02394nas 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.7003503255nas 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/S266601722400004X02111nas 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/10.1080/01431161.2021.198155901860nas 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/lol2.1020002597nas 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/full02051nas 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/8576F6BB1BCFDCA8409F5EA96CA00C6F02723nas 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/full00851nas 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/s41559-017-0253-002500nas 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.0369002451nas 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-y00939nas 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.html00637nas 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/S030438001400491800643nas 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-mountains