica0 aSatellitederived surface temperatures in the McMurdo Dry Valleys bDeepak a530-5331 aDana, Gayle, L.1 aWetzel, M.A.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/satellite-derived-surface-temperatures-mcmurdo-dry-valleys-antarctica00672nas a2200181 4500008004100000245008800041210006900129260002900198300001200227100002700239700001500266700002400281700002000305700001700325700002700342700001500369856010600384 1997 eng d00aSources and sinks of nutrients in a polar desert stream, the Onyx River, Antarctica0 aSources and sinks of nutrients in a polar desert stream the Onyx aRotterdambBalkema Press a155-1701 aHoward-Williams, Clive1 aHawes, Ian1 aSchwarz, Anne-Maree1 aHall, Julie, A.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/sources-and-sinks-nutrients-polar-desert-stream-onyx-river-antarctica00795nas a2200193 4500008004100000245015600041210006900197260002900266300001200295100002000307700002000327700002400347700001900371700002500390700001700415700002700432700001500459856012700474 1997 eng d00aSpecies composition and primary production of algal communities in Dry Valley streams in Antarctica: Examination of the functional role of biodiversity0 aSpecies composition and primary production of algal communities  bBalkema Press, Rotterdam a171-1791 aNiyogi, Dev, K.1 aTate, Cathy, M.1 aMcKnight, Diane, M.1 aDuff, John, H.1 aAlger, Alexander, S.1 aLyons, Berry1 aHoward-Williams, Clive1 aHawes, Ian uhttps://mcm.lternet.edu/content/species-composition-and-primary-production-algal-communities-dry-valley-streams-antarctica00555nas a2200121 4500008004100000245011700041210006900158260003000227490001000257100002000267700002000287856012600307 1996 eng d00aAlgal investigations at varying temporal scales in an extreme environment: McMurdo Dry Valley lakes, Antarctica0 aAlgal investigations at varying temporal scales in an extreme en bColorado State University0 vPh.D.1 aSpaulding, S.A.1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/algal-investigations-varying-temporal-scales-extreme-environment-mcmurdo-dry-valley-lakes00462nas a2200097 4500008004100000245009000041210006900131100003300200700002100233856011000254 1996 eng d00aBacterial growth in Antarctic lakes: The role of phytoplankton extracellular release0 aBacterial growth in Antarctic lakes The role of phytoplankton ex1 aTakacs-Vesbach, Cristina, D.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/bacterial-growth-antarctic-lakes-role-phytoplankton-extracellular-release00641nas a2200169 4500008004100000245010500041210006900146300001200215490000800227100002400235700001700259700001400276700001900290700002200309700001700331856012300348 1996 eng d00aDetermination of major element chemistry in terrestrial waters from Antarctica by ion chromatography0 aDetermination of major element chemistry in terrestrial waters f a257-2630 v7391 aWelch, Kathleen, A.1 aLyons, Berry1 aGraham, E1 aNeumann, Klaus1 aThomas, James, M.1 aMikesell, D. uhttps://mcm.lternet.edu/content/determination-major-element-chemistry-terrestrial-waters-antarctica-ion-chromatography00532nas a2200133 4500008004100000245009100041210006900132300000800201490000700209100002200216700002400238700002300262856011300285 1996 eng d00aEffects of human disturbance on soil nematode populations in Taylor Valley, Antarctica0 aEffects of human disturbance on soil nematode populations in Tay a3600 v771 aPowers, Laura, E.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/effects-human-disturbance-soil-nematode-populations-taylor-valley-antarctica00347nas a2200085 4500008004100000245005600041210005600097100002500153856008300178 1996 eng d00aEnvironmental Management of a Cold Desert Ecosystem0 aEnvironmental Management of a Cold Desert Ecosystem1 aVincent, Warwick, F. uhttps://mcm.lternet.edu/content/environmental-management-cold-desert-ecosystem00525nas a2200121 4500008004100000245010300041210006900144300001200213490000800225100002300233700002100256856012600277 1996 eng d00aEvolution of Temperature and Salt Structure of Lake Bonney, a Chemically Stratified Antarctic Lake0 aEvolution of Temperature and Salt Structure of Lake Bonney a Che a177-1900 v3211 aSpigel, Robert, H.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/evolution-temperature-and-salt-structure-lake-bonney-chemically-stratified-antarctic-lake00527nas a2200133 4500008004100000245008300041210006900124300001400193490000700207100002100214700002400235700002700259856010700286 1996 eng d00aExtreme Supersaturation of Nitrous Oxide in a Poorly Ventilated Antarctic Lake0 aExtreme Supersaturation of Nitrous Oxide in a Poorly Ventilated  a1544-15510 v411 aPriscu, John, C.1 aDownes, Malcolm, T.1 aMcKay, Christopher, P. uhttps://mcm.lternet.edu/content/extreme-supersaturation-nitrous-oxide-poorly-ventilated-antarctic-lake00428nas a2200133 4500008004100000245004300041210004200084300001200126100001800138700001700156700002400173700002200197856007500219 1996 eng d00aFood-web dynamics and applied problems0 aFoodweb dynamics and applied problems a327-3361 aCrowder, L.B.1 aReagan, D.P.1 aFreckman, Diana, W.1 aWinemiller, Polis uhttps://mcm.lternet.edu/content/food-web-dynamics-and-applied-problems00553nas a2200145 4500008004100000245008300041210006900124300001200193490000700205100002200212700002400234700002500258700002000283856010400303 1996 eng d00aGeochemistry of aquatic humic substances in the Lake Fryxell Basin, Antarctica0 aGeochemistry of aquatic humic substances in the Lake Fryxell Bas a157-1880 v341 aAiken, George, R.1 aMcKnight, Diane, M.1 aHarnish, Richard, A.1 aWershaw, Robert uhttps://mcm.lternet.edu/content/geochemistry-aquatic-humic-substances-lake-fryxell-basin-antarctica00548nas a2200097 4500008004100000245016300041210006900204100002400273700002600297856012700323 1996 eng d00aLakes Hoare, Fryxell and Bonney: Geophysical Determination of Bathymetry and Morphometry, Report Generated by Golder Associates Ltd, Burnaby, British Columbia0 aLakes Hoare Fryxell and Bonney Geophysical Determination of Bath1 aSchmok, Jeffrey, P.1 aWaddington, Brian, S. uhttps://mcm.lternet.edu/content/lakes-hoare-fryxell-and-bonney-geophysical-determination-bathymetry-and-morphometry-report00623nas a2200157 4500008004100000245009800041210006900139300001200208490000700220100002000227700002500247700001800272700002300290700002400313856012800337 1996 eng d00aMicrocosms and Soil Ecology: Critical Linkages Between Field Studies and Modelling Food Webs0 aMicrocosms and Soil Ecology Critical Linkages Between Field Stud a694-7050 v771 aMoore, John, C.1 aDe Ruiter, Peter, C.1 aHunt, William1 aColeman, David, C.1 aFreckman, Diana, W. uhttps://mcm.lternet.edu/content/microcosms-and-soil-ecology-critical-linkages-between-field-studies-and-modelling-food-webs00487nas a2200121 4500008004100000245006700041210006600108260004000174490001000214100002100224700002400245856009600269 1996 eng d00aPaleolimnology of Perenially Ice-Covered Antarctic Oasis Lakes0 aPaleolimnology of Perenially IceCovered Antarctic Oasis Lakes aReno, NVbUniversity of Nevada Reno0 vPh.D.1 aDoran, Peter, T.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/paleolimnology-perenially-ice-covered-antarctic-oasis-lakes00603nas a2200133 4500008004100000245015200041210006900193300001200262490000700274100002500281700002200306700002100328856012000349 1996 eng d00aPhytoplankton Dynamics in the Stratified Water Column of Lake Bonney, Antarctica. I. Biomass and Productivity During the Winter-Spring Transition0 aPhytoplankton Dynamics in the Stratified Water Column of Lake Bo a155-1620 v161 aLizotte, Michael, P.1 aSharp, Thomas, R.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/phytoplankton-dynamics-stratified-water-column-lake-bonney-antarctica-i-biomass-and00741nas a2200193 4500008004100000245014600041210006900187300001200256490000700268100002300275700001500298700001500313700001600328700002000344700002300364700001800387700002400405856011800429 1996 eng d00aReflectance spectroscopy and geochemical analyses of Lake Hoare sediments, Antarctica: Implications for remote sensing of the Earth and Mars0 aReflectance spectroscopy and geochemical analyses of Lake Hoare  a765-7850 v601 aBishop, Janice, L.1 aKoeberl, C1 aKralik, C.1 aFroschl, H.1 aEnglert, P.A.J.1 aAndersen, Dale, T.1 aPieters, C.M.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/reflectance-spectroscopy-and-geochemical-analyses-lake-hoare-sediments-antarctica00519nas a2200145 4500008004100000245005300041210005300094260004900147100001600196700002400212700002400236700001800260700001600278856007900294 1996 eng d00aSoil invertebrates as indicators of soil quality0 aSoil invertebrates as indicators of soil quality aMadison, WIbSoil Science Society of America1 aBlair, J.M.1 aBohlen, Patrick, J.1 aFreckman, Diana, W.1 aDoran, J., W.1 aJones, A.J. uhttps://mcm.lternet.edu/content/soil-invertebrates-indicators-soil-quality00529nas a2200121 4500008004100000245008600041210006900127260004800196490000900244100002600253700002000279856010800299 1996 eng d00aSoil nematode distribution and genetic diversity in the Dry Valleys of Antarctica0 aSoil nematode distribution and genetic diversity in the Dry Vall aFort Collins, CObColorado State University0 vM.S.1 aCourtright, Ericha, M1 aWall, Diana, H. uhttps://mcm.lternet.edu/content/soil-nematode-distribution-and-genetic-diversity-dry-valleys-antarctica00502nas a2200133 4500008004100000245007700041210006900118300000800187490000700195100001600202700002300218700002400241856010300265 1996 eng d00aSoil spatial variation along a toposequence in Taylor Valley, Antarctica0 aSoil spatial variation along a toposequence in Taylor Valley Ant a1970 v771 aHo, Mengchi1 aVirginia, Ross, A.1 aFreckman, Diana, W. uhttps://mcm.lternet.edu/content/soil-spatial-variation-along-toposequence-taylor-valley-antarctica00573nas a2200133 4500008004100000245012200041210006900163300000700232490000700239100002200246700002300268700002200291856012600313 1996 eng d00aSources and distribution of abundance of organic matter in the Dry Valley soils of southern Victoria Land, Antarctica0 aSources and distribution of abundance of organic matter in the D a560 v771 aBrown, Melody, J.1 aVirginia, Ross, A.1 aChamberlain, Page uhttps://mcm.lternet.edu/content/sources-and-distribution-abundance-organic-matter-dry-valley-soils-southern-victoria-land00546nas a2200121 4500008004100000245010400041210006900145260002700214490000900241100002100250700002400271856012900295 1996 eng d00aSurface energy balance and meltwater production for a dry valley glacier, Taylor Valley, Antarctica0 aSurface energy balance and meltwater production for a dry valley bUniversity of Colorado0 vM.S.1 aLewis, Karen, J.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/surface-energy-balance-and-meltwater-production-dry-valley-glacier-taylor-valley-antarctic-000486nas a2200133 4500008004100000245007300041210006900114300000800183490000700191100001700198700002400215700001700239856009600256 1996 eng d00aViruses in antarctic lakes: a first assessment of their distribution0 aViruses in antarctic lakes a first assessment of their distribut a2300 v771 aKepner, R.L.1 aWharton, Robert, A.1 aGalchenko, V uhttps://mcm.lternet.edu/content/viruses-antarctic-lakes-first-assessment-their-distribution00378nas a2200109 4500008004100000245005700041210005400098300000600152490000600158100002100164856008300185 1996 eng d00aA weather network in McMurdo Dry Valleys, Antarctica0 aweather network in McMurdo Dry Valleys Antarctica a30 v71 aDoran, Peter, T. uhttps://mcm.lternet.edu/content/weather-network-mcmurdo-dry-valleys-antarctica00575nas a2200133 4500008004100000245011800041210006900159300001200228490000700240100002200247700002400269700002200293856012600315 1995 eng d00aThe influence of stream channel characteristics on streamflow and annual water budgets for lakes in Taylor Valley0 ainfluence of stream channel characteristics on streamflow and an a284-2870 v301 aHouse, Harold, R.1 aMcKnight, Diane, M.1 aVon Guerard, Paul uhttps://mcm.lternet.edu/content/influence-stream-channel-characteristics-streamflow-and-annual-water-budgets-lakes-taylor00489nas a2200109 4500008004100000245010700041210006900148300001200217490000700229100002400236856011900260 1995 eng d00aMcMurdo Dry Valleys Long-Term Ecological Research (LTER): An overview of 1994-1995 research activities0 aMcMurdo Dry Valleys LongTerm Ecological Research LTER An overvie a275-2760 v301 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-long-term-ecological-research-lter-overview-1994-1995-research00596nas a2200145 4500008004100000245010000041210006900141300001200210490000700222100002100229700002000250700002900270700002400299856012700323 1995 eng d00aMcMurdo Dry Valleys Long-Term Ecological Research (LTER): LTER automatic weather network (LAWN)0 aMcMurdo Dry Valleys LongTerm Ecological Research LTER LTER autom a276-2800 v301 aDoran, Peter, T.1 aDana, Gayle, L.1 aHastings, Jordan, Towner1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-long-term-ecological-research-lter-lter-automatic-weather-network-lawn00539nas a2200121 4500008004100000245012300041210006900164300001200233490000700245100002400252700002000276856012100296 1995 eng d00aMcMurdo LTER: Algal mat distribution in glacial meltwater streams in Taylor Valley, southern Victoria Land, Antarctica0 aMcMurdo LTER Algal mat distribution in glacial meltwater streams a287-2890 v301 aMcKnight, Diane, M.1 aTate, Cathy, M. uhttps://mcm.lternet.edu/content/mcmurdo-lter-algal-mat-distribution-glacial-meltwater-streams-taylor-valley-southern00483nas a2200121 4500008004100000245008600041210006900127300001200196490000700208100002400215700001700239856010500256 1995 eng d00aMcMurdo LTER: Comparative limnology of the Taylor Valley lakes: The major solutes0 aMcMurdo LTER Comparative limnology of the Taylor Valley lakes Th a292-2930 v301 aWelch, Kathleen, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/mcmurdo-lter-comparative-limnology-taylor-valley-lakes-major-solutes00496nas a2200121 4500008004100000245009200041210006900133300001200202490000700214100001500221700002400236856011400260 1995 eng d00aMcMurdo LTER: Photosynthesis in benthic cyanobacterial mats from Lake Hoare, Antarctica0 aMcMurdo LTER Photosynthesis in benthic cyanobacterial mats from  a296-2970 v301 aHawes, Ian1 aSchwarz, Anne-Maree uhttps://mcm.lternet.edu/content/mcmurdo-lter-photosynthesis-benthic-cyanobacterial-mats-lake-hoare-antarctica00450nas a2200109 4500008004100000245008000041210006900121300001200190490000700202100002900209856010200238 1995 eng d00aMcMurdo LTER: Progress with the Taylor Valley geographic information system0 aMcMurdo LTER Progress with the Taylor Valley geographic informat a297-2990 v301 aHastings, Jordan, Towner uhttps://mcm.lternet.edu/content/mcmurdo-lter-progress-taylor-valley-geographic-information-system00564nas a2200121 4500008004100000245014800041210006900189300001200258490000700270100002000277700002100297856012400318 1995 eng d00aMcMurdo LTER: Relationships between vertical nutrient flux and phytoplankton biomass and productivity in lakes of the Taylor Valley, Antarctica0 aMcMurdo LTER Relationships between vertical nutrient flux and ph a294-2950 v301 aEdwards, R., L.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/mcmurdo-lter-relationships-between-vertical-nutrient-flux-and-phytoplankton-biomass-and00616nas a2200145 4500008004100000245013100041210006900172300001200241490000700253100002200260700002400282700001600306700002300322856012500345 1995 eng d00aMcMurdo LTER: Soil properties associated with nematode distribution along an elevational transect in Taylor Valley, Antarctica0 aMcMurdo LTER Soil properties associated with nematode distributi a282-2830 v301 aPowers, Laura, E.1 aFreckman, Diana, W.1 aHo, Mengchi1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/mcmurdo-lter-soil-properties-associated-nematode-distribution-along-elevational-transect00613nas a2200145 4500008004100000245011900041210006900160300001200229490000700241100002500248700002500273700002100298700002400319856012400343 1995 eng d00aMcMurdo LTER: Species composition and spatial distribution of algal mats in Green Creek, Taylor Valley, Antarctica0 aMcMurdo LTER Species composition and spatial distribution of alg a289-2910 v301 aAlger, Alexander, S.1 aSpaulding, Sarah, A.1 aShupe, Gordon, H1 aMcKnight, Diane, M. uhttps://mcm.lternet.edu/content/mcmurdo-lter-species-composition-and-spatial-distribution-algal-mats-green-creek-taylor00544nas a2200145 4500008004100000245008200041210006900123300001200192490000700204100002100211700002000232700002100252700002400273856010100297 1995 eng d00aMcMurdo LTER: The surface-energy balance of the Canada Glacier, Taylor Valley0 aMcMurdo LTER The surfaceenergy balance of the Canada Glacier Tay a280-2820 v301 aLewis, Karen, J.1 aDana, Gayle, L.1 aTyler, Scott, W.1 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/mcmurdo-lter-surface-energy-balance-canada-glacier-taylor-valley00383nas a2200145 4500008004100000245002300041210002300064300001200087490000700099100002400106700001500130700002700145700001300172856005200185 1995 eng d00aPaleolakes on Mars0 aPaleolakes on Mars a267-2830 v131 aWharton, Robert, A.1 aCrosby, J.1 aMcKay, Christopher, P.1 aRice, J. uhttps://mcm.lternet.edu/content/paleolakes-mars00563nas a2200121 4500008004100000245014200041210006900183300001200252490000700264100002300271700002100294856012600315 1995 eng d00aThe Photosynthetic Apparatus of Phytoplankton from a Perennially Ice-Covered Antarctic Lake: Acclimation to an Extreme Shade Environment0 aPhotosynthetic Apparatus of Phytoplankton from a Perennially Ice a253-2630 v361 aNeale, Patrick, J.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/photosynthetic-apparatus-phytoplankton-perennially-ice-covered-antarctic-lake-acclimation00540nas a2200121 4500008004100000245011800041210006900159300001200228490000700240100002100247700002300268856012700291 1995 eng d00aPhototactic response of phytoplankton forming discrete layers within the water column of Lake Bonney , Antarctica0 aPhototactic response of phytoplankton forming discrete layers wi a301-3030 v301 aPriscu, John, C.1 aNeale, Patrick, J. uhttps://mcm.lternet.edu/content/phototactic-response-phytoplankton-forming-discrete-layers-within-water-column-lake-bonney00476nas a2200121 4500008004100000245008600041210006900127300001200196490000700208653001100215100002100226856010700247 1995 eng d00aPhytoplankton Nutrient Deficiency in Lakes of the McMurdo Dry Valleys, Antarctica0 aPhytoplankton Nutrient Deficiency in Lakes of the McMurdo Dry Va a215-2270 v3410alegacy1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/phytoplankton-nutrient-deficiency-lakes-mcmurdo-dry-valleys-antarctica00501nas a2200121 4500008004100000245009300041210006900134300001200203490000700215100002400222700002100246856011200267 1995 eng d00aProfiles of electrode potential and dissolved oxygen in lakes of the McMurdo Dry Valleys0 aProfiles of electrode potential and dissolved oxygen in lakes of a305-3070 v301 aDownes, Malcolm, T.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/profiles-electrode-potential-and-dissolved-oxygen-lakes-mcmurdo-dry-valleys00551nas a2200121 4500008004100000245012300041210006900164300001200233490000700245100003300252700002100285856012300306 1995 eng d00aResponses of bacterial growth to inorganic and organic nutrient enrichment in the lakes of the dry valleys, Antarctica0 aResponses of bacterial growth to inorganic and organic nutrient  a303-3050 v301 aTakacs-Vesbach, Cristina, D.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/responses-bacterial-growth-inorganic-and-organic-nutrient-enrichment-lakes-dry-valleys00550nas a2200145 4500008004100000245008200041210006900123300001200192490000700204100001600211700002300227700002200250700002400272856010800296 1995 eng d00aSoil chemistry along a glacial chronosequence on Andrews Ridge, Taylor Valley0 aSoil chemistry along a glacial chronosequence on Andrews Ridge T a310-3110 v301 aHo, Mengchi1 aVirginia, Ross, A.1 aPowers, Laura, E.1 aFreckman, Diana, W. uhttps://mcm.lternet.edu/content/soil-chemistry-along-glacial-chronosequence-andrews-ridge-taylor-valley00490nas a2200133 4500008004100000245007400041210006900115300001200184490000700196100002200203700002100225700001800246856009200264 1995 eng d00aSome metamorphic processes in the lake ice of the McMurdo Dry Valleys0 aSome metamorphic processes in the lake ice of the McMurdo Dry Va a307-3090 v301 aAdams, Edward, E.1 aPriscu, John, C.1 aSato, Atsushi uhttps://mcm.lternet.edu/content/some-metamorphic-processes-lake-ice-mcmurdo-dry-valleys00503nas a2200133 4500008004100000245007400041210006900115300001200184490000700196100002200203700002400225700002300249856009700272 1995 eng d00aSpatial Distribution of Nematodes in Polar Desert Soils of Antarctica0 aSpatial Distribution of Nematodes in Polar Desert Soils of Antar a325-3330 v151 aPowers, Laura, E.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/spatial-distribution-nematodes-polar-desert-soils-antarctica00655nas a2200133 4500008004100000245017000041210006900211100002200280700002400302700002500326700002000351700002400371856012600395 1995 eng d00aStreamflow, water-temperature, and specific-conductance data for selected streams draining into Lake Fryxell, Lower Taylor Valley, Victoria Land, Antarctica, 1990-920 aStreamflow watertemperature and specificconductance data for sel1 aVon Guerard, Paul1 aMcKnight, Diane, M.1 aHarnish, Richard, A.1 aGartner, J., W.1 aAndrews, Edmund, D. uhttps://mcm.lternet.edu/content/streamflow-water-temperature-and-specific-conductance-data-selected-streams-draining-lake00543nas a2200169 4500008004100000245005500041210005400096260001200150300001400162490000700176653001100183100002400194700002400218700002500242700002200267856008400289 1994 eng d00aAquatic fulvic acids in algal-rich antarctic ponds0 aAquatic fulvic acids in algalrich antarctic ponds c07/1994 a1972-19790 v3910aBiggie1 aMcKnight, Diane, M.1 aAndrews, Edmund, D.1 aSpaulding, Sarah, A.1 aAiken, George, R. uhttps://mcm.lternet.edu/content/aquatic-fulvic-acids-algal-rich-antarctic-ponds00497nas a2200133 4500008004100000245007000041210006900111300001200180490000700192100002200199700002400221700002300245856009500268 1994 eng d00aDepth distribution of soil nematodes in Taylor Valley, Antarctica0 aDepth distribution of soil nematodes in Taylor Valley Antarctica a175-1760 v291 aPowers, Laura, E.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/depth-distribution-soil-nematodes-taylor-valley-antarctica00600nas a2200157 4500008004100000245008800041210006900129260001200198300001600210490000700226100002700233700001900260700002300279700002400302856011600326 1994 eng d00aLight transmission and reflection in perennially ice-covered Lake Hoare, Antarctica0 aLight transmission and reflection in perennially icecovered Lake c06/1994 a20427-204440 v991 aMcKay, Christopher, P.1 aClow, Gary, D.1 aAndersen, Dale, T.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/light-transmission-and-reflection-perennially-ice-covered-lake-hoare-antarctica00439nas a2200109 4500008004100000245007600041210006900117300001200186490000700198100002400205856010000229 1994 eng d00aMcMurdo Dry Valleys LTER: An overview of 1993-1994 research activities0 aMcMurdo Dry Valleys LTER An overview of 19931994 research activi a224-2260 v291 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-dry-valleys-lter-overview-1993-1994-research-activities00478nas a2200121 4500008004100000245007500041210006900116300001200185490000700197100002900204700001900233856010400252 1994 eng d00aMcMurdo LTER: Developing a geographic information system access system0 aMcMurdo LTER Developing a geographic information system access s a246-2470 v291 aHastings, Jordan, Towner1 aButt, Anya, Z. uhttps://mcm.lternet.edu/content/mcmurdo-lter-developing-geographic-information-system-access-system00468nas a2200121 4500008004100000245007000041210006900111300001200180490000700192100001900199700002900218856009900247 1994 eng d00aMcMurdo LTER: Developing a geographic information system database0 aMcMurdo LTER Developing a geographic information system database a244-2450 v291 aButt, Anya, Z.1 aHastings, Jordan, Towner uhttps://mcm.lternet.edu/content/mcmurdo-lter-developing-geographic-information-system-database00492nas a2200133 4500008004100000245006900041210006700110300001200177490000700189100002400196700002200220700002000242856009600262 1994 eng d00aMcMurdo LTER: Glacier mass balances of Taylor Valley, Antarctica0 aMcMurdo LTER Glacier mass balances of Taylor Valley Antarctica a226-2280 v291 aFountain, Andrew, G1 aVaughn, Bruce, H.1 aDana, Gayle, L. uhttps://mcm.lternet.edu/content/mcmurdo-lter-glacier-mass-balances-taylor-valley-antarctica00688nas a2200181 4500008004100000245010100041210006900142300001200211490000700223100002400230700001700254700002100271700002000292700002400312700002200336700002400358856012400382 1994 eng d00aMcMurdo LTER: Inorganic geochemical studies with special reference to calcium carbonate dynamics0 aMcMurdo LTER Inorganic geochemical studies with special referenc a237-2390 v291 aWelch, Kathleen, A.1 aLyons, Berry1 aPriscu, John, C.1 aEdwards, R., L.1 aMcKnight, Diane, M.1 aHouse, Harold, R.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-lter-inorganic-geochemical-studies-special-reference-calcium-carbonate-dynamics00506nas a2200145 4500008004100000245006200041210006000103300001200163490000700175100002100182700002400203700002500227700001900252856008900271 1994 eng d00aMcMurdo LTER: Paleolimnology of Taylor Valley, Antarctica0 aMcMurdo LTER Paleolimnology of Taylor Valley Antarctica a234-2370 v291 aDoran, Peter, T.1 aWharton, Robert, A.1 aSpaulding, Sarah, A.1 aFoster, J., S. uhttps://mcm.lternet.edu/content/mcmurdo-lter-paleolimnology-taylor-valley-antarctica00468nas a2200109 4500008004100000245009400041210006900135300001200204490000700216100002100223856011400244 1994 eng d00aMcMurdo LTER: Phytoplankton nutrient deficiency in lakes of the Taylor Valley, Antarctica0 aMcMurdo LTER Phytoplankton nutrient deficiency in lakes of the T a239-2410 v291 aPriscu, John, C. uhttps://mcm.lternet.edu/content/mcmurdo-lter-phytoplankton-nutrient-deficiency-lakes-taylor-valley-antarctica00513nas a2200121 4500008004100000245009500041210006900136300001200205490000700217100002400224700002400248856011900272 1994 eng d00aMcMurdo LTER: Primary production model of benthic microbial mats in Lake Hoare, Antarctica0 aMcMurdo LTER Primary production model of benthic microbial mats  a241-2430 v291 aMoorhead, Daryl, L.1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/mcmurdo-lter-primary-production-model-benthic-microbial-mats-lake-hoare-antarctica00465nas a2200133 4500008004100000245005900041210005800100300001200158490000700170100002400177700002200201700002100223856008700244 1994 eng d00aMcMurdo LTER: Streamflow Measurements in Taylor Valley0 aMcMurdo LTER Streamflow Measurements in Taylor Valley a230-2320 v291 aMcKnight, Diane, M.1 aHouse, Harold, R.1 aVon Gerard, Paul uhttps://mcm.lternet.edu/content/mcmurdo-lter-streamflow-measurements-taylor-valley00562nas a2200133 4500008004100000245011400041210006900155300001200224490000700236100002000243700002000263700002200283856012300305 1994 eng d00aMcMurdo LTER: Using narrow band spectroradiometry to assess algal and moss communities in a dry valley stream0 aMcMurdo LTER Using narrow band spectroradiometry to assess algal a232-2340 v291 aDana, Gayle, L.1 aTate, Cathy, M.1 aDewey, Sharon, L. uhttps://mcm.lternet.edu/content/mcmurdo-lter-using-narrow-band-spectroradiometry-assess-algal-and-moss-communities-dry00587nas a2200145 4500008004100000245010700041210006900148300001200217490000700229100002200236700002400258700001600282700002300298856012000321 1994 eng d00aMcMurdo LTER:Soil and nematode distribution along an elevational gradient in Taylor Valley, Antarctica0 aMcMurdo LTERSoil and nematode distribution along an elevational  a228-2290 v291 aPowers, Laura, E.1 aFreckman, Diana, W.1 aHo, Mengchi1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/mcmurdo-ltersoil-and-nematode-distribution-along-elevational-gradient-taylor-valley00545nas a2200121 4500008004100000245011800041210006900159300001400228490000700242100002500249700002100274856012800295 1994 eng d00aNatural Fluorescence and Quantum Yields in Vertically Stationary Phytoplankton from Perennially Ice-Covered Lakes0 aNatural Fluorescence and Quantum Yields in Vertically Stationary a1399-14100 v391 aLizotte, Michael, P.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/natural-fluorescence-and-quantum-yields-vertically-stationary-phytoplankton-perennially-ice00544nas a2200145 4500008004100000245008200041210006900123300000800192490000700200653001100207100002200218700002400240700002300264856011100287 1994 eng d00aNematode biodiversity and community structure in Antarctic Polar Desert Soils0 aNematode biodiversity and community structure in Antarctic Polar a1860 v7510aBiggie1 aPowers, Laura, E.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematode-biodiversity-and-community-structure-antarctic-polar-desert-soils00486nas a2200121 4500008004100000245006900041210006900110260001800179100002400197700002300221700002200244856009800266 1994 eng d00aNematode biodiversity and survival in Antarctic Dry Valley soils0 aNematode biodiversity and survival in Antarctic Dry Valley soils aVenice, Italy1 aFreckman, Diana, W.1 aVirginia, Ross, A.1 aPowers, Laura, E. uhttps://mcm.lternet.edu/content/nematode-biodiversity-and-survival-antarctic-dry-valley-soils00452nas a2200133 4500008004100000245005800041210005700099300001100156490000700167100002100174700002400195700001700219856008200236 1994 eng d00aPaleolimnology of the McMurdo Dry Valleys, Antarctica0 aPaleolimnology of the McMurdo Dry Valleys Antarctica a85-1140 v101 aDoran, Peter, T.1 aWharton, Robert, A.1 aLyons, Berry uhttps://mcm.lternet.edu/content/paleolimnology-mcmurdo-dry-valleys-antarctica00576nas a2200145 4500008004100000245009000041210006900131300001200200490000700212100002500219700002400244700002300268700002100291856011800312 1994 eng d00aPhytoplankton population dynamics in perennially ice-covered Lake Fryxell, Antarctica0 aPhytoplankton population dynamics in perennially icecovered Lake a527-5410 v161 aSpaulding, Sarah, A.1 aMcKnight, Diane, M.1 aSmith, Richard, L.1 aDufford, Richard uhttps://mcm.lternet.edu/content/phytoplankton-population-dynamics-perennially-ice-covered-lake-fryxell-antarctica00402nas a2200121 4500008004100000245004100041210004100082260002400123100002400147700002500171700001400196856007000210 1994 eng d00aStromatolite mats in Antarctic lakes0 aStromatolite mats in Antarctic lakes bKluwer, Netherlands1 aWharton, Robert, A.1 aBertrand-Sarfati, J.1 aMonty, C. uhttps://mcm.lternet.edu/content/stromatolite-mats-antarctic-lakes00456nas a2200109 4500008004100000245006900041210006900110100002200179700002400201700002300225856009800248 1994 eng d00aSurvival of Scottnema lindsayae under extreme osmotic conditions0 aSurvival of Scottnema lindsayae under extreme osmotic conditions1 aPowers, Laura, E.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/survival-scottnema-lindsayae-under-extreme-osmotic-conditions00438nas a2200109 4500008004100000245007400041210006900115300001400184490000700198100002100205856010200226 1993 eng d00aBook Review: Physical and biogeochemical processes in Antarctic lakes0 aBook Review Physical and biogeochemical processes in Antarctic l a1499-15000 v391 aPriscu, John, C. uhttps://mcm.lternet.edu/content/book-review-physical-and-biogeochemical-processes-antarctic-lakes00696nas a2200157 4500008004100000245017100041210006900212300001200281490000700293100002400300700002200324700002400346700001900370700002500389856012400414 1993 eng d00aDissolved Organic Material in Dry Valley Lakes: A Comparison of Lake Fryxell, Lake Hoare, and Lake Vanda, in Physical and Biogeochemical Processes in Antarctic Lakes0 aDissolved Organic Material in Dry Valley Lakes A Comparison of L a119-1330 v591 aMcKnight, Diane, M.1 aAiken, George, R.1 aAndrews, Edmund, D.1 aBowles, E., C.1 aHarnish, Richard, A. uhttps://mcm.lternet.edu/content/dissolved-organic-material-dry-valley-lakes-comparison-lake-fryxell-lake-hoare-and-lake00422nas a2200121 4500008004100000245005900041210005500100300001000155490000700165100002400172700002300196856008100219 1993 eng d00aThe ecology of nematodes in Antarctic Dry Valley soils0 aecology of nematodes in Antarctic Dry Valley soils a10-110 v281 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/ecology-nematodes-antarctic-dry-valley-soils00593nas a2200133 4500008004100000245014300041210006900184300001200253490000700265100002400272700001800296700002400314856012100338 1993 eng d00aEnvironmental regulators of microbial activity in continental antarctic lakes, in Physical and Biogeochemical Processes in Antarctic Lakes0 aEnvironmental regulators of microbial activity in continental an a165-1950 v591 aSimmons, George, M.1 aVestal, Robie1 aWharton, Robert, A. uhttps://mcm.lternet.edu/content/environmental-regulators-microbial-activity-continental-antarctic-lakes-physical-and00433nas a2200121 4500008004100000245006000041210006000101300001200161490000700173100002400180700002300204856008400227 1993 eng d00aExtraction of nematodes from Dry Valley Antarctic soils0 aExtraction of nematodes from Dry Valley Antarctic soils a483-4870 v131 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/extraction-nematodes-dry-valley-antarctic-soils00588nas a2200121 4500008004100000245016800041210006900209300001200278490000700290100001700297700002300314856012900337 1993 eng d00aThe geochemical evolution of terrestrial waters in the antarctic: the role of rock-water interactions, in Physical and Biogeochemical Processes in Antarctic Lakes0 ageochemical evolution of terrestrial waters in the antarctic the a135-1430 v591 aLyons, Berry1 aMayewski, Paul, A. uhttps://mcm.lternet.edu/content/geochemical-evolution-terrestrial-waters-antarctic-role-rock-water-interactions-physical-and00582nas a2200133 4500008004100000245012100041210006900162300001200231490000700243100002600250700002100276700003000297856012100327 1993 eng d00aInfluence of high salinity levels on ambient inorganic nitrogen and nitrogen-15 extraction efficiency in Lake Bonney0 aInfluence of high salinity levels on ambient inorganic nitrogen  a245-2460 v281 aBartlett, Richard, D.1 aPriscu, John, C.1 aWoolston, Christopher, D. uhttps://mcm.lternet.edu/content/influence-high-salinity-levels-ambient-inorganic-nitrogen-and-nitrogen-15-extraction00542nas a2200133 4500008004100000245009500041210006900136300001200205490000700217100001700224700002400241700002300265856012000288 1993 eng d00aLife Cycle of the Microbivorous Antarctic Dry Valley Nematode Scottnema lindsaye Timm 19710 aLife Cycle of the Microbivorous Antarctic Dry Valley Nematode Sc a151-1560 v131 aOverhoff, A.1 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/life-cycle-microbivorous-antarctic-dry-valley-nematode-scottnema-lindsaye-timm-197100549nas a2200121 4500008004100000245013900041210006900180300001200249490000700261100001900268700002100287856011900308 1993 eng d00aMicrobial communities in the permanent ice cap of Lake Bonney, Antarctica: Relationships among chlorophyll-a , gravel, and nutrients.0 aMicrobial communities in the permanent ice cap of Lake Bonney An a247-2490 v281 aWing, Kate, T.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/microbial-communities-permanent-ice-cap-lake-bonney-antarctica-relationships-among00508nas a2200121 4500008004100000245009400041210006900135300001200204490000700216100002100223700002100244856012100265 1993 eng d00aMicrobial respiration potential in Lake Bonney using a novel tetrazolium-reduction method0 aMicrobial respiration potential in Lake Bonney using a novel tet a244-2450 v281 aSmith, James, J.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/microbial-respiration-potential-lake-bonney-using-novel-tetrazolium-reduction-method00451nas a2200133 4500008004100000245005600041210005600097300001200153490000700165100001900172700002000191700002100211856008500232 1993 eng d00aNitrifying and denitrifying bacteria in Lake Bonney0 aNitrifying and denitrifying bacteria in Lake Bonney a239-2410 v281 aWard, Bess, B.1 aCockcroft, A.R.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/nitrifying-and-denitrifying-bacteria-lake-bonney00617nas a2200145 4500008004100000245013500041210006900176300001000245490000700255100002400262700002700286700001900313700002300332856011600355 1993 eng d00aPerennial ice covers and their influence on antarctic lake ecosystems, in Physical and Biogeochemical Processes in Antarctic Lakes0 aPerennial ice covers and their influence on antarctic lake ecosy a53-700 v591 aWharton, Robert, A.1 aMcKay, Christopher, P.1 aClow, Gary, D.1 aAndersen, Dale, T. uhttps://mcm.lternet.edu/content/perennial-ice-covers-and-their-influence-antarctic-lake-ecosystems-physical-and00517nas a2200121 4500008004100000245009700041210006900138300001200207490000700219100003000226700002100256856011800277 1993 eng d00aPhytoplankton utilization of ammonium and nitrate in Lake Bonney: A preliminary assessment.0 aPhytoplankton utilization of ammonium and nitrate in Lake Bonney a241-2430 v281 aWoolston, Christopher, D.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/phytoplankton-utilization-ammonium-and-nitrate-lake-bonney-preliminary-assessment00546nas a2200121 4500008004100000245012000041210006900161300001200230490000700242100002400249700002400273856012700297 1993 eng d00aPotential hydrologic and geochemical consequences of the 1992 merging of Lake Chad with Lake Hoare in Taylor Valley0 aPotential hydrologic and geochemical consequences of the 1992 me a249-2510 v281 aMcKnight, Diane, M.1 aAndrews, Edmund, D. uhttps://mcm.lternet.edu/content/potential-hydrologic-and-geochemical-consequences-1992-merging-lake-chad-lake-hoare-taylor00557nas a2200133 4500008004100000245010300041210006900144300001200213490000800225100002400233700001700257700002200274856012700296 1993 eng d00aStable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake0 aStable isotopic biogeochemistry of carbon and nitrogen in a pere a159-1720 v1071 aWharton, Robert, A.1 aLyons, Berry1 aMarais, D.J., Des uhttps://mcm.lternet.edu/content/stable-isotopic-biogeochemistry-carbon-and-nitrogen-perennially-ice-covered-antarctic-lake00549nas a2200157 4500008004100000020001800041245006800059210006800127260001000195300001000205490000700215100002400222700002400246700002400270856009700294 1993 eng d a978087590830400aTerrigenous clastic sedimentation in antarctic dry valley lakes0 aTerrigenous clastic sedimentation in antarctic dry valley lakes bWiley a71-810 v591 aAndersen, David, W.1 aWharton, Robert, A.1 aSquyres, Steven, W. uhttps://mcm.lternet.edu/content/terrigenous-clastic-sedimentation-antarctic-dry-valley-lakes00554nas a2200133 4500008004100000245010200041210006900143300001200212490000700224100002100231700001900252700002400271856012500295 1993 eng d00aWater column transformations of nitrogen in Lake Bonney, a perennially ice-covered antarctic lake0 aWater column transformations of nitrogen in Lake Bonney a perenn a237-2390 v281 aPriscu, John, C.1 aWard, Bess, B.1 aDownes, Malcolm, T. uhttps://mcm.lternet.edu/content/water-column-transformations-nitrogen-lake-bonney-perennially-ice-covered-antarctic-lake00497nas a2200121 4500008004100000245009100041210006900132300000800201490000700209100002400216700002300240856011200263 1992 eng d00aNematodes and soil properties in the Dry Valleys of southern Victoria Land, Antarctica0 aNematodes and soil properties in the Dry Valleys of southern Vic a1790 v731 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematodes-and-soil-properties-dry-valleys-southern-victoria-land-antarctica00468nas a2200121 4500008004100000245007300041210006900114300000800183490000700191100002400198700002300222856010100245 1992 eng d00aNematodes in Antarctic Dry Valley soils: extraction and distribution0 aNematodes in Antarctic Dry Valley soils extraction and distribut a5910 v241 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematodes-antarctic-dry-valley-soils-extraction-and-distribution00579nas a2200121 4500008004100000245016100041210006900202300001200271490000700283100002500290700002100315856012100336 1992 eng d00aPhotosynthesis-Irradiance Relationships in Phytoplankton From the Physically Stable Water Column of a Perennially Ice-Covered Lake (Lake Bonney, Antarctica)0 aPhotosynthesisIrradiance Relationships in Phytoplankton From the a179-1850 v281 aLizotte, Michael, P.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/photosynthesis-irradiance-relationships-phytoplankton-physically-stable-water-column00550nas a2200121 4500008004100000245013100041210006900172300000900241490000700250100002500257700002100282856012500303 1992 eng d00aSpectral Irradiance and Bio-Optical Properties in Perennially Ice-Covered Lakes of the Dry Valleys (McMurdo Sound, Antarctica)0 aSpectral Irradiance and BioOptical Properties in Perennially Ice a1-140 v571 aLizotte, Michael, P.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/spectral-irradiance-and-bio-optical-properties-perennially-ice-covered-lakes-dry-valleys00340nas a2200097 4500008004100000245004900041210004800090260001200138100002400150856006800174 1991 eng d00aMcMurdo Dry Valleys: A cold desert ecosystem0 aMcMurdo Dry Valleys A cold desert ecosystem c10/19911 aWharton, Robert, A. uhttps://mcm.lternet.edu/sites/default/files/MCM_1991_Report.pdf00452nas a2200121 4500008004100000245006700041210006700108300001200175490000700187100002400194700002300218856008900241 1991 eng d00aNematodes in the McMurdo Dry Valleys of Southern Victoria Land0 aNematodes in the McMurdo Dry Valleys of Southern Victoria Land a233-2340 v261 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematodes-mcmurdo-dry-valleys-southern-victoria-land00513nas a2200121 4500008004100000245010000041210006900141300001000210490000800220100002200228700002100250856012000271 1990 eng d00aDevelopment and Application of a Technique for Estimating Nutrient Deficiency in Soft Sediments0 aDevelopment and Application of a Technique for Estimating Nutrie a93-970 v2031 aDodds, Walter, K.1 aPriscu, John, C. uhttps://mcm.lternet.edu/content/development-and-application-technique-estimating-nutrient-deficiency-soft-sediments00315nas a2200097 4500008004100000245004000041210004000081490000700121100002400128856006500152 1990 eng d00aGlaciers of the southern hemisphere0 aGlaciers of the southern hemisphere0 v221 aFountain, Andrew, G uhttps://mcm.lternet.edu/content/glaciers-southern-hemisphere00428nas a2200121 4500008004100000245005800041210005800099300001200157490000700169100002400176700002300200856008300223 1990 eng d00aNematode Ecology of the McMurdo Dry Valley Ecosystems0 aNematode Ecology of the McMurdo Dry Valley Ecosystems a229-2300 v251 aFreckman, Diana, W.1 aVirginia, Ross, A. uhttps://mcm.lternet.edu/content/nematode-ecology-mcmurdo-dry-valley-ecosystems00573nas a2200133 4500008004100000245011000041210006900151300001200220490000700232100002100239700002500260700002700285856012700312 1989 eng d00aInorganic Nitrogen Uptake and Regeneration in Perennially Ice-Covered Lakes Fryxell and Vanda, Antarctica0 aInorganic Nitrogen Uptake and Regeneration in Perennially IceCov a335-3510 v111 aPriscu, John, C.1 aVincent, Warwick, F.1 aHoward-Williams, Clive uhttps://mcm.lternet.edu/content/inorganic-nitrogen-uptake-and-regeneration-perennially-ice-covered-lakes-fryxell-and-vanda00496nas a2200109 4500008004100000245011400041210006900155300001200224490000800236100002100244856012100265 1989 eng d00aPhoton Dependence of Inorganic Nitrogen Transport by Phytoplankton in Perennially Ice-Covered Antarctic Lakes0 aPhoton Dependence of Inorganic Nitrogen Transport by Phytoplankt a173-1820 v1721 aPriscu, John, C. uhttps://mcm.lternet.edu/content/photon-dependence-inorganic-nitrogen-transport-phytoplankton-perennially-ice-covered00594nas a2200145 4500008004100000245010500041210006900146300001200215490000600227100002100233700002400254700002200278700002800300856012000328 1989 eng d00aTemperature Dependence of Inorganic Nitrogen Uptake and Assimilation in Antarctic Sea-Ice Microalgae0 aTemperature Dependence of Inorganic Nitrogen Uptake and Assimila a443-4460 v91 aPriscu, John, C.1 aPalmisano, Anna, C.1 aPriscu, Linda, R.1 aSullivan, Cornelius, W. uhttps://mcm.lternet.edu/content/temperature-dependence-inorganic-nitrogen-uptake-and-assimilation-antarctic-sea-ice00629nas a2200145 4500008004100000245013400041210006900175300001200244490000700256100002100263700002200284700002700306700002500333856012500358 1988 eng d00aDiel Patterns of Photosynthate Biosynthesis by Phytoplankton in Permanently Ice-Covered Antarctic Lakes Under Continuous Sunlight0 aDiel Patterns of Photosynthate Biosynthesis by Phytoplankton in  a333-3400 v101 aPriscu, John, C.1 aPriscu, Linda, R.1 aHoward-Williams, Clive1 aVincent, Warwick, F. uhttps://mcm.lternet.edu/content/diel-patterns-photosynthate-biosynthesis-phytoplankton-permanently-ice-covered-antarctic00592nas a2200145 4500008004100000245009800041210006900139300001200208490000700220100002100227700002200248700002500270700002700295856012400322 1987 eng d00aPhotosynthate Distribution by Microplankton in Permanently Ice-Covered Antarctic Desert Lakes0 aPhotosynthate Distribution by Microplankton in Permanently IceCo a260-2700 v321 aPriscu, John, C.1 aPriscu, Linda, R.1 aVincent, Warwick, F.1 aHoward-Williams, Clive uhttps://mcm.lternet.edu/content/photosynthate-distribution-microplankton-permanently-ice-covered-antarctic-desert-lakes