@article {4868, title = {An Antarctic worm and its soil ecosystem: A review of an emerging research program in ecological genomics}, journal = {Applied Soil Ecology}, volume = {193}, year = {2024}, month = {01/2024}, pages = {105110}, abstract = {

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.

}, keywords = {LTER-MCM, ecological amplitude, ecological succession, elemental stoichiometry, extreme environments, life history evolution, model systems}, issn = {09291393}, doi = {10.1016/j.apsoil.2023.105110}, url = {https://www.sciencedirect.com/science/article/pii/S0929139323003086}, author = {Xue, Xia and Thompson, Andrew R. and Adams, Byron J.} } @article {4929, title = {The application and modification of WRF-Hydro/Glacier to a cold-based Antarctic glacier}, journal = {Hydrology and Earth System Sciences}, volume = {28}, year = {2024}, month = {02/2024}, pages = {459 - 478}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/hess-28-459-2024}, url = {https://hess.copernicus.org/articles/28/459/2024/}, author = {Pletzer, Tamara and Conway, Jonathan P. and Cullen, Nicolas J. and Eidhammer, Trude and Katurji, Marwan} } @article {4938, title = {Brief communication: Significant biases in ERA5 output for the McMurdo Dry Valleys region, Antarctica}, journal = {The Cryosphere}, volume = {18}, year = {2024}, month = {03/2024}, pages = {1207 - 1213}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-18-1207-2024}, url = {https://tc.copernicus.org/articles/18/1207/2024}, author = {Garza-Gir{\'o}n, Ricardo and Tulaczyk, Slawek M.} } @article {4939, title = {Detectability of surface biosignatures for directly imaged rocky exoplanets}, journal = {Astrobiology}, volume = {24}, year = {2024}, month = {03/2024}, pages = {283 - 299}, abstract = {

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.

}, keywords = {LTER-MCM, extremophiles, false positive, pigments, red edge, reflectance spectroscopy, telescope}, issn = {1531-1074}, doi = {10.1089/ast.2023.0099}, url = {https://www.liebertpub.com/doi/10.1089/ast.2023.0099}, author = {Borges, Schuyler R. and Jones, Gabrielle G. and Robinson, Tyler D.} } @article {4926, title = {Long days and long nights: An integrative study reveals survival strategies of an Antarctic diatom during the cold and dark polar winter}, journal = {New Phytologist}, year = {2024}, month = {01/2024}, abstract = {

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.

}, keywords = {LTER-MCM, aquatic habitats, circadian cycle, light environments, phytoplankton, polar}, issn = {0028-646X}, doi = {10.1111/nph.19536}, url = {https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19536}, author = {Rachael M. Morgan-Kiss} } @article {4928, title = {Remotely characterizing photosynthetic biocrust in snowpack-fed microhabitats of Taylor Valley, Antarctica}, journal = {Science of Remote Sensing}, year = {2024}, month = {02/2024}, pages = {100120}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, biocrust, carbon, reflectance spectroscopy, snow, soil ecology}, issn = {26660172}, doi = {10.1016/j.srs.2024.100120}, url = {https://www.sciencedirect.com/science/article/pii/S266601722400004X}, author = {Power, Sarah N. and Salvatore, Mark R. and Eric R. Sokol and Lee F. Stanish and Borges, Schuyler R. and Byron Adams and John E. Barrett} } @article {4935, title = {Sentinel protist taxa of the McMurdo Dry Valley lakes, Antarctica: A review}, journal = {Frontiers in Ecology and Evolution}, volume = {12}, year = {2024}, month = {03/2024}, pages = {1323472}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Disturbance, McMurdo Dry Valley lakes, phytoplankton, protist}, doi = {10.3389/fevo.2024.1323472}, url = {https://www.frontiersin.org/articles/10.3389/fevo.2024.1323472}, author = {Rachael M. Morgan-Kiss and Popson, Devon and Pereira, Rochelle and Dolhi-Binder, J and Teufel, Amber G. and Li, Wei and Kalra, Isha and Sherwell, Shasten S. and Reynebeau, Emily and Cristina D. Takacs-Vesbach} } @article {4855, title = {Better together? The values, obstacles, opportunities, and prospects for collaborative research in environmental history}, journal = {Environmental History}, volume = {28}, year = {2023}, month = {04/2023}, pages = {269 - 299}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {1084-5453}, doi = {10.1086/723784}, url = {https://www.journals.uchicago.edu/doi/full/10.1086/723784}, author = {Alagona, Peter and Carey, Mark and Howkins, Adrian} } @article {4842, title = {Biogeography and genetic diversity of terrestrial mites in the Ross Sea region, Antarctica}, journal = {Genes}, volume = {14}, year = {2023}, month = {03/2023}, pages = {606}, abstract = {

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.

}, keywords = {LTER-MCM, Acari, Antarctic conservation, DNA barcoding, geographic isolation, speciation}, doi = {10.3390/genes14030606}, url = {https://www.mdpi.com/2073-4425/14/3/606}, author = {Gemma E. Collins and Young, Monica R. and Peter Convey and Steven L. Chown and Craig S Cary and Byron Adams and Diana H. Wall and Hogg, Ian D.} } @article {4844, title = {Causes and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {128}, year = {2023}, month = {02/2023}, pages = {e2022JF006696}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM, active layer, airborne electromagnetic surveys, McMurdo Dry Valleys, permafrost dynamics}, issn = {2169-9003}, doi = {10.1029/2022JF006696}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006696}, author = {Gutterman, William S. and Peter T. Doran and Ross A. Virginia and John E. Barrett and Myers, Krista F. and Tulaczyk, Slawek M. and Foley, Neil T. and Jill A. Mikucki and Hilary A. Dugan and Grombacher, Denys and Bording, Thue S. and Auken, E.} } @article {4856, title = {Differentiating physical and biological storage of nitrogen along an intermittent Antarctic stream corridor}, journal = {Freshwater Science}, volume = {42}, year = {2023}, month = {09/2023}, abstract = {

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.

}, keywords = {LTER-MCM, hyporheic zone, McMurdo LTER, nitrogen cycling, nutrient budget, organic matter, periphyton}, issn = {2161-9549}, doi = {10.1086/725676}, url = {https://www.journals.uchicago.edu/doi/10.1086/725676}, author = {Singley, Joel G. and Salvatore, Mark R. and Michael N. Gooseff and Diane M. McKnight and Eve-Lyn S. Hinckley} } @article {4833, title = {Ecological stoichiometry drives the evolution of soil nematode life history traits}, journal = {Soil Biology and Biochemistry}, volume = {177}, year = {2023}, month = {02/2023}, pages = {108891}, abstract = {

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.

}, keywords = {LTER-MCM, elemental stoichiometry, growth rate hypothesis, life history theory, molecular evolution, nematoda, rRNA}, doi = {10.1016/j.soilbio.2022.108891}, url = {https://www.sciencedirect.com/science/article/pii/S0038071722003480}, author = {Xue, Xia and Bishwo N. Adhikari and Ball, Becky and John E. Barrett and Miao, Jinxin and Perkes, Ammon and Martin, Mac and Breana L. Simmons and Diana H. Wall and Byron Adams} } @article {4843, title = {Extreme cold (-69.1{\textdegree}C) in the McMurdo Dry Valleys}, journal = {Antarctic Science}, volume = {30}, year = {2023}, month = {03/2023}, pages = {1-4}, keywords = {LTER-MCM, climate, extreme, meteorology, temperature, weather}, issn = {0954-1020}, doi = {10.1017/S0954102022000451}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/extreme-cold-691c-in-the-mcmurdo-dry-valleys/3516874750E5EF96365A26E8D49CA4EC}, author = {Peter T. Doran and Myers, Krista F. and Christopher P. McKay and David Bromwich} } @article {4937, title = {High salt-induced PSI-supercomplex is associated with high CEF and attenuation of state transitions}, journal = {Photosynthesis Research}, volume = {157}, year = {2023}, month = {09/2023}, pages = {65 - 84}, abstract = {

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.

}, keywords = {LTER-MCM, acclimation, Antarctica, Chlamydomonas, Cyclic electron flow, PSI-supercomplex, salinity, state transitions}, issn = {0166-8595}, doi = {10.1007/s11120-023-01032-y}, url = {https://link.springer.com/10.1007/s11120-023-01032-y}, author = {Kalra, Isha and Wang, Xin and Zhang, Ru and Rachael M. Morgan-Kiss} } @article {4839, title = {Impact of meltwater flow intensity on the spatiotemporal heterogeneity of microbial mats in the McMurdo Dry Valleys, Antarctica}, journal = {ISME Communications}, volume = {3}, year = {2023}, month = {01/2023}, pages = {3}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s43705-022-00202-8}, url = {https://www.nature.com/articles/s43705-022-00202-8}, author = {Zoumplis, Angela and Kolody, Bethany C. and Kaul, Drishti and Zheng, Hong and Venepally, Pratap and Diane M. McKnight and Cristina D. Takacs-Vesbach and DeVries, Arthur L. and Allen, Andrew E.} } @mastersthesis {4863, title = {Influence of landscape-variation in geochemistry on taxonomic and functional composition of microbial mat communities in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2023}, school = {Virginia Tech}, type = {masters}, address = {Blacksburg, VA}, abstract = {

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.

}, keywords = {LTER-MCM, carbon, microbial community, microbial mat, nitrogen, phosphorus, polar desert, soil}, url = {http://hdl.handle.net/10919/115384}, author = {Risteca, Paul J.}, editor = {John E. Barrett} } @article {4867, title = {Long-term changes in concentration and yield of riverine dissolved silicon from the poles to the tropics}, journal = {Global Biogeochemical Cycles}, year = {2023}, month = {08/2023}, abstract = {

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.

}, keywords = {LTER-MCM, biogeochemistry, river, silica, silicon, stream, trends}, issn = {0886-6236}, doi = {10.1029/2022GB007678}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GB007678}, author = {Jankowski, Kathi Jo and Johnson, Keira and Sethna, Lienne and Julian, Paul and Wymore, Adam S. and Shogren, Arial J. and Thomas, Patrick K. and Sullivan, Pamela L. and Diane M. McKnight and McDowell, William H. and Heindel, Ruth C and Jones, Jeremy B. and Wollheim, Wilfred and Abbott, Benjamin and Deegan, Linda and Carey, Joanna C.} } @article {4865, title = {MacroSheds: A synthesis of long-term biogeochemical, hydroclimatic, and geospatial data from small watershed ecosystem studies}, journal = {Limnology and Oceanography Letters}, volume = {8}, year = {2023}, month = {06/2023}, pages = {419 - 452}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.v8.310.1002/lol2.10325}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lol2.10325}, author = {Vlah, Michael J. and Rhea, Spencer and Bernhardt, Emily S. and Slaughter, Weston and Gubbins, Nick and DelVecchia, Amanda G. and Thellman, Audrey and Ross, Matthew R. V.} } @article {4925, title = {Meteorological drivers of melt at two nearby glaciers in the McMurdo Dry Valleys of Antarctica}, journal = {Journal of Glaciology}, year = {2023}, month = {12/2023}, pages = {1 - 13}, abstract = {

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 f{\"o}hn events, occurring more frequently at Taylor Glacier. At Taylor Glacier melt occurs most often with positive air temperatures, but f{\"o}hn 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 f{\"o}hn 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.

}, keywords = {LTER-MCM, Antarctic glaciology, energy balance, glacier meteorology, ice/atmosphere interactions, melt-surface}, issn = {0022-1430}, doi = {10.1017/jog.2023.98}, url = {https://www.cambridge.org/core/journals/journal-of-glaciology/article/meteorological-drivers-of-melt-at-two-nearby-glaciers-in-the-mcmurdo-dry-valleys-of-antarctica/2B8ED17DEC26AB5F0905BC4C7ACA02FA}, author = {Hofsteenge, Marte G. and Cullen, Nicolas J. and Conway, Jonathan P. and Reijmer, Carleen H. and van den Broeke, Michiel R. and Katurji, Marwan} } @phdthesis {4862, title = {Microbial life in challenging environments}, volume = {Ph.D.}, year = {2023}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, environmental conditions, microbial ecology, microorganisms, soils, tonga}, url = {https://www.proquest.com/docview/2814734209}, author = {Dragone, Nicholas B.}, editor = {Noah Fierer} } @article {4864, title = {Nitrogen fixation facilitates stream microbial mat biomass across the McMurdo Dry Valleys, Antarctica}, journal = {Biogeochemistry}, year = {2023}, month = {07/2023}, abstract = {

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.

}, keywords = {LTER-MCM, biofilm, C, cyanobacteria, hyporheic zone, MCM LTER, mineralization, N, P biogeochemistry}, doi = {10.1007/s10533-023-01069-0}, url = {https://link.springer.com/article/10.1007/s10533-023-01069-0}, author = {Tyler J. Kohler and Singley, Joel G. and Wlostowski, Adam and Diane M. McKnight} } @article {4841, title = {Postglacial adaptations enabled colonization and quasi-clonal dispersal of ammonia-oxidizing archaea in modern European large lakes}, journal = {Science Advances}, volume = {9}, year = {2023}, month = {02/2023}, pages = {eadc9392}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1126/sciadv.adc9392}, url = {https://www.science.org/doi/10.1126/sciadv.adc9392}, author = {Ngugi, David Kamanda and Salcher, Michaela M. and Andrei, Adrian-Stefan and Ghai, Rohit and Klotz, Franziska and Chiriac, Maria-Cecilia and Ionescu, Danny and B{\"u}sing, Petra and Grossart, Hans-Peter and Xing, Peng and John C. Priscu and Alymkulov, Salmor and Pester, Michael} } @article {4866, title = {Sediment oxygen consumption in Antarctic subglacial environments}, journal = {Limnology and Oceanography}, volume = {68}, year = {2023}, month = {07/2023}, pages = {1557 - 1566}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0024-3590}, doi = {10.1002/lno.12366}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lno.12366}, author = {Alexander B. Michaud and John C. Priscu} } @mastersthesis {4857, title = {Snow distribution and influence in Taylor Valley, Antarctica, using remote sensing}, volume = {M.S.}, year = {2023}, month = {04/2023}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/5749}, author = {McNulty, Katherine} } @article {4845, title = {Spatial patterns of major ions and their relationship to sediment concentration in near surface glacier ice, Taylor Valley Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, year = {2023}, month = {03/2024}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2169-9003}, doi = {10.1029/2022JF006980}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2022JF006980}, author = {Bergstrom, Anna J. and Kathleen A. Welch and Michael N. Gooseff} } @article {4840, title = {Temperature response of metabolic activity of an Antarctic nematode}, journal = {Biology}, volume = {12}, year = {2023}, month = {01/2023}, pages = {109}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, carbon cycling, climate change, nematode, respiration rates, soil temperature}, doi = {10.3390/biology12010109}, url = {https://www.mdpi.com/2079-7737/12/1/109}, author = {Robinson, Colin Michael and Hansen, Lee D. and Xue, Xia and Adams, Byron J.} } @article {4767, title = {An Antarctic alga that can survive the extreme cold}, journal = {Frontiers for Young Minds}, volume = {10}, year = {2022}, month = {05/2022}, pages = {740838}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.3389/frym.2022.740838}, url = {https://kids.frontiersin.org/articles/10.3389/frym.2022.740838}, author = {Smith, David R. and Leung, Arthur and Zhang, Xi and Cvetkovska, Marina and Rachael M. Morgan-Kiss and H{\"u}ner, Norman P. A.} } @article {4814, title = {Antarctic lake phytoplankton and bacteria from near-surface waters exhibit high sensitivity to climate-driven disturbance}, journal = {Environmental Microbiology}, year = {2022}, month = {07/2022}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/1462-2920.16113}, url = {https://onlinelibrary.wiley.com/doi/10.1111/1462-2920.16113}, author = {Sherwell, Shasten S. and Kalra, Isha and Li, Wei and Diane M. McKnight and John C. Priscu and Rachael M. Morgan-Kiss} } @article {4936, title = {Antibiotic resistance genes and taxa analysis from mat and planktonic microbiomes of Antarctic perennial ice-covered Lake Fryxell and Lake Bonney}, journal = {Antarctic Science}, volume = {34}, year = {2022}, month = {12/2022}, pages = {408 - 422}, abstract = {

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.

}, keywords = {LTER-MCM, microbial mat, Rhodoferax, Taylor Valley}, issn = {0954-1020}, doi = {10.1017/S0954102022000360}, url = {https://www.cambridge.org/core/product/identifier/S0954102022000360/type/journal_article}, author = {Tallada, Sheetal and Hall, Grant and Barich, Daniel and Rachael M. Morgan-Kiss and Slonczewski, Joan L.} } @article {4714, title = {Barotropic seiches in a perennially ice-covered lake, East Antarctica}, journal = {Limnology and Oceanography Letters}, volume = {7}, year = {2022}, month = {02/2022}, pages = {26 - 33}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.10226}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10226}, author = {Castendyk, Devin and Hilary A. Dugan and Gallagher, Hugh A. and Pujara, Nimish and Peter T. Doran and John C. Priscu and W. Berry Lyons} } @article {4713, title = {Blowin{\textquoteright} in the wind: Dispersal, structure, and metacommunity dynamics of aeolian diatoms in the McMurdo Sound region, Antarctica}, journal = {Journal of Phycology}, volume = {58}, year = {2022}, month = {02/2022}, pages = {36-54}, abstract = {

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.

}, keywords = {LTER-MCM, 18S rRNA, airborne, algae, assembly, Bacillariophyta, biogeography, connectivity, high-throughput sequencing}, issn = {0022-3646}, doi = {10.1111/jpy.13223}, url = {https://onlinelibrary.wiley.com/doi/10.1111/jpy.13223}, author = {Schulte, Nicholas O. and Khan, Alia L. and Smith, Emma W. and Zoumplis, Angela and Kaul, Drishti and Allen, Andrew E. and Adams, Byron J. and Diane M. McKnight} } @article {4826, title = {Community assembly in the wake of glacial retreat: A meta-analysis}, journal = {Global Change Biology}, year = {2022}, month = {09/2022}, abstract = {

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\&$\#$39;s extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species\&$\#$39; 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.

}, keywords = {LTER-MCM, chronosequence, climate change, community assembly, deglaciation, ecological succession, glacial forefields, soil ecosystems}, doi = {10.1111/gcb.16427}, url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.16427}, author = {Pothula, Satyendra K. and Byron Adams} } @article {4818, title = {Cross-site comparisons of dryland ecosystem response to climate change in the US Long-Term Ecological Research Network}, journal = {BioScience}, year = {2022}, month = {08/2022}, abstract = {

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.

}, keywords = {LTER-MCM, ANPP, climate change, Disturbance, drought, LTER, wildfire}, issn = {0006-3568}, doi = {10.1093/biosci/biab134}, url = {https://academic.oup.com/bioscience/advance-article/doi/10.1093/biosci/biab134/6654840}, author = {Hudson, Amy R. and Debra P. C. Peters and J.M. Blair and Childers, Daniel L. and Peter T. Doran and Geil, Kerrie and Michael N. Gooseff and Gross, Katherine L. and Haddad, Nick M. and Pastore, Melissa A. and Rudgers, Jennifer A. and Osvaldo E. Sala and Seabloom, Eric W. and Shaver, Gaius} } @article {4766, title = {Cyclic electron flow (CEF) and ascorbate pathway activity provide constitutive photoprotection for the photopsychrophile, Chlamydomonas sp. UWO 241~(renamed Chlamydomonas priscuii)}, journal = {Photosynthesis Research}, volume = {151}, year = {2022}, month = {03/2022}, pages = {235 - 250}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, ascorbate, Cyclic electron flow, Photosystem I, Psychrophile, ROS}, doi = {10.1007/s11120-021-00877-5}, url = {https://link.springer.com/article/10.1007/s11120-021-00877-5}, author = {Stahl-Rommel, Sarah and Kalra, Isha and D{\textquoteright}Silva, Susanna and Hahn, Mark M. and Popson, Devon and Cvetkovska, Marina and Rachael M. Morgan-Kiss} } @article {4815, title = {Dissolved organic carbon chemostasis in Antarctic polar desert streams}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {127}, year = {2022}, month = {07/2022}, pages = {e2021JG006649}, abstract = {

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\&$\#$39; 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.

}, keywords = {LTER-MCM, Antarctica, chemostasis, concentration-discharge, DOC, ephemeral streams, LTER}, doi = {10.1029/2021JG006649}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2021JG006649}, author = {Torrens, Christa L. and Michael N. Gooseff and Diane M. McKnight} } @article {4836, title = {A draft mitogenome of Plectus murrayi}, journal = {Journal of Nematology}, volume = {54}, year = {2022}, month = {02/2022}, abstract = {

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

}, keywords = {LTER-MCM, Antarctica, genome decay, genomics, mitochondrial genome, MitoZ, phylogeny}, doi = {10.2478/jofnem-2022-0035}, url = {https://www.sciendo.com/article/10.2478/jofnem-2022-0035https://www.sciendo.com/pdf/10.2478/jofnem-2022-0035}, author = {Xue, Xia and Adams, Byron J. and Dilman, Adler R.} } @thesis {4835, title = {Effect of climate history on the genetic structure of an Antarctic soil nematode}, volume = {MS}, year = {2022}, month = {12/2022}, school = {Brigham Young University}, type = {Master{\textquoteright}s thesis}, address = {Provo, UT, USA}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, biogeography, climate disturbance, evolution, McMurdo Dry Valleys, polar, population genetics}, url = {http://hdl.lib.byu.edu/1877/etd12622}, author = {Jackson, Abigail C.}, editor = {Adams, Byron J.} } @article {4718, title = {Elevational constraints on the composition and genomic attributes of microbial communities in Antarctic soils}, journal = {mSystems}, volume = {7}, year = {2022}, month = {01/2022}, pages = {e01330-21}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, microbial ecology, soil microbiology, soils}, doi = {10.1128/msystems.01330-21}, url = {https://journals.asm.org/doi/full/10.1128/msystems.01330-21}, author = {Dragone, Nicholas B. and Henley, Jessica B. and Holland-Moritz, Hannah and Melisa A. Diaz and Hogg, Ian D. and W. Berry Lyons and Diana H. Wall and Byron Adams and Noah Fierer}, editor = {Mackelprang, Rachel} } @article {4825, title = {Glacial legacies: Microbial communities of Antarctic refugia}, journal = {Biology}, volume = {11}, year = {2022}, month = {10/2022}, pages = {1440}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, McMurdo Dry Valleys, metabarcoding, microbial communities, refugia, soil biodiversity}, doi = {10.3390/biology11101440}, url = {https://www.mdpi.com/2079-7737/11/10/1440}, author = {Jackson, Abigail C. and Jorna, Jesse and Chaston, J and Adams, Byron J.} } @article {4817, title = {Islands in the ice: Potential impacts of habitat transformation on Antarctic biodiversity}, journal = {Global Change Biology}, year = {2022}, month = {07/2022}, abstract = {

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\&$\#$39;s extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species\&$\#$39; 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.

}, keywords = {LTER-MCM, Antarctica, biodiversity, biotic homogenization, climate change, connectivity, ice-free, non-native species}, doi = {10.1111/gcb.16331}, url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.16331}, author = {Lee, Jasmine R. and Waterman, Melinda J. and Shaw, Justine D. and Bergstrom, Dana M. and Lynch, Heather J. and Diana H. Wall and Robinson, Sharon A.} } @article {4759, title = {Limits to the three domains of life: Lessons from community assembly along an Antarctic salinity gradient}, journal = {Extremophiles}, volume = {26}, year = {2022}, month = {04/2022}, pages = {15}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, inter-domain response, McMurdo Dry Valleys, salinity, species richness patterns}, doi = {10.1007/s00792-022-01262-3}, url = {https://link.springer.com/article/10.1007/s00792-022-01262-3}, author = {Jiang, Xiaoben and David J. Van Horn and Okie, Jordan G. and Heather N. Buelow and Schwartz, Egbert and Colman, Daniel R. and Feeser, Kelli L. and Cristina D. Takacs-Vesbach} } @article {4834, title = {Lipid biomarkers from microbial mats on the McMurdo Ice Shelf, Antarctica: Signatures for life in the cryosphere}, journal = {Frontiers in Microbiology}, volume = {13}, year = {2022}, month = {06/2022}, pages = {903621}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, bacteriohopanepolyol, cyanobacteria, heterocyte glycolipids, homeoviscous adaptation, intact polar lipid, microbial mats}, doi = {10.3389/fmicb.2022.90362110.3389/fmicb.2022.903621.s001}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2022.903621/full}, author = {Evans, Thomas W. and Kalambokidis, Maria J. and Jungblut, Anne D. and Millar, Jasmin L. and Bauersachs, Thorsten and Grotheer, Hendrik and Mackey, Tyler J. and Ian Hawes and Summons, Roger E.} } @article {4777, title = {Long-term stream hydrology and meteorology of a polar desert, the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {36}, year = {2022}, month = {06/2022}, pages = {e14623}, abstract = {

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).

}, keywords = {LTER-MCM, Antarctica, LTER, McMurdo Dry Valleys, meltwater streams, polar desert, research catchment}, issn = {0885-6087}, doi = {10.1002/hyp.14623}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.14623}, author = {Gooseff, Michael N. and McKnight, Diane M. and Doran, Peter T. and Fountain, Andrew} } @article {4776, title = {Organic matter distribution in the icy environments of Taylor Valley, Antarctica}, journal = {Science of The Total Environment}, volume = {841}, year = {2022}, month = {10/2022}, pages = {156639}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, bacteria, ice cores, katabatic wind, marine aerosol, organic matter}, issn = {00489697}, doi = {10.1016/j.scitotenv.2022.156639}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0048969722037366}, author = {Guo, Bixi and Li, Wei and Santib{\'a}{\~n}ez, Pamela and John C. Priscu and Liu, Yongqin and Liu, Keshao} } @article {4758, title = {Patterns of interdisciplinary collaboration resemble biogeochemical relationships in the McMurdo Dry Valleys, Antarctica: A historical social network analysis of science, 1907{\textendash}2016}, journal = {Polar Research}, volume = {41}, year = {2022}, month = {04/2022}, pages = {8037}, abstract = {

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.

}, keywords = {LTER-MCM, critical physical geography, environmental history, history of science, science and technology studies, scientometrics, visual network analysis}, doi = {10.33265/polar.v41.8037}, url = {https://polarresearch.net/index.php/polar/article/view/8037}, author = {Chignell, Stephen M. and Howkins, Adrian and Gullett, Poppie and Andrew G Fountain} } @article {4716, title = {Photosynthetic adaptation to polar life: Energy balance, photoprotection and genetic redundancy}, journal = {Journal of Plant Physiology}, volume = {268}, year = {2022}, month = {01/2022}, pages = {153557}, abstract = {

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.

}, keywords = {LTER-MCM, genomic redundancy, light, photoprotection, photopsychrophily, photopsychrotolerance, Photosynthesis, temperature}, doi = {10.1016/j.jplph.2021.153557}, url = {https://www.sciencedirect.com/science/article/pii/S0176161721001966}, author = {H{\"u}ner, Norman P. A. and Smith, David R. and Cvetkovska, Marina and Zhang, Xi and Alexander G. Ivanov and Szyszka-Mroz, Beth and Kalra, Isha and Rachael M. Morgan-Kiss} } @article {4689, title = {Response of Antarctic soil fauna to climate-driven changes since the Last Glacial Maximum}, journal = {Global Change Biology}, volume = {28}, year = {2022}, month = {01/2022}, abstract = {

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.

}, keywords = {LTER-MCM, biodiversity, climate change, glacial retreat, nematodes, Shackleton Glacier, soil invertebrates}, issn = {1354-1013}, doi = {10.1111/gcb.15940}, url = {https://onlinelibrary.wiley.com/doi/10.1111/gcb.15940}, author = {Franco, Andr{\'e} L. C. and Byron Adams and Melisa A. Diaz and Lemoine, Nathan P. and Dragone, Nicholas B. and Noah Fierer and W. Berry Lyons and Hogg, Ian D. and Diana H. Wall} } @article {4735, title = {Ten scientific messages on risks and opportunities for life in the Antarctic}, year = {2022}, month = {02/2022}, institution = {Antarctic Environments Portal}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://environments.aq/publications/ten-scientific-messages-on-risks-and-opportunities-for-life-in-the-antarctic/}, author = {Gutt, Julian and Isla, Enrique and Xavier, Jos{\'e} C. and Adams, Byron J. and Ahn, In-Young and Cheng, C.-H. Christina and Colesie, Claudia and Cummings, Vonda J. and Griffiths, Huw J. and Hogg, Ian D. and McIntyre, Trevor and Meiners, Klaus M. and Pearce, David A. and Lloyd S. Peck and Piepenburg, Dieter and Reisinger, Ryan R. and Saba, Grace and Schloss, Irene R. and Signori, Camila N. and Smith, Craig R. and Vacchi, Marino and Verde, Cinzia and Diana H. Wall} } @article {4838, title = {The time is right for an Antarctic biorepository network}, journal = {Proceedings of the National Academy of Sciences}, volume = {119}, year = {2022}, month = {12/2022}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {0027-8424}, doi = {10.1073/pnas.2212800119}, url = {https://www.pnas.org/doi/10.1073/pnas.2212800119}, author = {O{\textquoteright}Brien, Kristin M. and Crockett, Elizabeth L. and Byron Adams and Amsler, Charles D. and Appiah-Madson, Hannah J. and Collins, Allen and Desvignes, Thomas and Detrich, H. William and Distel, Daniel L. and Eppley, Sarah M. and Frable, Benjamin W. and Franz, Nico M. and Grim, Jeffrey M. and Kocot, Kevin M. and Mahon, Andrew R. and Mayfield-Meyer, Teresa J. and Jill A. Mikucki and Moser, William E. and Schmull, Michaela and Seid, Charlotte A. and Smith, Craig R. and Todgham, Anne E. and Watkins-Colwell, Gregory J.} } @article {4823, title = {Valley-floor snowfall in Taylor Valley, Antarctica, from 1995 to 2017: Spring, summer and autumn}, journal = {Antarctic Science}, volume = {34}, year = {2022}, month = {08/2022}, pages = {325-335}, abstract = {

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.

}, keywords = {LTER-MCM, automated weather station, camera, McMurdo Dry Valleys, snow cover, snow persistence}, doi = {10.1017/S0954102022000256}, url = {https://www.cambridge.org/core/product/identifier/S0954102022000256/type/journal_article}, author = {Myers, Madeline and Peter T. Doran and Myers, Krista F.} } @article {4733, title = {Wintertime brine discharge at the surface of a cold polar glacier and the unexpected absence of associated seismicity}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {127}, year = {2022}, month = {03/2022}, abstract = {

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.

}, keywords = {LTER-MCM, crevasses, cryoseismology, glacier hydrology, Rayleigh waves}, issn = {2169-9003}, doi = {10.1029/2021JF006325}, url = {https://onlinelibrary.wiley.com/doi/10.1029/2021JF006325}, author = {Carr, Chris G. and Carmichael, Joshua D. and Pettit, Erin C.} } @article {4578, title = {Antarctic ecosystems in transition {\textendash} life between stresses and opportunities}, journal = {Biological Reviews}, year = {2021}, month = {06/2021}, abstract = {

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.

}, keywords = {LTER-MCM, adaptation, benthic dynamism, biogeochemical cycles, climate change, invasion, new habitats, ocean acidification, Primary production, range shifts, sea ice}, doi = {10.1111/brv.12679}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12679}, author = {Gutt, Julian and Isla, Enrique and Xavier, Jos{\'e} C. and Adams, Byron J. and Ahn, In-Young and Cheng, C.-H. Christina and Colesie, Claudia and Cummings, Vonda J. and di Prisco, Guido and Griffiths, Huw J. and Ian Hawes and Hogg, Ian D. and McIntyre, Trevor and Meiners, Klaus M. and Pearce, David A. and Lloyd S. Peck and Piepenburg, Dieter and Reisinger, Ryan R. and Saba, Grace and Schloss, Irene R. and Signori, Camila N. and Smith, Craig R. and Vacchi, Marino and Verde, Cinzia and Diana H. Wall} } @article {4585, title = {Antarctic water tracks: Microbial community responses to variation in soil moisture, pH, and salinity}, journal = {Frontiers in Microbiology}, volume = {12}, year = {2021}, month = {01/2021}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, extremophiles, Mars analog, microbial ecology, water tracks}, doi = {10.3389/fmicb.2021.616730}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2021.616730}, author = {George, Scott F. and Noah Fierer and Joseph S. Levy and Byron Adams} } @article {4769, title = {Antarctica during the Pandemic: Scaled-back field season prioritizes infrastructure, precious climate data}, journal = {BioScience}, volume = {71}, year = {2021}, month = {05/2021}, pages = {434 - 440}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biab031}, url = {https://academic.oup.com/bioscience/article/71/5/434/6188800}, author = {Mayer, Amy} } @mastersthesis {4642, title = {Causes and characteristics of electrical resistivity variability in shallow (<4 m) soils in Taylor Valley, East Antarctica}, volume = {M.S.}, year = {2021}, month = {07/2021}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/5411}, author = {Gutterman, William S.} } @inbook {4581, title = {Chemical weathering in the McMurdo Dry Valleys, Antarctica}, booktitle = {Hydrogeology, Chemical Weathering, and Soil Formation}, series = {Geophysical Monograph Series}, number = {257}, year = {2021}, pages = {205-216}, publisher = {John Wiley \& Sons, Inc.}, organization = {John Wiley \& Sons, Inc.}, chapter = {11}, address = {Hoboken, NJ}, abstract = {

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.

}, keywords = {LTER-MCM, aluminosilicate weathering, CaCO3 dissolution/precipitation, chemical weathering, hyporheic zone, McMurdo Dry Valleys}, doi = {10.1002/9781119563952.ch11}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119563952.ch11}, author = {W. Berry Lyons and Leslie, Deborah L. and Michael N. Gooseff}, editor = {Hunt, Allen and Egli, Markus and Faybishenko, Boris} } @article {4627, title = {Connectivity: Insights from the U.S. Long Term Ecological Research Network}, journal = {Ecosphere}, volume = {12}, year = {2021}, month = {05/2021}, pages = {e03432}, abstract = {

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.

}, keywords = {LTER-MCM, alpine tundra, Antarctic polar desert, arid grassland, arid shrubland, coastal, estuary, salt marsh, Special Feature: Forecasting Earth{\textquoteright}s Ecosystems with Long-Term Ecological Research, urban ecosystem}, issn = {2150-8925}, doi = {10.1002/ecs2.v12.510.1002/ecs2.3432}, url = {https://onlinelibrary.wiley.com/doi/10.1002/ecs2.3432}, author = {Iwaniec, David M. and Michael N. Gooseff and Suding, Katharine N. and Johnson, David Samuel and Reed, Daniel C. and Debra P. C. Peters and Byron Adams and John E. Barrett and Bestelmeyer, Brandon T. and Castorani, Max C. N. and Cook, Elizabeth M. and Davidson, Melissa J. and Groffman, Peter M. and Hanan, Niall P. and Huenneke, L and Johnson, Pieter T. J. and Diane M. McKnight and Miller, Robert J. and Okin, Gregory S. and Preston, Daniel L. and Rassweiler, Andrew and Ray, Chris and Osvaldo E. Sala and Schooley, Robert and Seastedt, Timothy and Spasojevic, Marko J. and Vivoni, Enrique R.} } @mastersthesis {4762, title = {Controls on microbial mat coverage and diatom species turnover in Antarctic desert streams: A transplant experiment}, volume = {M.S.}, year = {2021}, school = {University of Colorado Boulder}, type = {masters}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, diatom, microbial mat, streams, transplant, turnover}, url = {https://www.proquest.com/docview/2634590982}, author = {Darling, Joshua P.}, editor = {Diane M. McKnight} } @article {4717, title = {Counting carbon: Quantifying biomass in the McMurdo Dry Valleys through orbital and field observations}, journal = {International Journal of Remote Sensing}, volume = {42}, year = {2021}, month = {10/2021}, pages = {8597 - 8623}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1080/01431161.2021.1981559}, url = {https://www.tandfonline.com/doi/full/10.1080/01431161.2021.1981559}, author = {Salvatore, Mark R. and John E. Barrett and Borges, Schuyler R. and Power, Sarah N. and Lee F. Stanish and Eric R. Sokol and Michael N. Gooseff} } @article {4576, title = {Diatoms define a novel freshwater biogeography of the Antarctic}, journal = {Ecography}, volume = {44}, year = {2021}, month = {01/2021}, pages = {1-13}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, biogeography, diatoms, endemism, freshwater, lake}, doi = {10.1111/ecog.05374}, url = {https://onlinelibrary.wiley.com/doi/10.1111/ecog.05374}, author = {Elie Verleyen and Bart Van de Vijver and Tytgat, Bjorn and Pinseel, Eveline and Hodgson, Dominic A. and Kopalov{\'a}, Kate{\v r}ina and Steven L. Chown and Van Ranst, Eric and Imura, Satoshi and Kudoh, Sakae and Van Nieuwenhuyze, Wim and Sabbe, Koen and Vyverman, Wim} } @article {4586, title = {Diatoms in hyporheic sediments trace organic matter retention and processing in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {02/2021}, pages = {e2020JG006097}, abstract = {

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.

}, keywords = {LTER-MCM, benthic processes, biogenic silica, biogeochemical cycles processes and modeling, carbon cycling, diatoms, groundwater/surface water interactions, hyporheic zone, McMurdo Dry Valleys, nitrogen cycling, particulate organic matter}, doi = {10.1029/2020JG006097}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG006097}, author = {Heindel, Ruth C and Darling, Joshua P. and Singley, Joel G. and Bergstrom, Anna J. and Diane M. McKnight and Lukkari, Braeden M. and Kathleen A. Welch and Michael N. Gooseff} } @article {4634, title = {Draft genome sequence of the Antarctic green alga Chlamydomonas sp. UWO241}, journal = {iScience}, volume = {24}, year = {2021}, month = {2021-02}, pages = {102084}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {25890042}, doi = {10.1016/j.isci.2021.102084}, url = {https://www.sciencedirect.com/science/article/pii/S2589004221000523}, author = {Zhang, Xi and Cvetkovska, Marina and Rachael M. Morgan-Kiss and H{\"u}ner, Norman P. A. and Smith, David Roy} } @article {4691, title = {Episodic basin-scale soil moisture anomalies associated with high relative humidity events in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, year = {2021}, month = {08/2021}, pages = {1-15}, abstract = {

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.

}, keywords = {LTER-MCM, deliquescence, hydrology, microclimate, micrometeorology, pedology, remote sensing}, issn = {0954-1020}, doi = {10.1017/S0954102021000341}, url = {https://www.cambridge.org/core/product/identifier/S0954102021000341/type/journal_article}, author = {Joseph S. Levy} } @article {4636, title = {Exploring the boundaries of microbial habitability in soil}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {06/2021}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, astrobiology, bacteria, extremophiles, fungi, soils}, issn = {2169-8953}, doi = {10.1029/2020JG006052}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG006052}, author = {Dragone, Nicholas B. and Melisa A. Diaz and Hogg, Ian D. and W. Berry Lyons and W. Andrew Jackson and Diana H. Wall and Adams, Byron J. and Noah Fierer} } @article {4644, title = {From the Heroic Age to today: What diatoms from Shackleton{\textquoteright}s Nimrod expedition can tell us about the ecological trajectory of Antarctic ponds}, journal = {Limnology and Oceanography Letters}, year = {2021}, month = {07/2021}, abstract = {

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\&$\#$39;s Nimrod expedition at Cape Royds, Antarctica, to compare with the same waterbodies a century later. We find historical samples to be almost identical to modern counterparts, and provide no evidence of exotic introductions despite increasing human activity. However, a shift occurred in the pond nearest Shackleton\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {2378-2242}, doi = {10.1002/lol2.10200}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/10.1002/lol2.10200}, author = {Tyler J. Kohler and Howkins, Adrian and Eric R. Sokol and Kopalov{\'a}, Kate{\v r}ina and Cox, Aneliya and Darling, Joshua P. and Michael N. Gooseff and Diane M. McKnight} } @article {4583, title = {Genome analysis of Plectus murrayi, a nematode from continental Antarctica}, journal = {G3 Genes|Genomes|Genetics}, year = {2021}, month = {01/2021}, abstract = {

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.

}, keywords = {LTER-MCM, gene loss, genome architecture, genome assembly, genome decay, Plectus murrayi}, doi = {10.1093/g3journal/jkaa045}, url = {https://academic.oup.com/g3journal/advance-article/doi/10.1093/g3journal/jkaa045/6044189}, author = {Xue, Xia and Suvorov, Anton and Fujimoto, Stanley and Dilman, Adler R. and Byron Adams} } @article {4646, title = {Geochemical zones and environmental gradients for soils from the central Transantarctic Mountains, Antarctica}, journal = {Biogeosciences}, volume = {18}, year = {2021}, month = {03/2021}, pages = {1629 - 1644}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/bg-18-1629-2021}, url = {https://bg.copernicus.org/articles/18/1629/2021/}, author = {Melisa A. Diaz and Christopher B. Gardner and Welch, Susan A. and W. Andrew Jackson and Adams, Byron J. and Diana H. Wall and Hogg, Ian D. and Noah Fierer and W. Berry Lyons} } @article {4577, title = {Geochemistry of contrasting stream types, Taylor Valley, Antarctica}, journal = {GSA Bulletin}, volume = {133}, year = {2021}, month = {01/2021}, pages = {425-448}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1130/B35479.1}, url = {https://pubs.geoscienceworld.org/gsa/gsabulletin/article/133/1-2/425/587799/Geochemistry-of-contrasting-stream-types-Taylor}, author = {Harmon, Russell S. and Leslie, Deborah L. and W. Berry Lyons and Kathleen A. Welch and Diane M. McKnight} } @article {4589, title = {How long do population level field experiments need to be? Utilising data from the 40-year-old LTER network}, journal = {Ecology Letters}, year = {2021}, month = {02/2021}, abstract = {

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.

}, keywords = {LTER-MCM, data mining, isothermality, long-term, moving window, population dynamics, time series, trajectory}, doi = {10.1111/ele.13710}, url = {https://onlinelibrary.wiley.com/doi/10.1111/ele.13710}, author = {Cusser, Sarah and Helms, Jackson and Bahlai, Christie A. and Haddad, Nick M.} } @mastersthesis {4588, title = {Hydrologic response to foehn winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, volume = {M.S.}, year = {2021}, month = {2020}, school = {University of Colorado Boulder}, type = {masters}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, foehn, foehn winds, hydrologic, katabatic, McMurdo, wind}, url = {https://www.proquest.com/docview/2488126937}, author = {Beane, Samuel J. and Michael N. Gooseff} } @article {4643, title = {Long-term shifts in feedbacks among glacier surface change, melt generation, and runoff, McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, year = {2021}, month = {07/2021}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0885-6087}, doi = {10.1002/hyp.14292}, url = {https://onlinelibrary.wiley.com/doi/10.1002/hyp.14292}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Andrew G Fountain and Hoffman, Matthew} } @article {4732, title = {The magnitude and climate sensitivity of isotopic fractionation from ablation of Antarctic Dry Valley lakes}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {53}, year = {2021}, month = {12/2021}, pages = {352 - 371}, abstract = {

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.

}, keywords = {LTER-MCM, Dry Valley lakes, isotope fractionation, stable water isotopes}, issn = {1523-0430}, doi = {10.1080/15230430.2021.2001899}, url = {https://www.tandfonline.com/doi/full/10.1080/15230430.2021.2001899}, author = {Bellagamba, Anthony W. and Berkelhammer, Max and Winslow, Luke A. and Peter T. Doran and Myers, Krista F. and Devlin, Shawn and Ian Hawes} } @article {4690, title = {Meta-analysis of Cryogenian through modern quartz microtextures reveals sediment transport histories}, journal = {Journal of Sedimentary Research}, volume = {91}, year = {2021}, month = {09/2021}, pages = {929-944}, abstract = {

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 Br{\r a}vika Member (Svalbard). Integrating PCA with field observations, we find evidence that the Br{\r a}vika 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.

}, keywords = {LTER-MCM}, issn = {1527-1404}, doi = {10.2110/jsr.2020.151}, url = {https://pubs.geoscienceworld.org/jsedres/article/91/9/929/607764/Meta-analysis-of-Cryogenian-through-modern-quartz}, author = {Reahl, Jocelyn N. and Cantine, Marjorie D. and Wilcots, Julia and Mackey, Tyler J. and Bergmann, Kristin D.} } @article {4597, title = {Metabolic capacity of the Antarctic cyanobacterium Phormidium pseudopriestleyi that sustains oxygenic photosynthesis in the presence of hydrogen sulfide}, journal = {Genes}, volume = {12}, year = {2021}, month = {03/2021}, pages = {426}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.3390/genes12030426}, url = {https://www.mdpi.com/2073-4425/12/3/426}, author = {Lumian, Jessica E. and Jungblut, Anne D. and Dillon, Megan L. and Hawes, Ian and Peter T. Doran and Mackey, Tyler J. and Dick, Gregory J. and Grettenberger, Christen L. and Sumner, Dawn Y.} } @article {4768, title = {Patterns and trends of organic matter processing and transport: Insights from the US Long-term Ecological Research Network}, journal = {Climate Change Ecology}, volume = {2}, year = {2021}, month = {12/2021}, pages = {100025}, abstract = {

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.

}, keywords = {LTER-MCM, coupled biogeochemical cycles, cross-site synthesis, organic matter composition, organic matter storage, stabilization, transport}, issn = {26669005}, doi = {10.1016/j.ecochg.2021.100025}, url = {https://www.sciencedirect.com/science/article/pii/S2666900521000253}, author = {Harms, Tamara K. and Groffman, Peter M. and Aluwihare, Lihini and Craft, Christopher and Wieder, William R and Hobbie, S and Baer, Sara G. and J.M. Blair and Frey, Serita D. and Remucal, Christina K. and Rudgers, Jennifer A. and Collins, SL and Kominoski, John S. and Ball, Becky and John C. Priscu and John E. Barrett} } @article {4645, title = {Phagotrophic protists and their associates: Evidence for preferential grazing in an abiotically driven soil ecosystem}, journal = {Microorganisms}, volume = {9}, year = {2021}, month = {08/2021}, pages = {1555}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, co-occurrence networks, McMurdo Dry Valleys, Rhogostoma sp., Sandona sp., soil food webs, variation partitioning}, doi = {10.3390/microorganisms9081555}, url = {https://www.mdpi.com/2076-2607/9/8/1555}, author = {Thompson, Andrew R. and Roth-Monz{\'o}n, Andrea J. and Aanderud, Zachary T. and Adams, Byron J.} } @article {4734, title = {Phagotrophic protists (protozoa) in Antarctic terrestrial ecosystems: Diversity, distribution, ecology, and best research practices}, journal = {Polar Biology}, volume = {44}, year = {2021}, month = {08/2021}, pages = {1467-1484}, abstract = {

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.

}, keywords = {LTER-MCM, abiotic drivers of protist communities, Antarctic protozoa, Corythion dubium, phagotrophic soil protists, protist diversity}, issn = {0722-4060}, doi = {10.1007/s00300-021-02896-3}, url = {https://link.springer.com/article/10.1007/s00300-021-02896-3}, author = {Thompson, Andrew R.} } @article {4715, title = {Research sites get closer to field camps over time: Informing environmental management through a geospatial analysis of science in the McMurdo Dry Valleys, Antarctica}, journal = {PLOS ONE}, volume = {16}, year = {2021}, month = {11/2021}, pages = {e0257950}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0257950}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0257950}, author = {Chignell, Stephen M. and Myers, Madeline and Howkins, Adrian and Andrew G Fountain} } @phdthesis {4678, title = {Role of cyclic electron flow (CEF) and photosystem I (PSI) supercomplex formation during acclimation to long-term salinity stress in green algae: A comparative study}, volume = {PhD}, year = {2021}, month = {2021}, pages = {236}, school = {Miami University}, type = {Doctoral}, address = {Oxford, OH}, abstract = {Photosynthesis 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.}, keywords = {LTER-MCM, acclimation, CEF, extremophile, Photosynthesis, salinity stress, supercomplex}, url = {https://www.proquest.com/docview/2572560585}, author = {Kalra, Isha}, editor = {Rachael M. Morgan-Kiss} } @article {4626, title = {The role of hyporheic connectivity in determining nitrogen availability: Insights from an intermittent Antarctic stream}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2021}, month = {04/2022}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, autochthonous nitrogen, hyporheic zone, nitrogen cycling, streamflow}, issn = {2169-8953}, doi = {10.1029/2021JG006309}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JG006309}, author = {Singley, Joel G. and Gooseff, Michael N. and Diane M. McKnight and Eve-Lyn S. Hinckley} } @phdthesis {4692, title = {Stream corridor connectivity controls on nitrogen cycling}, volume = {PhD}, year = {2021}, month = {05/2021}, school = {University of Colorado Boulder}, type = {Doctoral}, address = {Boulder, CO, USA}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, hyporheic zone, nitrogen cycling, streams}, url = {https://www.proquest.com/docview/2572593127}, author = {Singley, Joel G.}, editor = {Eve-Lyn S. Hinckley and Michael N. Gooseff} } @article {4648, title = {Supporting simultaneous air revitalization and thermal control in a crewed habitat with temperate Chlorella vulgaris and eurythermic Antarctic Chlorophyta}, journal = {Frontiers in Microbiology}, volume = {12}, year = {2021}, month = {08/2021}, pages = {709746}, abstract = {

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.

}, keywords = {LTER-MCM, air revitalization, Antarctica, bioregenerative life support systems, Chlorophyta, McMurdo Dry Valleys, thermal control}, doi = {10.3389/fmicb.2021.709746}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2021.709746}, author = {Matula, Emily E. and Nabity, James A. and Diane M. McKnight} } @article {4647, title = {Thermal legacy of a large paleolake in Taylor Valley, East Antarctica, as evidenced by an airborne electromagnetic survey}, journal = {The Cryosphere}, volume = {15}, year = {2021}, month = {08/2021}, pages = {3577 - 3593}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-15-3577-2021}, url = {https://tc.copernicus.org/articles/15/3577/2021/}, author = {Myers, Krista F. and Peter T. Doran and Tulaczyk, Slawek M. and Foley, Neil T. and Bording, Thue S. and Auken, Esben and Hilary A. Dugan and Jill A. Mikucki and Foged, Nikolaj and Grombacher, Denys and Ross A. Virginia} } @article {4613, title = {Year-round and long-term phytoplankton dynamics in Lake Bonney, a permanently ice-covered Antarctic lake}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {126}, year = {2021}, month = {04/2021}, pages = {e2020JG005925}, abstract = {

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).

}, keywords = {LTER-MCM, algae, Antarctic, fluorometry, ice, lakes, light, profiling, winter}, issn = {2169-8953}, doi = {10.1029/2020JG005925}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JG005925}, author = {Patriarche, Jeffrey D. and John C. Priscu and Cristina D. Takacs-Vesbach and Winslow, Luke A. and Myers, Krista F. and Heather N. Buelow and Rachael M. Morgan-Kiss and Peter T. Doran} } @thesis {4443, title = {Analysis of acid-leachable barium, copper, iron, lead, \& zinc concentrations in Taylor Valley, Antarctic stream sediments}, volume = {B.S.}, year = {2020}, month = {05/2020}, school = {The Ohio State University}, type = {bachelors}, address = {Columbus, OH}, abstract = {

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.

}, keywords = {LTER-MCM, acid-leachable metal, Antarctica, geochemistry, McMurdo Dry Valleys, polar sediments, sedimentation rate}, url = {http://hdl.handle.net/1811/91772}, author = {Piergallini, Brianna and W. Berry Lyons} } @proceedings {4575, title = {Change in Pictures: Creating best practices in archiving ecological imagery for reuse}, journal = {Biodiversity Information Science and Standards}, volume = {4}, year = {2020}, month = {09/2020}, abstract = {

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.

}, keywords = {LTER-MCM, data repository, ecological data, metadata}, doi = {10.3897/biss.4.59082}, url = {https://biss.pensoft.net/article/59082/}, author = {Gries, Corinna and Beaulieu, Stace and Brown, Ren{\'e}e F. and Gastil-Buhl, Gastil and Elmendorf, Sarah C. and Hsieh, Hsun-Yi and Kui, Li and Maurer, Greg and Porter, John H.} } @phdthesis {4587, title = {Characterization of spatial and environmental influences on stream diatoms and cyanobacteria}, volume = {Ph.D.}, year = {2020}, month = {2020}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, algae, dispersal, environmental assessment, human disturbance, metacommunity ecology, species distribution models}, url = {https://www.proquest.com/docview/2476216263}, author = {Schulte, Nicholas O. and Diane M. McKnight} } @article {4419, title = {Chlamydomonas sp. UWO 241 exhibits high cyclic electron flow and rewired metabolism under high salinity}, journal = {Plant Physiology}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1104/pp.19.01280}, url = {http://www.plantphysiol.org/content/early/2020/04/03/pp.19.01280}, author = {Kalra, Isha and Wang, Xin and Cvetkovska, Marina and Jeong, Jooyeon and McHargue, William and Zhang, Ru and H{\"u}ner, Norman and Yuan, Joshua S. and Rachael M. Morgan-Kiss} } @article {4448, title = {Climate from the McMurdo Dry Valleys, Antarctica, 1986 {\textendash} 2017: Surface air temperature trends and redefined summer season}, journal = {Journal of Geophysical Research: Atmospheres}, year = {2020}, month = {05/2020}, abstract = {

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.

}, keywords = {LTER-MCM, McMurdo Dry Valleys, summer season, weather observations}, doi = {10.1029/2019JD032180}, url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD032180}, author = {Obryk, M. K. and Doran, P. T. and Fountain, A. G. and Myers, M. and McKay, C. P.} } @article {4438, title = {A digital archive of human activity in the McMurdo Dry Valleys, Antarctica}, journal = {Earth System Science Data}, volume = {12}, year = {2020}, month = {05/2020}, abstract = {

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).

}, keywords = {LTER-MCM}, doi = {10.5194/essd-12-1117-2020}, url = {https://www.earth-syst-sci-data.net/12/1117/2020/}, author = {Howkins, Adrian and Chignell, Stephen M. and Gullett, Poppie and Andrew G Fountain and Brett, Melissa and Preciado, Evelin} } @phdthesis {4629, title = {The effect of sediment on hydrological and biogeochemical connectivity of glaciers within the McMurdo Dry Valley ecosystem, Antarctica}, volume = {Ph.D.}, year = {2020}, month = {2020}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, glaciers, LTER, McMurdo Dry Valleys, meltwater, sediment}, url = {https://www.proquest.com/docview/2408273839}, author = {Bergstrom, Anna J. and Michael N. Gooseff} } @article {4395, title = {Energetic and environmental constraints on the community structure of benthic microbial mats in Lake Fryxell, Antarctica}, journal = {FEMS Microbiology Ecology}, volume = {96}, year = {2020}, month = {02/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, energy, Lake Fryxell, microbial mat, Oxygen, Photosynthetically Active Radiation}, doi = {10.1093/femsec/fiz207}, url = {https://academic.oup.com/femsec/article/96/2/fiz207/5697196}, author = {Dillon, Megan L. and Ian Hawes and Jungblut, Anne D. and Mackey, Tyler J. and Eisen, Jonathan A. and Peter T. Doran and Sumner, Dawn Y.} } @article {4582, title = {Environmental control on the distribution of metabolic strategies of benthic microbial mats in Lake Fryxell, Antarctica}, journal = {PLoS ONE}, volume = {15}, year = {2020}, month = {04/2020}, pages = {e0231053}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0231053}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0231053}, author = {Dillon, Megan L. and Hawes, Ian and Jungblut, Anne D. and Mackey, Tyler J. and Eisen, Jonathan A. and Peter T. Doran and Sumner, Dawn Y.} } @article {4516, title = {Estimating microbial mat biomass in the McMurdo Dry Valleys, Antarctica using satellite imagery and ground surveys}, journal = {Polar Biology}, year = {2020}, month = {09/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, microbial mat, multispectral imagery, NDVI, Nostocales, remote sensing}, doi = {10.1007/s00300-020-02742-y}, url = {https://link.springer.com/article/10.1007\%2Fs00300-020-02742-y}, author = {Power, Sarah N. and Salvatore, Mark R. and Eric R. Sokol and Lee F. Stanish and John E. Barrett} } @article {4515, title = {Evaluating alternative metacommunity hypotheses for diatoms in the McMurdo Dry Valleys using simulations and remote sensing data}, journal = {Frontiers in Ecology and Evolution}, volume = {8}, year = {2020}, month = {09/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Bacillariophyceae, dispersal, Nostoc, stream ecology}, doi = {10.3389/fevo.2020.521668}, url = {https://www.frontiersin.org/article/10.3389/fevo.2020.521668/full}, author = {Eric R. Sokol and John E. Barrett and Tyler J. Kohler and Diane M. McKnight and Salvatore, Mark R. and Lee F. Stanish} } @inbook {4440, title = {Following the Astrobiology Roadmap: Origins, Habitability and Future Exploration}, booktitle = {Astrobiology: Current, Evolving, and Emerging Perspectives}, year = {2020}, publisher = {Caister Academic Press}, organization = {Caister Academic Press}, chapter = {1}, address = {Norfolk, United Kingdom}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.21775/9781912530304.01}, url = {https://www.caister.com/astro}, author = {O{\textquoteright}Rourke, Aubrie and Zoumplis, Angela and Wilburn, Paul and Lee, Michael D. and Lee, Zhi and Vecina, Marissa and Mercader, Kysha} } @article {4488, title = {Genetic diversity of soil invertebrates corroborates timing estimates for past collapses of the West Antarctic Ice Sheet}, journal = {Proceedings of the National Academy of Sciences}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, climate change, microarthropods, molecular clock, phylogeography, terrestrial biodiversity}, doi = {10.1073/pnas.2007925117}, url = {https://www.pnas.org/content/early/2020/08/19/2007925117}, author = {Gemma E. Collins and Hogg, Ian D. and Convey, Peter and Sancho, Leopoldo G. and Cowan, Don A. and W. Berry Lyons and Byron Adams and Diana H. Wall and Allan Green, T. G.} } @article {4471, title = {Geochemistry of aeolian material from the McMurdo Dry Valleys, Antarctica: Insights into Southern Hemisphere dust sources}, journal = {Earth and Planetary Science Letters}, volume = {547}, year = {2020}, month = {10/2020}, abstract = {

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.

}, keywords = {LTER-MCM, aeolian material, Antarctica, major oxides, mineralogy, rare earth elements, trace elements}, doi = {10.1016/j.epsl.2020.116460}, url = {https://www.sciencedirect.com/science/article/pii/S0012821X20304040}, author = {Melisa A. Diaz and Welch, Susan A. and Sheets, J. M. and Kathleen A. Welch and Khan, Alia L. and Byron Adams and Diane M. McKnight and Craig S Cary and W. Berry Lyons} } @article {4418, title = {GIS tool to predict photosynthetically active radiation in a Dry Valley}, journal = {Antarctic Science}, year = {2020}, month = {04/2020}, abstract = {

Understanding primary productivity is a core research area of the National Science Foundation\&$\#$39;s Long-Term Ecological Research Network. This study presents the development of the GIS-based Topographic Solar Photosynthetically Active Radiation (T-sPAR) toolbox for Taylor Valley. It maps surface photosynthetically active radiation using four meteorological stations with ~20 years of data. T-sPAR estimates were validated with ground-truth data collected at Taylor Valley\&$\#$39;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\%.

}, keywords = {LTER-MCM, ArcMap, automated weather station, digital elevation model, ice-covered lakes, McMurdo Dry Valleys, R model, Taylor Valley}, doi = {10.1017/S0954102020000218}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/gis-tool-to-predict-photosynthetically-active-radiation-in-a-dry-valley/BD0BE4FF6A8F3DAAF32D698797287078}, author = {Acosta, Dimitri R. and Peter T. Doran and Myers, Madeline} } @mastersthesis {4451, title = {Glacial meltwater modeling to simulate lake water budget (1996-2013) in Taylor Valley, Antarctica}, volume = {M.S.}, year = {2020}, month = {01/2020}, school = {Portland State University}, type = {masters}, address = {Portland, OR}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.15760/etd.7237}, url = {https://archives.pdx.edu/ds/psu/30806}, author = {Cross, Julian M. and Andrew G Fountain} } @article {4420, title = {A global database of soil nematode abundance and functional group composition}, journal = {Scientific Data}, volume = {7}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41597-020-0437-3}, url = {https://www.nature.com/articles/s41597-020-0437-3}, author = {van den Hoogen, Johan and Geisen, Stefan and Diana H. Wall and Wardle, D and Traunspurger, Walter and de Goede, Ron G. M. and Byron Adams and Ahmad, Wasim and Ferris, Howard and Richard D. Bardgett and Bonkowski, Michael and Campos-Herrera, Raquel and Cares, Juvenil E. and Caruso, Tancredi and de Brito Caixeta, Larissa and Chen, Xiaoyun and Costa, Sofia R. and Creamer, Rachel and da Cunha e Castro, Jos{\'e} and Dam, Marie and Djigal, Djibril and Escuer, Miguel and Griffiths, Bryan S. and Guti{\'e}rrez, Carmen and Hohberg, Karin and Kalinkina, Daria and Kardol, Paul and Kergunteuil, Alan and Korthals, Gerard and Krashevska, Valentyna and Kudrin, Alexey A. and Li, Qi and Liang, Wenju and Magilton, Matthew and Marais, Mariette and Mart{\'\i}n, Jos{\'e} Antonio Rodr{\'\i}guez and Matveeva, Elizaveta and Mayad, El Hassan and Mzough, E. and Mulder, Christian and Mullin, Peter and Neilson, Roy and Nguyen, T. A. Duong and Uffe N. Nielsen and Okada, Hiroaki and Rius, Juan Emilio Palomares and Pan, Kaiwen and Peneva, Vlada and Pellissier, Lo{\"\i}c and Carlos Pereira da Silva, Julio and Pitteloud, Camille and Powers, Thomas O. and Powers, Kirsten and Quist, Casper W. and Rasmann, Sergio and Moreno, Sara S{\'a}nchez and Scheu, Stefan and Set{\"a}l{\"a}, Heikki and Sushchuk, Anna and Tiunov, Alexei V. and Trap, Jean and Vesterg{\r a}rd, Mette and Villenave, Cecile and Waeyenberge, Lieven and Wilschut, Rutger and Wright, Daniel G. and Keith, Aidan M. and Yang, Jiue-in and Schmidt, Olaf and Bouharroud, R. and Ferji, Z. and van der Putten, Wim H. and Routh, Devin and Crowther, Thomas Ward} } @article {4487, title = {Glycerol is an osmoprotectant in two Antarctic Chlamydomonas species from an ice-covered saline lake and is synthesized by an unusual bidomain enzyme}, journal = {Frontiers in Plant Science}, volume = {11}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Chlamydomonas, glycerol synthesis, glycerol-3-phosphate dehydrogenase, Lake Bonney, phosphoserine phosphatase}, doi = {10.3389/fpls.2020.01259}, url = {https://www.frontiersin.org/articles/10.3389/fpls.2020.01259/full}, author = {Raymond, James A. and Rachael M. Morgan-Kiss and Stahl-Rommel, Sarah} } @article {4472, title = {The influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting}, journal = {Journal of Glaciology}, year = {2020}, month = {07/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1017/jog.2020.48}, url = {https://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/E1A441425341F677117509351F3C6763}, author = {Carr, Chris G. and Carmichael, J. D. and Pettit, Erin C. and Truffer, Martin} } @article {4297, title = {Methane production in the oxygenated water column of a perennially ice-covered Antarctic lake}, journal = {Limnology and Oceanography}, volume = {65}, year = {2020}, month = {01/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/lno.11257}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11257}, author = {Li, Wei and John E. Dore and Steigmeyer, August J. and Cho, Yong-Joon and Kim, Ok-Sun and Liu, Yongqin and Rachael M. Morgan-Kiss and Skidmore, Mark L. and John C. Priscu} } @article {4447, title = {Modeling present and future ice covers in two Antarctic lakes}, journal = {Journal of Glaciology}, volume = {66}, year = {2020}, month = {02/2020}, abstract = {

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.

}, keywords = {LTER-MCM, climate change, energy balance, ice and climate, ice-sheet modeling, lake ice}, doi = {10.1017/jog.2019.78}, url = {https://www.cambridge.org/core/journals/journal-of-glaciology/article/modeling-present-and-future-ice-covers-in-two-antarctic-lakes/9306439ADD5492BC05F3BAF0E076B1C3}, author = {Echeverr{\'\i}a, Sebasti{\'a}n and Hausner, Mark B. and Bambach, Nicol{\'a}s and Vicu{\~n}a, Sebasti{\'a}n and Su{\'a}rez, Francisco} } @article {4489, title = {Nutrient uptake in the supraglacial stream network of an Antarctic glacier}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, McMurdo Dry Valleys, nitrogen, nutrient tracers, nutrient uptake, sediments, supraglacial streams}, doi = {10.1029/2020JG005679}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005679}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Singley, Joel G. and Cohen, Matthew J. and Kathleen A. Welch} } @article {4410, title = {Picocyanobacterial cells in near-surface air above terrestrial and freshwater substrates in Greenland and Antarctica}, journal = {Environmental Microbiology Reports}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/1758-2229.12832}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/1758-2229.12832}, author = {Trout-Haney, Jessica V. and Heindel, Ruth C and Ross A. Virginia} } @article {4449, title = {Remote characterization of photosynthetic communities in the Fryxell basin of Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM, ecology, hydrology, McMurdo Dry Valleys, microbiology, remote sensing, spectroscopy}, doi = {10.1017/S0954102020000176}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/remote-characterization-of-photosynthetic-communities-in-the-fryxell-basin-of-taylor-valley-antarctica/8576F6BB1BCFDCA8409F5EA96CA00C6F}, author = {Salvatore, Mark R. and Borges, Schuyler R. and John E. Barrett and Eric R. Sokol and Lee F. Stanish and Power, Sarah N. and Morin, Paul} } @mastersthesis {4628, title = {Response of microbial communities to climatic disturbances in Lake Bonney, McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2020}, month = {2020}, school = {Miami University}, type = {masters}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM, climate change, McMurdo Dry Valleys, microbial communities, phytoplankton}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1595958688364877}, author = {Sherwell, Shasten S. and Rachael M. Morgan-Kiss} } @article {4439, title = {The rise of technocratic environmentalism: the United States, Antarctica, and the globalisation of the environmental impact statement}, journal = {Journal of Historical Geography}, year = {2020}, month = {05/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Conservation, Environmental impact statements, Environmental protection, National Environmental Policy Act (NEPA)}, doi = {10.1016/j.jhg.2020.03.004}, url = {https://www.sciencedirect.com/science/article/abs/pii/S030574882030027X}, author = {Antonello, Alessandro and Howkins, Adrian} } @article {4413, title = {The seasonal evolution of albedo across glaciers and the surrounding landscape of Taylor Valley, Antarctica}, journal = {The Cryosphere}, volume = {14}, year = {2020}, month = {03/2020}, pages = {769-788}, abstract = {

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\ oC, 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.

}, keywords = {LTER-MCM}, doi = {10.5194/tc-14-769-2020}, url = {https://www.the-cryosphere.net/14/769/2020/}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Myers, Madeline and Peter T. Doran and Cross, Julian M.} } @article {4490, title = {Shotgun metagenomics reveal a diverse assemblage of protists in a model Antarctic soil ecosystem}, journal = {Environmental Microbiology}, year = {2020}, month = {08/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, extremophiles, functional groups, metagenomics, protozoa, soil microbiology}, doi = {10.1111/1462-2920.15198}, url = {https://sfamjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1462-2920.15198}, author = {Thompson, Andrew R. and Geisen, Stefan and Byron Adams} } @article {4463, title = {Silicon isotopes reveal a non-glacial source of silicon to Crescent Stream, McMurdo Dry Valleys, Antarctica}, journal = {Frontiers in Earth Science}, volume = {8}, year = {2020}, month = {06/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.3389/feart.2020.00229}, url = {https://www.frontiersin.org/articles/10.3389/feart.2020.00229/full}, author = {Hirst, Catherine and Opfergelt, Sophie and Fran{\c c}ois Gaspard and Hendry, Katharine R. and Hatton, Jade E. and Sue Welch and Diane M. McKnight and W. Berry Lyons} } @article {4466, title = {Silicon isotopic composition of dry and wet-based glaciers in Antarctica}, journal = {Frontiers in Earth Science}, volume = {8}, year = {2020}, month = {07/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.3389/feart.2020.00286}, url = {https://www.frontiersin.org/articles/10.3389/feart.2020.00286/full}, author = {Hatton, Jade E. and Hendry, Katharine R. and Hirst, Catherine and Opfergelt, Sophie and Henkel, Susann and Silva-Busso, Adri{\'a}n and Welch, Susan A. and Wadham, Jemma L. and W. Berry Lyons and Bagshaw, Elizabeth and Staubwasser, Michael and Diane M. McKnight} } @article {4403, title = {Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica}, journal = {Antarctic Science}, year = {2020}, month = {02/2020}, abstract = {

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.

}, keywords = {LTER-MCM, Dry valleys, hypersalinity, lakes, proglacial, temperature}, doi = {10.1017/S0954102020000036}, url = {https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102020000036}, author = {Lawrence, Jade and Peter T. Doran and Winslow, Luke A. and John C. Priscu} } @article {4331, title = {Vertical stratification and stability of biogeochemical processes in the deep saline waters of Lake Vanda, Antarctica}, journal = {Limnology and Oceanography}, volume = {65}, year = {2020}, month = {03/2020}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/lno.11327}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.11327}, author = {Schutte, Charles A. and Samarkin, Vladimir A. and Peters, Brian and Madigan, Michael T. and Bowles, Marshall W. and Rachael M. Morgan-Kiss and Karen L. Casciotti and Joye, Samantha B.} } @article {4154, title = {The Antarctic psychrophiles Chlamydomonas spp. UWO241 and ICE-MDV exhibit differential restructuring of photosystem I in response to iron}, journal = {Photosynthesis Research}, volume = {9}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Cyclic electron flow, Iron, Photosystem I, Psychrophile}, issn = {0166-8595}, doi = {10.1007/s11120-019-00621-0}, url = {https://link.springer.com/article/10.1007/s11120-019-00621-0}, author = {Cook, Greg and Teufel, Amber and Kalra, Isha and Li, Wei and Wang, Xin and John C. Priscu and Rachael M. Morgan-Kiss} } @article {4153, title = {Biotic interactions are an unexpected yet critical control on the complexity of an abiotically driven polar ecosystem}, journal = {Communications Biology}, volume = {2}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s42003-018-0274-5}, url = {https://www.nature.com/articles/s42003-018-0274-5}, author = {Charles K. Lee and Laughlin, Daniel C. and Bottos, Eric M. and Caruso, Tancredi and Joy, Kurt and John E. Barrett and Brabyn, Lars and Uffe N. Nielsen and Byron Adams and Diana H. Wall and D. W. Hopkins and Pointing, Steve B. and McDonald, Ian R. and Cowan, Don A. and Banks, Jonathan C. and Stichbury, Glen A. and Jones, Irfon and Zawar-Reza, Peyman and Katurji, Marwan and Hogg, Ian D. and Sparrow, Ashley D. and Storey, Bryan C. and Allan Green, T. G. and Craig S Cary} } @article {4334, title = {Biotic interactions in experimental Antarctic soil microcosms vary with abiotic stress}, journal = {Soil Systems}, volume = {3}, year = {2019}, month = {08/2019}, abstract = {

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.

}, keywords = {LTER-MCM, bacteria, biological interactions, desert, nematode, polar, soil communities, top-down effects, trophic interactions}, doi = {10.3390/soilsystems3030057}, url = {https://www.mdpi.com/2571-8789/3/3/57}, author = {Shaw, E. Ashley and Diana H. Wall} } @phdthesis {4362, title = {Characterizing photobioregenerative technology for simulataneous thermal control and air revitalization of spacecraft and surface habitats}, volume = {Ph.D.}, year = {2019}, month = {11/2019}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://scholar.colorado.edu/asen_gradetds/258/}, author = {Matula, Emily E.} } @article {4332, title = {Community response of microbial primary producers to salinity is primarily driven by nutrients in lakes}, journal = {Science of the Total Environment}, volume = {696}, year = {2019}, month = {12/2019}, pages = {134001}, abstract = {

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.

}, keywords = {LTER-MCM, cbbL, lake waters, microbial primary producers, nutrient, salinity}, doi = {10.1016/j.scitotenv.2019.134001}, url = {https://www.sciencedirect.com/science/article/pii/S0048969719339786}, author = {Yue, Linyan and Weidong Kong and Ji, Mukan and Liu, Jinbo and Rachael M. Morgan-Kiss} } @inbook {4187, title = {Complex Structure but Simple Function in Microbial Mats from Antarctic Lakes}, booktitle = {The Structure and Function of Aquatic Microbial Communities}, year = {2019}, pages = {91 - 120}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, address = {Cham}, abstract = {

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.

}, keywords = {LTER-MCM, biofilm, microbial ecology, microbial structures, self-organising structures, stromatolite}, isbn = {978-3-030-16775-2}, doi = {10.1007/978-3-030-16775-2_4}, url = {https://link.springer.com/chapter/10.1007/978-3-030-16775-2_4}, author = {Ian Hawes and Sumner, Dawn Y. and Jungblut, Anne D.}, editor = {Hurst, Christon J.} } @article {4150, title = {Differential incorporation of bacteria, organic matter, and inorganic ions into lake ice during ice formation}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {124}, year = {2019}, month = {02/2019}, pages = {585 - 600}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2018JG004825}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JG004825}, author = {Santib{\'a}{\~n}ez, Pamela and Alexander B. Michaud and Trista J. Vick-Majors and D{\textquoteright}Andrilli, Juliana and Amy Chiuchiolo and Hand, Kevin P. and John C. Priscu} } @article {4244, title = {Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica}, journal = {E3S Web of Conferences}, volume = {98}, year = {2019}, month = {06/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1051/e3sconf/20199801020}, url = {https://www.e3s-conferences.org/articles/e3sconf/abs/2019/24/e3sconf_wri-162018_01020/e3sconf_wri-162018_01020.html}, author = {Harmon, Mark E. and Leslie, D.L. and W. Berry Lyons and Kathleen A. Welch and Diane M. McKnight}, editor = {Chudaev, O. and Kharaka, Y. and Harmon, R.S. and Millot, R. and Shouakar-Stash, O.} } @article {4152, title = {Drivers of protistan community autotrophy and heterotrophy in chemically stratified Antarctic lakes}, journal = {Aquatic Microbial Ecology}, volume = {82}, year = {2019}, month = {01/2019}, pages = {225 - 239}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctic lakes, Aquatic protists, Autotrophy, Heterotrophy, McMurdo Dry Valleys, RubisCO, β-D-glucosaminidase}, issn = {0948-3055}, doi = {10.3354/ame01891}, url = {https://www.int-res.com/abstracts/ame/v82/n3/p225-239/}, author = {Li, Wei and Dolhi-Binder, J and Cariani, ZE and Rachael M. Morgan-Kiss} } @article {4294, title = {Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica}, journal = {Geobiology}, year = {2019}, month = {07/2019}, abstract = {

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.

}, keywords = {LTER-MCM, anammox, bacteriohopanepolyol, bacteriohopanetetrol isomer, biomarker, McMurdo Dry Valleys}, doi = {10.1111/gbi.12353}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/gbi.12353}, author = {Matys, Emily D. and Mackey, Tyler J. and Grettenberger, Christen and Mueller, Elliott and Jungblut, Anne D. and Sumner, Dawn Y. and Ian Hawes and Summons, Roger E.} } @article {4450, title = {The Geochemistry of Englacial Brine From Taylor Glacier, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {124}, year = {2019}, month = {03/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2018JG004411}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JG004411}, author = {W. Berry Lyons and Jill A. Mikucki and German, Laura A. and Kathleen A. Welch and Sue Welch and Christopher B. Gardner and Tulaczyk, Slawek M. and Pettit, Erin C. and Kowalski, Julia and Dachwald, Bernd} } @article {4188, title = {The geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances}, journal = {Applied Geochemistry}, year = {2019}, month = {05/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, geochemistry, glacial deposits, polar dry-based glaciers, Taylor Valley}, doi = {10.1016/j.apgeochem.2019.05.006}, url = {https://www.sciencedirect.com/science/article/pii/S0883292719301246}, author = {Carolyn Dowling and Sue Welch and W. Berry Lyons} } @phdthesis {4761, title = {Heterotrophic protists as useful models for studying microbial food webs in a model soil ecosystem and the universality of complex unicellular life}, volume = {PhD}, year = {2019}, school = {Brigham Young University}, type = {doctoral}, address = {Provo, UT}, abstract = {

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.

}, keywords = {LTER-MCM, heterotrophic soil protists, key evolutionary innovations, life on Mars, McMurdo Dry Valleys, network analysis, shotgun metagenomics, universal complex unicellular life}, url = {https://www.proquest.com/docview/2310631977}, author = {Thompson, Andrew R.}, editor = {Adams, Byron J.} } @article {4373, title = {The hydroecology of an ephemeral wetland in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2019}, month = {11/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, desert hydrology, diatom biodiversity, hyporheic interactions, wetlands}, doi = {10.1029/2019JG005153}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JG005153}, author = {Wlostowski, Adam and Schulte, Nicholas O. and Byron Adams and Ball, Becky and Rhea M.M. Esposito and Michael N. Gooseff and W. Berry Lyons and Uffe N. Nielsen and Ross A. Virginia and Diana H. Wall and Kathleen A. Welch and Diane M. McKnight} } @mastersthesis {4165, title = {Impact of simulated polar night on Antarctic mixotrophic and strict photoautotrophic phytoplankton}, volume = {M.S.}, year = {2019}, month = {2018}, school = {Miami University}, type = {masters}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM, algae, Antarctic phytoplankton, chlorophyll fluorescence analysis, McMurdo Dry Valleys, Photosynthesis, phytoplankton, polar microbiology, polar night}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1547204599969081}, author = {Cariani, ZE and Rachael M. Morgan-Kiss} } @article {4140, title = {In a PICL: The sedimentary deposits and facies of perennially ice-covered lakes}, journal = {Sedimentology}, volume = {66}, year = {2019}, month = {04/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/sed.12522}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/sed.12522}, author = {Rivera-Hernandez, Frances and Sumner, Dawn Y. and Mackey, Tyler J. and Ian Hawes and Dale T. Andersen} } @article {4186, title = {Influence of environmental drivers and potential interactions on the distribution of microbial communities from three permanently stratified Antarctic lakes}, journal = {Frontiers in Microbiology}, volume = {10}, year = {2019}, month = {05/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Aquatic protists, environmental drivers, heterotrophic bacteria, interactions, McMurdo Dry Valley lakes}, doi = {10.3389/fmicb.2019.01067}, url = {https://www.frontiersin.org/articles/10.3389/fmicb.2019.01067/full}, author = {Li, Wei and Rachael M. Morgan-Kiss} } @article {4176, title = {Inorganic carbon fixation in ice-covered lakes of the McMurdo Dry Valleys}, journal = {Antarctic Science}, volume = {72}, year = {2019}, month = {04/2019}, abstract = {

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.

}, keywords = {LTER-MCM, ammonia oxidation, carbon budget, chemoautotrophy, chemolithoautotrophy}, issn = {0954-1020}, doi = {10.1017/S0954102019000075}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/inorganic-carbon-fixation-in-icecovered-lakes-of-the-mcmurdo-dry-valleys/4B5CA9E91C85B307EFDA69F8D7B5BFD9}, author = {Trista J. Vick-Majors and John C. Priscu} } @article {4335, title = {Sabbea gen. nov., a new diatom genus (Bacillariophyta) from continental Antarctica}, journal = {Phytotaxa}, volume = {418}, year = {2019}, month = {09/2019}, abstract = {

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.

}, keywords = {LTER-MCM, Bacillariophyta, Cape Royds, East Antarctica, McMurdo Dry Valleys, new genus, Vestfold Hills}, doi = {10.11646/phytotaxa.418.1.2}, url = {https://www.mapress.com/j/pt/article/view/phytotaxa.418.1.2}, author = {Bishop, Jordan and Kopalov{\'a}, Kate{\v r}ina and Darling, Joshua P. and Schulte, Nicholas O. and Tyler J. Kohler and McMinn, Andrew and Sarah A. Spaulding and Diane M. McKnight and Bart Van de Vijver} } @article {4837, title = {Meteorological connectivity from regions of high biodiversity within the McMurdo Dry Valleys of Antarctica}, journal = {Journal of Applied Meteorology and Climatology}, volume = {58}, year = {2019}, month = {11/2019}, pages = {2437 - 2452}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, atmosphere, biosphere-atmosphere interaction, mesoscale models, mesoscale processes, numerical analysis/modeling}, issn = {1558-8424}, doi = {10.1175/JAMC-D-18-0336.1}, url = {https://journals.ametsoc.org/view/journals/apme/58/11/jamc-d-18-0336.1.xml}, author = {Katurji, Marwan and Khan, Basit and Sprenger, Michael A. and Datta, Rajasweta and Joy, Kurt and Zawar-Reza, Peyman and Ian Hawes} } @article {4164, title = {Nematodes in a polar desert reveal the relative role of biotic interactions in the coexistence of soil animals}, journal = {Communications Biology}, volume = {2}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s42003-018-0260-y}, url = {http://www.nature.com/articles/s42003-018-0260-y}, author = {Caruso, Tancredi and Hogg, Ian D. and Uffe N. Nielsen and Bottos, Eric M. and Charles K. Lee and D. W. Hopkins and Craig S Cary and John E. Barrett and Green, T. G. Allan and Storey, Bryan C. and Diana H. Wall and Byron Adams} } @inbook {4333, title = {Placing the past: The McMurdo Dry Valleys and the problem of geographical specificity in Antarctic history}, booktitle = {Anthropocene Antarctica: Perspectives from the Humanities, Law and Social Sciences}, year = {2019}, publisher = {Routledge}, organization = {Routledge}, edition = {1st}, chapter = {11}, address = {London}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {9780429429705}, doi = {10.4324/9780429429705}, url = {https://www.taylorfrancis.com/books/e/9780429429705}, author = {Howkins, Adrian} } @article {4374, title = {The polar regions in a 2{\textdegree}C warmer world}, journal = {Science Advances}, volume = {5}, year = {2019}, month = {12/2019}, pages = {eaaw9883}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1126/sciadv.aaw9883}, url = {http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aaw9883}, author = {Post, Eric and Alley, Richard B. and Christensen, Torben R. and Macias-Fauria, Marc and Forbes, Bruce C. and Michael N. Gooseff and Iler, Amy and Kerby, Jeffrey T. and Laidre, Kristin L. and Mann, Michael E. and Olofsson, Johan and Stroeve, Julienne C. and Ulmer, Fran and Ross A. Virginia and Wang, Muyin} } @article {4151, title = {Prediction of ice-free conditions for a perennially ice-covered Antarctic lake}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {124}, year = {2019}, month = {02/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2018JF004756}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018JF004756}, author = {Maciek K. Obryk and Peter T. Doran and John C. Priscu} } @article {4360, title = {Provisional checklist of terrestrial heterotrophic protists from Antarctica}, journal = {Antarctic Science}, year = {2019}, month = {11/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1017/S0954102019000361}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/provisional-checklist-of-terrestrial-heterotrophic-protists-from-antarctica/DC08D89ABDC5AF2CC83E38B1C6F1F78C}, author = {Thompson, Andrew R. and Powell, Gareth S. and Byron Adams} } @article {4295, title = {Soil nematode abundance and functional group composition at a global scale}, journal = {Nature}, volume = {572}, year = {2019}, month = {08/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41586-019-1418-6}, url = {https://www.nature.com/articles/s41586-019-1418-6}, author = {van den Hoogen, Johan and Geisen, Stefan and Routh, Devin and Ferris, Howard and Traunspurger, Walter and Wardle, D and de Goede, Ron G. M. and Byron Adams and Ahmad, Wasim and Andriuzzi, Walter S. and Richard D. Bardgett and Bonkowski, Michael and Campos-Herrera, Raquel and Cares, Juvenil E. and Caruso, Tancredi and de Brito Caixeta, Larissa and Chen, Xiaoyun and Costa, Sofia R. and Creamer, Rachel and Mauro da Cunha Castro, Jos{\'e} and Dam, Marie and Djigal, Djibril and Escuer, Miguel and Griffiths, Bryan S. and Guti{\'e}rrez, Carmen and Hohberg, Karin and Kalinkina, Daria and Kardol, Paul and Kergunteuil, Alan and Korthals, Gerard and Krashevska, Valentyna and Kudrin, Alexey A. and Li, Qi and Liang, Wenju and Magilton, Matthew and Marais, Mariette and Mart{\'\i}n, Jos{\'e} Antonio Rodr{\'\i}guez and Matveeva, Elizaveta and Mayad, El Hassan and Mulder, Christian and Mullin, Peter and Neilson, Roy and Nguyen, T. A. Duong and Uffe N. Nielsen and Okada, Hiroaki and Rius, Juan Emilio Palomares and Pan, Kaiwen and Peneva, Vlada and Pellissier, Lo{\"\i}c and Carlos Pereira da Silva, Julio and Pitteloud, Camille and Powers, Thomas O. and Powers, Kirsten and Quist, Casper W. and Rasmann, Sergio and Moreno, Sara S{\'a}nchez and Scheu, Stefan and Set{\"a}l{\"a}, Heikki and Sushchuk, Anna and Tiunov, Alexei V. and Trap, Jean and van der Putten, W and Vesterg{\r a}rd, Mette and Villenave, Cecile and Waeyenberge, Lieven and Diana H. Wall and Wilschut, Rutger and Wright, Daniel G. and Yang, Jiue-in and Crowther, Thomas Ward} } @mastersthesis {4365, title = {Spatiotemporal impact of snow on underwater photosynthetically active radiation in Taylor Valley, East Antarctica}, volume = {M.S.}, year = {2019}, month = {08/2019}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/4965}, author = {Myers, Madeline and Peter T. Doran} } @article {4196, title = {Unimodal productivity{\textendash}diversity relationships among bacterial communities in a simple polar soil ecosystem}, journal = {Environmental Microbiology}, volume = {21}, year = {2019}, month = {07/2019}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/1462-2920.14639}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/1462-2920.14639}, author = {Kevin M. Geyer and John E. Barrett} } @article {4156, title = {Aeolian material transport and its role in landscape connectivity in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {123}, year = {2018}, month = {12/2018}, pages = {3323 - 3337}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2017JF004589}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JF004589}, author = {Melisa A. Diaz and Byron Adams and Kathleen A. Welch and Sue Welch and Opiyo, Stephen O. and Khan, Alia L. and Diane M. McKnight and Craig S Cary and W. Berry Lyons} } @mastersthesis {4166, title = {Antarctic Chlamydomonas strains C. sp. UWO241 and ICE-MDV exhibit differential restructuring of the photosynthetic apparatus in response to iron}, volume = {M.S.}, year = {2018}, month = {2018}, school = {Miami University}, type = {masters}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1525455621778836}, author = {Cook, Greg and Rachael M. Morgan-Kiss} } @article {4138, title = {Barium and barite dynamics in Antarctic streams}, journal = {Geology}, volume = {46}, year = {2018}, month = {08/2018}, pages = {811 - 814}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G45048.1}, url = {https://pubs.geoscienceworld.org/gsa/geology/article/545184/Barium-and-barite-dynamics-in-Antarctic-streams}, author = {Saelens, Elsa D. and Christopher B. Gardner and Kathleen A. Welch and Sue Welch and W. Berry Lyons} } @article {4063, title = {Biogeochemical weathering of soil apatite grains in the McMurdo Dry Valleys, Antarctica}, journal = {Geoderma}, volume = {320}, year = {2018}, month = {01/2018}, pages = {136-145}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00167061}, doi = {10.1016/j.geoderma.2018.01.027}, url = {https://www.sciencedirect.com/science/article/pii/S0016706117320694}, author = {Heindel, Ruth C and W. Berry Lyons and Sue Welch and Spickard, Angela M and Ross A. Virginia} } @phdthesis {4189, title = {Biogeochemistry, contaminant transport, and atmospheric exchange in glacial cryoconite meltwater of the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2018}, month = {2018}, pages = {245}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, applied sciences, contaminant transport, cryoconite, earth sciences, glacier, hydrology, melt}, url = {https://search.proquest.com/docview/2048314678}, author = {Mass, Alex Q. and Diane M. McKnight} } @article {4159, title = {BioTIME: A database of biodiversity time series for the Anthropocene}, journal = {Global Ecology and Biogeography}, volume = {27}, year = {2018}, month = {07/2018}, pages = {760-786}, abstract = {

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.

}, keywords = {LTER-MCM, biodiversity, global, spatial, species richness, temporal, turnover}, doi = {10.1111/geb.12729}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/geb.12729}, author = {Dornelas, Maria and Ant{\~a}o, Laura H. and Moyes, Faye and Bates, Amanda E. and Magurran, Anne E. and Adam, Du{\v s}an and Akhmetzhanova, Asem A. and Appeltans, Ward and Arcos, Jos{\'e} Manuel and Arnold, Haley and Ayyappan, Narayanan and Badihi, Gal and Baird, Andrew H. and Barbosa, Miguel and Barreto, Tiago Egydio and B{\"a}ssler, Claus and Bellgrove, Alecia and Belmaker, Jonathan and Benedetti-Cecchi, Lisandro and Bett, Brian J. and Bjorkman, Anne D. and B{\l}a{\.z}ewicz, Magdalena and Blowes, Shane A. and Bloch, Christopher P. and Bonebrake, Timothy C. and Boyd, Susan and Bradford, Matt and Brooks, Andrew J. and Brown, James H. and Bruelheide, Helge and Budy, Phaedra and Carvalho, Fernando and Casta{\~n}eda-Moya, Edward and Chen, Chaolun Allen and Chamblee, John F. and Chase, Tory J. and Siegwart Collier, Laura and Collinge, Sharon K. and Condit, Richard and Cooper, Elisabeth J. and Cornelissen, J. Hans C. and Cotano, Unai and Kyle Crow, Shannan and Damasceno, Gabriella and Davies, Claire H. and Davis, Robert A. and Day, Frank P. and Degraer, Steven and Doherty, Tim S. and Dunn, Timothy E. and Durigan, Giselda and Duffy, J. Emmett and Edelist, Dor and Edgar, Graham J. and Elahi, Robin and Elmendorf, Sarah C. and Enemar, Anders and Ernest, S. K. Morgan and Escribano, Rub{\'e}n and Estiarte, Marc and Evans, Brian S. and Fan, Tung-Yung and Turini Farah, Fabiano and Loureiro Fernandes, Luiz and Farneda, F{\'a}bio Z. and Fidelis, Alessandra and Fitt, Robert and Fosaa, Anna Maria and Daher Correa Franco, Geraldo Antonio and Frank, Grace E. and Fraser, William R. and Garc{\'\i}a, Hernando and Cazzolla Gatti, Roberto and Givan, Or and Gorgone-Barbosa, Elizabeth and Gould, William A. and Gries, Corinna and Grossman, Gary D. and Gutierr{\'e}z, Julio R. and Hale, Stephen and Harmon, Mark E. and Harte, John and Haskins, Gary and Henshaw, Donald L. and Hermanutz, Luise and Hidalgo, Pamela and Higuchi, Pedro and Hoey, Andrew and Van Hoey, Gert and Hofgaard, Annika and Holeck, Kristen and Hollister, Robert D. and Holmes, Richard and Hoogenboom, Mia and Hsieh, Chih-hao and Hubbell, Stephen P. and Huettmann, Falk and Huffard, Christine L. and Hurlbert, Allen H. and Macedo Ivanauskas, Nat{\'a}lia and Jan{\'\i}k, David and Jandt, Ute and Ja{\.z}d{\.z}ewska, Anna and Johannessen, Tore and Johnstone, Jill and Jones, Julia and Jones, Faith A. M. and Kang, Jungwon and Kartawijaya, Tasrif and Keeley, Erin C. and Kelt, Douglas A. and Kinnear, Rebecca and Klanderud, Kari and Knutsen, Halvor and Koenig, Christopher C. and Kortz, Alessandra R. and Kr{\'a}l, Kamil and Kuhnz, Linda A. and Kuo, Chao-Yang and Kushner, David J. and Laguionie-Marchais, Claire and Lancaster, Lesley T. and Min Lee, Cheol and Lefcheck, Jonathan S. and L{\'e}vesque, Esther and Lightfoot, David and Lloret, Francisco and Lloyd, John D. and L{\'o}pez-Baucells, Adri{\`a} and Louzao, Maite and Madin, Joshua S. and Magn{\'u}sson, Borg{\th}{\'o}r and Malamud, Shahar and Matthews, Iain and McFarland, Kent P. and McGill, Brian and Diane M. McKnight and McLarney, William O. and Meador, Jason and Meserve, Peter L. and Metcalfe, Daniel J. and Meyer, Christoph F. J. and Michelsen, Anders and Milchakova, Nataliya and Moens, Tom and Moland, Even and Moore, Jon and Mathias Moreira, Carolina and M{\"u}ller, J{\"o}rg and Murphy, Grace and Myers-Smith, Isla H. and Myster, Randall W. and Naumov, Andrew and Neat, Francis and Nelson, James A. and Paul Nelson, Michael and Newton, Stephen F. and Norden, Natalia and Oliver, Jeffrey C. and Olsen, Esben M. and Onipchenko, Vladimir G. and Pabis, Krzysztof and Pabst, Robert J. and Paquette, Alain and Pardede, Sinta and Paterson, David M. and P{\'e}lissier, Rapha{\"e}l and Pe{\~n}uelas, Josep and P{\'e}rez-Matus, Alejandro and Pizarro, Oscar and Pomati, Francesco and Post, Eric and Prins, Herbert H. T. and John C. Priscu and Provoost, Pieter and Prudic, Kathleen L. and Pulliainen, Erkki and Ramesh, B. R. and Mendivil Ramos, Olivia and Rassweiler, Andrew and Rebelo, Jose Eduardo and Reed, Daniel C. and Reich, Peter B. and Remillard, Suzanne M. and Richardson, Anthony J. and Richardson, J. Paul and van Rijn, Itai and Rocha, Ricardo and Rivera-Monroy, Victor H. and Rixen, Christian and Robinson, Kevin P. and Ribeiro Rodrigues, Ricardo and de Cerqueira Rossa-Feres, Denise and Rudstam, Lars and Ruhl, Henry and Ruz, Catalina S. and Sampaio, Erica M. and Rybicki, Nancy and Rypel, Andrew and Sal, Sofia and Salgado, Beatriz and Santos, Flavio A. M. and Savassi-Coutinho, Ana Paula and Scanga, Sara and Schmidt, Jochen and Schooley, Robert and Setiawan, Fakhrizal and Shao, Kwang-Tsao and Shaver, Gaius R. and Sherman, Sally and Sherry, Thomas W. and Sici{\'n}ski, Jacek and Sievers, Caya and da Silva, Ana Carolina and Rodrigues da Silva, Fernando and Silveira, Fabio L. and Slingsby, Jasper and Smart, Tracey and Snell, Sara J. and Soudzilovskaia, Nadejda A. and Souza, Gabriel B. G. and Maluf Souza, Flaviana and Castro Souza, Vin{\'\i}cius and Stallings, Christopher D. and Stanforth, Rowan and Stanley, Emily H. and Mauro Sterza, Jos{\'e} and Stevens, Maarten and Stuart-Smith, Rick and Rondon Suarez, Yzel and Supp, Sarah} } @article {4110, title = {Catch and release: Hyporheic retention and mineralization of N-fixing Nostoc sustains downstream microbial mat biomass in two polar desert streams}, journal = {Limnology and Oceanography Letters}, volume = {3}, year = {2018}, month = {07/2018}, pages = {357 - 364}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/lol2.10087}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.1002/lol2.10087}, author = {Tyler J. Kohler and Lee F. Stanish and Liptzin, D. and John E. Barrett and Diane M. McKnight} } @article {4105, title = {Dissolved Trace and Minor Elements in Cryoconite Holes and Supraglacial Streams, Canada Glacier, Antarctica}, journal = {Frontiers in Earth Science}, volume = {6}, year = {2018}, month = {04/2018}, abstract = {

We present a synthesis of the trace element chemistry in melt on the surface Canada Glacier, Taylor Valley, McMurdo Dry Valleys (MDV), Antarctica (\∼78{\textopenbullet}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.

}, keywords = {LTER-MCM, Antarctica, cryoconite holes, glacier melt chemistry, supraglacial streams, trace elements}, doi = {10.3389/feart.2018.00031}, url = {http://journal.frontiersin.org/article/10.3389/feart.2018.00031/full}, author = {Sarah Fortner and W. Berry Lyons} } @article {4079, title = {Drivers of solar radiation variability in the McMurdo Dry Valleys, Antarctica}, journal = {Scientific Reports}, volume = {8}, year = {2018}, month = {03/2018}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41598-018-23390-7}, url = {http://www.nature.com/articles/s41598-018-23390-7.pdf}, author = {Maciek K. Obryk and Andrew G Fountain and Peter T. Doran and W. Berry Lyons and Eastman, R.} } @article {4157, title = {Fe and Nutrients in Coastal Antarctic Streams: Implications for Primary Production in the Ross Sea}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {123}, year = {2018}, month = {12/2018}, pages = {3507 - 3522}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2169-8953}, doi = {10.1029/2017JG004352}, url = {https://agupubs.pericles-prod.literatumonline.com/doi/full/10.1029/2017JG004352}, author = {Sydney A. Olund and W. Berry Lyons and Sue Welch and Kathleen A. Welch} } @phdthesis {4363, title = {Genomics and transcriptomics of Antarctic nematodes reveal drivers of life history evolution and genome evolution}, volume = {Ph.D.}, year = {2018}, school = {Brigham Young University}, type = {doctoral}, address = {Provo, UT}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctic nematodes, Caenorhabditis elegans, genome evolution, growth rate hypothesis, Plectus murrayi, Scottnema lindsayae, transcriptome}, url = {https://search.proquest.com/docview/2081899003}, author = {Xue, Xia and Byron Adams} } @mastersthesis {4364, title = {Groundwater and thermal legacy of a large paleolake in Taylor Valley, East Antarctica as evidenced by airborne electromagnetic and sedimentological techniques}, volume = {M.S.}, year = {2018}, month = {07/2018}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/4776}, author = {Myers, Krista F. and Peter T. Doran} } @article {4106, title = {The impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited}, journal = {Elementa: Science of the Anthropocene}, volume = {6}, year = {2018}, month = {04/2018}, abstract = {

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.

}, keywords = {LTER-MCM, carbon dynamics, emissions, fossil fuels, helicopter, management, McMurdo Dry Valleys, nitrogen, science activites}, doi = {10.1525/elementa.288}, url = {https://www.elementascience.org/article/10.1525/elementa.288/}, author = {W. Berry Lyons and Saelens, Elsa D. and Kathleen A. Welch} } @article {4136, title = {Local and Regional Scale Heterogeneity Drive Bacterial Community Diversity and Composition in a Polar Desert}, journal = {Frontiers in Microbiology}, volume = {9}, year = {2018}, month = {08/2018}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2018.01928}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2018.01928/full}, author = {Feeser, Kelli L. and David J. Van Horn and Heather N. Buelow and Colman, Daniel R. and McHugh, Theresa A. and Okie, Jordan G. and Schwartz, Egbert and Cristina D. Takacs-Vesbach} } @mastersthesis {4441, title = {Microbial and CO2 responses to water stresses show decreased productivity and diversity through time}, volume = {M.S.}, year = {2018}, month = {05/2018}, school = {Brigham Young University}, type = {masters}, address = {Provo, UT}, abstract = {

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.

}, keywords = {LTER-MCM, dormancy, PiCRUST, turnover}, url = {https://scholarsarchive.byu.edu/etd/6830}, author = {Robinson, David M. and Aanderud, Zachary T.} } @article {4068, title = {Near-surface refractory black carbon observations in the atmosphere and snow in the McMurdo Dry Valleys, Antarctica and potential impacts of foehn winds}, journal = {Journal of Geophysical Research: Atmospheres}, volume = {123}, year = {2018}, month = {01/2018}, pages = {2877 - 2887}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/2017JD027696}, url = {http://doi.wiley.com/10.1002/2017JD027696}, author = {Khan, Alia L. and McMeeking, Gavin and Schwarz, Joshua P. and Xian, Peng and Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight} } @article {4060, title = {Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change}, journal = {Ecology}, volume = {99}, year = {2018}, month = {02/2018}, pages = {312 - 321}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/ecy.2090}, url = {http://doi.wiley.com/10.1002/ecy.2090/full}, author = {Andriuzzi, Walter S. and Byron Adams and John E. Barrett and Ross A. Virginia and Diana H. Wall} } @article {4155, title = {Photoecology of the Antarctic cyanobacterium Leptolyngbya sp. BC1307 brought to light through community analysis, comparative genomics and in vitro photophysiology}, journal = {Molecular Ecology}, volume = {27}, year = {2018}, month = {11/2018}, pages = {5279 - 5293}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, cyanobacteria, genomics, photoecology, photophysiology}, doi = {10.1111/mec.14953}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/mec.14953}, author = {Chrismas, Nathan A. M. and Williamson, Christopher J. and Yallop, Marian L. and Alexandre M. Anesio and S{\'a}nchez-Baracaldo, Patricia} } @article {4061, title = {The physical limnology of a permanently ice-covered and chemically stratified Antarctic lake using high resolution spatial data from an autonomous underwater vehicle}, journal = {Limnology and Oceanography}, volume = {63}, year = {2018}, month = {05/2018}, pages = {1234 - 1252}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/lno.10768}, url = {http://onlinelibrary.wiley.com/wol1/doi/10.1002/lno.10768/full}, author = {Spigel, Robert H. and John C. Priscu and Maciek K. Obryk and Stone, William C. and Peter T. Doran} } @inbook {4113, title = {Physiological and Biochemical Adaptations of Psychrophiles}, booktitle = {Extremophiles}, year = {2018}, publisher = {CRC Press}, organization = {CRC Press}, chapter = {9}, address = {Boca Raton}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://www.taylorfrancis.com/books/e/9781498774932/chapters/10.1201\%2F9781315154695-9}, author = {Teufel, Amber G. and Rachael M. Morgan-Kiss} } @article {4080, title = {Soil biological responses to C, N and P fertilization in a polar desert of Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {122}, year = {2018}, month = {07/2018}, chapter = {7}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00380717}, doi = {10.1016/j.soilbio.2018.03.025}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0038071718301081}, author = {Ball, Becky and Byron Adams and John E. Barrett and Diana H. Wall and Ross A. Virginia} } @article {4058, title = {Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {123}, year = {2018}, month = {01/2018}, chapter = {46-59}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/2017JG004018}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JG004018}, author = {Wlostowski, Adam and Michael N. Gooseff and Byron Adams} } @article {4107, title = {Spatial and temporal patterns of microbial mats and associated invertebrates along an Antarctic stream}, journal = {Polar Biology}, volume = {41}, year = {2018}, month = {10/2018}, pages = {1911{\textendash}1921}, abstract = {

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.

}, keywords = {LTER-MCM, diatoms, Disturbance, Dry valleys, Epilithon, Microfauna, Stream flow}, doi = {10.1007/s00300-018-2331-4}, url = {http://link.springer.com/10.1007/s00300-018-2331-4}, author = {Andriuzzi, Walter S. and Lee F. Stanish and Breana L. Simmons and Chris Jaros and Byron Adams and Diana H. Wall and Diane M. McKnight} } @article {4059, title = {Stable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore{\textendash}predator in~Taylor Valley, Antarctica}, journal = {Polar Biology}, volume = {41}, year = {2018}, month = {05/2018}, pages = {1013{\textendash}1018}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1007/s00300-017-2243-8}, url = {http://link.springer.com/10.1007/s00300-017-2243-8}, author = {Shaw, E. Ashley and Byron Adams and John E. Barrett and W. Berry Lyons and Ross A. Virginia and Diana H. Wall} } @article {4139, title = {Stoichiometric Shifts in Soil C:N:P Promote Bacterial Taxa Dominance, Maintain Biodiversity, and Deconstruct Community Assemblages}, journal = {Frontiers in Microbiology}, volume = {9}, year = {2018}, month = {07/2018}, abstract = {

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.

}, keywords = {LTER-MCM, ecological stoichiometry, Lake Fryxell Basin, McMurdo Dry Valleys, network community modeling, nutrient colimitation, Solirubrobacteriaceae}, doi = {10.3389/fmicb.2018.01401}, url = {https://www.frontiersin.org/article/10.3389/fmicb.2018.01401/full}, author = {Aanderud, Zachary T. and Saurey, Sabrina D. and Ball, Becky and Diana H. Wall and John E. Barrett and Muscarella, Mario E. and Griffin, Natasha A. and Ross A. Virginia and Byron Adams} } @article {4160, title = {Transit times and rapid chemical equilibrium explain chemostasis in glacial meltwater streams in the McMurdo Dry Valleys, Antarctica}, journal = {Geophysical Research Letters}, volume = {45}, year = {2018}, month = {12/2018}, pages = {13322 - 13331}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2018GL080369}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GL080369}, author = {Wlostowski, Adam and Michael N. Gooseff and Diane M. McKnight and W. Berry Lyons} } @phdthesis {4158, title = {Trophic relationships in soil communities how abiotic stress affects biotic interactions in the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2018}, pages = {119}, school = {Colorado State University}, type = {doctoral}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://search.proquest.com/openview/0d494a3f115b75da1c7a2464e341808f/1?pq-origsite=gscholar\&cbl=18750\&diss=y}, author = {Shaw, E. Ashley and Diana H. Wall} } @article {4027, title = {Ca isotopic geochemistry of an Antarctic aquatic system}, journal = {Geophysical Research Letters}, volume = {44}, year = {2017}, month = {01/2017}, pages = {882 - 891}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/2016GL071169}, url = {http://onlinelibrary.wiley.com/doi/10.1002/2016GL071169/full}, author = {W. Berry Lyons and Bullen, T and Kathleen A. Welch} } @article {4031, title = {Characterizing hyporheic exchange processes using high-frequency electrical conductivity-discharge relationships on subhourly to interannual timescales}, journal = {Water Resources Research}, volume = {53}, year = {2017}, month = {05/2017}, pages = {4124 - 4141}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/wrcr.v53.510.1002/2016WR019739}, url = {http://onlinelibrary.wiley.com/doi/10.1002/2016WR019739/full}, author = {Singley, Joel G. and Wlostowski, Adam and Bergstrom, Anna J. and Eric R. Sokol and Torrens, Christa L. and Chris Jaros and Wilson, Colleen E. and Hendrickson, Patrick J. and Michael N. Gooseff} } @inbook {4100, title = {The Climate of Snow and Ice as Boundary Condition for Microbial Life in Psychrophiles: From Biodiversity to Biotechnology}, year = {2017}, publisher = {Springer}, organization = {Springer}, edition = {2}, abstract = {

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.

}, keywords = {LTER-MCM}, isbn = {978-3-319-57056-3}, doi = {10.1007/978-3-319-57057-010.1007/978-3-319-57057-0_1}, url = {http://link.springer.com/content/pdf/10.1007/978-3-319-57057-0}, author = {Kuhn, Michael and Andrew G Fountain}, editor = {R. Margesin} } @article {4112, title = {A communal catalogue reveals Earth{\textquoteright}s multiscale microbial diversity}, journal = {Nature}, volume = {551}, year = {2017}, month = {11/2017}, chapter = {457}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/nature24621}, url = {https://www.nature.com/articles/nature24621}, author = {Thompson, Luke R. and Sanders, Jon G. and McDonald, Daniel and Amir, Amnon and Ladau, Joshua and Locey, Kenneth J. and Prill, Robert J. and Tripathi, Anupriya and Gibbons, Sean M. and Ackermann, Gail and Navas-Molina, Jose A. and Janssen, Stefan and Kopylova, Evguenia and V{\'a}zquez-Baeza, Yoshiki and Antonio Gonz{\'a}lez and Morton, James T. and Mirarab, Siavash and Zech Xu, Zhenjiang and Jiang, Lingjing and Haroon, Mohamed F. and Kanbar, Jad and Zhu, Qiyun and Jin Song, Se and Kosciolek, Tomasz and Bokulich, Nicholas A. and Lefler, Joshua and Brislawn, Colin J. and Humphrey, Gregory and Owens, Sarah M. and Hampton-Marcell, Jarrad and Berg-Lyons, Donna and McKenzie, Valerie and Noah Fierer and Fuhrman, Jed A. and Clauset, Aaron and Stevens, Rick L. and Shade, Ashley and Pollard, Katherine S. and Goodwin, Kelly D. and Jansson, Janet K. and Gilbert, Jack A. and Knight, Rob and The Earth Microbiome Project Consortium} } @thesis {4083, title = {Comparing the Weathering Environment of Permian and Modern Antarctic Proglacial Lake Sediments: Mineralogical and Geochemical Study}, volume = {B.S.}, year = {2017}, school = {The Ohio State University}, type = {bachelors}, address = {Columbus, OH}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://hdl.handle.net/1811/80763}, author = {Brewster, Shelby A.}, editor = {W. Berry Lyons} } @article {4022, title = {Decadal ecosystem response to an anomalous melt season in a polar desert in Antarctica}, journal = {Nature Ecology \& Evolution}, volume = {1}, year = {2017}, month = {09/2017}, pages = {1334-1338}, keywords = {LTER-MCM}, doi = {10.1038/s41559-017-0253-0}, url = {https://www.nature.com/articles/s41559-017-0253-0}, author = {Michael N. Gooseff and John E. Barrett and Byron Adams and Peter T. Doran and Andrew G Fountain and W. Berry Lyons and Diane M. McKnight and John C. Priscu and Eric R. Sokol and Cristina D. Takacs-Vesbach and Martijn L. Vandegehuchte and Ross A. Virginia and Diana H. Wall} } @article {4024, title = {Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys}, journal = {Ecology Letters}, volume = {20}, year = {2017}, month = {10/2017}, pages = {1242-1249}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/ele.12819}, url = {http://onlinelibrary.wiley.com/doi/10.1111/ele.12819/full}, author = {Matthew Knox and Andriuzzi, Walter S. and Heather N. Buelow and Cristina D. Takacs-Vesbach and Byron Adams and Diana H. Wall} } @article {4002, title = {Dissolved black carbon in the global cryosphere: Concentrations and chemical signatures}, journal = {Geophysical Research Letters}, volume = {44}, year = {2017}, month = {06/2017}, pages = {6226-6234}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/2017GL073485}, url = {http://doi.wiley.com/10.1002/2017GL073485}, author = {Khan, Alia L. and Wagner, Sasha and Jaff{\'e}, Rudolf and Xian, Peng and Williams, Mark and Armstrong, Richard and Diane M. McKnight} } @article {4019, title = {Diversity and Distribution of Freshwater Aerobic Anoxygenic Phototrophic Bacteria across a Wide Latitudinal Gradient}, journal = {Frontiers in Microbiology}, volume = {8}, year = {2017}, month = {02/2017}, abstract = {

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).

}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2017.00175}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2017.00175/full}, author = {Ferrera, Isabel and Sarmento, Hugo and John C. Priscu and Amy Chiuchiolo and Jos{\'e} M. Gonz{\'a}lez and Grossart, Hans-Peter} } @article {4111, title = {Early diverging lineages within Cryptomycota and Chytridiomycota dominate the fungal communities in ice-covered lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Scientific Reports}, volume = {7}, year = {2017}, month = {11/2017}, chapter = {15348}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1038/s41598-017-15598-w}, url = {https://www.nature.com/articles/s41598-017-15598-w}, author = {Rojas-Jimenez, Keilor and Wurzbacher, Christian and Bourne, Elizabeth Charlotte and Amy Chiuchiolo and John C. Priscu and Grossart, Hans-Peter} } @mastersthesis {4089, title = {Evidence of subglacial brine inflow and wind-induced mixing from high resolution temperature measurements in Lake Bonney, Antarctica}, volume = {M.S.}, year = {2017}, school = {Louisiana State University}, type = {masters}, address = {Baton Rouge, LA}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://digitalcommons.lsu.edu/gradschool_theses/4343}, author = {Lawrence, Jade and Peter T. Doran} } @mastersthesis {4066, title = {Fe and Nutrients in Coastal Antarctic Streams: Implications for Marine Primary Production in the Ross Sea}, volume = {M.S.}, year = {2017}, school = {Ohio State University}, type = {masters}, abstract = {

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.
}, keywords = {LTER-MCM}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=osu1492697894343546}, author = {Sydney A. Olund}, editor = {W. Berry Lyons} } @article {4064, title = {Freshwater diatom biogeography and the genus Luticola: an extreme case of endemism in Antarctica}, journal = {Polar Biology}, volume = {40}, year = {2017}, month = {03/2017}, pages = {1185-1196}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-017-2090-7}, url = {https://link.springer.com/article/10.1007/s00300-017-2090-7}, author = {J. Patrick Kociolek and Kopalova, K and Hamsher, S. E. and Tyler J. Kohler and Bart Van de Vijver and Convey, Peter and Diane M. McKnight} } @thesis {4099, title = {The geochemistry of minor cations within Antarctic stream water: Determining the role of the hyporheic zone}, volume = {B.A.}, year = {2017}, school = {The Ohio State University}, type = {bachelors}, address = {Columbus, OH}, keywords = {LTER-MCM}, url = {http://library.ohio-state.edu/record=b8218699~S7}, author = {Saelens, Elsa D.}, editor = {W. Berry Lyons} } @article {4101, title = {High-resolution elevation mapping of the McMurdo Dry Valleys, Antarctica, and surrounding regions}, journal = {Earth System Science Data}, volume = {9}, year = {2017}, month = {07/2017}, pages = {435 - 443}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.5194/essd-9-435-2017}, url = {https://www.earth-syst-sci-data.net/9/435/2017/essd-9-435-2017.pdf}, author = {Andrew G Fountain and Fernandez-Diaz, Juan C. and Maciek K. Obryk and Joseph S. Levy and Michael N. Gooseff and David J. Van Horn and Morin, P and Shrestha, Ramesh} } @article {4023, title = {Hydrologic connectivity and implications for ecosystem processes - Lessons from naked watersheds}, journal = {Geomorphology}, volume = {277}, year = {2017}, month = {01/2017}, pages = {63 - 71}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0169555X}, doi = {10.1016/j.geomorph.2016.04.024}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0169555X16302483}, author = {Michael N. Gooseff and Wlostowski, Adam and Diane M. McKnight and Chris Jaros} } @phdthesis {4161, title = {Hydrologic connectivity in the McMurdo Dry Valleys, Antarctica: Water-mediated mass and energy fluxes in streams and soils}, volume = {Ph.D.}, year = {2017}, school = {University of Colorado Boulder}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://scholar.colorado.edu/cven_gradetds/77/}, author = {Wlostowski, Adam and Michael N. Gooseff} } @article {4115, title = {Impact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach}, journal = {Polar Biology}, volume = {40}, year = {2017}, month = {05/2017}, chapter = {1007}, abstract = {

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.

}, keywords = {LTER-MCM, Algal{\textendash}bacteria interactions, climate change, McMurdo Dry Valleys, Nutrient bioassay, Primary production}, issn = {0722-4060}, doi = {10.1007/s00300-016-2025-8}, url = {https://link.springer.com/article/10.1007/s00300-016-2025-8}, author = {Teufel, Amber G. and Li, Wei and Kiss, Andor J. and Rachael M. Morgan-Kiss} } @article {4032, title = {Impacts of permafrost degradation on a stream in Taylor Valley, Antarctica}, journal = {Geomorphology}, volume = {285}, year = {2017}, month = {05/2017}, pages = {205 - 213}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2017.02.009}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0169555X16308467}, author = {Sudman, Zachary and Michael N. Gooseff and Andrew G Fountain and Joseph S. Levy and Maciek K. Obryk and David J. Van Horn} } @article {4029, title = {The influence of f{\"o}hn winds on Glacial Lake Washburn and palaeotemperatures in the McMurdo Dry Valleys, Antarctica, during the Last Glacial Maximum}, journal = {Antarctic Science}, volume = {29}, year = {2017}, month = {10/2017}, pages = {457-467}, keywords = {LTER-MCM}, doi = {10.1017/S0954102017000062}, url = {https://www.cambridge.org/core/product/identifier/S0954102017000062/type/journal_article}, author = {Maciek K. Obryk and Peter T. Doran and Waddington, E.D. and Christopher P. McKay} } @article {3990, title = {Landscape-scale soil phosphorus variability in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, volume = {29}, year = {2017}, month = {06/2017}, pages = {252-263}, keywords = {LTER-MCM}, doi = {10.1017/S0954102016000742}, url = {https://www.cambridge.org/core/product/identifier/S0954102016000742/type/journal_article}, author = {Heindel, Ruth C and Spickard, Angela M and Ross A. Virginia} } @article {4016, title = {Life cycle size dynamics in Didymosphenia geminata (Bacillariophyceae)}, journal = {Journal of Phycology}, volume = {53}, year = {2017}, month = {06/2017}, pages = {652 - 663}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1111/jpy.2017.53.issue-310.1111/jpy.12528}, url = {http://onlinelibrary.wiley.com/doi/10.1111/jpy.12528/full}, author = {Bishop, Ian W. and Sarah A. Spaulding} } @mastersthesis {4092, title = {Long-term and over winter phytoplankton community dynamics in Lake Bonney, Antarctica}, volume = {M.S.}, year = {2017}, month = {2017}, school = {Montana State University}, type = {masters}, address = {Bozeman, MT}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://scholarworks.montana.edu/xmlui/handle/1/12803}, author = {Patriarche, Jeffrey D.}, editor = {John C. Priscu} } @article {4114, title = {Multiple ice-binding proteins of probable prokaryotic origin in an Antarctic lake alga, Chlamydomonas sp. ICE-MDV (Chlorophyceae)}, journal = {Journal of Phycology}, volume = {53}, year = {2017}, month = {08/2017}, chapter = {848}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/jpy.12550}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jpy.12550}, author = {Raymond, James A. and Rachael M. Morgan-Kiss}, editor = {Valentin, K.} } @article {4103, title = {Niche specialization of bacteria in permanently ice-covered lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Environmental Microbiology}, volume = {19}, year = {2017}, month = {06/2017}, pages = {2258 - 2271}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/emi.2017.19.issue-610.1111/1462-2920.13721}, url = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/1462-2920.13721}, author = {Kwon, Miye and Kim, Mincheol and Cristina D. Takacs-Vesbach and Lee, Jaejin and Hong, Soon Gyu and Kim, Sang Jong and John C. Priscu and Kim, Ok-Sun} } @mastersthesis {4067, title = {Nitrate Dynamics Under Unsteady and Intermittent Flow in an Antarctic Stream}, volume = {M.S.}, year = {2017}, school = {University of Colorado at Boulder}, type = {masters}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://search.proquest.com/openview/88a6ce6614e2a0cfc757c8fd7a887504/1?pq-origsite=gscholar\&cbl=18750\&diss=y}, author = {Singley, Joel G.}, editor = {Eve-Lyn S. Hinckley} } @article {4021, title = {Primary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem}, journal = {PeerJ}, volume = {5}, year = {2017}, month = {07/2017}, pages = {e3377}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.7717/peerj.3377}, url = {https://peerj.com/articles/3377/}, author = {Kevin M. Geyer and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {3965, title = {A simulation-based approach to understand how metacommunity characteristics influence emergent biodiversity patterns}, journal = {Oikos}, volume = {126}, year = {2017}, month = {05/2017}, pages = {723-737}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/oik.03690}, url = {http://doi.wiley.com/10.1111/oik.03690}, author = {Eric R. Sokol and Brown, Bryan L. and John E. Barrett} } @mastersthesis {4065, title = {Spatial and Temporal Geochemical Characterization of Aeolian Material from the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2017}, school = {Ohio State University}, type = {masters}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=osu1500468216147725}, author = {Melisa A. Diaz}, editor = {W. Berry Lyons} } @article {4026, title = {A temporal stable isotopic (δ18O, δD, d-excess) comparison in glacier meltwater streams, Taylor Valley, Antarctica}, journal = {Hydrological Processes}, volume = {31}, year = {2017}, month = {08/2017}, pages = {3069 - 3083}, abstract = {

In this paper, we describe the importance of hyporheic dynamics within Andersen Creek and Von Guerard Stream, Taylor Valley, Antarctica, from the 2010\–2011 melt season using natural tracers. Water collection started at flow onset and continued, with weekly hyporheic-zone sampling. The water δ18O and δD values were isotopically lighter in the beginning and heavier later in the season. D-excess measurements were used as an indicator of mixing because an evaporative signature was evident and distinguishable between 2 primary end-members (glacier meltwater and hyporheic zone). Hyporheic-zone 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 hyporheic-zone solute interaction through the influence from subsurface hypersaline flow. Overall, the evolution of Taylor Valley hyporheic-zone hydrology is described seasonally. In mid-December, 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 zone\–stream interaction in these glacier meltwater streams.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.v31.1710.1002/hyp.11245}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.11245/full}, author = {Leslie, D.L. and Kathleen A. Welch and W. Berry Lyons} } @article {4018, title = {Thermal autecology describes the occurrence patterns of four benthic diatoms in McMurdo Dry Valley streams}, journal = {Polar Biology}, volume = {40}, year = {2017}, month = {06/2017}, pages = {2381-2396}, abstract = {

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.
}, keywords = {LTER-MCM}, doi = {10.1007/s00300-017-2151-y}, url = {https://link.springer.com/article/10.1007/s00300-017-2151-y}, author = {Darling, Joshua P. and Garland, Deena D. and Lee F. Stanish and Rhea M.M. Esposito and Eric R. Sokol and Diane M. McKnight} } @article {3713, title = {Aerobiology Over Antarctica {\textendash} A New Initiative for Atmospheric Ecology}, journal = {Frontiers in Microbiology}, volume = {776796194610314927235011365134445142846479110123936574}, year = {2016}, month = {02/2016}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.00016}, url = {http://journal.frontiersin.org/Article/10.3389/fmicb.2016.00016/abstract}, author = {Pearce, David A. and Alekhina, Irina A. and Terauds, Aleks and Wilmotte, Annick and Quesada, Antonio and Edwards, Arwyn and Dommergue, Aurelien and Sattler, Birgit and Byron Adams and Magalhaes, Catarina and Chu, Wan-Loy and Lau, Maggie C. Y. and Craig S Cary and Smith, David J. and Diana H. Wall and Eguren, Gabriela and Matcher, Gwynneth and Bradley, James A. and de Vera, Jean-Pierre and Elster, Josef and Hughes, Kevin A. and Cuthbertson, Lewis and Benning, Liane G. and Gunde-Cimerman, Nina and Convey, Peter and Hong, Soon Gyu and Pointing, Steve B. and Pellizari, Vivian H. and Vincent, Warwick F.} } @phdthesis {4034, title = {Biogeochemical processes in Antarctic aquatic environments: Linkages and limitations}, volume = {Ph.D.}, year = {2016}, pages = {228}, school = {Montana State University}, type = {doctoral}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://search.proquest.com/openview/9118336399cac113f488d77fb07bce26/1?pq-origsite=gscholar\&cbl=18750\&diss=y}, author = {Trista J. Vick-Majors} } @article {3717, title = {Biogeochemistry and microbial diversity in the marine cavity beneath the McMurdo Ice Shelf, Antarctica}, journal = {Limnology and Oceanography}, volume = {61}, year = {2016}, month = {11/2015}, pages = {572 - 586}, keywords = {LTER-MCM}, doi = {10.1002/lno.v61.210.1002/lno.10234}, url = {http://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.10234}, author = {Trista J. Vick-Majors and Achberger, Amanda and Santib{\'a}{\~n}ez, Pamela and John E. Dore and Hodson, Timothy and Alexander B. Michaud and Brent C. Christner and Jill Ai, Jill. Mikucki and Skidmore, Mark L. and Powell, Ross and Adkins, W. Peyton and Barbante, Carlo and Mitchell, Andrew and Scherer, Reed and John C. Priscu} } @article {3917, title = {Dissolved black carbon in Antarctic lakes: chemical signatures of past and present sources}, journal = {Geophysical Research Letters}, year = {2016}, month = {06/2016}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/2016GL068609}, url = {http://doi.wiley.com/10.1002/2016GL068609}, author = {Khan, Alia L. and Jaff{\'e}, Rudolf and Ding, Yan and Diane M. McKnight} } @article {3714, title = {Evidence for dispersal and habitat controls on pond diatom communities from the McMurdo Sound Region of Antarctica}, journal = {Polar Biology}, year = {2016}, month = {02/2016}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-016-1901-6}, url = {http://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.html}, author = {Sakaeva, A. and Eric R. Sokol and Tyler J. Kohler and Lee F. Stanish and Sarah A. Spaulding and Howkins, Adrian and Kathleen A. Welch and W. Berry Lyons and John E. Barrett and Diane M. McKnight} } @phdthesis {4035, title = {Factors influencing the abundance of microorganisms in icy environments}, volume = {Ph.D.}, year = {2016}, pages = {236}, school = {Montana State University}, type = {doctoral}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://search.proquest.com/openview/eb36d8ca7f2f1308b69e87a6c37f0a72/1?pq-origsite=gscholar\&cbl=18750\&diss=y}, author = {Santib{\'a}{\~n}ez, Pamela} } @article {4014, title = {Genetic diversity among populations of Antarctic springtails (Collembola) within the Mackay Glacier ecotone 1}, journal = {Genome}, volume = {59}, year = {2016}, month = {Jan-09-2016}, pages = {762 - 770}, keywords = {LTER-MCM}, issn = {0831-2796}, doi = {10.1139/gen-2015-0194}, url = {http://www.nrcresearchpress.com/doi/10.1139/gen-2015-0194}, author = {Clare R. Beet and Hogg, Ian D. and Gemma E. Collins and Cowan, Don A. and Diana H. Wall and Byron Adams and John-James Wilson} } @article {4020, title = {Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {62}, year = {2016}, month = {07/2016}, pages = {976 - 989}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, glaciers, mass balance}, issn = {0022-1430}, doi = {10.1017/jog.2016.86}, url = {https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143016000861}, author = {Andrew G Fountain and Hassan J. Basagic and Niebuhr, Spencer} } @article {3708, title = {Growth dynamics of a laminated microbial mat in response to variable irradiance in an Antarctic lake}, journal = {Freshwater Biology}, volume = {61}, year = {2016}, month = {02/2016}, pages = {396 - 410}, abstract = {
  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.
}, keywords = {LTER-MCM}, doi = {10.1111/fwb.2016.61.issue-410.1111/fwb.12715}, url = {http://doi.wiley.com/10.1111/fwb.12715}, author = {Ian Hawes and Jungblut, Anne D. and Maciek K. Obryk and Peter T. Doran} } @article {4015, title = {High levels of intraspecific genetic divergences revealed for Antarctic springtails: evidence for small-scale isolation during Pleistocene glaciation}, journal = {Biological Journal of the Linnean Society}, volume = {119}, year = {2016}, month = {Jan-09-2016}, pages = {166 - 178}, keywords = {LTER-MCM}, doi = {10.1111/bij.12796}, url = {https://academic.oup.com/biolinnean/article-lookup/doi/10.1111/bij.12796https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111\%2Fbij.12796}, author = {Bennett, Kristi R. and Hogg, Ian D. and Byron Adams and Hebert, Paul D. N.} } @article {3707, title = {High-resolution ground-penetrating radar profiles of perennial lake ice in the McMurdo Dry Valleys, Antarctica: Horizon attributes, unconformities, and subbottom penetration}, journal = {GEOPHYSICS}, volume = {81}, year = {2016}, month = {01/2016}, pages = {WA13 - WA20}, keywords = {LTER-MCM}, issn = {0016-8033}, doi = {10.1190/geo2015-0159.1}, url = {http://library.seg.org/doi/10.1190/geo2015-0159.1}, author = {Hilary A. Dugan and Arcone, Steven A. and Maciek K. Obryk and Peter T. Doran} } @article {3951, title = {Hydrological Controls on Ecosystem Dynamics in Lake Fryxell, Antarctica}, journal = {PLOS ONE}, volume = {11}, year = {2016}, month = {07/2016}, pages = {e0159038}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.015903810.1371}, url = {http://dx.plos.org/10.1371/journal.pone.0159038}, author = {Herbei, Radu and Rytel, Alexander L. and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Michael N. Gooseff and John C. Priscu}, editor = {Hewitt, Judi} } @article {4102, title = {The Impact of a Large-Scale Climate Event on Antarctic Ecosystem Processes}, journal = {BioScience}, volume = {66}, year = {2016}, month = {10/2016}, pages = {848 - 863}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw110}, url = {http://academic.oup.com/bioscience/article-pdf/66/10/848/7510601/biw110.pdf}, author = {Andrew G Fountain and Saba, Grace and Byron Adams and Peter T. Doran and Fraser, William and Michael N. Gooseff and Maciek K. Obryk and John C. Priscu and Sharon E. Stammerjohn and Ross A. Virginia} } @article {4025, title = {Impact of diurnal freeze{\textendash}thaw cycles on the soil nematode Scottnema lindsayae in Taylor Valley, Antarctica}, journal = {Polar Biology}, volume = {39}, year = {2016}, month = {04/2016}, pages = {583 - 592}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-015-1809-6}, url = {https://link.springer.com/article/10.1007/s00300-015-1809-6}, author = {Matthew Knox and Diana H. Wall and Ross A. Virginia and Martijn L. Vandegehuchte and Inigo San Gil and Byron Adams} } @phdthesis {4167, title = {Influence of abiotic drivers (light and nutrients) on photobiology and diversity of Antarctic lake phytoplankton communities}, volume = {Ph.D.}, year = {2016}, month = {2016}, school = {Miami University}, type = {doctoral}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, bacterial production, Chlamydomonas sp ICE MDV, Chlorophyll fluorescence, circadian rhythm, climate change, McMurdo Dry Valleys, nutrient amendment, photobiology, Primary production}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1468411564}, author = {Teufel, Amber G. and Rachael M. Morgan-Kiss} } @phdthesis {4168, title = {Influence of environmental drivers and interactions on the microbial community structures in permanently stratified meromictic Antarctic lakes}, volume = {Ph.D.}, year = {2016}, month = {2016}, school = {Miami University}, type = {doctoral}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1469757316}, author = {Li, Wei and Rachael M. Morgan-Kiss} } @article {3961, title = {Lake Vanda: A sentinel for climate change in the McMurdo Sound Region of Antarctica}, journal = {Global and Planetary Change}, volume = {144}, year = {2016}, month = {Jan-09-2016}, pages = {213 - 227}, abstract = {

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, f{\"o}hn 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.

}, keywords = {LTER-MCM}, issn = {09218181}, doi = {10.1016/j.gloplacha.2016.06.007}, url = {http://www.sciencedirect.com/science/article/pii/S092181811530014X}, author = {Castendyk, Devin and Maciek K. Obryk and Leidman, Sasha Z. and Michael N. Gooseff and Ian Hawes} } @article {4017, title = {Microbial Community Dynamics in Two Polar Extremes: The Lakes of the McMurdo Dry Valleys and the West Antarctic Peninsula Marine Ecosystem}, journal = {BioScience}, volume = {66}, year = {2016}, month = {Jan-10-2016}, pages = {829 - 847}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw103}, url = {https://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-Extremes}, author = {Bowman, Jeff S. and Trista J. Vick-Majors and Rachael M. Morgan-Kiss and Cristina D. Takacs-Vesbach and Hugh W. Ducklow and John C. Priscu} } @article {3952, title = {Microbial Community Responses to Increased Water and Organic Matter in the Arid Soils of the McMurdo Dry Valleys, Antarctica}, journal = {Frontiers in Microbiology}, volume = {7}, year = {2016}, month = {07/2016}, chapter = {1040}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.01040}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2016.01040}, author = {Heather N. Buelow and Winter, Ara S. and David J. Van Horn and John E. Barrett and Michael N. Gooseff and Schwartz, Egbert and Cristina D. Takacs-Vesbach} } @article {4013, title = {Microbial Community Structure of Subglacial Lake Whillans, West Antarctica}, journal = {Frontiers in Microbiology}, volume = {7}, year = {2016}, month = {Oct-09-2017}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.01457}, url = {http://journal.frontiersin.org/Article/10.3389/fmicb.2016.01457/abstract}, author = {Achberger, Amanda and Brent C. Christner and Alexander B. Michaud and John C. Priscu and Skidmore, Mark L. and Trista J. Vick-Majors} } @article {3710, title = {Microbial Mat Communities along an Oxygen Gradient in a Perennially Ice-Covered Antarctic Lake}, journal = {Applied and Environmental Microbiology}, volume = {82}, year = {2016}, month = {01/2016}, pages = {620 - 630}, keywords = {LTER-MCM}, issn = {0099-2240}, doi = {10.1128/AEM.02699-15}, url = {http://aem.asm.org/lookup/doi/10.1128/AEM.02699-15}, author = {Jungblut, Anne D. and Ian Hawes and Mackey, Tyler J. and Krusor, Megan and Peter T. Doran and Sumner, Dawn Y. and Eisen, Jonathan A. and Hillman, Colin and Goroncy, Alexander K.}, editor = {Stams, A. J.} } @phdthesis {4090, title = {Microbially mediated biogeochemical cycles in polar ice covered lakes}, volume = {Ph.D.}, year = {2016}, school = {Montana State University}, type = {doctoral}, address = {Bozeman, MT}, abstract = {

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\&$\#$39;s carbon cycle due to their methane emissions from organic carbon degradation. In the Antarctic, over 400 unexplored lakes exist beneath the Antarctic ice sheet with unknown biogeochemical contributions to the Earth system. This dissertation seeks to investigate the biogeochemical role of microorganisms in the lake habitat and how they interact with the seasonal and permanent ice covers of lakes in polar environments. Microbiologically clean hot water drilling was used to access a subglacial lake beneath Antarctica\&$\#$39;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.

}, keywords = {LTER-MCM}, url = {https://scholarworks.montana.edu/xmlui/handle/1/13793}, author = {Alexander B. Michaud}, editor = {John C. Priscu} } @mastersthesis {4081, title = {Modeling Surface Photosynthetic Active Radiation in Taylor Valley, McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2016}, school = {University of Illinois at Chicago}, type = {masters}, address = {Chicago, IL}, abstract = {

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.

}, keywords = {LTER-MCM, digital elevation model (DEM), geographical information system (GIS), ice-covered lakes, meteorological data, R model}, url = {http://indigo.uic.edu/handle/10027/21180}, author = {Acosta, Dimitri R.}, editor = {Berkelhammer, Max} } @article {3919, title = {Modeling the thickness of perennial ice covers on stratified lakes of the Taylor Valley, Antarctica}, journal = {Journal of Glaciology}, year = {2016}, month = {06/2016}, pages = {1 - 10}, chapter = {1}, abstract = {
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.

}, keywords = {LTER-MCM}, issn = {0022-1430}, doi = {10.1017/jog.2016.69}, url = {http://www.journals.cambridge.org/abstract_S0022143016000691}, author = {Maciek K. Obryk and Peter T. Doran and J. A. Hicks and Christopher P. McKay and John C. Priscu} } @mastersthesis {4096, title = {Noble Gas Radioisotope Constraints on Water Residence Time and Solvent Sources in Lake Bonney}, volume = {M.S.}, year = {2016}, school = {University of Illinois}, type = {masters}, address = {Chicago, IL}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, noble gas, radioargon, radiokrypton, residence time}, url = {http://hdl.handle.net/10027/21570}, author = {Cronin, Kyle D. and Peter T. Doran} } @article {3959, title = {Nutrient treatments alter microbial mat colonization in two glacial meltwater streams from the McMurdo Dry Valleys, Antarctica}, journal = {FEMS Microbiology Ecology}, volume = {92}, year = {2016}, month = {03/2016}, pages = {fiw049}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1093/femsec/fiw049}, url = {http://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw049}, author = {Tyler J. Kohler and David J. Van Horn and Darling, Joshua P. and Cristina D. Takacs-Vesbach and Diane M. McKnight}, editor = {Wagner, Dirk} } @article {3958, title = {Patterns of bacterial biodiversity in the glacial meltwater streams of the McMurdo Dry Valleys, Antarctica}, journal = {FEMS Microbiology Ecology}, volume = {92}, year = {2016}, month = {08/2016}, pages = {fiw148}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1093/femsec/fiw148}, url = {http://femsec.oxfordjournals.org/lookup/doi/10.1093/femsec/fiw148}, author = {David J. Van Horn and Wolf, Caitlin R. and Colman, Daniel R. and Jiang, Xiaoben and Tyler J. Kohler and Diane M. McKnight and Lee F. Stanish and Yazzie, Terrill and Cristina D. Takacs-Vesbach} } @article {3718, title = {Patterns of hydrologic connectivity in the McMurdo dry valleys, Antarctica: a synthesis of 20 years of hydrologic data}, journal = {Hydrological Processes}, volume = {30}, year = {2016}, month = {04/2016}, pages = {2958-2975}, chapter = {2958}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.10818}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.10818}, author = {Wlostowski, Adam and Michael N. Gooseff and Diane M. McKnight and Chris Jaros and W. Berry Lyons} } @article {1061, title = {Photoadaptation to the polar night by phytoplankton in a permanently ice-covered Antarctic lake}, journal = {Limnology and Oceanography}, volume = {61}, year = {2016}, month = {05/2015}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/lno.10107}, url = {https://aslopubs.onlinelibrary.wiley.com/doi/full/10.1002/lno.10107}, author = {Rachael M. Morgan-Kiss and Michael P. Lizotte and Weidong Kong and John C. Priscu} } @mastersthesis {4088, title = {Physiological characteristics of fungi associated with Antarctic environments}, volume = {M.S.}, year = {2016}, school = {Montana State University}, type = {masters}, address = {Bozeman, MT}, abstract = {

The permanent ice covers on the lakes of Antarctica\&$\#$39;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.

}, keywords = {LTER-MCM}, url = {https://scholarworks.montana.edu/xmlui/handle/1/9835}, author = {Kudalkar, Priyanka S. and John C. Priscu} } @article {4033, title = {Physiological Ecology of Microorganisms in Subglacial Lake Whillans}, journal = {Frontiers in Microbiology}, volume = {7}, year = {2016}, month = {Mar-10-2018}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2016.01705}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/fullhttp://journal.frontiersin.org/article/10.3389/fmicb.2016.01705/full}, author = {Trista J. Vick-Majors and Mitchell, Andrew and Achberger, Amanda and Brent C. Christner and John E. Dore and Alexander B. Michaud and Jill A. Mikucki and Purcell, Alicia M. and Skidmore, Mark L. and John C. Priscu} } @phdthesis {4098, title = {Quantifying sources, distribution, and processing of light absorbing aerosols in the cryosphere: A comparison of dissolved and refractory black carbon in polar and high mountain regions}, volume = {Ph.D.}, year = {2016}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, applied sciences, black carbon, cryosphere, earth sciences, glacial melt, health and environmental sciences, light absorbing aerosols, polar regions, snow}, url = {https://search.proquest.com/docview/1834518541?accountid=14503}, author = {Khan, Alia L. and Diane M. McKnight} } @article {4030, title = {Responses of Antarctic Marine and Freshwater Ecosystems to Changing Ice Conditions}, journal = {BioScience}, volume = {66}, year = {2016}, month = {Jan-10-2016}, pages = {864 - 879}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw109}, url = {https://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-Freshwater}, author = {Maciek K. Obryk and Peter T. Doran and Friedlaender, Ari S. and Michael N. Gooseff and Li, Wei and Rachael M. Morgan-Kiss and John C. Priscu and Schofield, Oscar and Sharon E. Stammerjohn and Steinberg, Deborah K. and Hugh W. Ducklow} } @article {3875, title = {Stream biogeochemical and suspended sediment responses to permafrost degradation in stream banks in Taylor Valley, Antarctica}, journal = {Biogeosciences}, volume = {13}, year = {2016}, month = {03/2016}, pages = {1723 - 1732}, abstract = {

\ 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.

}, keywords = {LTER-MCM}, doi = {10.5194/bg-13-1723-2016}, url = {http://www.biogeosciences.net/13/1723/2016/bg-13-1723-2016.pdf}, author = {Michael N. Gooseff and David J. Van Horn and Sudman, Zachary and Diane M. McKnight and Kathleen A. Welch and W. Berry Lyons} } @article {3709, title = {Taylor{\textquoteright}s Valley: What the History of Antarctica{\textquoteright}s {\textquoteright}Heroic Era{\textquoteright} Can Contribute to Contemporary Ecological Research in the McMurdo Dry Valleys}, journal = {Environment and History}, volume = {22}, year = {2016}, month = {01/2016}, pages = {3 - 28}, keywords = {LTER-MCM}, issn = {09673407}, doi = {10.3197/096734016X14497391602125}, url = {http://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/art00003}, author = {Howkins, Adrian} } @article {3921, title = {Ultrastructural and Single-Cell-Level Characterization Reveals Metabolic Versatility in a Microbial Eukaryote Community from an Ice-Covered Antarctic Lake}, journal = {Applied and Environmental Microbiology}, volume = {82}, year = {2016}, month = {06/2016}, pages = {3659 - 3670}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0099-2240}, doi = {10.1128/AEM.00478-16}, url = {http://aem.asm.org/lookup/doi/10.1128/AEM.00478-16}, author = {Li, Wei and Podar, Mircea and Rachael M. Morgan-Kiss}, editor = {Kelly, R. M.} } @article {4169, title = {Unraveling ecosystem responses to climate change on the Antarctic continent through Long-Term Ecological Research}, journal = {BioScience}, volume = {66}, year = {2016}, month = {10/2016}, pages = {799 - 800}, keywords = {LTER-MCM}, issn = {0006-3568}, doi = {10.1093/biosci/biw131}, url = {https://academic.oup.com/bioscience/article/66/10/799/2236166}, author = {John C. Priscu} } @article {3223, title = {Accumulation and marine forcing of ice dynamics in the western Ross Sea during the last~deglaciation}, journal = {Nature Geoscience}, volume = {8}, year = {2015}, month = {Jan-07-2016}, pages = {625 - 628}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {1752-0894}, doi = {10.1038/ngeo2478}, url = {http://www.nature.com/doifinder/10.1038/ngeo2478}, author = {Brenda L. Hall and George H. Denton and Heath, Stephanie L. and Margaret S. Jackson and Koffman, Tobias N. B.} } @article {3248, title = {Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases}, journal = {Geology}, year = {2015}, month = {10/2015}, pages = {G36966.1}, abstract = {

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.\ 

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G36966.1}, url = {http://geology.gsapubs.org/lookup/doi/10.1130/G36966.1}, author = {Sumner, Dawn Y. and Ian Hawes and Mackey, Tyler J. and Jungblut, Anne D. and Peter T. Doran} } @article {3306, title = {Antarctic streams as a potential source of iron for the Southern Ocean: Figure 1.}, journal = {Geology}, volume = {43}, year = {2015}, month = {11/2016}, pages = {1003 - 1006}, chapter = {1003}, abstract = {

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\ 

}, keywords = {LTER-MCM}, issn = {0091-7613}, doi = {10.1130/G36989.1}, url = {http://geology.gsapubs.org/lookup/doi/10.1130/G36989.1http://geology.geoscienceworld.org/lookup/doi/10.1130/G36989.1}, author = {W. Berry Lyons and Dailey, Kelsey R. and Kathleen A. Welch and Deuerling, Kelly M. and Sue Welch and Diane M. McKnight} } @thesis {3200, title = {Chemical Weathering and Mineralogy of McMurdo Dry Valley Streams: Examining the Controls of Current and Future Ephemeral Stream Geochemistry}, volume = {Undergraduate Theses}, year = {2015}, month = {05/2015}, pages = {38}, type = {bachelors}, address = {Ohio State University}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://hdl.handle.net/1811/68887}, author = {Scheuermann, Jordan and W. Berry Lyons} } @article {3204, title = {Comparison of arsenic and molybdenum geochemistry in meromictic lakes of the McMurdo Dry Valleys, Antarctica: Implications for oxyanion-forming trace element behavior in permanently stratified lakes}, journal = {Chemical Geology}, volume = {404}, year = {2015}, month = {05/2015}, pages = {110 - 125}, chapter = {110}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00092541}, doi = {10.1016/j.chemgeo.2015.03.029}, url = {http://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/plain}, author = {Yang, Ningfang and Kathleen A. Welch and Mohajerin, T. Jade and Telfeyan, Katherine and Chevis, Darren A. and Grimm, Deborah A. and W. Berry Lyons and White, Christopher D. and Johannesson, Karen H.} } @article {1057, title = {Controls on diel soil CO2 flux across moisture gradients in a polar desert}, journal = {Antarctic Science}, year = {2015}, month = {06/2015}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1017/S0954102015000255}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=9776001\&fileId=S0954102015000255}, author = {Ball, Becky and Ross A. Virginia} } @article {3254, title = {Cyanobacterial diversity in benthic mats of the McMurdo Dry Valley lakes, Antarctica}, journal = {Polar Biology}, volume = {38}, year = {2015}, month = {01/2015}, pages = {1097 - 1110}, abstract = {
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.
}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-015-1669-0}, url = {http://link.springer.com/10.1007/s00300-015-1669-0http://link.springer.com/content/pdf/10.1007/s00300-015-1669-0}, author = {Zhang, L. and Jungblut, Anne D. and Ian Hawes and Dale T. Andersen and Sumner, Dawn Y. and Mackey, Tyler J.} } @article {3012, title = {Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley}, journal = {Nature Communications}, volume = {6}, year = {2015}, month = {Apr-04-2017}, pages = {6831}, abstract = {The 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).}, keywords = {LTER-MCM}, doi = {10.1038/ncomms7831}, url = {http://www.nature.com/doifinder/10.1038/ncomms7831}, author = {Jill A. Mikucki and Auken, E. and Tulaczyk, S and Ross A. Virginia and Schamper, C. and S{\o}rensen, K. I. and Peter T. Doran and Hilary A. Dugan and Foley, N.} } @article {3210, title = {Experimental formation of pore fluids in McMurdo Dry Valleys soils}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {04/2015}, pages = {163 - 171}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102014000479}, url = {http://www.journals.cambridge.org/abstract_S0954102014000479}, author = {Joseph S. Levy and Andrew G Fountain and W. Berry Lyons and Kathleen A. Welch} } @article {3475, title = {Fostering ecological data sharing: collaborations in the International Long Term Ecological Research Network}, journal = {Ecosphere}, volume = {6}, year = {2015}, month = {10/2015}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {2150-8925}, doi = {10.1890/ES14-00281.1}, url = {http://www.esajournals.org/doi/10.1890/ES14-00281.1}, author = {Vanderbilt, Kristin L. and Lin, Chau-Chin and Lu, Sheng-Shan and Kassim, Abd Rahman and He, Honglin and Guo, Xuebing and Inigo San Gil and Blankman, David and Porter, John H.} } @article {3711, title = {The genus Luticola D.G.Mann (Bacillariophyta) from the McMurdo Sound Region, Antarctica, with the description of four new species}, journal = {Phytotaxa}, volume = {208}, year = {2015}, month = {10/2015}, pages = {103}, keywords = {LTER-MCM}, doi = {10.11646/phytotaxa.208.2.1}, url = {https://www.biotaxa.org/Phytotaxa/article/view/phytotaxa.208.2.1}, author = {Tyler J. Kohler and Kopalov{\'a}, Kate{\v r}ina and Bart Van de Vijver and J. Patrick Kociolek} } @article {3715, title = {Global environmental change and the nature of aboveground net primary productivity responses: insights from long-term experiments}, journal = {Oecologia}, volume = {177}, year = {2015}, month = {04/2015}, pages = {935 - 947}, keywords = {LTER-MCM}, issn = {0029-8549}, doi = {10.1007/s00442-015-3230-9}, url = {http://link.springer.com/10.1007/s00442-015-3230-9http://link.springer.com/content/pdf/10.1007/s00442-015-3230-9}, author = {Smith, Melinda D. and La Pierre, Kimberly J. and Collins, SL and Knapp, Alan K. and Gross, Katherine L. and John E. Barrett and Frey, Serita D. and Gough, Laura and Miller, Robert J. and Morris, James T. and Rustad, Lindsey E. and Yarie, John} } @mastersthesis {4192, title = {The impacts of thermokarst activity on a stream in the McMurdo Dry Valleys}, volume = {M.S.}, year = {2015}, month = {2015}, pages = {70}, school = {University of Colorado}, type = {masters}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, Dry valleys, earth sciences, stream, thermokarst}, url = {https://search.proquest.com/docview/1717582573}, author = {Sudman, Zachary and Michael N. Gooseff} } @article {3720, title = {Linking management to biodiversity in built ponds using metacommunity simulations}, journal = {Ecological Modelling}, volume = {296}, year = {2015}, month = {01/2015}, pages = {36 - 45}, keywords = {LTER-MCM}, issn = {03043800}, doi = {10.1016/j.ecolmodel.2014.10.022}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0304380014004918}, author = {Eric R. Sokol and Brown, Bryan L. and Carey, Cayelan C. and Tornwall, Brett M. and Swan, Christopher M. and John E. Barrett} } @article {3721, title = { Long-Term Hydrologic Control of Microbial Mat Abundance in McMurdo Dry Valley Streams, Antarctica.}, journal = {Ecosystems}, volume = {18}, year = {2015}, month = {03/2015}, pages = {310-327}, chapter = {310}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://link.springer.com/article/10.1007\%2Fs10021-014-9829-6}, author = {Tyler J. Kohler and Lee F. Stanish and Stenven Crisp and Koch, J. and Liptzin, D. and Baeseman, J. and Diane M. McKnight} } @article {3716, title = {Mitochondrial DNA analyses reveal widespread tardigrade diversity in Antarctica}, journal = {Invertebrate Systematics}, volume = {29}, year = {2015}, month = {12/2015}, pages = {578}, keywords = {LTER-MCM}, issn = {1445-5226}, doi = {10.1071/IS14019}, url = {http://www.publish.csiro.au/?paper=IS14019}, author = {Velasco-Castrillon, Alejandro and McInnes, Sandra J. and Schultz, Mark B. and Arroniz-Crespo, Maria and D{\textquoteright}Haese, Cyrille A. and Gibson, John A. E. and Byron Adams and Page, Timothy J. and Austin, Andrew D. and Cooper, Steven J. B. and Stevens, Mark I.} } @article {3522, title = {Niche and metabolic principles explain patterns of diversity and distribution: theory and a case study with soil bacterial communities}, journal = {Proceedings of the Royal Society B: Biological Sciences}, volume = {282}, year = {2015}, month = {05/2015}, pages = {2630}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0962-8452}, doi = {10.1098/rspb.2014.2630}, url = {http://rspb.royalsocietypublishing.org/lookup/doi/10.1098/rspb.2014.2630}, author = {Okie, Jordan G. and David J. Van Horn and Storch, David and John E. Barrett and Michael N. Gooseff and Kopsova, Lenka and Cristina D. Takacs-Vesbach} } @article {3205, title = {Patterns and processes of salt efflorescences in the McMurdo region, Antarctica}, journal = {Artic, Antarctic and Alpine Research}, year = {2015}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://aaarjournal.org/doi/abs/10.1657/AAAR0014-024}, author = {Bisson, K. M. and Kathleen A. Welch and Sue Welch and Sheets, J. M. and W. Berry Lyons and Joseph S. Levy and Andrew G Fountain} } @phdthesis {4087, title = {Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2015}, pages = {272}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, algae, Antarctica, biological sciences, climate change, Disturbance, earth sciences, McMurdo Dry Valleys, microbial mats}, url = {https://search.proquest.com/docview/1690497718?accountid=14503}, author = {Tyler J. Kohler}, editor = {Diane M. McKnight} } @book {3305, title = {The Polar Regions: An Environmental History}, year = {2015}, pages = {248}, publisher = {Polity}, organization = {Polity}, address = {Cambridge}, abstract = {

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.

}, keywords = {LTER-MCM}, isbn = {978-0-7456-7080-5}, url = {http://www.wiley.com/WileyCDA/WileyTitle/productCd-0745670806.html}, author = {Howkins, Adrian} } @article {3712, title = {Potential for real-time understanding of coupled hydrologic and biogeochemical processes in stream ecosystems: Future integration of telemetered data with process models for glacial meltwater streams}, journal = {Water Resources Research}, volume = {51}, year = {2015}, month = {08/2015}, pages = {6725 - 6738}, keywords = {LTER-MCM}, doi = {10.1002/2015WR017618}, url = {http://doi.wiley.com/10.1002/2015WR017618http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002\%2F2015WR017618}, author = {Diane M. McKnight and Cozzetto, K and Cullis, James D.S. and Michael N. Gooseff and Chris Jaros and Koch, J. and W. Berry Lyons and Neupauer, R. M. and Wlostowski, Adam} } @article {3189, title = {Pressure-driven, shoreline currents in a perennially ice-covered, pro-glacial lake in Antarctica, identified from a LiCl tracer injected into a pro-glacial stream}, journal = {Hydrological Processes}, volume = {29}, year = {2015}, month = {05-2015}, pages = {2212 - 2231}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/hyp.v29.910.1002/hyp.10352}, url = {http://doi.wiley.com/10.1002/hyp.v29.9http://doi.wiley.com/10.1002/hyp.10352}, author = {Castendyk, Devin and Diane M. McKnight and Kathleen A. Welch and Niebuhr, Spencer and Chris Jaros} } @mastersthesis {4084, title = {Quantifying long-term geomorphology of Antarctic streams}, volume = {MS}, year = {2015}, pages = {185}, school = {University of Colorado}, type = {masters}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://search.proquest.com/docview/1727444346?accountid=14503}, author = {Crisp, Steven W.}, editor = {Diane M. McKnight} } @article {3213, title = {Reconstructing the evolution of Lake Bonney, Antarctica using dissolved noble gases}, journal = {Applied Geochemistry}, volume = {58}, year = {2015}, month = {Jan-07-2015}, pages = {46 - 61}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {08832927}, doi = {10.1016/j.apgeochem.2015.02.013}, url = {http://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/plain}, author = {Warrier, Rohit B. and Clara M. Castro and Chris M. Hall and Kenig, Fabien and Peter T. Doran} } @article {3215, title = {Recovery of Antarctic stream epilithon from simulated scouring events}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {Jan-08-2015}, pages = {341 - 354}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102015000024}, url = {http://www.journals.cambridge.org/abstract_S0954102015000024}, author = {Tyler J. Kohler and Ethan Chatfield and Michael N. Gooseff and John E. Barrett and Diane M. McKnight} } @article {3222, title = {A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {Jan-02-2015}, pages = {3 - 18}, abstract = {

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

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102014000674}, url = {http://www.journals.cambridge.org/abstract_S0954102014000674}, author = {Kennicutt, M.C. and Steven L. Chown and Cassano, J.J. and Liggett, D. and Lloyd S. Peck and Massom, R. and Rintoul, S.R. and Storey, J. and Vaughan, D.G. and Wilson, T.J. and Allison, I. and Ayton, J. and Badhe, R. and Baeseman, J. and Barrett, P.J. and Elanor R. Bell and Bertler, N. and Bo, S. and Brandt, A. and David Bromwich and Craig S Cary and Clark, M.S. and Peter Convey and Costa, E.S. and Cowan, D. and Deconto, R. and Dunbar, R. and Elfring, C. and Escutia, C. and Francis, J. and Fricker, H.A. and Fukuchi, M. and Gilbert, N. and Gutt, J. and Havermans, C. and Hik, D. and Hosie, G. and Jones, C. and Kim, Y.D. and Le Maho, Y. and Lee, S.H. and Leppe, M. and Leitchenkov, G. and Li, X. and Lipenkov, V. and Lochte, K. and L{\'o}pez-Mart{\'\i}nez, J. and {\"u}decke, C. and W. Berry Lyons and Marenssi, S. and Miller, H. and Morozova, P. and Naish, T. and Nayak, S. and Ravindra, R. and Retamales, J. and Ricci, C.A. and Rogan-Finnemore, M. and Ropert-Coudert, Y. and Samah, A.A. and Sanson, L. and Scambos, T. and I.R. Schloss and Shiraishi, K. and Siegert, M.J. and Sim{\~o}es, J.C. and Storey, B. and Sparrow, M.D. and Diana H. Wall and Walsh, J.C. and Wilson, G. and Winther, J.G. and J.C. Xavier and Yang, H. and Sutherland, W.J.} } @article {1063, title = {Sediment transport dynamics on an ice-covered lake: The {\textquotedblleft}floating{\textquotedblright} boulders of Lake Hoare, Antarctica}, journal = {Antartic Science}, volume = {firstview}, year = {2015}, month = {04/2015}, pages = {1-12}, chapter = {1}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {1365-2079}, doi = {10.1017/S0954102014000558}, url = {http://dx.doi.org/10.1017/S0954102014000558}, author = {P. P. Allen and R. Hewitt and Maciek K. Obryk and Peter T. Doran} } @article {3532, title = {Soil biodiversity and human health}, journal = {Nature}, year = {2015}, month = {11/2015}, keywords = {LTER-MCM}, issn = {0028-0836}, doi = {10.1038/nature15744}, url = {http://www.nature.com/doifinder/10.1038/nature15744}, author = {Diana H. Wall and Uffe N. Nielsen and Six, Johan} } @article {1066, title = {Spatiotemporal Dynamics of Wetted Soils across a Polar Desert Landscape, McMurdo Dry Valleys Antarctica}, journal = {Antarctic Science}, volume = {27}, year = {2015}, month = {04/2015}, pages = {197-209}, chapter = {197}, abstract = {Liquid 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{\textendash}10 to 2011{\textendash}12 summers. The remote sensing analyses reveal that cumulative area and number of wet soil patches varies among summers. The 2010{\textendash}11 summer provided the most wetted soil area (10.21 km2) and 2009{\textendash}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.}, keywords = {LTER-MCM}, doi = {10.1017/S0954102014000601}, url = {http://dx.doi.org/10.1017/S0954102014000601}, author = {Langford, Z. L. and Michael N. Gooseff and Lampkin, Derrick J.} } @article {3208, title = {Tipping the Iceberg: A Collaborative Approach to Redesigning the Undergraduate Research Assignment in an Antarctic History Capstone Seminar}, volume = {48}, year = {2015}, month = {03/2015}, pages = {339-370}, chapter = {339}, keywords = {LTER-MCM}, url = {http://scholar.colorado.edu/cgi/viewcontent.cgi?article=1034\&context=libr_facpapers}, author = {Hicks, Alison and Howkins, Adrian} } @inbook {3221, title = {Antarctic Terrestrial Microbiology : Invertebrates}, year = {2014}, pages = {55 - 78}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, abstract = {

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.

}, keywords = {LTER-MCM}, isbn = {978-3-642-45212-3}, doi = {10.1007/978-3-642-45213-0_4}, url = {http://link.springer.com/content/pdf/10.1007/978-3-642-45213-0_4}, author = {Hogg, Ian D. and Stevens, Mark I. and Diana H. Wall}, editor = {Cowan, Don A.} } @article {3214, title = {Autonomous Year-Round Sampling and Sensing to Explore the Physical and Biological Habitability of Permanently Ice-Covered Antarctic Lakes}, journal = {Marine Technology Society Journal}, volume = {48}, year = {2014}, month = {Jan-09-2014}, pages = {8 - 17}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00253324}, doi = {10.4031/MTSJ.48.5.6}, url = {http://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/art00002}, author = {Winslow, Luke A. and Hilary A. Dugan and Heather N. Buelow and Cronin, Kyle D. and John C. Priscu and Cristina D. Takacs-Vesbach and Peter T. Doran} } @article {1054, title = {Bacterial community composition of divergent soil habitats from a polar desert.}, journal = {FEMS Microbiology Ecology}, volume = {89}, year = {2014}, month = {08/2014}, pages = {490-494}, type = {Short Communication}, chapter = {490}, abstract = {Edaphic 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 nic}, keywords = {LTER-MCM}, doi = {10.1111/1574-6941.12306}, author = {Kevin M. Geyer and Adam E. Altrichter and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {3203, title = {Boron isotopic geochemistry of the McMurdo Dry Valley lakes, Antarctica}, journal = {Chemical Geology}, volume = {386}, year = {2014}, month = {10/2014}, pages = {152 - 164}, chapter = {152}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {00092541}, doi = {10.1016/j.chemgeo.2014.08.016}, url = {http://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/plain}, author = {Leslie, D.L. and W. Berry Lyons and Warner, Nathaniel and Vengosh, Avner and Olesik, J and Kathleen A. Welch and Deuerling, Kelly} } @article {1055, title = {Characterization of Growing Bacterial Populations in McMurdo Dry Valley Soils through Stable Isotope Probing with 18O-water.}, journal = {FEMS Microbiology Ecology.}, volume = {89}, year = {2014}, month = {08/2014}, pages = {415-425}, chapter = {415}, abstract = {Soil 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.}, keywords = {LTER-MCM}, doi = {10.1111/1574-6941.12349}, author = {Schwartz, E. and David J. Van Horn and Heather N. Buelow and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach and Okie, J.G.} } @article {1056, title = {Ciliate diversity, community structure and novel taxa in lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Biological Bulleting}, volume = {227}, year = {2014}, month = {10/2014}, pages = {175-190}, chapter = {175}, abstract = {We 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.}, keywords = {LTER-MCM}, author = {Yuan, Xu and Trista J. Vick-Majors and Rachael M. Morgan-Kiss and John C. Priscu and Linda A. Amaral-Zettler} } @article {1067, title = {Diel flow pulses drive particulate organic matter transport from microbial mats in a glacial meltwater stream in the McMurdo Dry Valleys}, journal = {Water Resources Research}, volume = {50}, year = {2014}, month = {01/2014}, pages = {86-97}, chapter = {86}, abstract = { 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{\textquoteright}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.}, keywords = {LTER-MCM}, doi = {10.1002/2013WR014061}, author = {Cullis, James D.S. and Lee F. Stanish and Diane M. McKnight} } @article {3218, title = {Ecological Biogeography of the Terrestrial Nematodes~of Victoria Land, Antarctica}, journal = {ZooKeys}, volume = {419}, year = {2014}, month = {06/2015}, pages = {29 - 71}, keywords = {LTER-MCM}, issn = {1313-2989}, doi = {10.3897/zookeys.419.7180}, url = {http://zookeys.pensoft.net/articles.php?id=3899}, author = {Byron Adams and Diana H. Wall and Ross A. Virginia and Broos, Emma and Matthew Knox} } @article {1071, title = {The ecological role of moss in a polar desert: implications for aboveground- belowground and terrestrial -aquatic linkages.}, journal = {Polar Biology}, volume = {37}, year = {2014}, month = {04/2014}, pages = {651-664}, type = {Journal}, keywords = {LTER-MCM}, doi = {10.1007/s00300-014-1465-2}, url = {http://link.springer.com/article/10.1007/s00300-014-1465-2}, author = {Ball, Becky and Ross A. Virginia} } @mastersthesis {4094, title = {Ecology and biogeography of freshwater diatoms in ponds of McMurdo Dry Valleys and parts of the Ross Island}, volume = {M.S.}, year = {2014}, school = {University of Colorado}, type = {masters}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, biological sciences, freshwater diatoms, health and environmental sciences, McMurdo Dry Valleys, ponds}, url = {https://search.proquest.com/docview/1655818365?accountid=14503}, author = {Sakaeva, A.}, editor = {Diane M. McKnight} } @article {3216, title = {The effects of high meltwater on the limnology of Lake Fryxell and Lake Hoare, Taylor Valley, Antarctica, as shown by dissolved gas, tritium and chlorofluorocarbons}, journal = {Antarctic Science}, volume = {26}, year = {2014}, month = {Jan-08-2014}, pages = {331 - 340}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S095410201300062X}, url = {http://www.journals.cambridge.org/abstract_S095410201300062X}, author = {Carolyn Dowling and Robert J. Poreda and W. Berry Lyons} } @mastersthesis {3201, title = {Elemental Cycling in a Flow-Through Lake in the McMurdo Dry Valleys, Antarctica: Lake Miers}, volume = {Master Thesis}, year = {2014}, month = {06/2014}, pages = {122}, school = {Ohio State University}, type = {masters}, address = {Columbus}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://etd.ohiolink.edu/!etd.send_file?accession=osu1413291502\&disposition=inline}, author = {Alexandria Corinne Fair and W. Berry Lyons}, editor = {Anne E. Carey and Yu-Ping Chin} } @phdthesis {4086, title = {Environmental Controls Over the Distribution and Function of Antarctic Soil Bacterial Communities}, volume = {Ph.D.}, year = {2014}, school = {Virginia Tech}, type = {doctoral}, address = {Blacksburg, VA}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM, biogeochemistry, biogeography, McMurdo Dry Valleys, microbial ecology, productivity/diversity theory}, url = {http://hdl.handle.net/10919/64417}, author = {Kevin M. Geyer}, editor = {John E. Barrett} } @phdthesis {4170, title = {Environmental impacts on RubisCO from green algal laboratory isolates to Antarctic lake communities}, volume = {Ph.D.}, year = {2014}, month = {2014}, school = {Miami University}, type = {doctoral}, address = {Oxford, OH}, abstract = {

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.

}, keywords = {LTER-MCM, carbon fixation, green algae, ice-covered lakes, RubisCO}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=miami1407056783}, author = {Jenna M. Dolhi and Rachael M. Morgan-Kiss} } @article {1059, title = {Estimating photosynthetic activity in microbial mats in an ice-covered Antarctic lake using automated oxygen microelectode profiling and variable chlorophyll fluorescence}, journal = {Limnology and Oceanography}, volume = {59}, year = {2014}, month = {08/2014}, pages = {674-688}, chapter = {674}, abstract = { 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 {\textmu}mol m-2 s-1, through to midnight (< 2 {\textmu}mol photons m-2 s-1). Daily average oxygen flux was 200 {\textmu}mol 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{\textendash}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.}, keywords = {LTER-MCM}, doi = {10.4319/lo.2014.59.3.0674}, author = {Ian Hawes and H. Giles and Peter T. Doran} } @article {3207, title = {Forum: Climate Change and Environmental History}, journal = {Environmental History}, volume = {19}, year = {2014}, month = {04/2014}, pages = {281 - 364}, abstract = {

This Forum explores global climate change, one of this century\&$\#$39;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.

}, keywords = {LTER-MCM}, issn = {1084-5453}, doi = {10.1093/envhis/emu004}, url = {http://envhis.oxfordjournals.org/cgi/doi/10.1093/envhis/emu004}, author = {Carey, M. and Garone, P. and Howkins, Adrian and Endfield, G. H. and Culver, L. and White, S. and Johnson, S. and Fleming, J. R. and Garone, P.} } @phdthesis {4097, title = {Geophysics, Water Balance, and History of Thick Perennial Ice Covers on Antarctic Lakes}, volume = {Ph.D.}, year = {2014}, school = {University of Illinois}, type = {doctoral}, address = {Chicago, IL}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, brine, lake ice, McMurdo Dry Valleys, polar lakes, sublimation}, url = {http://hdl.handle.net/10027/19407}, author = {Hilary A. Dugan}, editor = {Peter T. Doran} } @article {3533, title = {Global-scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties}, journal = {Global Ecology and Biogeography}, volume = {23}, year = {2014}, month = {01/2014}, pages = {968 - 978}, keywords = {LTER-MCM}, doi = {10.1111/geb.2014.23.issue-910.1111/geb.12177}, url = {http://doi.wiley.com/10.1111/geb.12177}, author = {Uffe N. Nielsen and Edward Ayres and Diana H. Wall and Li, Grace and Richard D. Bardgett and Wu, Tiehang and James R. Garey} } @phdthesis {4091, title = {Hydrological and Biogeochemical Modeling of Taylor Valley Lakes, East Antarctica}, volume = {Ph.D.}, year = {2014}, school = {University of Illinois}, type = {doctoral}, address = {Chicago, IL}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://hdl.handle.net/10027/18909}, author = {Maciek K. Obryk}, editor = {Peter T. Doran} } @article {3209, title = {Hyperspectral measurements of wet, dry and saline soils from the McMurdo Dry Valleys: soil moisture properties from remote sensing}, journal = {Antarctic Science}, volume = {26}, year = {2014}, month = {10/2014}, pages = {565 - 572}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102013000977}, url = {http://www.journals.cambridge.org/abstract_S0954102013000977}, author = {Joseph S. Levy and Nolin, Anne and Andrew G Fountain and Head, James W.} } @article {3202, title = {The McMurdo Dry Valleys: A landscape on the threshold of change}, journal = {Geomorphology}, volume = {225}, year = {2014}, month = {11/2014}, pages = {25 - 35}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0169555X}, doi = {10.1016/j.geomorph.2014.03.044}, url = {http://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/plain}, author = {Andrew G Fountain and Joseph S. Levy and Michael N. Gooseff and David J. Van Horn} } @article {1072, title = {Microbial biomass and respiration responses to nitrogen fertilization in a polar desert}, journal = {Polar Biology}, year = {2014}, month = {01/2014}, keywords = {LTER-MCM}, doi = {10.1007/s00300-014-1459-0}, url = {http://link.springer.com/article/10.1007\%2Fs00300-014-1459-0}, author = {Ball, Becky and Ross A. Virginia} } @article {1085, title = {Modular community structure suggests metabolic plasticity during the transition to polar night in ice-covered Antarctic lakes}, journal = {The ISME Journal}, year = {2014}, month = {10/2013}, keywords = {LTER-MCM}, doi = {10.1038/ismej.2013.190}, url = {http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej2013190a.html}, author = {Trista J. Vick-Majors and John C. Priscu and Linda A. Amaral-Zettler} } @article {1068, title = {Near-Surface Internal Melting - a Substantial Mass Loss on Antarctic Dry Valley Glaciers.}, journal = {Journal of Glaciology}, volume = {60}, year = {2014}, month = {04/2014}, pages = {361-374}, chapter = {361}, abstract = {The 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.}, keywords = {LTER-MCM}, doi = {10.3189/2014JoG13J095}, author = {Hoffman, M and Andrew G Fountain and Liston, G} } @article {3212, title = {The 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 column}, journal = {Journal of Geophysical Research: Biogeosciences}, volume = {119}, year = {2014}, month = {09/2014}, pages = {1879 - 1891}, chapter = {1879}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1002/2014JG002672}, url = {http://doi.wiley.com/10.1002/2014JG002672}, author = {Maciek K. Obryk and Peter T. Doran and John C. Priscu} } @article {3525, title = {Polar and alpine microbiology in a changing world}, journal = {FEMS Microbiology Ecology}, volume = {89}, year = {2014}, month = {08/2014}, pages = {209 - 210}, chapter = {209}, keywords = {LTER-MCM}, doi = {10.1111/fem.2014.89.issue-210.1111/1574-6941.12371}, url = {http://onlinelibrary.wiley.com/doi/10.1111/1574-6941.12371/abstract}, author = {John C. Priscu and Johanna Laybourn-Parry and H{\"a}ggblom, Max} } @article {1062, title = {Radiocarbon abundance and reservoir effects in lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Limnology and Oceanography}, volume = {59}, year = {2014}, month = {05/2014}, pages = {811-826}, chapter = {811}, keywords = {LTER-MCM}, author = {Peter T. Doran and Kenig, Fabien and Lawson Knoepfle and Jill A. Mikucki and W. Berry Lyons} } @article {3220, title = {Soil animal responses to moisture availability are largely scale, not ecosystem dependent: insight from a cross-site study}, journal = {Global Change Biology}, volume = {20}, year = {2014}, month = {08/2014}, pages = {2631 - 2643}, chapter = {2631}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/gcb.2014.20.issue-810.1111/gcb.12522}, url = {http://doi.wiley.com/10.1111/gcb.2014.20.issue-8http://doi.wiley.com/10.1111/gcb.12522}, author = {Sylvain, Zachary A. and Diana H. Wall and Cherwin, Karie L. and Debra P. C. Peters and Reichmann, Lara G. and Osvaldo E. Sala} } @article {1064, title = {Soil microbial responses to increased moisture and organic resources along a salinity gradient in a polar desert.}, journal = {Applied and Environmental Microbiology.}, volume = {80}, year = {2014}, month = {05/2014}, pages = {3034-3043}, chapter = {3034}, abstract = {Microbial 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.}, keywords = {LTER-MCM}, doi = {10.1128/AEM.03414-13}, author = {David J. Van Horn and Okie, J.G. and Heather N. Buelow and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {3219, title = {The spatial structure of Antarctic biodiversity}, journal = {Ecological Monographs}, volume = {84}, year = {2014}, month = {05/2014}, pages = {203 - 244}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0012-9615}, doi = {10.1890/12-2216.1}, url = {http://www.esajournals.org/doi/abs/10.1890/12-2216.1}, author = {Peter Convey and Steven L. Chown and Clarke, Andrew and Barnes, David K. A. and Bokhorst, Stef and Vonda Cummings and Hugh W. Ducklow and Francesco Frati and Green, T. G. Allan and Shulamit Gordon and Griffiths, Huw J. and Clive Howard-Williams and Huiskes, Ad H. L. and Johanna Laybourn-Parry and W. Berry Lyons and McMinn, Andrew and Morley, Simon A. and Lloyd S. Peck and Quesada, Antonio and Robinson, Sharon A. and Schiaparelli, Stefano and Diana H. Wall} } @article {3206, title = {Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes}, journal = {Frontiers in Microbiology}, volume = {5}, year = {2014}, month = {12/2014}, abstract = {

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

}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2014.00694}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2014.00694/abstract}, author = {Telling, J. and Alexandre M. Anesio and Martyn Tranter and Andrew G Fountain and Thomas H. Nylen and Hawkings, Jon and Singh, Virendra B. and Kaur, Preeti and Musilova, Michaela and Wadham, J. L.} } @article {1091, title = {Accelerated thermokarst formation in the McMurdo Dry Valleys, Antarctica}, journal = {Scientific Reports}, volume = {3}, year = {2013}, month = {07/2013}, keywords = {LTER-MCM}, doi = {10.1038/srep02269}, url = {http://www.nature.com/srep/2013/130724/srep02269/full/srep02269.html?WT.ec_id=SREP-20130730}, author = {Joseph S. Levy and Andrew G Fountain and Dickson, James L. and Head, James W. and Okal, Marianne and Marchant, David R. and Watters, Jaclyn} } @article {3217, title = {Antarctic Thresholds - Ecosystem Resilience and Adaptation (AnT-ERA), a new SCAR-biology programme}, journal = {Polarforschung}, volume = {82}, year = {2013}, month = {10/2013}, pages = {147-150.}, chapter = {147}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {http://epic.awi.de/34238/1/Polarforschung_82-2_147-150.pdf}, author = {Gutt, J. and Byron Adams and T Bracegirdle and Cowan, D. and Vonda Cummings and di Prisco, G. and Gradinger, R. and Isla, E. and McIntyre, T. and Murphy, E and Lloyd S. Peck and I.R. Schloss and Smith, C. and Suckling, C. C. and Takahashi, A. and Diana H. Wall and J.C. Xavier} } @phdthesis {4367, title = {The application of stable isotopes, δ11B, δ18O, and δD, in geochemical and hydrological investigations}, volume = {Ph.D.}, year = {2013}, school = {Ohio State University}, type = {doctoral}, address = {Columbus, OH}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, boron isotopes, hyporheic zone, McMurdo Dry Valleys, Ohio precipitation source, oxygen-18 and deuterium isotopes, saline lake}, url = { http://rave.ohiolink.edu/etdc/view?acc_num=osu1386000037}, author = {Leslie, D.L. and W. Berry Lyons} } @mastersthesis {4172, title = {Are the Dry Valleys getting wetter? A preliminary assessment of wetness across the McMurdo Dry Valleys landscape}, volume = {M.S.}, year = {2013}, month = {2013}, school = {Pennsylvania State University}, type = {masters}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://etda.libraries.psu.edu/catalog/17364}, author = {Langford, Z. L. and Michael N. Gooseff} } @article {3211, title = {Carbon Sequestration and Release from Antarctic Lakes: Lake Vida and West Lake Bonney (McMurdo Dry Valleys)}, journal = {Aquatic Geochemistry}, volume = {19}, year = {2013}, month = {03/2013}, pages = {135 - 145}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {1380-6165}, doi = {10.1007/s10498-012-9184-1}, url = {http://link.springer.com/10.1007/s10498-012-9184-1http://link.springer.com/content/pdf/10.1007/s10498-012-9184-1}, author = {G. M. Marion and A. E. Murray and Wagner, Bernd and Christian H. Fritsen and Kenig, Fabien and Peter T. Doran} } @article {1093, title = {The carbon stable isotope biogeochemistry of streams, Taylor Valley, Antarctica}, journal = {Applied Geochemistry}, volume = {32}, year = {2013}, month = {05/2013}, pages = {26 - 36}, keywords = {LTER-MCM}, doi = {10.1016/j.apgeochem.2012.08.019}, author = {W. Berry Lyons and Leslie, D.L. and Harmon, R.S. and Klaus Neumann and Kathleen A. Welch and Bisson, K. M. and Diane M. McKnight} } @article {1077, title = {Characterization of fulvic acid fractions of dissolved organic matter during ice-out in a hyper-eutrophic, coastal pond in Antarctica}, journal = {Environmental Research Letters}, volume = {8}, year = {2013}, month = {12/2013}, pages = {045015}, abstract = {Dissolved 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{\textendash}vis and fluorescence spectroscopy, and 13C NMR spectroscopy) of the three fulvic acid fractions helped to explain their behavior during isolation.}, keywords = {LTER-MCM}, doi = {10.1088/1748-9326/8/4/045015}, author = {Kaelin M. Cawley and Diane M. McKnight and Penney L. Miller and Rose M. Cory and Fimmen, Ryan L and Guerard, Jennifer and Markus Dieser and Chris Jaros and Yu-Ping Chin and Christine M. Foreman} } @article {1078, title = {Characterization of IHSS Pony Lake fulvic acid dissolved organic matter by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and fluorescence spectroscopy}, journal = {Organic Geochemistry}, volume = {65}, year = {2013}, month = {12/2013}, pages = {19 - 28}, keywords = {LTER-MCM}, doi = {10.1016/j.orggeochem.2013.09.013}, url = {http://www.sciencedirect.com/science/article/pii/S0146638013002167}, author = {D{\textquoteright}Andrilli, Juliana and Christine M. Foreman and Marshall, Alan G. and Diane M. McKnight} } @article {1074, title = {CORRIGENDUM: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth{\textquoteright}s most saline lake and implications for Mars}, journal = {Scientific Reports}, volume = {3}, year = {2013}, month = {3/2013}, keywords = {LTER-MCM}, doi = {10.1038/srep01424}, author = {Dickson, James L. and Head, James W. and Joseph S. Levy and Marchant, David R.} } @article {1076, title = {Distribution of Siliceous-Walled Algae in Taylor Valley, Antarctica Lakes}, journal = {International Journal of Geosciences}, volume = {04}, year = {2013}, month = {2013}, pages = {688 - 699}, keywords = {LTER-MCM}, doi = {10.4236/ijg.2013.44064}, author = {Jonathan P. Warnock and Peter T. Doran} } @article {1082, title = {Do Cryoconite Holes have the Potential to be Significant Sources of C, N, and P to Downstream Depauperate Ecosystems of Taylor Valley, Antarctica?}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {45}, year = {2013}, month = {11/2013}, pages = {440 - 454}, keywords = {LTER-MCM}, doi = {10.1657/1938-4246-45.4.440}, author = {Bagshaw, Elizabeth and Martyn Tranter and Andrew G Fountain and Kathleen A. Welch and Hassan J. Basagic and W. Berry Lyons} } @article {1097, title = {Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth{\textquoteright}s most saline lake and implications for Mars}, journal = {Scientific Reports}, volume = {3}, year = {2013}, month = {01/2013}, keywords = {LTER-MCM}, doi = {10.1038/srep01166}, url = {http://www.nature.com/srep/2013/130130/srep01166/full/srep01166.html?WT.ec_id=SREP-704-20130201}, author = {Dickson, James L. and Head, James W. and Joseph S. Levy and Marchant, David R.} } @article {1084, title = {Environmental controls over bacterial communities in polar desert soils}, journal = {Ecosphere}, volume = {4}, year = {2013}, month = {10/2013}, pages = {art127}, keywords = {LTER-MCM}, doi = {10.1890/ES13-00048.1}, author = {Kevin M. Geyer and Adam E. Altrichter and David J. Van Horn and Cristina D. Takacs-Vesbach and Michael N. Gooseff and John E. Barrett} } @article {1079, title = {Environmental factors influencing diatom communities in Antarctic cryoconite holes}, journal = {Environmental Research Letters}, volume = {8}, year = {2013}, month = {12/2013}, pages = {045006}, keywords = {LTER-MCM}, doi = {10.1088/1748-9326/8/4/045006}, url = {http://iopscience.iop.org/1748-9326/8/4/045006/pdf/1748-9326_8_4_045006.pdf}, author = {Lee F. Stanish and Bagshaw, Elizabeth and Diane M. McKnight and Andrew G Fountain and Martyn Tranter} } @article {1092, title = {Factors Controlling Soil Microbial Biomass and Bacterial Diversity and Community Composition in a Cold Desert Ecosystem: Role of Geographic Scale}, journal = {PLoS ONE}, volume = {8}, year = {2013}, month = {06/2013}, pages = {e66103}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0066103.s003}, url = {http://www.plosone.org/article/info\%3Adoi\%2F10.1371\%2Fjournal.pone.0066103}, author = {David J. Van Horn and Van Horn, M. Lee and John E. Barrett and Michael N. Gooseff and Adam E. Altrichter and Kevin M. Geyer and Lydia H. Zeglin and Cristina D. Takacs-Vesbach} } @article {1094, title = {The future of soil invertebrate communities in polar regions: different climate change responses in the Arctic and Antarctic?}, journal = {Ecology Letters}, volume = {16}, year = {2013}, month = {03/2013}, pages = {409 - 419}, keywords = {LTER-MCM}, doi = {10.1111/ele.12058}, url = {http://onlinelibrary.wiley.com/doi/10.1111/ele.12058/abstract;jsessionid=2591020317030CE8FCDC37FE39B4F0B2.f01t04}, author = {Uffe N. Nielsen and Diana H. Wall} } @article {1086, title = {Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys}, journal = {Geological Society of America Bulletin}, volume = {125}, year = {2013}, month = {09/2013}, pages = {1484 - 1502}, keywords = {LTER-MCM}, doi = {10.1130/B30783.1}, url = {http://bulletin.geoscienceworld.org/content/early/2013/06/07/B30783.1.abstract}, author = {Joseph S. Levy and Andrew G Fountain and O{\textquoteright}Connor, J. E. and Kathleen A. Welch and W. Berry Lyons} } @article {1095, title = {How big are the McMurdo Dry Valleys? Estimating ice-free area using Landsat image data}, journal = {Antarctic Science}, volume = {25}, year = {2013}, month = {02/2013}, pages = {119 - 120}, keywords = {LTER-MCM}, doi = {10.1017/S0954102012000727}, author = {Joseph S. Levy} } @article {1087, title = {The influence of stream thermal regimes and preferential flow paths on hyporheic exchange in a glacial meltwater stream}, journal = {Water Resources Research}, volume = {49}, year = {2013}, month = {09/2013}, pages = {5552 - 5569}, keywords = {LTER-MCM}, doi = {10.1002/wrcr.20410}, url = {http://onlinelibrary.wiley.com/doi/10.1002/wrcr.20410/pdf}, author = {Cozzetto, K and Kenneth E. Bencala and Michael N. Gooseff and Diane M. McKnight} } @article {1098, title = {Lake ice ablation rates from permanently ice-covered Antarctic lakes}, journal = {Journal of Glaciology}, volume = {59}, year = {2013}, month = {01/2013}, keywords = {LTER-MCM}, author = {Hilary A. Dugan and Maciek K. Obryk and Peter T. Doran} } @article {1075, title = {The Life Cycle of the Antarctic Nematode Plectus murrayi Under Laboratory Conditions.}, journal = {Journal of nematology}, volume = {45}, year = {2013}, month = {2013 Mar}, pages = {39-42}, keywords = {LTER-MCM}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3625130/}, author = {Cecilia M. Tomasel and Byron Adams and Fernando G. Tomasel and Diana H. Wall} } @article {1083, title = {Local and regional influences over soil microbial metacommunities in the Transantarctic Mountains}, journal = {Ecosphere}, volume = {4}, year = {2013}, month = {11/2013}, pages = {art136}, keywords = {LTER-MCM}, doi = {10.1890/ES13-00136.1}, author = {Eric R. Sokol and Herbold, Craig W. and Charles K. Lee and Craig S Cary and John E. Barrett} } @article {1088, title = {Microbial growth under humic-free conditions in a supraglacial stream system on the Cotton Glacier, Antarctica}, journal = {Environmental Research Letters}, volume = {8}, year = {2013}, month = {09/2013}, pages = {035022}, abstract = {During 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{\textendash}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 {\texttimes} 104 to 4.97 {\texttimes} 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.}, keywords = {LTER-MCM}, doi = {10.1088/1748-9326/8/3/035022}, url = {http://iopscience.iop.org/1748-9326/8/3/035022}, author = {Christine M. Foreman and Rose M. Cory and Morris, Cindy E and Michael D. SanClements and Smith, Heidi J and John T. Lisle and Penney L. Miller and Yu-Ping Chin and Diane M. McKnight} } @article {1080, title = {Micro-hole and multigrain quartz luminescence dating of Paleodeltas at Lake Fryxell, McMurdo Dry Valleys (Antarctica), and relevance for lake history}, journal = {Quaternary Geochronology}, volume = {18}, year = {2013}, month = {12/2013}, pages = {119 - 134}, keywords = {LTER-MCM}, doi = {10.1016/j.quageo.2013.04.002}, url = {http://www.sciencedirect.com/science/article/pii/S1871101413000423}, author = {G. W. Berger and Peter T. Doran and Thomsen, K.J.} } @article {1081, title = {Physicochemical and biological dynamics in a coastal Antarctic lake as it transitions from frozen to open water}, journal = {Antarctic Science}, volume = {25}, year = {2013}, month = {12/2013}, pages = {663{\textendash}675}, keywords = {LTER-MCM}, author = {Markus Dieser and Christine M. Foreman and Chris Jaros and John T. Lisle and Mark C. Greenwood and Johanna Laybourn-Parry and Penney L. Miller and Yu-Ping Chin and Diane M. McKnight} } @mastersthesis {4093, title = {Resource Legacies and Priming Regulate Microbial Communities in Antarctica{\textquoteright}s Dry Valleys}, volume = {M.S.}, year = {2013}, school = {Brigham Young University}, type = {masters}, address = {Provo, UT}, abstract = {

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.

}, keywords = {LTER-MCM, 454 pyrosequencing, Antarctica, bacteria, microbial ecology, soil, soil ecology, stable isotope probing, target metagenomics}, url = {http://hdl.lib.byu.edu/1877/etd6229}, author = {Saurey, Sabrina D.}, editor = {Aanderud, Zachary T.} } @article {1089, title = {Seasonal controls on snow distribution and aerial ablation at the snow-patch and landscape scales, McMurdo Dry Valleys, Antarctica}, journal = {The Cryosphere}, volume = {7}, year = {2013}, month = {09/2013}, pages = {917 - 931}, keywords = {LTER-MCM}, doi = {10.5194/tc-7-917-2013}, url = {http://www.the-cryosphere.net/7/917/2013/tc-7-917-2013.html}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1096, title = {Shallow groundwater systems in a polar desert, McMurdo Dry Valleys}, journal = {Hydrogeology Journal}, volume = {21}, year = {2013}, month = {02/2013}, pages = {171 - 183}, keywords = {LTER-MCM}, doi = {10.1007/s10040-012-0926-3}, url = {http://link.springer.com/article/10.1007\%2Fs10040-012-0926-3}, author = {Michael N. Gooseff and John E. Barrett and Joseph S. Levy} } @article {1090, title = {Spatial and temporal patterns of snow accumulation and aerial ablation across the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {27}, year = {2013}, month = {09/2013}, pages = {2864 - 2875}, keywords = {LTER-MCM}, doi = {10.1002/hyp.9407}, url = {http://onlinelibrary.wiley.com/doi/10.1002/hyp.9407/pdf}, author = {Eveland, Jeffery and Michael N. Gooseff and Lampkin, Derrick J. and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1099, title = {Understanding Terrestrial Ecosystem Response to Antarctic Climate Change}, journal = {Eos, Transactions American Geophysical Union}, volume = {94}, year = {2013}, month = {01/2013}, pages = {33 - 33}, keywords = {LTER-MCM}, doi = {10.1002/2013EO030009}, url = {http://onlinelibrary.wiley.com/doi/10.1002/2013EO030009/abstract}, author = {Joseph S. Levy and W. Berry Lyons and Byron Adams} } @article {1100, title = {Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica}, journal = {Antarctic Science}, year = {2013}, pages = {1 - 10}, keywords = {LTER-MCM}, doi = {10.1017/S095410201300045X}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and John E. Barrett and Robert Vantreese and Kathleen A. Welch and W. Berry Lyons and Uffe N. Nielsen and Diana H. Wall} } @article {1101, title = {Aeolian flux of biotic and abiotic material in Taylor Valley, Antarctica}, journal = {Geomorphology}, volume = {155-156}, year = {2012}, month = {6/2012}, pages = {102 - 111}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2011.12.009}, url = {http://www.sciencedirect.com/science/article/pii/S0169555X11006222}, author = {Marie {\v S}aback{\'a} and John C. Priscu and Hassan J. Basagic and Andrew G Fountain and Diana H. Wall and Ross A. Virginia and Mark C. Greenwood} } @article {1105, title = {Antarctic Tardigrada: a first step in understanding molecular operational taxonomic units (MOTUs) and biogeography of cryptic meiofauna}, journal = {Invertebrate Systematics}, volume = {26}, year = {2012}, month = {12/2012}, pages = {526}, keywords = {LTER-MCM}, doi = {10.1071/IS12034}, author = {Czechowski, Paul and Sands, Chester J. and Byron Adams and D{\textquoteright}Haese, Cyrille A. and John A. E. Gibson and McInnes, Sandra J. and Stevens, Mark I.} } @article {3534, title = {At Limits of Life: Multidisciplinary Insights Reveal Environmental Constraints on Biotic Diversity in Continental Antarctica}, journal = {PLoS ONE}, volume = {7}, year = {2012}, month = {Jul-09-2013}, pages = {e44578}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1371/journal.pone.0044578}, url = {http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0044578}, author = {Magalhaes, Catarina and Stevens, Mark I. and Craig S Cary and Ball, Becky and Storey, Bryan C. and Diana H. Wall and T{\"u}rk, Roman and Ruprecht, Ulrike}, editor = {de Bello, Francesco} } @article {1115, title = {Bacteria and diatom co-occurrence patterns in microbial mats from polar desert streams}, journal = {Environmental Microbiology}, year = {2012}, month = {10/2012}, keywords = {LTER-MCM}, doi = {10.1111/j.1462-2920.2012.02872.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2012.02872.x/abstract}, author = {Lee F. Stanish and Sean P. O{\textquoteright}Neill and Antonio Gonz{\'a}lez and Teresa M. Legg and Joseph Knelman and Diane M. McKnight and Sarah A. Spaulding and Diana R. Nemergut} } @article {3527, title = {Bacterioplankton productivity in lakes of the Taylor Valley, Antarctica, during the polar night transition}, journal = {Aquatic Microbial Ecology}, volume = {68}, year = {2012}, month = {12/2013}, pages = {77 - 90}, abstract = {

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.

}, keywords = {LTER-MCM}, issn = {0948-3055}, doi = {10.3354/ame01604}, url = {http://www.int-res.com/abstracts/ame/v68/n1/p77-90}, author = {Trista J. Vick-Majors and John C. Priscu} } @article {3535, title = {Challenges to the Future Conservation of the Antarctic}, journal = {Science}, volume = {337}, year = {2012}, month = {Jan-07-2013}, pages = {158 - 159}, abstract = {

The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globe\&$\#$39;s largest commons (1), is under substantial pressure. Concerns have been raised about increased stress on Antarctic systems from global environmental change and growing interest in the region\&$\#$39;s resources (2,\ 3). 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 (2,\ 3). 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.

}, keywords = {LTER-MCM}, issn = {0036-8075}, doi = {10.1126/science.1222821}, url = {http://www.sciencemag.org/cgi/doi/10.1126/science.1222821}, author = {Steven L. Chown and Lee, J. E. and Hughes, K. A. and Barnes, J. and Barrett, P.J. and D.M. Bergstrom and Convey, P. and Cowan, Don A. and Crosbie, K. and Dyer, G. and Frenot, Y. and Grant, S. M. and Herr, D. and Kennicutt, M. C. and Lamers, M. and Murray, A. and Possingham, H. P. and Reid, K. and Riddle, M. J. and Ryan, P. G. and Sanson, L. and Shaw, J. D. and Sparrow, M.D. and Summerhayes, C. and Terauds, A. and Diana H. Wall} } @article {1106, title = {Chemical analysis of ice vein microenvironments: II. Analysis of glacial samples from Greenland and Antarctica}, journal = {Journal of Glaciology}, volume = {58}, year = {2012}, month = {12/2012}, pages = {1109 - 1118}, keywords = {LTER-MCM}, doi = {10.3189/2012JoG12J112}, url = {http://www.montana.edu/priscu/DOCS/Publications/BarlettaEtAl2012IceVein.pdf}, author = {Barletta, Robert E. and John C. Priscu and Mader, Heidy M. and Jones, Warren L. and Roe, Christopher H.} } @article {1108, title = {Cross-biome metagenomic analyses of soil microbial communities and their functional attributes}, journal = {Proceedings Bational Academy of Sciences}, year = {2012}, month = {11/2012}, keywords = {LTER-MCM}, doi = {10.1073/pnas.1215210110}, url = {www.pnas.org/cgi/doi/10.1073/pnas.1215210110}, author = {Noah Fierer and Jonathan W. Leff and Byron Adams and Uffe N. Nielsen and Scott T. Bates and Christian L. Lauber and Sarah Owens and Jack A. Gilbert and Diana H. Wall and J. Gregory Caporaso} } @article {1109, title = {Cyanobacterial diversity across landscape units in a polar desert: Taylor Valley, Antarctica}, journal = {FEMS Microbiology Ecology}, volume = {82}, year = {2012}, month = {11/2012}, pages = {268 - 278}, keywords = {LTER-MCM}, doi = {10.1111/j.1574-6941.2012.01297.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01297.x/full}, author = {Alexander B. Michaud and Marie {\v S}aback{\'a} and John C. Priscu} } @article {1119, title = {The Disappearing Cryosphere: Impacts and Ecosystem Responses to Rapid Cryosphere Loss}, journal = {BioScience}, volume = {62}, year = {2012}, month = {04/2012}, pages = {405 - 415}, keywords = {LTER-MCM}, doi = {10.1525/bio.2012.62.4.11}, url = {http://bioscience.oxfordjournals.org/content/62/4/405.full}, author = {Andrew G Fountain and John L. Campbell and Edward A. G. Schuur and Sharon E. Stammerjohn and Mark W. Williams and Hugh W. Ducklow} } @article {1118, title = {Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition}, journal = {Applied and Environmental Microbiology}, volume = {78}, year = {2012}, month = {04/2012}, pages = {4358-4366}, keywords = {LTER-MCM}, url = {http://aem.asm.org/content/78/12/4358.short}, author = {Weidong Kong and David C. Ream and John C. Priscu and Rachael M. Morgan-Kiss} } @article {1122, title = {The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem}, journal = {Ecosphere}, volume = {3}, year = {2012}, month = {02/2012}, pages = {art17}, keywords = {LTER-MCM}, doi = {10.1890/ES11-00325.1}, url = {http://www.esajournals.org/doi/abs/10.1890/ES11-00325.1}, author = {Uffe N. Nielsen and Diana H. Wall and Byron Adams and Ross A. Virginia and Ball, Becky and Michael N. Gooseff and Diane M. McKnight} } @article {1110, title = {Evidence of form II RubisCO ( cbbM) in a perennially ice-covered Antarctic lake}, journal = {FEMS Microbiology Ecology}, volume = {82}, year = {2012}, month = {11/2012}, pages = {491 - 500}, keywords = {LTER-MCM}, doi = {10.1111/j.1574-6941.2012.01431.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01431.x/full}, author = {Weidong Kong and Jenna M. Dolhi and Amy Chiuchiolo and John C. Priscu and Rachael M. Morgan-Kiss} } @article {1116, title = {Extreme streams: flow intermittency as a control on diatom communities in meltwater streams in the McMurdo Dry Valleys, Antarctica}, journal = {Canadian Journal of Fisheries and Aquatic Sciences}, volume = {69}, year = {2012}, month = {08/2012}, pages = {1405 - 1419}, keywords = {LTER-MCM}, doi = {10.1139/f2012-022}, url = {http://www.nrcresearchpress.com/doi/abs/10.1139/f2012-022$\#$.UH2NlWcnq9g}, author = {Lee F. Stanish and Tyler J. Kohler and Rhea M.M. Esposito and Breana L. Simmons and Uffe N. Nielsen and Diana H. Wall and Diana R. Nemergut and Diane M. McKnight} } @article {1104, title = {The geochemistry of upland ponds, Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {24}, year = {2012}, month = {2/2012}, pages = {3 - 14}, keywords = {LTER-MCM}, doi = {10.1017/S0954102011000617}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=8483351}, author = {W. Berry Lyons and Kathleen A. Welch and Christopher B. Gardner and Chris Jaros and Daryl L. Moorhead and Knoepfle, J and Peter T. Doran} } @article {1121, title = {Hypersaline {\textquotedblleft}wet patches{\textquotedblright} in Taylor Valley, Antarctica}, journal = {Geophysical Research Letters}, volume = {39}, year = {2012}, month = {03/2012}, keywords = {LTER-MCM}, doi = {10.1029/2012GL050898}, author = {Joseph S. Levy and Andrew G Fountain and Kathleen A. Welch and W. Berry Lyons} } @article {1111, title = {Leaving scientific footprints}, journal = {Frontiers in Ecology and the Environment}, volume = {10}, year = {2012}, month = {11/2012}, pages = {502 - 503}, keywords = {LTER-MCM}, doi = {10.1890/1540-9295-10.9.502}, author = {Diana H. Wall} } @article {1112, title = {Meltwater seep patches increase heterogeneity of soil geochemistry and therefore habitat suitability}, journal = {Geoderma}, volume = {189-190}, year = {2012}, month = {11/2012}, pages = {652 - 660}, keywords = {LTER-MCM}, doi = {10.1016/j.geoderma.2012.06.028}, author = {Ball, Becky and Ross A. Virginia} } @article {1113, title = {Microbial dynamics and flagellate grazing during transition to winter in Lakes Hoare and Bonney, Antarctica}, journal = {FEMS Microbiology Ecology}, volume = {82}, year = {2012}, month = {11/2012}, pages = {449 - 458}, keywords = {LTER-MCM}, doi = {10.1111/j.1574-6941.2012.01423.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2012.01423.x/full}, author = {Jill Thurman and Jacqueline Parry and Philip J. Hill and John C. Priscu and Trista J. Vick-Majors and Amy Chiuchiolo and Johanna Laybourn-Parry} } @article {3528, title = {Microbial life at -13 ~C in the brine of an ice-sealed Antarctic lake}, journal = {Proceedings of the National Academy of Sciences}, volume = {109}, year = {2012}, month = {12/2012}, pages = {20626 - 20631}, keywords = {LTER-MCM}, issn = {0027-8424}, doi = {10.1073/pnas.1208607109}, url = {http://www.pnas.org/cgi/doi/10.1073/pnas.1208607109}, author = {A. E. Murray and Kenig, Fabien and Christian H. Fritsen and Christopher P. McKay and Kaelin M. Cawley and R. L. Edwards and Kuhn, Emanuele and Diane M. McKnight and Nathaniel E Ostrom and Vivian Peng and Adrian Ponce and John C. Priscu and Samarkin, Vladimir A. and Ashley T Townsend and Protima Wagh and Seth A Young and Pung To Yung and Peter T. Doran} } @mastersthesis {4162, title = {Modeling nitrate concentrations in an Antarctic glacial meltwater stream under fluctuating hydrologic conditions and nitrate inputs}, volume = {M.S.}, year = {2012}, school = {Pennsylvania State University}, type = {masters}, abstract = {

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.

}, keywords = {LTER-MCM, hydrology, hyporheic zone, nitrate, nutrients, primary productivity, stream}, url = {https://etda.libraries.psu.edu/catalog/15316}, author = {Bernzott, Emily D. and Michael N. Gooseff} } @article {1107, title = {Perchlorate and chlorate biogeochemistry in ice-covered lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Geochimica et Cosmochimica Acta}, volume = {98}, year = {2012}, month = {12/2012}, pages = {19 - 30}, keywords = {LTER-MCM}, doi = {10.1016/j.gca.2012.09.014}, url = {http://www.sciencedirect.com/science/article/pii/S001670371200511X}, author = {W. Andrew Jackson and Alfonso F. Davila and Nubia Estrada and W. Berry Lyons and John D. Coates and John C. Priscu} } @book {1123, title = {Poisson Reconstruction of Extreme Submersed Environments: The ENDURANCE Exploration of an Under-Ice Antarctic Lake}, series = {Advances in Visual Computing. ISVC 2012. Lecture Notes in Computer Science.}, volume = {7431}, year = {2012}, pages = {394 - 403}, publisher = {Springer Berlin Heidelberg}, organization = {Springer Berlin Heidelberg}, address = {Berlin, Heidelberg}, abstract = {

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.

}, keywords = {LTER-MCM}, isbn = {978-3-642-33179-4}, doi = {10.1007/978-3-642-33179-4_38}, url = {http://www.springerlink.com/content/hg97w43588229087/}, author = {Alessandro Febretti and Kristof Richmond and Gulati, Shilpa and Flesher, Christopher and Hogan, Bartholomew P. and Andrew Johnson and Stone, William C. and John C. Priscu and Peter T. Doran}, editor = {Bebis, George and Boyle, Richard and Parvin, Bahram and Koracin, Darko and Fowlkes, Charless and Wang, Sen and Choi, Min-Hyung and Mantler, Stephan and Schulze, J{\"u}rgen and Acevedo, Daniel and Mueller, Klaus and Papka, Michael} } @article {4062, title = {Seismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica}, journal = {Journal of Geophysical Research: Earth Surface}, volume = {117}, year = {2012}, month = {07/2012}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1029/2011JF002221}, url = {http://onlinelibrary.wiley.com/doi/10.1029/2011JF002221/full}, author = {Carmichael, J. D. and Pettit, E. and Hoffman, M and Andrew G Fountain and Hallet, B.} } @mastersthesis {4171, title = {Snow dynamics in a polar desert, McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2012}, month = {2012}, school = {Pennsylvania State University}, type = {masters}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://etda.libraries.psu.edu/catalog/12680}, author = {Eveland, Jeffery and Michael N. Gooseff} } @article {1124, title = {Taylor{\textquoteright}s {\textquoteleft}missing{\textquoteright} lake: Integrating history into LTER research in the McMurdo Dry Valley}, volume = {2013}, year = {2012}, publisher = {LTER News}, address = {Albuquerque}, keywords = {LTER-MCM}, url = {http://news.lternet.edu/Article2568.html}, author = {Khan, A and Howkins, Adrian and W. Berry Lyons} } @article {1102, title = {Thawing permafrost alters nematode populations and soil habitat characteristics in an Antarctic polar desert ecosystem}, journal = {Pedobiologia}, volume = {55}, year = {2012}, month = {3/2012}, pages = {75 - 81}, keywords = {LTER-MCM}, doi = {10.1016/j.pedobi.2011.11.001}, url = {http://www.sciencedirect.com/science/article/pii/S0031405611001156}, author = {Smith, T.E. and Diana H. Wall and Hogg, I and Byron Adams and Uffe N. Nielsen and Ross A. Virginia} } @phdthesis {4193, title = {Wind as an ecological factor in the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2012}, month = {2012}, pages = {201}, school = {Montana State University}, type = {doctoral}, address = {Bozeman, MT}, abstract = {

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 f{\"o}hn 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.

}, keywords = {LTER-MCM}, url = {https://scholarworks.montana.edu/xmlui/handle/1/2171}, author = {Marie {\v S}aback{\'a} and John C. Priscu} } @article {1130, title = {15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: Evidence for a hydantoin derivative}, journal = {Magnetic Resonance in Chemistry}, volume = {49}, year = {2011}, month = {12/2011}, pages = {775 - 780}, keywords = {LTER-MCM}, doi = {10.1002/mrc.2816}, author = {Xiaowen Fang and Jingdong Mao and Rose M. Cory and Diane M. McKnight and Klaus Schmidt-Rohr} } @article {1132, title = {Antarctic nematode communities: observed and predicted responses to climate change}, journal = {Polar Biology}, volume = {34}, year = {2011}, month = {11/2011}, pages = {1701 - 1711}, keywords = {LTER-MCM}, doi = {10.1007/s00300-011-1021-2}, url = {http://www.springerlink.com/content/v588t5671p1w1323/}, author = {Uffe N. Nielsen and Diana H. Wall and Byron Adams and Ross A. Virginia} } @article {1128, title = {Bacterial Community Structure Along Moisture Gradients in the Parafluvial Sediments of Two Ephemeral Desert Streams}, journal = {Microbial Ecology}, volume = {61}, year = {2011}, month = {4/2011}, pages = {543 - 556}, keywords = {LTER-MCM}, doi = {10.1007/s00248-010-9782-7}, url = {http://www.springerlink.com/content/r83j53334v5n505w/}, author = {Lydia H. Zeglin and Clifford N. Dahm and John E. Barrett and Michael N. Gooseff and Shannon K. Fitpatrick and Cristina D. Takacs-Vesbach} } @article {1140, title = {Determination of Dissolved Oxygen in the Cryosphere: A Comprehensive Laboratory and Field Evaluation of Fiber Optic Sensors}, journal = {Environmental Science \& Technology}, volume = {45}, year = {2011}, month = {01/2011}, pages = {700 - 705}, keywords = {LTER-MCM}, doi = {10.1021/es102571j}, author = {Bagshaw, Elizabeth and Wadham, J. L. and Mowlem, M. and Martyn Tranter and Eveness, J. and Andrew G Fountain and Telling, J.} } @article {1136, title = {A diatom record of environmental change in Fryxell Basin, Taylor Valley, Antarctica, late Pleistocene to present}, journal = {Journal of Paleolimnology}, volume = {46}, year = {2011}, month = {08/2011}, pages = {257 - 272}, keywords = {LTER-MCM}, doi = {10.1007/s10933-011-9537-6}, url = {http://www.springerlink.com/content/y3483576u8220081/}, author = {Matthew A. Konfirst and Charlotte Sjunneskog and Reed P. Scherer and Peter T. Doran} } @phdthesis {4095, title = {Ecological controls on stream diatom communities in the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2011}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, biological sciences, community ecology, diatoms, earth sciences, McMurdo Dry Valleys, streams}, url = {https://search.proquest.com/docview/915694114?accountid=14503}, author = {Lee F. Stanish}, editor = {Diane M. McKnight} } @proceedings {1139, title = {Environmental Protection and Stewardship of Subglacial Aquatic Environments}, journal = {AGU Chapman Conference}, volume = {192}, year = {2011}, month = {03/2011}, pages = {149-157}, publisher = {American Geophysical Union, Washington, DC}, address = {Baltimore}, keywords = {LTER-MCM}, author = {Peter T. Doran and Warwick F. Vincent} } @book {1142, title = {Frontiers in Understanding Climate Change and Polar Ecosystems}, series = {Committee on Frontiers in Understanding Climate Change and Polar Ecosystems Polar Research Board Division of Earth and Life Studies}, year = {2011}, publisher = {The National Academies Press}, organization = {The National Academies Press}, keywords = {LTER-MCM}, isbn = {0-309-21087-9}, author = {Grebmeier, J. and John C. Priscu} } @article {3536, title = {Global change and Antarctic terrestrial biodiversity}, journal = {Polar Biology}, volume = {34}, year = {2011}, month = {11/2011}, pages = {1625 - 1627}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-011-1108-9}, url = {http://link.springer.com/10.1007/s00300-011-1108-9}, author = {Hogg, Ian D. and Diana H. Wall} } @article {1137, title = {High-resolution monitoring reveals dissolved oxygen dynamics in an Antarctic cryoconite hole}, journal = {Hydrological Processes}, volume = {25}, year = {2011}, month = {08/2011}, pages = {2868 - 2877}, keywords = {LTER-MCM}, doi = {10.1002/hyp.8049}, author = {Bagshaw, Elizabeth and Martyn Tranter and Wadham, J. L. and Andrew G Fountain and Mowlem, M.} } @article {1127, title = {The Holocene environmental history of Lake Hoare, Taylor Valley, Antarctica, reconstructed from sediment cores}, journal = {Antarctic Science}, volume = {23}, year = {2011}, month = {6/2011}, pages = {307 - 319}, keywords = {LTER-MCM}, doi = {10.1017/S0954102011000125}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=8275374}, author = {Wagner, Bernd and Ortlepp, Sabrina and Peter T. Doran and Kenig, Fabien and Melles, Martin and Andy Burkemper} } @mastersthesis {4163, title = {Hydrologic controls of nutrient fluxes in glacial meltwater streams at inter-annual, seasonal, and daily timescales in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2011}, school = {Pennsylvania State University}, type = {masters}, abstract = {

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\&$\#$39;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.

}, keywords = {LTER-MCM, Antarctica, biogeochemistry, chemical weathering, discharge, electrical conductivity, glacial melt, glaciers, hydrology, hyporheic, MCM LTER, McMurdo Dry Valleys, nutrient fluxes, nutrients, polar desert, solute chemistry, stream chemistry, streamflow, water chemistry}, url = {https://etda.libraries.psu.edu/catalog/11568}, author = {Weaver, Mitchell R. and Michael N. Gooseff} } @article {1131, title = {Hydrologic processes influence diatom community composition in Dry Valley streams}, journal = {Journal of the North American Benthological Society}, volume = {30}, year = {2011}, month = {12/2011}, pages = {1057-1073}, keywords = {LTER-MCM}, doi = {10.1899/11-008.1}, url = {http://www.jnabs.org/doi/abs/10.1899/11-008.1}, author = {Lee F. Stanish and Diana R. Nemergut and Diane M. McKnight} } @article {1135, title = {Hydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica}, journal = {Geography Compass}, volume = {5}, year = {2011}, month = {09/2011}, pages = {666 - 681}, keywords = {LTER-MCM}, doi = {10.1111/j.1749-8198.2011.00445.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1749-8198.2011.00445.x}, author = {Michael N. Gooseff and Diane M. McKnight and Peter T. Doran and Andrew G Fountain and W. Berry Lyons} } @article {3537, title = {Implications of meltwater pulse events for soil biology and biogeochemical cycling in a polar desert}, journal = {Polar Research}, volume = {3081281030352511340}, year = {2011}, month = {12/2011}, keywords = {LTER-MCM}, issn = {0800-0395}, doi = {10.3402/polar.v30i0.14555}, url = {http://www.polarresearch.net/index.php/polar/article/view/14555}, author = {Ball, Becky and John E. Barrett and Michael N. Gooseff and Ross A. Virginia and Diana H. Wall} } @article {3539, title = {Long-term ecosystem networks to record change: an international imperative}, journal = {Antarctic Science}, volume = {23}, year = {2011}, month = {06/2011}, pages = {209}, keywords = {LTER-MCM}, issn = {0954-1020}, doi = {10.1017/S0954102011000319}, url = {http://www.journals.cambridge.org/abstract_S0954102011000319}, author = {Diana H. Wall and W. Berry Lyons and Steven L. Chown and Peter Convey and Clive Howard-Williams and Quesada, Antonio and Warwick F. Vincent} } @article {1143, title = {MCM IV: Getting Connected}, volume = {2013}, year = {2011}, publisher = {LTER News}, edition = {Fall 2011}, keywords = {LTER-MCM}, url = {http://news.lternet.edu/Article2316.html}, author = {Howkins, Adrian} } @article {3538, title = {Microclimate impacts of passive warming methods in Antarctica: implications for climate change studies}, journal = {Polar Biology}, volume = {34}, year = {2011}, month = {10/2011}, pages = {1421 - 1435}, keywords = {LTER-MCM}, issn = {0722-4060}, doi = {10.1007/s00300-011-0997-y}, url = {http://link.springer.com/10.1007/s00300-011-0997-y}, author = {Bokhorst, Stef and Huiskes, Ad and Peter Convey and Sinclair, Brent J. and Lebouvier, Marc and Bart Van de Vijver and Diana H. Wall} } @inbook {1144, title = {Molecular analysis of desiccation survival in Antarctic nematodes}, booktitle = {Molecular and Physiological Basis of Nematode Survival}, year = {2011}, pages = {205-232}, publisher = {CABI International}, organization = {CABI International}, address = {Wallingford}, keywords = {LTER-MCM}, isbn = {9781845936877}, author = {Bishwo N. Adhikari and Byron Adams} } @book {1145, title = {Molecular and physiological basis of nematode survival: Molecular analyses of desiccation survival in Antarctic nematodes.}, year = {2011}, pages = {205 - 232}, publisher = {CABI}, organization = {CABI}, address = {Wallingford}, keywords = {LTER-MCM}, doi = {10.1079/9781845936877.0205}, author = {Bishwo N. Adhikari and Byron Adams}, editor = {Perry, R. N. and Wharton, D. A.} } @article {1134, title = {Molecular study of worldwide distribution and diversity of soil animals}, journal = {Proceedings of the National Academy of Sciences}, volume = {108}, year = {2011}, month = {10/2011}, pages = {17720 - 17725}, keywords = {LTER-MCM}, doi = {10.1073/pnas.1103824108}, author = {Tiehang Wu and Edward Ayres and Richard D. Bardgett and Diana H. Wall and James R. Garey} } @article {1126, title = {Nematode communities of Byers Peninsula, Livingston Island, maritime Antarctica}, journal = {Antarctic Science}, volume = {23}, year = {2011}, month = {8/2011}, pages = {349 - 357}, keywords = {LTER-MCM}, doi = {10.1017/S0954102011000174}, author = {Uffe N. Nielsen and Diana H. Wall and Li, Grace and Toro, Manuel and Byron Adams and Ross A. Virginia} } @article {1125, title = {Protist diversity in a permanently ice-covered Antarctic Lake during the polar night transition}, journal = {The ISME Journal}, volume = {5}, year = {2011}, month = {9/2011}, pages = {1559 - 1564}, keywords = {LTER-MCM}, doi = {10.1038/ismej.2011.23}, url = {http://www.nature.com/ismej/journal/v5/n9/abs/ismej201123a.html}, author = {Scott Bielewicz and Elanor R. Bell and Weidong Kong and Iddo Friedberg and John C. Priscu and Rachael M. Morgan-Kiss} } @phdthesis {4085, title = {Removal of benthic algae in swift-flowing streams: The significance of spatial and temporal variation in shear stress and bed disturbance}, volume = {Ph.D.}, year = {2011}, pages = {263}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://search.proquest.com/docview/916604693?accountid=14503}, author = {Cullis, James D.S.}, editor = {Diane M. McKnight} } @article {1129, title = {Simulating unsteady flow, anabranching, and hyporheic dynamics in a glacial meltwater stream using a coupled surface water routing and groundwater flow model}, journal = {Water Resources Research}, volume = {47}, year = {2011}, month = {2011}, keywords = {LTER-MCM}, doi = {10.1029/2010WR009508}, author = {Koch, J. and Diane M. McKnight and Neupauer, R. M.} } @phdthesis {1141, title = {Spatial and Temporal Variability of Glacier Melt in the McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2011}, month = {01/2011}, pages = {296}, school = {Portland State University}, type = {doctoral}, address = {Portland}, keywords = {LTER-MCM}, author = {Hoffman, M} } @book {1146, title = {Spectral Methods to Advance Understanding of Dissolved Organic Carbon Dynamics in Forested Catchments}, series = {Ecological StudiesForest Hydrology and Biogeochemistry}, volume = {216}, year = {2011}, pages = {117 - 135}, publisher = {Springer Netherlands}, organization = {Springer Netherlands}, address = {Dordrecht}, keywords = {LTER-MCM}, isbn = {978-94-007-1363-5}, doi = {10.1007/978-94-007-1363-5_6}, url = {http://www.springerlink.com/content/lv9365ml54192m29/}, author = {Rose M. Cory and Elizabeth W. Boyer and Diane M. McKnight}, editor = {Levia, Delphis F. and Carlyle-Moses, Darryl and Tanaka, Tadashi} } @article {1133, title = {Water tracks and permafrost in Taylor Valley, Antarctica: Extensive and shallow groundwater connectivity in a cold desert ecosystem}, journal = {Geological Society of America Bulletin}, volume = {123}, year = {2011}, month = {11/2011}, pages = {2295-2311}, keywords = {LTER-MCM}, doi = {10.1130/B30436.1}, url = {http://bulletin.geoscienceworld.org/content/123/11-12/2295.short}, author = {Joseph S. Levy and Andrew G Fountain and Michael N. Gooseff and Kathleen A. Welch and W. Berry Lyons} } @article {1138, title = {When a habitat freezes solid: microorganisms over-winter within the ice column of a coastal Antarctic lake}, journal = {FEMS Microbiology Ecology}, volume = {76}, year = {2011}, month = {06/2011}, pages = {401 - 412}, keywords = {LTER-MCM}, doi = {10.1111/j.1574-6941.2011.01061.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1574-6941.2011.01061.x/full}, author = {Christine M. Foreman and Markus Dieser and Mark Greenwood and Rose M. Cory and Johanna Laybourn-Parry and John T. Lisle and Chris Jaros and Penney L. Miller and Yu-Ping Chin and Diane M. McKnight} } @article {1148, title = {Abiotic nitrous oxide emission from the hypersaline Don Juan Pond in Antarctica}, journal = {Nature Geoscience}, volume = {3}, year = {2010}, month = {5/2010}, pages = {341 - 344}, keywords = {LTER-MCM}, doi = {10.1038/ngeo847}, url = {http://www.nature.com/ngeo/journal/v3/n5/full/ngeo847.html}, author = {Samarkin, Vladimir A. and Madigan, Michael T. and Bowles, Marshall W. and Karen L. Casciotti and John C. Priscu and Christopher P. McKay and Joye, Samantha B.} } @mastersthesis {4366, title = {Aeolian sediments of the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2010}, school = {Ohio State University}, type = {masters}, address = {Columbus, OH}, abstract = {

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.

}, keywords = {LTER-MCM, aeolian transport, Antarctica, dust, experimental leaching, geochemistry, McMurdo Dry Valleys, sediment provenance, weathering}, url = {http://rave.ohiolink.edu/etdc/view?acc_num=osu1290524862}, author = {Deuerling, Kelly M. and W. Berry Lyons} } @article {1151, title = {Antarctic lakes suggest millennial reorganizations of Southern Hemisphere atmospheric and oceanic circulation}, journal = {Proceedings of the National Academy of Sciences}, volume = {107}, year = {2010}, month = {12/2010}, pages = {21355 - 21359}, keywords = {LTER-MCM}, doi = {10.1073/pnas.1007250107}, url = {http://www.pnas.org/content/107/50/21355.full.pdf$\#$page=1\&view=FitH}, author = {Brenda L. Hall and George H. Denton and Andrew G Fountain and Chris H. Hendy and Gideon M. Henderson} } @inbook {1168, title = {Antarctic McMurdo Dry Valley stream ecosystems as analog to fluvial systems on Mars}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, year = {2010}, pages = {139 - 159}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.005}, author = {Michael N. Gooseff and Diane M. McKnight and Carr, M. H. and Baeseman, J.}, editor = {Peter T. Doran and W. Berry Lyons and Diane M. McKnight} } @article {1155, title = {The Antarctic Nematode Plectus murrayi: An Emerging Model to Study Multiple Stress Survival}, journal = {Cold Spring Harbor Protocols}, volume = {2010}, year = {2010}, month = {11/2010}, pages = {pdb.emo142 - pdb.emo142}, keywords = {LTER-MCM}, doi = {10.1101/pdb.emo142}, author = {Bishwo N. Adhikari and Cecilia M. Tomasel and Li, G and Diana H. Wall and Byron Adams} } @mastersthesis {4194, title = {Bacterioplakton dynamics in stratified lakes of the Taylor Valley, Antarctica during the transition to polar night}, volume = {M.S.}, year = {2010}, month = {2010}, pages = {83}, school = {Montana State University}, type = {masters}, address = {Bozeman, MT}, abstract = {

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.

}, keywords = {LTER-MCM}, url = {https://scholarworks.montana.edu/xmlui/handle/1/2477}, author = {Trista J. Vick-Majors and John C. Priscu} } @article {1150, title = {Biogeochemical weathering under ice: Size matters}, journal = {Global Biogeochemical Cycles}, volume = {24}, year = {2010}, month = {2010}, keywords = {LTER-MCM}, doi = {10.1029/2009GB003688}, author = {Wadham, J. L. and Martyn Tranter and Skidmore, M and Hodson, A. J. and John C. Priscu and W. Berry Lyons and Sharp, M. and Wynn, P. and Margaret S. Jackson} } @inbook {1169, title = {The biogeochemistry and hydrology of Dry Valley glaciers: is there life on Martian ice now?}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, year = {2010}, pages = {195-220}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, author = {Martyn Tranter and Bagshaw, Elizabeth and Andrew G Fountain and Forman, C.} } @article {1156, title = {Culturing the Antarctic Nematode Plectus murrayi}, journal = {Cold Spring Harbor Protocols}, volume = {2010}, year = {2010}, month = {11/2010}, pages = {pdb.prot5522 - pdb.prot5522}, keywords = {LTER-MCM}, doi = {10.1101/pdb.prot5522}, url = {http://cshprotocols.cshlp.org/content/2010/11/pdb.emo142.short}, author = {Bishwo N. Adhikari and Cecilia M. Tomasel and Li, G and Diana H. Wall and Byron Adams} } @article {1157, title = {Design and deployment of a four-degrees-of-freedom hovering autonomous underwater vehicle for sub-ice exploration and mapping}, journal = {Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment}, volume = {224}, year = {2010}, month = {11/2010}, pages = {341 - 361}, keywords = {LTER-MCM}, doi = {10.1243/14750902JEME214}, author = {Stone, W and Bartholomew P Hogan and Flesher, C and Gulati, S and Kristof Richmond and Murarka, A and Kuhlman, G and Idharan, M and Siegel, V and Price, R M and Peter T. Doran and John C. Priscu} } @inbook {1170, title = {Diatoms as indicators of environmental change in Antarctic and subantarctic freshwaters}, booktitle = {The Diatoms Applications for the Environmental and Earth Sciences}, year = {2010}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, edition = {2}, keywords = {LTER-MCM}, isbn = {9780521509961}, url = {http://www.cambridge.org/us/academic/subjects/life-sciences/plant-science/diatoms-applications-environmental-and-earth-sciences-2nd-edition}, author = {Sarah A. Spaulding and Bart Van de Vijver and Hodgson, D and Diane M. McKnight and Elie Verleyen and Lee F. Stanish} } @article {1162, title = {Dynamic behaviour of supraglacial lakes on cold polar glaciers: Canada Glacier, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {56}, year = {2010}, month = {06/2010}, pages = {366 - 368}, keywords = {LTER-MCM}, doi = {10.3189/002214310791968449}, author = {Bagshaw, Elizabeth and Martyn Tranter and Wadham, J. L. and Andrew G Fountain and Hassan J. Basagic} } @article {1165, title = {A dynamic physical model for soil temperature and water in Taylor Valley, Antarctica.}, journal = {Antarctic Science}, year = {2010}, month = {05/13/2010}, pages = {419-434}, type = {Journal}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000234}, author = {H. W. Hunt and Andrew G Fountain and Peter T. Doran and Hassan J. Basagic} } @article {1161, title = {Effect of instrument-specific response on the analysis of fulvic acid fluorescence spectra}, journal = {Limnology and Oceanography: Methods}, volume = {8}, year = {2010}, month = {07/2010}, pages = {67-78}, keywords = {LTER-MCM}, url = {http://www.aslo.org/lomethods/free/2010/0067.html}, author = {Rose M. Cory and Mathew P. Miller and Diane M. McKnight and Guerard, Jennifer and Penney L. Miller} } @article {1163, title = {Effect of slow desiccation and freezing on gene transcription and stress survival of an Antarctic nematode}, journal = {Journal of Experimental Biology}, volume = {213}, year = {2010}, month = {06/2010}, pages = {1803 - 1812}, keywords = {LTER-MCM}, doi = {10.1242/jeb.032268}, author = {Bishwo N. Adhikari and Diana H. Wall and Byron Adams} } @article {4816, title = {Effect of unsteady flow on nitrate loss in an oligotrophic, glacial meltwater stream}, journal = {Journal of Geophysical Research}, volume = {115}, year = {2010}, month = {03/2010}, pages = {G01001}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, hot spots/hot moments, hyporheic exchange, nitrogen cycling, unsteady flow}, doi = {10.1029/2009JG001030}, url = {http://doi.wiley.com/10.1029/2009JG001030}, author = {Koch, J. and Diane M. McKnight and Baeseman, J.} } @mastersthesis {1230, title = {An Energy Balance Model of Melt-water Production for Polar Glaciers in Taylor Valley, Antarctica}, volume = {M.S.}, year = {2010}, school = {Portland State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ebnet, J and Andrew G Fountain} } @article {1147, title = {Experimentally increased snow accumulation alters soil moisture and animal community structure in a polar desert}, journal = {Polar Biology}, volume = {33}, year = {2010}, month = {7/2010}, pages = {897 - 907}, keywords = {LTER-MCM}, doi = {10.1007/s00300-010-0766-3}, author = {Edward Ayres and Johnson N. Nkem and Diana H. Wall and Byron Adams and John E. Barrett and Breana L. Simmons and Ross A. Virginia and Andrew G Fountain} } @inbook {1171, title = {Factors promoting microbial diversity in the McMurdo Dry Valleys}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments: Astrobiological Analogues}, series = {Cambridge Astrobiology}, volume = {5}, year = {2010}, pages = {221-257}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.008}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258\&cid=CBO9780511712258A015}, author = {Cristina D. Takacs-Vesbach and Lydia H. Zeglin and Michael N. Gooseff and John E. Barrett and John C. Priscu} } @phdthesis {4442, title = {Genomic analysis of nematode-environment interaction}, volume = {Ph.D.}, year = {2010}, month = {08/2010}, school = {Brigham Young University}, type = {doctoral}, address = {Provo, UT}, abstract = {

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.

}, keywords = {LTER-MCM, anhydrobiosis, Antarctic nematode, comparative transcriptomics, complementary DNA library, desiccation, functional analysis, Heterorhabditis bacteriophora, McMurdo Dry Valleys, microarray analysis, Plectus murrayi, quantative real-time polymerase chain reaction, Scottnema lindsayae, stoichiometry, stress survival, subtractive hybridization, trait deterioration, transcriptional profiling}, url = {https://scholarsarchive.byu.edu/etd/2578}, author = {Bishwo N. Adhikari and Byron Adams} } @phdthesis {4190, title = {Hydrologic and biogeochemical implications of flooding in two catchments underlain by continuous permafrost}, volume = {Ph.D.}, year = {2010}, month = {2010}, pages = {206}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, carbon, catchments, earth sciences, flooding, nitrogen, permafrost, surface-groundwater interactions}, url = {https://search.proquest.com/docview/839008865}, author = {Koch, J. and Diane M. McKnight} } @mastersthesis {4082, title = {Landscape history and contemporary environmental drivers of microbial community structure and function}, volume = {MS}, year = {2010}, school = {Virginia Tech}, type = {masters}, address = {Blacksburg, VA}, abstract = {

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.

}, keywords = {LTER-MCM, community similarity, extracellular enzyme activity, McMurdo Dry Valleys, microbial biogeography, soil geochemistry, T-RFLP}, url = {http://hdl.handle.net/10919/31883}, author = {Adam E. Altrichter}, editor = {John E. Barrett} } @article {1152, title = {Latitudinal distribution and mitochondrial DNA (COI) variability of Stereotydeus spp. (Acari: Prostigmata) in Victoria Land and the central Transantarctic Mountains}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {12/2010}, pages = {749 - 756}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000659}, author = {Demetras, Nicholas J. and Hogg, I and Banks, Jonathan C. and Byron Adams} } @inbook {1172, title = {The legacy of aqueous environments on soils of the McMurdo Dry Valleys: contexts for future exploration of martian soils}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, volume = {5}, year = {2010}, pages = {78 - 109}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.003}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258\&cid=CBO9780511712258A010}, author = {John E. Barrett and Poage, M and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @book {1173, title = {Life in Antarctic Deserts and Other Cold Environments}, series = {Astrobiological Analogs}, volume = {5}, year = {2010}, pages = {307}, publisher = {Cambridge University Press.}, organization = {Cambridge University Press.}, address = {Cambridge}, keywords = {LTER-MCM, Planetary Science}, isbn = {9780511712258}, doi = {10.1017/CBO9780511712258}, url = {http://ebooks.cambridge.org/ebook.jsf?bid=CBO9780511712258}, author = {Peter T. Doran and W. Berry Lyons and Diane M. McKnight}, editor = {Diane M. McKnight and Michael N. Gooseff and Cristina D. Takacs-Vesbach and Jill A. Mikucki and Martyn Tranter and Sun, Henry J} } @phdthesis {1177, title = {Microbial interactions with dissolved organic matter in saline natural waters}, year = {2010}, school = {University of Colorado}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Cawley, K} } @article {1167, title = {New insights into the origin and evolution of Lake Vida, McMurdo Dry Valleys, Antarctica {\textemdash} A noble gas study in ice and brines}, journal = {Earth and Planetary Science Letters}, volume = {289}, year = {2010}, month = {01/2010}, pages = {112 - 122}, keywords = {LTER-MCM}, doi = {10.1016/j.epsl.2009.10.034}, url = {http://www.sciencedirect.com/science/article/pii/S0012821X09006335}, author = {Jessica L. Malone and Clara M. Castro and Chris M. Hall and Peter T. Doran and Kenig, Fabien and Christopher P. McKay} } @article {1149, title = {Origin and tentative identification of tri to pentaunsaturated ketones in sediments from Lake Fryxell, East Antarctica}, journal = {Organic Geochemistry}, volume = {41}, year = {2010}, month = {4/2010}, pages = {386 - 397}, keywords = {LTER-MCM}, doi = {10.1016/j.orggeochem.2009.12.004}, author = {Jaraula, Caroline M.B. and Brassell, Simon C. and Rachael M. Morgan-Kiss and Peter T. Doran and Kenig, Fabien} } @article {1158, title = {Palaeoenvironmental implications derived from a piston core from east lobe Bonney, Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {10/2010}, pages = {522 - 530}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000556}, author = {Wagner, Bernd and Ortlepp, Sabrina and Kenig, Fabien and Peter T. Doran and Melles, Martin} } @article {1174, title = {Physiochemical properties influencing biomass abundance and primary production in Lake Hoare, Antarctica}, journal = {Ecological Modelling}, year = {2010}, keywords = {LTER-MCM}, doi = {LTER}, author = {Herbei, Radu and W. Berry Lyons and Johanna Laybourn-Parry and Christopher B. Gardner and John C. Priscu and Diane M. McKnight} } @inbook {1175, title = {Saline lakes and ponds in the McMurdo Dry Valleys: ecological analogs to martian paleolake environments}, booktitle = {Life in Antarctic Deserts and other Cold Dry Environments}, year = {2010}, pages = {160 - 194}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, address = {Cambridge}, keywords = {LTER-MCM}, isbn = {9780521889193}, doi = {10.1017/CBO9780511712258.006}, url = {http://ebooks.cambridge.org/chapter.jsf?bid=CBO9780511712258\&cid=CBO9780511712258A013}, author = {Jill A. Mikucki and W. Berry Lyons and Ian Hawes and Brian D. Lanoil and Peter T. Doran} } @article {1176, title = {Sediment Melt Dynamics in Permanent Antarctic Lake Ice}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {42}, year = {2010}, pages = {57-66}, keywords = {LTER-MCM}, doi = {10.1657/1938-4246-42.1.57}, url = {http://mcmlter.lternet.edu/reports/lakes/JepsenEtAl2010SedimentMeltMigration.pdf}, author = {Steven M. Jepsen and Edward E. Adams and John C. Priscu} } @article {1153, title = {Single-grain and multigrain luminescence dating of on-ice and lake-bottom deposits at Lake Hoare, Taylor Valley, Antarctica}, journal = {Quaternary Geochronology}, volume = {5}, year = {2010}, month = {12/2010}, pages = {679 - 690}, keywords = {LTER-MCM}, doi = {10.1016/j.quageo.2010.05.003}, author = {G. W. Berger and Peter T. Doran and Thomsen, K.J.} } @article {1166, title = {Snow in the McMurdo Dry Valleys, Antarctica.}, journal = {International Journal of Climatology}, volume = {30}, year = {2010}, month = {04/2010}, pages = {633-642}, type = {Journal}, abstract = {

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

}, keywords = {LTER-MCM, Biggie}, doi = {10.1002/joc.1933}, author = {Andrew G Fountain and Thomas H. Nylen and Andrew Monaghan and Hassan J. Basagic and David Bromwich} } @article {1154, title = {Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {12/2010}, pages = {662 - 672}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000702}, url = {http://www.montana.edu/lkbonney/DOCS/Publications/WelchEtAl2010Geochemistry.pdf}, author = {Kathleen A. Welch and W. Berry Lyons and Whisner, Carla and Christopher B. Gardner and Michael N. Gooseff and Diane M. McKnight and John C. Priscu} } @conference {1164, title = {Toward autonomous scientific exploration of ice-covered lakes{\textemdash}Field experiments with the ENDURANCE AUV in an Antarctic Dry Valley}, booktitle = {2010 IEEE International Conference on Robotics and Automation (ICRA 2010)2010 IEEE International Conference on Robotics and Automation}, year = {2010}, month = {05/2010}, pages = {308 - 315}, publisher = {IEEE}, organization = {IEEE}, address = {Anchorage, AK}, keywords = {LTER-MCM}, isbn = {978-1-4244-5038-1}, doi = {10.1109/ROBOT.2010.5509224}, author = {Gulati, S and Kristof Richmond and Flesher, C and Bartholomew P Hogan and Murarka, A and Gregory Kuhlmann and Mohan Sridharan and Stone, W and Peter T. Doran} } @article {1159, title = {Viable microbes in ice: application of molecular assays to McMurdo Dry Valley lake ice communities}, journal = {Antarctic Science}, volume = {22}, year = {2010}, month = {10/2010}, pages = {470 - 476}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1017/S0954102010000404}, url = {http://journals.cambridge.org/action/displayAbstract?fromPage=online\&aid=7909836\&fileId=S0954102010000404}, author = {Markus Dieser and Nocker, Andreas and John C. Priscu and Christine M. Foreman} } @article {1197, title = {Accelerate Synthesis in Ecology and Environmental Sciences.}, journal = {Bioscience}, volume = {59}, year = {2009}, pages = {699-701}, keywords = {LTER-MCM}, doi = {LTER}, author = {Carpenter, S and Lundberg, P and Mangel, M and Merchant, N and Murdoch, W and Palmer, M and Debra P. C. Peters and Pickett, S and Smith, K and Diana H. Wall and Maggie K. Zimmerman and Armbrust, E and Arzberger, E and F. S. Chapin and Elser, J and Hackett, E and Ives, A and Kareiva, P and Leibold, M} } @article {1185, title = {Composition and Biodegradation of a Synthetic Oil Spilled on the Perennial Ice Cover of Lake Fryxell, Antarctica}, journal = {Environmental Science \& Technology}, volume = {43}, year = {2009}, pages = {2708-2713}, keywords = {LTER-MCM}, doi = {LTER}, author = {Jaraula, C and Kenig, Fabien and Peter T. Doran and John C. Priscu and Kathleen A. Welch} } @article {1184, title = {A Contemporary Microbially Maintained Subglacial Ferrous "Ocean"}, journal = {Science}, volume = {324}, year = {2009}, month = {04/2009}, pages = {397-400}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1126/science.1167350}, url = {http://www.sciencemag.org/content/324/5925/397.short}, author = {Jill A. Mikucki and Pearson, A and Johnston, D and Turchyn, A and Farquhar, J and Schrag, D and Anbar, A and John C. Priscu and Lee, P} } @phdthesis {4191, title = {Controls on stream and hyporheic temperatures, Taylor Valley, Antarctica and large-scale climate influences on interannual flow variation in the Onyx River, Antarctica}, volume = {Ph.D.}, year = {2009}, month = {2009}, pages = {317}, school = {University of Colorado}, type = {doctoral}, address = {Boulder, CO}, abstract = {

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.

}, keywords = {LTER-MCM, Antarctica, earth sciences, hydroclimatology, hyporheic flow paths, hyporheic zone, stream temperature}, url = {https://search.proquest.com/docview/304866366}, author = {Cozzetto, K and Diane M. McKnight} } @article {1182, title = {Desiccation survival in an Antarctic nematode: molecular analysis using expressed sequenced tags.}, journal = {BMC GENOMICS}, volume = {10}, year = {2009}, month = {09/2009}, pages = {69}, keywords = {LTER-MCM}, doi = {10.1186/1471-2164-10-69}, url = {http://www.biomedcentral.com/1471-2164/10/69}, author = {Bishwo N. Adhikari and Diana H. Wall and Byron Adams} } @article {1180, title = {Environmental DNA sequencing primers for eutardigrades and bdelloid rotifers}, journal = {BMC Ecology}, volume = {9}, year = {2009}, month = {11/2009}, pages = {25}, keywords = {LTER-MCM}, doi = {10.1186/1472-6785-9-25}, author = {Robeson, Michael S and Costello, Elizabeth K and Freeman, Kristen R and Whiting, Jeremy and Byron Adams and Martin, Andrew P and Schmidt, Steve K} } @article {1178, title = {Examining the Scientific Consensus on Climate Change}, journal = {Eos, Transactions American Geophysical Union}, volume = {90}, year = {2009}, month = {2009}, pages = {22}, keywords = {LTER-MCM}, doi = {10.1029/2009EO030002}, url = {http://www.agu.org/pubs/crossref/2009/2009EO030002.shtm}, author = {Peter T. Doran and Maggie K. Zimmerman} } @article {1186, title = {Hydrologic characteristics of lake- and stream-side riparian wetted margins in the McMurdo Dry Valleys, Antarctica}, journal = {Hydrological Processes}, volume = {23}, year = {2009}, pages = {1255-1267}, keywords = {LTER-MCM}, doi = {LTER}, author = {Northcott, M and Michael N. Gooseff and John E. Barrett and Lydia H. Zeglin and Cristina D. Takacs-Vesbach and Humphrey, J} } @article {1187, title = {Interactions between physical and biotic factors influence CO_2 flux in Antarctic dry valley soils}, journal = {Soil Biology and Biochemistry}, volume = {41}, year = {2009}, pages = {1510-1517}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ball, Becky and Ross A. Virginia and John E. Barrett and Andrew N. Parsons and Diana H. Wall} } @article {1181, title = {Lakes and reservoirs as regulators of carbon cycling and climate}, journal = {Limnology and Oceanography}, volume = {54 part 2}, year = {2009}, month = {11/2009}, pages = {2298{\textendash}2314}, keywords = {LTER-MCM}, doi = {10.4319/lo.2009.54.6_part_2.2298}, url = {http://aslo.org/lo/toc/vol_54/issue_6_part_2/2298.pdf}, author = {Lars J. Tranvik and John A. Downing and James B. Cotner and Steven A. Loiselle and Robert G. Striegl and Thomas J. Ballatore and Peter Dillon and Kerri Finlay and Kenneth Fortino and Lesley B. Knoll and Pirkko L. Kortelainen and Tiit Kutser and Soren Larsen and Isabelle Laurion and Dina M. Leech and S. Leigh McCallister and Diane M. McKnight and John M. Melack and Erin Overholt and Jason A. Porter and Yves Prairie and William H. Renwick and Fabio Roland and Bradford S. Sherman and David W. Schindler and Sebastian Sobek and Alain Tremblay and Michael J. Vanni and Antonie M. Verschoor and Eddie von Wachenfeldt and Gesa A. Weyhenmeyer} } @inbook {1188, title = {Lakes of Antarctica}, booktitle = {Encyclopedia of Inland Waters volume 2}, year = {2009}, pages = {555-566}, publisher = {Elsevier Press}, organization = {Elsevier Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {John C. Priscu and Christine M. Foreman}, editor = {G.E. Likens} } @article {1189, title = {Landscape Distribution of Microbial Activity in the McMurdo Dry Valleys: Linked Biotic Processes, Hydrology, and Geochemistry in a Cold Desert Ecosystem}, journal = {Ecosystems}, volume = {12}, year = {2009}, pages = {562-573}, keywords = {LTER-MCM}, doi = {LTER}, author = {Lydia H. Zeglin and Sinsabaugh, R and John E. Barrett and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @article {1190, title = {Long-term experimental warming reduces soil nematode populations in the McMurdo Dry Valleys, Antarctica}, journal = {Soil Biology \& Biochemistry}, volume = {41}, year = {2009}, pages = {2052-2060}, keywords = {LTER-MCM}, doi = {10.1016/j.soilbio.2009.07.009}, author = {Breana L. Simmons and Diana H. Wall and Byron Adams and Edward Ayres and John E. Barrett and Ross A. Virginia} } @article {1198, title = {Managing for ocean biodiversity to sustain marine ecosystem services}, journal = {FRONTIERS IN ECOLOGY AND THE ENVIRONMENT}, volume = {7}, year = {2009}, pages = {204-211}, keywords = {LTER-MCM}, doi = {LTER}, author = {Palumbi, S and Norse, E and Stachowicz, J and Diana H. Wall and Sandifer, P and Allan, J and Beck, M and Fautin, D and Fogerty, M and Halpern, B and Incze, L and Leong, J} } @phdthesis {1199, title = {The Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-basin Lakes}, year = {2009}, school = {The Ohio State University}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R} } @article {1200, title = {Molecular profiling of soil animal diversity in natural ecosystems: incongruence of molecular and morphological results}, journal = {Soil Biology and Biochemistry}, year = {2009}, pages = {849-857}, keywords = {LTER-MCM}, doi = {10.1016/j.soilbio.2009.02.003}, author = {Wu, T and Edward Ayres and Li, G and Richard D. Bardgett and Diana H. Wall and James R. Garey} } @article {1191, title = {Particulate organic and dissolved inorganic carbon stable isotopic compositions in Taylor Valley lakes, Antarctica: the effect of legacy}, journal = {Hydrobiologia}, volume = {632}, year = {2009}, pages = {139-156}, keywords = {LTER-MCM}, doi = {LTER}, author = {Knoepfle, J and Peter T. Doran and Kenig, Fabien and W. Berry Lyons and Galchenko, V} } @article {1179, title = {Reply to Comments on {\textquotedblleft}Examining the Scientific Consensus on Climate Change{\textquotedblright}}, journal = {Eos, Transactions American Geophysical Union}, volume = {90}, year = {2009}, month = {2009}, pages = {233}, keywords = {LTER-MCM}, doi = {10.1029/2009EO270010}, author = {Peter T. Doran and Maggie K. Zimmerman} } @article {1192, title = {The saline lakes of the McMurdo Dry Valleys, Antarctica,}, journal = {Aquatic Geochemistry}, year = {2009}, pages = {321-348}, keywords = {LTER-MCM}, doi = {LTER}, author = {William J. Green and W. Berry Lyons} } @article {1193, title = {Spatial variation in soil active-layer geochemistry across hydrologic margins in polar desert ecosystems.}, journal = {Hydrology and Earth System Sciences}, volume = {13}, year = {2009}, pages = {2349-2358}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Michael N. Gooseff and Cristina D. Takacs-Vesbach} } @article {1194, title = {State of the Antarctic and the Southern Ocean climate system,}, journal = {Review of Geophysics}, volume = {47}, year = {2009}, keywords = {LTER-MCM}, doi = {LTER}, author = {Paul A. Mayewski and David Bromwich and Campbell, H and Hamilton, G and W. Berry Lyons and Maasch, K and Aoki, S and Xiao, C and van Ommen, T and Meredith, M and Summerhayes, C and Turner, J and Worby, A and John E. Barrett and Casassa, G and Bertler, N and T Bracegirdle} } @article {1195, title = {Terrestrial mesofauna in above- and below-ground habitats: Taylor Valley, Antarctica}, journal = {Polar Biology}, volume = {32}, year = {2009}, pages = {1549-1558}, keywords = {LTER-MCM}, doi = {LTER}, author = {Breana L. Simmons and Diana H. Wall and Byron Adams and Edward Ayres and John E. Barrett and Ross A. Virginia} } @article {1196, title = {Thermal Characterisation of Active Layer Across a Soil Moisture Gradient in the McMurdo Dry Valleys, Antarctica}, journal = {Permafrost and Periglacial Processes}, volume = {20}, year = {2009}, pages = {27-39}, keywords = {LTER-MCM}, doi = {10.1002/ppp.634}, author = {Ikard, S and Michael N. Gooseff and John E. Barrett and Cristina D. Takacs-Vesbach} } @article {1183, title = {Where{\textquoteright}s the ecology in molecular ecology?}, journal = {Oikos}, volume = {118}, year = {2009}, month = {05/2009}, pages = {1601-1609}, keywords = {LTER-MCM}, doi = {10.1111/j.1600-0706.2009.17557.x}, author = {Jerry B. Johnson and Scott M. Peat and Byron Adams} } @inbook {1206, title = {Antarctic subglacial water: origin, evolution, and ecology}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, author = {John C. Priscu and Tulaczyk, S and Studinger, M and Kenicutt, M and Brent C. Christner and Christine M. Foreman} } @inbook {1207, title = {Bacteria in Subglacial Environments}, booktitle = {Psychrophiles: from biodiversity to biotechnology}, year = {2008}, pages = {51-71}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {New York}, keywords = {LTER-MCM}, author = {Brent C. Christner and Skidmore, M and John C. Priscu and Martyn Tranter and Christine M. Foreman} } @article {1208, title = {Bacteriophage in polar inland waters}, journal = {Extremophiles}, volume = {12}, year = {2008}, pages = {167-175}, keywords = {LTER-MCM}, doi = {LTER}, url = {/reports/lakes/SawstromEtAl2008Bacteriophage.pdf}, author = {Sawstrom, C and John T. Lisle and Alexandre M. Anesio and John C. Priscu and Johanna Laybourn-Parry} } @inbook {1209, title = {Biogeochemical processes in high-latitude lakes and rivers}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Finlay, J}, editor = {Warwick F. Vincent and Johanna Laybourn-Parry} } @phdthesis {1228, title = {The Biogeochemistry of Cryoconite Holes on Glaciers in Taylor Valley, Antarctica}, year = {2008}, school = {University of Bristol, UK}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Bagshaw, Elizabeth} } @mastersthesis {1229, title = {A comparison of anhydrobiosis in nematodes of the McMurdo Dry Valleys, Antarctica and Short Grass Steppe, Colorado}, year = {2008}, school = {Colorado School of Mines,}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Seaver, K} } @article {1210, title = {Decline in a dominant invertebrate species contributes to altered carbon cycling in a low-diversity soil ecosystem}, journal = {Global Change Biology}, volume = {14}, year = {2008}, pages = {1734-1744}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Ross A. Virginia and Diana H. Wall and Byron Adams} } @article {1211, title = {Effects of Human Trampling on Populations of Soil Fauna in the McMurdo Dry Valleys, Antarctica.}, journal = {Conservation Biology}, volume = {22}, year = {2008}, month = {12/2008}, pages = {1544-1551}, abstract = {

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.

}, keywords = {LTER-MCM}, doi = {10.1111/j.1523-1739.2008.01034.x}, author = {Edward Ayres and Johnson N. Nkem and Diana H. Wall and Byron Adams and John E. Barrett and Broos, E and Andrew N. Parsons and Powers, Laura E. and Breana L. Simmons and Ross A. Virginia} } @article {1212, title = {Entry approach into pristine ice-sealed lakes - Lake Vida, East Antarctica, a model ecosystem}, journal = {Limnology and Oceanography-Methods}, volume = {6}, year = {2008}, pages = {542-547}, keywords = {LTER-MCM}, doi = {LTER}, author = {Peter T. Doran and Christian H. Fritsen and A. E. Murray and Kenig, Fabien and Christopher P. McKay and Kyne, J} } @phdthesis {1231, title = {The geochemistry of glacier snow and melt: The Oregon Cascades and Taylor Valley, Antarctica.}, volume = {Ph.D.}, year = {2008}, school = {The Ohio State University}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Sarah Fortner} } @inbook {1213, title = {Glacial ecosystems}, booktitle = {Ecological Monographs}, volume = {78}, year = {2008}, pages = {41-67}, edition = {1}, abstract = {
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.
}, keywords = {LTER-MCM, Biggie, snow ecology}, doi = {10.1890/07-0187.1}, url = {http://dx.doi.org/10.1890/07-0187.1}, author = {Hodson, A and Alexandre M. Anesio and Martyn Tranter and Andrew G Fountain and Osborn, M and John C. Priscu and Johanna Laybourn-Parry and Sattler, B} } @article {1202, title = {Global decomposition experiment shows soil animal impacts on decomposition are climate dependent}, journal = {Global Change Biology}, volume = {14}, year = {2008}, month = {11/2008}, pages = {2661-2677}, keywords = {LTER-MCM}, doi = {10.1111/j.1365-2486.2008.01672.x}, url = {http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2008.01672.x/full}, author = {Diana H. Wall and Mark A. Bradford and Mark G. StJohn and John A. Trofymow and Valerie Behan-Pelletier and David E. Bignell and J. Mark Dangerfield and William J. Parton and Josef Rusek and Winfried Voigt and Volkmar Wolters and Holley Zadeh Gardel and Fred O. Ayuke and Richard Bashford and Olga I. Beljakova and Patrick J. Bohlen and Alain Brauman and Stephen Flemming and Joh R. Henschel and Dan L. Johnson and T. Hefin Jones and Marcela Kovarova and J. Marty Kranabetter and Les Kutny and Kuo-Chuan Lin and Mohamed Maryati and Dominique Masse and Andrei Pokarzhevskii and Homathevi Rahman and Millor G. Sabara and Joerg-Alfred Salamon and Michael J. Swift and Amanda Varela and Heraldo L. Vasconcelos and Don White and Xiaming Zou} } @inbook {1214, title = {High-latitude rivers and streams.}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diane M. McKnight and Michael N. Gooseff and Warwick F. Vincent and Peterson, B}, editor = {Warwick F. Vincent and Johanna Laybourn-Parry} } @article {1204, title = {Hydrologic response to extreme warm and cold summers in the McMurdo Dry Valleys, East Antarctica}, journal = {Antarctic Science}, volume = {20}, year = {2008}, month = {05/16/2008}, pages = {499-509}, type = {Journal}, keywords = {LTER-MCM, Climate Response, streams}, doi = {10.1017/S0954102008001272}, author = {Peter T. Doran and Christopher P. McKay and Andrew G Fountain and Thomas H. Nylen and Diane M. McKnight and Chris Jaros and John E. Barrett} } @inbook {1215, title = {Ice-based freshwater ecosystems}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ian Hawes and Clive Howard-Williams and Andrew G Fountain}, editor = {Warwick F. Vincent and Johanna Laybourn-Parry} } @article {1205, title = {The influence of soil geochemistry on nematode distribution, McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {40}, year = {2008}, month = {02/2008}, pages = {119-128}, keywords = {LTER-MCM}, doi = {10.1657/1523-0430(06-051)[POAGE]2.0.CO;2}, author = {Poage, M and John E. Barrett and Ross A. Virginia and Diana H. Wall} } @article {1216, title = {Inland diatoms from the McMurdo Dry Valleys and James Ross Island, Antarctica}, journal = {Botany-Botanique}, volume = {12}, year = {2008}, pages = {1378-1392}, keywords = {LTER-MCM}, doi = {LTER}, author = {Rhea M.M. Esposito and Sarah A. Spaulding and Diane M. McKnight and De Vijver, B and Kopalova, K and Lubinski, D and Brenda L. Hall and Whittaker, T} } @article {1217, title = {Introduction - The Biogeochemistry of Cryoconite Holes}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2008}, keywords = {LTER-MCM}, doi = {10.1029/2008JG000698}, author = {Andrew G Fountain and Martyn Tranter} } @article {1218, title = {Mercury Deposition in a Polar Desert Ecosystem}, journal = {Environmental Science and Technology}, volume = {42}, year = {2008}, pages = {4710-4716}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R and W. Berry Lyons} } @article {1232, title = {Microbial community composition in soils of Northern Victoria Land, Antarctica}, journal = {Environmental Microbiology}, volume = {10}, year = {2008}, pages = {1713-1724}, keywords = {LTER-MCM}, doi = {LTER}, author = {Niederberger, T and McDonald, i and Hacker, A and Soo, R and John E. Barrett and Diana H. Wall and Craig S Cary} } @phdthesis {1219, title = {Microbial diversity and function at aquatic- terrestrial interfaces in desert ecosystems.}, volume = {Ph.D.}, year = {2008}, school = {University of New Mexico}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Lydia H. Zeglin} } @inbook {1220, title = {Origin and geomorphology of lakes in the polar regions}, booktitle = {Polar Lakes and Rivers: Limnology of Arctic and Antarctic Aquatic Ecosystems}, year = {2008}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {Oxford}, keywords = {LTER-MCM}, doi = {LTER}, author = {Pienitz, R and Peter T. Doran and Lamoureuz, S}, editor = {Warwick F. Vincent and Johanna Laybourn-Parry} } @article {1203, title = {Persistent effects of a discrete climate event on a polar desert ecosystem}, journal = {Global Change Biology}, volume = {14}, year = {2008}, month = {06/2008}, pages = {2249-2261}, type = {Journal}, keywords = {LTER-MCM, Climate Response, nematodes}, doi = {10.1111/j.1365-2486.2008.01641.x}, author = {John E. Barrett and Ross A. Virginia and Diana H. Wall} } @article {1221, title = {Plankton Dynamics in the McMurdo Dry Valley Lakes During the Transition to Polar Night - A Project Contributing to EBA}, journal = {SCAR EBA (Evolution and Biodiversity in the Antarctic) Newsletter, October 2008}, volume = {2}, year = {2008}, keywords = {LTER-MCM}, doi = {LTER}, author = {John C. Priscu} } @mastersthesis {1222, title = {Provenance of organic matter in Taylor Valley, Antarctica lakes: Scanning Electron Microscopy of sediment}, volume = {M.S.}, year = {2008}, school = {University of Illinois, Chicago}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Jonathan P. Warnock} } @article {1201, title = {Reply to comment by K. Gajewski on {\textquotedblleft}Abrupt environmental change in Canada{\textquoteright}s northernmost lake{\textquotedblright}}, journal = {Geophysical Research Letters}, volume = {35}, year = {2008}, month = {2008}, keywords = {LTER-MCM}, doi = {10.1029/2007GL032889}, url = {http://www.agu.org/pubs/crossref/2008/2007GL032889.shtml}, author = {Dermot Antoniades and Catherine Crawley and Douglas, Marianne S. V. and Pienitz, R and Dale T. Andersen and Peter T. Doran and Ian Hawes and Pollard, W and Warwick F. Vincent} } @article {1233, title = {Soil phosphorus cycling in an Antarctic polar desert}, journal = {Geochimica et Cosmochimica Acta}, volume = {144}, year = {2008}, pages = {21-32}, keywords = {LTER-MCM}, doi = {LTER}, author = {D. Brad Bate and John E. Barrett and Poage, M and Ross A. Virginia} } @article {1223, title = {SPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica}, journal = {Science of the Total Environment}, volume = {407}, year = {2008}, pages = {250-262}, keywords = {LTER-MCM}, author = {Jaraula, C and Kenig, Fabien and Peter T. Doran and John C. Priscu and Kathleen A. Welch} } @article {1224, title = {Stoichiometry of soil enzyme activity at global scale.}, journal = {Ecology Letters}, volume = {11}, year = {2008}, pages = {1252-1264}, keywords = {LTER-MCM}, doi = {LTER}, author = {Sinsabaugh, R and Gallo, M and Gartner, T and Hobbie, S and Holland, K and Keeler, B and Powers, J and Stursova, M and Cristina D. Takacs-Vesbach and Waldrop, M and Wallenstein, M and Lauber, M and Zak, D and Lydia H. Zeglin and Weintraub, M and Ahmed, B and Allison, S and Crenshaw, C and Contosta, A and Cusack, D and Frey, S} } @article {1225, title = {Supersaturated N2O in a perennially ice-covered Antarctic lake: Molecular and stable isotopic evidence for a biogeochemical relict.}, journal = {Limnology and Oceanography}, volume = {53}, year = {2008}, pages = {2439-2450}, keywords = {LTER-MCM}, doi = {LTER}, url = {http://brent.xner.net/pdf/Priscu_etal2008_ELB-N2O.pdf}, author = {John C. Priscu and Brent C. Christner and John E. Dore and Marian B. Westley and Brian N. Popp and Karen L. Casciotti and W. Berry Lyons} } @article {1226, title = {Surface energy balance and melt thresholds over 11 years at Taylor Glacier, Antarctica}, journal = {Journal of Geophysical Research-Earth Surface}, volume = {113}, year = {2008}, keywords = {LTER-MCM}, doi = {10.1029/2008JF001029}, author = {Hoffman, M and Andrew G Fountain and Liston, G} } @article {1227, title = {Temporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2008}, pages = {G01S92}, keywords = {LTER-MCM}, doi = {10.1029/2008JG000698}, author = {Andrew G Fountain and Thomas H. Nylen and Martyn Tranter and Bagshaw, Elizabeth} } @article {1238, title = {Bacterial diversity associated with Blood Falls, A subglacial outflow from the Taylor Glacier, Antarctica}, journal = {Applied and Environmental Microbiology}, volume = {73}, year = {2007}, pages = {4029-4039}, keywords = {LTER-MCM}, doi = {LTER}, author = {Jill A. Mikucki and John C. Priscu} } @article {1239, title = {The biogeochemical evolution of cryoconite holes on glaciers in Taylor Valley, Antarctica}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2007}, pages = {G04S35}, keywords = {LTER-MCM}, doi = {LTER}, author = {Bagshaw, Elizabeth and Martyn Tranter and Andrew G Fountain and Kathleen A. Welch and Hassan J. Basagic and W. Berry Lyons} } @article {1236, title = {Biogeochemical stoichiometry of Antarctic Dry Valley ecosystems}, journal = {Journal of Geophysical Research}, volume = {112}, year = {2007}, month = {02/2007}, pages = {G01010+12}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2005JG000141}, author = {John E. Barrett and Ross A. Virginia and W. Berry Lyons and Diane M. McKnight and John C. Priscu and Andrew G Fountain and Diana H. Wall and Daryl L. Moorhead and Peter T. Doran} } @article {1240, title = {Controls on the spatial dimensions of wetted hydrologic margins of two antarctic lakes}, journal = {Vadose Zone Journal}, volume = {6}, year = {2007}, pages = {841-848}, keywords = {LTER-MCM}, doi = {10.2136/​vzj2006.0161}, author = {Michael N. Gooseff and John E. Barrett and Melissa L. Northcott and D. Brad Bate and Kenneth R. Hill and Lydia H. Zeglin and Bobb, M and Cristina D. Takacs-Vesbach} } @thesis {1241, title = {Ecotoxicity and microbial biogeochemistry of Fluoride in Antarctic soils}, volume = {B.S.}, year = {2007}, month = {07/2007}, school = {Dartmouth College}, type = {bachelors}, keywords = {LTER-MCM}, author = {Collins, Pamela M.} } @article {1234, title = {Global Change tipping points: Above- and below-ground biotic interactions in a low diversity ecosystem}, journal = {Philosophical Transactions of the Royal Society B, Biological Sciences}, volume = {362}, year = {2007}, month = {12/2007}, pages = {2291-2306}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie, soil}, doi = {10.1098/rstb.2006.1950}, url = {http://rstb.royalsocietypublishing.org/content/362/1488/2291.full}, author = {Diana H. Wall} } @booklet {1242, title = {Hidden Assets: Biodiversity Below-Surface.}, year = {2007}, publisher = {UNESCO-SCOPE Policy Brief $\#$5}, keywords = {LTER-MCM}, doi = {LTER}, url = {http://www.icsu-scope.org/unesco/USPB05_SOIL_En.pdf}, author = {Diana H. Wall and Valerie Behan-Pelletier} } @mastersthesis {1243, title = {Lacustrine History of Lake Hoare, McMurdo Dry Valleys, Antarctica, Based on Long Sediment Cores}, volume = {M.S.}, year = {2007}, school = {University of Illinois, Chicago}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andy Burkemper} } @article {1254, title = {A mathematical model for variation in water-retention curves among sandy soils}, journal = {Antarctic Science}, volume = {19}, year = {2007}, pages = {427-436}, keywords = {LTER-MCM}, doi = {LTER}, author = {Hunt , H and Amy M Treonis and Diana H. Wall and Ross A. Virginia} } @article {1244, title = {Mesoscale dynamics of ephemeral wetlands in the Antarctic Dry Valleys: Implications to production and distribution of organic matter}, journal = {Ecosystems}, year = {2007}, pages = {87-95}, keywords = {LTER-MCM}, doi = {LTER}, author = {Daryl L. Moorhead} } @article {1245, title = {Metabolic activity and diversity of cryoconites in the Taylor Valley, Antarctica}, journal = {Journal of Geophysical Research}, volume = {112}, year = {2007}, keywords = {LTER-MCM}, doi = {LTER}, author = {Christine M. Foreman and Sattler, B and Jill A. Mikucki and Porazinska, D and John C. Priscu} } @mastersthesis {1246, title = {Microbial Processes in the Moats of Lakes in the Taylor Valley, Antarctica}, volume = {M.S.}, year = {2007}, school = {Montana State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Moore, J} } @article {1247, title = {Organic carbon in Antarctic precipitation}, journal = {Geophysical Research Letters}, volume = {34}, year = {2007}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Doggett, J} } @article {1235, title = {Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment}, journal = {Geomorphology}, volume = {89}, year = {2007}, month = {09/2007}, pages = {186-204}, keywords = {LTER-MCM}, doi = {10.1016/j.geomorph.2006.07.025}, author = {Diane M. McKnight and Cathy M. Tate and Edmund D. Andrews and Dev K. Niyogi and Cozzetto, K and Kathleen A. Welch and W. Berry Lyons and D. G. Capone} } @mastersthesis {1255, title = {Soil organic matter sources and quality in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2007}, school = {Dartmouth College}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {D. Brad Bate} } @article {1237, title = {Solute and isotope geochemistry of subsurface ice melt seeps in Taylor Valley, Antarctica}, journal = {Geological Society of America Bulletin}, volume = {119}, year = {2007}, month = {01/2007}, pages = {548-555}, keywords = {LTER-MCM, Climate Response}, doi = {10.1130/B25913.1}, url = {http://gsabulletin.gsapubs.org/content/119/5-6/548.short}, author = {Harris, K and Anne E. Carey and Kathleen A. Welch and W. Berry Lyons and Andrew G Fountain} } @article {1248, title = {The southernmost worm, Scottnema lindsayae (Nematoda): diversity, dispersal and ecological stability.}, journal = {Polar Biology}, volume = {30}, year = {2007}, pages = {809-815}, keywords = {LTER-MCM}, doi = {LTER}, author = {Byron Adams and Diana H. Wall and Gozel, U and Dillman, A and Chaston, J and Hogg, I} } @mastersthesis {1249, title = {Spatial and Temporal Active Layer Thermal Dynamics from Temperature Time Series Analysis: Case Studies from Lake Fryxell, McMurdo Dry Valleys, Antarctica.}, volume = {M.S.}, year = {2007}, school = {Colorado School of Mines}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ikard, S} } @mastersthesis {1250, title = {Stable Carbon Isotope Analyses of Sediments from Lake Fryxell, Antarctica}, volume = {M.S.}, year = {2007}, school = {University of Illinois, Chicago}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Moore-Topinka, N} } @proceedings {1251, title = {Trends in discharge and flow season timing of the Onyx River, Wright Valley, Antarctica since 1969}, journal = {Antarctica; A keystone in a changing world--online proceedings for the tenth international symposium}, year = {2007}, publisher = {U.S. Geological Survey Open-File Report 2007-1047}, keywords = {LTER-MCM}, doi = {LTER}, author = {Michael N. Gooseff and Diane M. McKnight and Peter T. Doran and W. Berry Lyons}, editor = {Alan Cooper and Carol Raymond and ISAES Editorial Team} } @article {1252, title = {Unique similarity of faunal communities across aquatic terrestrial interfaces in a polar desert ecosystem}, journal = {Ecosystems}, year = {2007}, keywords = {LTER-MCM}, doi = {LTER}, author = {Edward Ayres and Diana H. Wall and Byron Adams and John E. Barrett and Ross A. Virginia} } @mastersthesis {1253, title = {WETTED MARGIN HYDROLOGY OF THE DRY VALLEYS OF ANTARCTICA}, volume = {M.S.}, year = {2007}, school = {Colorado School of Mines,}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Northcott, M} } @article {1257, title = {Adaptation and acclimation of photosynthetic microorganisms to permanently cold environments}, journal = {Microbial and Molecular Biology Review}, volume = {70}, year = {2006}, month = {03/2006}, pages = {222-252}, abstract = {

Persistently cold environments constitute one of our world\&$\#$39;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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1128/​MMBR.70.1.222-252.2006}, author = {Rachael M. Morgan-Kiss and John C. Priscu and Pocock, T and Gudynaite-Savitch, L and Norman P.A. Huner} } @article {1259, title = {The aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis}, journal = {Antarctic Science}, volume = {18}, year = {2006}, pages = {497-505}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R and Bertler, N and Kathleen A. Welch and W. Berry Lyons and Paul A. Mayewski and Sneed, S and Thomas H. Nylen and Handley, M and Andrew G Fountain} } @article {1256, title = {Antarctic Climate Cooling and Response of Diatoms in Glacial Meltwater Streams}, journal = {Geophysical Research Letters}, volume = {33}, year = {2006}, month = {04/2006}, pages = {L07406}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2006GL025903}, author = {Rhea M.M. Esposito and Horn, S and Diane M. McKnight and Cox, M and Grant, M and Sarah A. Spaulding and Peter T. Doran and Cozzetto, K} } @inbook {1260, title = {Antarctic lake systems and climate change}, booktitle = {Trends in Antarctic Terrestrial and Limnetic Ecosystems: Antarctica as a Global Indicator}, year = {2006}, publisher = {S}, organization = {S}, address = {Dordrecht, The Netherlands}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Johanna Laybourn-Parry and Kathleen A. Welch and John C. Priscu}, editor = {D.M. Bergstrom and Peter Convey and A.H.L. Huiskes} } @inbook {1261, title = {Biogeochemistry, terrestrial}, booktitle = {Encyclopedia of the Antarctic Vol 1}, volume = {1}, year = {2006}, pages = {154-155}, publisher = {Routledge Press}, organization = {Routledge Press}, address = {New York}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Ross A. Virginia}, editor = {B. Riffenburgh} } @article {1263, title = {Biotic interactions in Antarctic terrestrial ecosystems: Are they a factor?}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3035-3040}, keywords = {LTER-MCM}, doi = {10.1016/j.soilbio.2006.04.026}, url = {http://www.sciencedirect.com/science/article/pii/S0038071706002173}, author = {Hogg, I and Diana H. Wall and Craig S Cary and Convey, K and Newsham, K and ODonnell, G and Byron Adams and Aislabie, J and Francesco Frati and Stevens, M} } @article {1264, title = {Co-variation in soil biodiversity and biogeochemistry in Northern and Southern Victoria Land, Antarctica}, journal = {Antarctic Science}, volume = {18}, year = {2006}, pages = {535-548}, keywords = {LTER-MCM}, doi = {10.1017/S0954102006000587}, url = {https://www.cambridge.org/core/journals/antarctic-science/article/covariation-in-soil-biodiversity-and-biogeochemistry-in-northern-and-southern-victoria-land-antarctica/C3514C28DB75F3A19DB5F266D4B1B56E}, author = {John E. Barrett and Ross A. Virginia and Diana H. Wall and Craig S Cary and Byron Adams and Hacker, A and Aislabie, J} } @article {1265, title = {Diversity and distribution of Victoria Land biota}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3003-3018}, keywords = {LTER-MCM}, doi = {10.1016/j.soilbio.2006.04.030}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0038071706002215}, author = {Byron Adams and Connell, L and Peter Convey and Fell, J and Francesco Frati and Hogg, I and Newsham, K and O{\textquoteright}Donnell, A and Russell, N and Seppelt, R and Stevens, M and Richard D. Bardgett and Edward Ayres and Diana H. Wall and Aislabie, J and Bamforth, S and Bargagli, R and Craig S Cary and Cavacini, P} } @article {1266, title = {Environmental factors associated with deep chlorophyll maxima in dry valley lakes, South Victoria Land, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {38}, year = {2006}, pages = {179-189}, keywords = {LTER-MCM}, doi = {LTER}, author = {Burnett, L and Daryl L. Moorhead and Ian Hawes and Clive Howard-Williams} } @article {1267, title = {Experimental investigations into processes controlling stream and hyporheic temperatures, Fryxell Basin, Antarctica}, journal = {Advances in Water Resources}, volume = {29}, year = {2006}, pages = {130-153}, keywords = {LTER-MCM}, doi = {LTER}, author = {Cozzetto, K and Diane M. McKnight and Thomas H. Nylen and Andrew G Fountain} } @article {1268, title = {Fuel movement between grain boundaries in ice}, journal = {Cold Regions Science and Technology}, volume = {45}, year = {2006}, pages = {158-165}, keywords = {LTER-MCM}, doi = {LTER}, author = {Steven M. Jepsen and Edward E. Adams and John C. Priscu} } @article {1269, title = {Glacial and postglacial sedimentation in the Fryxell basin, Taylor Valley, Southern Victoria Land, Antarctica}, journal = {Palaeography, Palaeoclimatology, Palaeoecology}, volume = {341}, year = {2006}, pages = {320}, keywords = {LTER-MCM}, doi = {LTER}, author = {Wagner, B and Melles, M and Peter T. Doran and Kenig, Fabien and Forman, S and Pierau, R and Allan, P} } @article {1270, title = {Glacier mass balances (1993-2001) Taylor Valley, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {52}, year = {2006}, pages = {451}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andrew G Fountain and Thomas H. Nylen and MacClune, K and Gayle L. Dana} } @book {1271, title = {The Lost Seal}, year = {2006}, pages = {40}, publisher = {Moonlight Publishing LLC}, organization = {Moonlight Publishing LLC}, address = {Lafayette}, keywords = {LTER-MCM}, isbn = {978-0972342278}, doi = {LTER}, author = {Diane M. McKnight} } @article {1272, title = {Measuring ecosystem response in a rapidly changing environment: the Latitudinal Gradient Project}, journal = {Antarctic Science.}, volume = {10}, year = {2006}, keywords = {LTER-MCM}, doi = {LTER}, author = {Clive Howard-Williams and Peterson, D and W. Berry Lyons and Cattaneo-Vietti, R and Shulamit Gordon} } @inbook {1273, title = {Pedogenic carbonate distribution within glacial till in Taylor Valley, Southern Victoria Land, Antarctica}, booktitle = {Paleoenvironmental Record and Applications of Calcretes and Palustrine Carbonates}, year = {2006}, pages = {89-103}, publisher = {Geological Society of America}, organization = {Geological Society of America}, keywords = {LTER-MCM}, doi = {10.1130/2006.2416(06)}, author = {Foley, K and W. Berry Lyons and John E. Barrett and Ross A. Virginia} } @article {1281, title = {Phosphorus fractions in soils of Taylor Valley, Antarctica}, journal = {Soil Science Society of America Journal}, volume = {70}, year = {2006}, pages = {806-815}, keywords = {LTER-MCM}, doi = {LTER}, author = {Blecker, S and Ippolito, J and John E. Barrett and Diana H. Wall and Ross A. Virginia and Norvell, K} } @thesis {1282, title = {A Qualitative Approach to Understanding the Rate of Weathering, Taylor Valley, Antarctica}, year = {2006}, school = {The Ohio State University}, type = {bachelors}, keywords = {LTER-MCM}, doi = {LTER}, author = {Miller, E} } @article {1283, title = {Salt tolerance and survival thresholds for two species of Antarctic soil nematodes}, journal = {Polar Biology}, volume = {29}, year = {2006}, pages = {643-651}, keywords = {LTER-MCM}, doi = {LTER}, author = {Johnson N. Nkem and Ross A. Virginia and John E. Barrett and Diana H. Wall and Li, G} } @article {1284, title = {Simulating energy flow through a pelagic food web in Lake Fryxell, Antarctica}, journal = {Ecological Modelling}, volume = {192}, year = {2006}, pages = {457-472}, keywords = {LTER-MCM}, doi = {LTER}, author = {McKenna, K and Daryl L. Moorhead and Emily C. Roberts and Johanna Laybourn-Parry} } @article {1274, title = {Soil carbon turnover model for the McMurdo Dry Valleys, Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3065-3082}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Ross A. Virginia and Andrew N. Parsons and Diana H. Wall} } @mastersthesis {1285, title = {Soil nitrogen cycling in cold desert (McMurdo Dry Valleys) and hot desert ecosystems}, volume = {M.S.}, year = {2006}, school = {Dartmouth College}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Stucker, A} } @article {1275, title = {Spatial and temporal active layer dynamics along three glacial meltwater streams in the McMurdo Dry Valleys, Antarctica}, journal = {Arctic Antarctic and Alpine Research}, volume = {38}, year = {2006}, pages = {42-53}, keywords = {LTER-MCM}, doi = {LTER}, author = {Peter A. Conovitz and Lee H. MacDonald and Diane M. McKnight} } @thesis {1276, title = {Spatial Patterns of Bacterial Diversity in Cold Desert Riparian Zones.}, volume = {B.S.}, year = {2006}, school = {University of New Mexico}, type = {bachelors}, keywords = {LTER-MCM}, doi = {LTER}, author = {Bobb, M} } @article {1258, title = {A stable isotopic investigation of a polar desert hydrologic system, McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {38}, year = {2006}, month = {02/2006}, pages = {60-71}, keywords = {LTER-MCM}, doi = {10.1657/1523-0430(2006)038[0060:ASIIOA]2.0.CO;2}, author = {Michael N. Gooseff and W. Berry Lyons and Diane M. McKnight and Bruce H. Vaughn and Andrew G Fountain and Carolyn Dowling} } @article {1277, title = {A synthesis of soil biodiversity and ecosystem functioning in Victoria Land, Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3001-3002}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall and Byron Adams and John E. Barrett and D. W. Hopkins} } @article {1278, title = {Terrestrial ecosystem processes of Victoria Land, Antarctica}, journal = {Soil Biology and Biochemistry}, volume = {38}, year = {2006}, pages = {3019-3034}, keywords = {LTER-MCM}, doi = {LTER}, author = {John E. Barrett and Johnson N. Nkem and Sletten, R and Steltzer, H and Diana H. Wall and Wallenstein, M and Ross A. Virginia and D. W. Hopkins and Aislabie, J and Bargagli, R and Bockheim, J and Campbell, I and W. Berry Lyons and Daryl L. Moorhead} } @article {1279, title = {Wind dispersal of soil invertebrates in the McMurdo Dry Valleys, Antarctica}, journal = {Polar Biology}, volume = {29}, year = {2006}, pages = {346-352}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1007/s00300-005-0061-x}, url = {http://link.springer.com/content/pdf/10.1007\%2Fs00300-005-0061-x}, author = {Johnson N. Nkem and Diana H. Wall and Ross A. Virginia and John E. Barrett and Broos, E and Porazinska, D and Byron Adams} } @article {1287, title = {Biodiversity and ecosystem functioning in terrestrial habitats of Antarctica}, journal = {Antarctic Science}, volume = {17}, year = {2005}, month = {07/2005}, pages = {523-531}, keywords = {LTER-MCM}, doi = {10.1017/S0954102005002944}, url = {http://journals.cambridge.org/download.php?file=\%2FANS\%2FANS17_04\%2FS0954102005002944a.pdf\&code=f0bfb3b7eb4345bde6bbfbf916a408e1}, author = {Diana H. Wall} } @article {1291, title = {Biogeological Raman spectroscopic studies of Antarctic lacustrine sediments}, journal = {Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy}, volume = {61}, year = {2005}, keywords = {LTER-MCM}, author = {Moody, C and Villar, S and Edwards, H and Hodgson, D and Peter T. Doran and J.L. Bishop} } @article {1292, title = {The chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {15-19}, keywords = {LTER-MCM}, doi = {LTER}, author = {Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Thomas H. Nylen and Kathleen A. Welch} } @article {1293, title = {Comment on {\textquoteleft}{\textquoteleft}El Ni{\~n}o suppresses Antarctic warming{\textquoteright}{\textquoteright} by N. Bertler et al.}, journal = {Geophysical Research Letters}, volume = {32}, year = {2005}, pages = {L07706}, keywords = {LTER-MCM, Tropical meteorology}, doi = {10.1029/2004GL021716}, author = {Peter T. Doran and Gary D. Clow and Christian H. Fritsen and Christopher P. McKay and Andrew N. Parsons and John C. Priscu and W. Berry Lyons and Walsh, J and Andrew G Fountain and Diane M. McKnight and Daryl L. Moorhead and Ross A. Virginia and Diana H. Wall} } @article {1310, title = {Contributions of Benthic Microbial Mats to Net Primary Production in Lake Hoare, Antarctica}, journal = {Antarctic Science}, volume = {17}, year = {2005}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Schmeling, S and Ian Hawes} } @article {1294, title = {Dating water and solute additions to ice-covered Antarctic lakes}, journal = {Geochimica et Cosmochimica Acta}, volume = {69}, year = {2005}, pages = {A720}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Carolyn Dowling and Kathleen A. Welch and Snyder, G and Robert J. Poreda and Peter T. Doran and Andrew G Fountain} } @mastersthesis {1311, title = {Determining the role of chemical weathering reactions and hyporheic exchange on silicate concentrations in Dry Valley streams, Antarctica.}, volume = {M.S.}, year = {2005}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Joslin, J} } @inbook {1295, title = {Developing new perspectives from advances in soil biodiversity research}, booktitle = {Biological Diversity and Function in Soils}, year = {2005}, pages = {3-30}, publisher = {Cambridge University Press}, organization = {Cambridge University Press}, keywords = {LTER-MCM}, author = {Diana H. Wall and Fritter, A and E. A. Paul}, editor = {Richard D. Bardgett and M. B. Usher and D. W. Hopkins} } @article {1312, title = {Distribution and diversity of soil protozoa in the McMurdo Dry Valleys of Antarctica}, journal = {Polar Biology}, volume = {28}, year = {2005}, pages = {756-762}, keywords = {LTER-MCM}, author = {Bamforth, S and Diana H. Wall and Ross A. Virginia} } @article {1296, title = {An Ecosystem of Superlatives}, journal = {Bioscience}, volume = {55}, year = {2005}, pages = {804-806}, keywords = {LTER-MCM}, doi = {10.1641/0006-3568(2005)055[0804:AEOS]2.0.CO;2}, url = {http://www.jstor.org/stable/10.1641/0006-3568\%282005\%29055\%5B0804:AEOS\%5D2.0.CO;2}, author = {John C. Priscu} } @article {1297, title = {The Geochemistry of Supraglacial Streams of Canada Glacier, Taylor Valley (Antarctica), and their Evolution into Proglacial Waters}, journal = {Aquatic Geochemistry}, volume = {11}, year = {2005}, pages = {391-412}, keywords = {LTER-MCM}, author = {Sarah Fortner and Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Kathleen A. Welch} } @article {1298, title = {Glacial ice cores: a model system for developing extraterrestrial decontamination protocols}, journal = {Icarus}, volume = {174}, year = {2005}, pages = {572-584}, keywords = {LTER-MCM}, doi = {LTER}, url = {/reports/lakes/ChristnerEtAl2005Decontamination.pdf}, author = {Brent C. Christner and Jill A. Mikucki and Christine M. Foreman and Denson, J and John C. Priscu} } @article {1299, title = {Groundwater seeps in Taylor Valley Antarctica: An example of a subsurface melt event}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {200-206}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Kathleen A. Welch and Anne E. Carey and Diana H. Wall and Ross A. Virginia and Andrew G Fountain and Peter T. Doran and Csatho, B and Tremper, C} } @article {1300, title = {Halogen geochemistry of the McMurdo Dry Valleys Lakes, Antarctica: clues to the origin of solutes and lake evolution}, journal = {Geochimica et Cosmochimica Acta}, volume = {69}, year = {2005}, pages = {305-323}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Snyder, G and Olesik, J and Graham, E and G. M. Marion and Robert J. Poreda} } @article {1290, title = {An index model of stream flow at below freezing-temperatures in Taylor Valley, Antarctica}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, month = {01/2005}, pages = {76-82}, type = {Journal}, keywords = {LTER-MCM, Climate Response}, doi = {10.3189/172756405781813519}, url = {http://dx.doi.org/10.3189/172756405781813519}, author = {Ebnet, A and Andrew G Fountain and Thomas H. Nylen} } @article {1313, title = {Invertebrate diversity in Taylor Valley soils and sediments}, journal = {Antarctic Journal of the United States}, volume = {33}, year = {2005}, pages = {13-16}, keywords = {LTER-MCM}, author = {Amy M Treonis and Diana H. Wall and Ross A. Virginia} } @phdthesis {1301, title = {Lacustrine Biogeochemistry of the McMurdo Dry Valleys}, volume = {Ph.D.}, year = {2005}, school = {University of Illinois, Chicago}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Lawson, J} } @mastersthesis {1314, title = {Mathematical Modeling of a Hydrocarbon Spill on the Ice Cover of Lake Fryxell, Antarctica}, volume = {M.S.}, year = {2005}, month = {06/2005}, pages = {114}, school = {The Ohio State University}, type = {masters}, address = {Columbus}, abstract = {

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\&$\#$39;s Antarctic Research Program crashed on the frozen surface of Lake Fryxell on January 17, 2003. This resulted in the release of approximately 731 Liters (193 gallons) of diesel fuel and amounts of engine oil and hydraulic fluid. Two physically based models are developed that simulate heat, meltwater flow and solute transport. The first is a transient, one-dimensional, thermodynamic model, which can predict the temperature distribution in the ice cover, melting rate at the surface and at the bottom of ice cover, and ice thickness. The second model simulates unsaturated flow and solute transport and is used to estimate water content distribution and solute transport through the ice cover. The validation of heat transport model was accomplished by comparing model results with the original measurements of ice temperature at various depth in Lake Fryxell. Because of lack of the field data, validation of the unsaturated flow and solute transport model couldn\&$\#$39;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.

}, keywords = {LTER-MCM}, author = {Marinko Karnovic and Anne E. Carey and Scott E. Bair and van der Veen, Cornelis} } @mastersthesis {1315, title = {Mercury Concentrations in Snow and the Modern Mercury Flux to Taylor Valley, Antarctica}, volume = {M.S.}, year = {2005}, school = {The Ohio State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R} } @phdthesis {1302, title = {Microbial Ecology of an Antarctic Subglacial Environment}, volume = {Ph.D.}, year = {2005}, school = {Montana State University}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Jill A. Mikucki} } @article {1303, title = {The origin of channels on lower Taylor Glacier, McMurdo Dry Valleys Antarctica and their implication for water runoff}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {1-7}, keywords = {LTER-MCM}, doi = {LTER}, author = {Johnston, R and Andrew G Fountain and Thomas H. Nylen} } @mastersthesis {1316, title = {Pedogenic Carbonate Distribution within Glacial Till in Taylor Valley, Southern Victoria Land, Antarctica}, volume = {M.S.}, year = {2005}, school = {The Ohio State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Foley, K} } @inbook {1304, title = {Perennial Antarctic lake ice: A refuge for cyanobacteria in an extreme environment}, booktitle = {Life in Ancient Ice}, year = {2005}, pages = {22-49}, publisher = {Princeton University Press}, organization = {Princeton University Press}, keywords = {LTER-MCM}, url = {http://www.montana.edu/lkbonney/DOCS/Publications/PriscuEtAl2005CyanobacteriaRefuge.pdf}, author = {John C. Priscu and Edward E. Adams and Hans W. Paerl and Christian H. Fritsen and John E. Dore and John T. Lisle and Craig F. Wolf and Jill A. Mikucki}, editor = {S. O. Rogers and J. Castello} } @article {1305, title = {Perturbation of hydrochemical conditions in natural microcosms entombed within Antarctic ice}, journal = {Ice and Climate News}, volume = {6}, year = {2005}, pages = {22-23}, keywords = {LTER-MCM}, author = {Martyn Tranter and Andrew G Fountain and Christian H. Fritsen and W. Berry Lyons and John C. Priscu and Stratham, P and Kathleen A. Welch} } @inbook {1306, title = {Polar lakes, streams, and springs as analogs for the hydrological cycle on Mars.}, booktitle = {Advances in Astrobiology and Biogeophysics}, year = {2005}, pages = {219-233}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {Berlin, Heidelberg}, keywords = {LTER-MCM}, doi = {LTER}, url = {/reports/lakes/McKayEtAl2005StreamsSprings.pdf}, author = {Christopher P. McKay and Dale T. Andersen and Pollard, W and Heldmann, J and Peter T. Doran and Christian H. Fritsen and John C. Priscu} } @inbook {1307, title = {Polar Systems}, booktitle = {Millennium Ecosystem Assessment. Current State and Trends: Findings of the Condition and Trends Working Group}, year = {2005}, pages = {717-743}, publisher = {Island Press}, organization = {Island Press}, keywords = {LTER-MCM}, doi = {LTER}, author = {F. S. Chapin and McGuire, A and Nuttall, M and Ross A. Virginia and Young, O and Zimov, S and Christensen, T and Godduhn, A and Murphy, E and Diana H. Wall and Zockler, C and Berman, M and Callaghan, T and Peter Convey and A. S. Crepin and Danell, K and Hugh W. Ducklow and Forbes, B and Kofinas, G}, editor = {R. Hassan and R. Scholes and N. Ash} } @article {1289, title = {Potential soil organic matter turnover in Taylor Valley, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {37}, year = {2005}, month = {02/2005}, pages = {108-117}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1657/1523-0430(2005)037[0108:PSOMTI]2.0.CO;2}, url = {http://instaar.metapress.com/content/e653225425230175/}, author = {John E. Barrett and Ross A. Virginia and Andrew N. Parsons and Diana H. Wall} } @article {1288, title = {Sensitivity analysis of conservative and reactive stream transient storage models applied to field data from multiple-reach experiments}, journal = {Advances in Water Resources}, volume = {28}, year = {2005}, month = {05/2005}, pages = {479-492}, keywords = {LTER-MCM}, doi = {10.1016/j.advwatres.2004.11.012}, author = {Michael N. Gooseff and Kenneth E. Bencala and Durelle T. Scott and Robert L. Runkel and Diane M. McKnight} } @inbook {1309, title = {Soils, freshwater and marine sediments: the need for integrative landscape science}, booktitle = {Marine Ecology Progress Series}, series = {Theme Section: Bridging the Gap between Aquatic and Terrestrial Ecology.}, volume = {304}, year = {2005}, pages = {302-307}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall and Edward Ayres and Valerie Behan-Pelletier and Covich, A and P.V.R. Snelgrove}, editor = {H. Browman and K. I. Stergiou} } @mastersthesis {1317, title = {A temperature-index model of stream flow in Taylor Valley, Antarctica}, volume = {M.S.}, year = {2005}, school = {Portland State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ebnet, A} } @inbook {1322, title = {Antarctic Paleolimnology}, booktitle = {Long-Term Environmental Change in Arctic and Antarctic Lakes}, year = {2004}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, keywords = {LTER-MCM}, author = {Hodgson, D and John A. E. Gibson and Peter T. Doran}, editor = {Pienitz, R and Douglas, Marianne S. V. and J.P. Smol} } @article {1323, title = {The Biodiversity and Biogeochemistry of Cryoconite Holes from McMurdo Dry Valley Glaciers, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {36}, year = {2004}, pages = {84-91}, keywords = {LTER-MCM}, author = {Porazinska, D and Andrew G Fountain and Thomas H. Nylen and Martyn Tranter and Ross A. Virginia and Diana H. Wall} } @article {1318, title = {Can warming induce advances of polar glaciers, Taylor Valley, Antarctica}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, month = {12/2004}, pages = {556-564}, keywords = {LTER-MCM}, doi = {10.3189/172756504781829701}, author = {Andrew G Fountain and Thomas A. Neumann and Paul L. Glenn and Trevor Chinn} } @article {1324, title = {The Carbon Isotopic Composition of Dissolved Inorganic Carbon in Perennially Ice-Covered Antarctica Lakes: Searching for a Biogenic Signature.}, journal = {Annals of Glaciology}, volume = {39}, year = {2004}, keywords = {LTER-MCM}, author = {Klaus Neumann and W. Berry Lyons and John C. Priscu and David J. DesMarais and Kathleen A. Welch} } @article {1325, title = {Changes in fulvic acid redox state through the oxycline of a permanently ice-covered Antarctic lake}, journal = {Aquatic Sciences}, volume = {66}, year = {2004}, pages = {1-20}, keywords = {LTER-MCM}, author = {Fulton, J and Diane M. McKnight and Christine M. Foreman and Rose M. Cory and Stedmon, C and Blunt, E} } @article {1326, title = {Climatology of Katabatic Winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, journal = {Journal of Geophysical Research}, volume = {109}, year = {2004}, keywords = {LTER-MCM}, author = {Thomas H. Nylen and Andrew G Fountain and Peter T. Doran} } @article {1327, title = {Cryoconite holes on polar glaciers and their importance for meltwater runoff}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, pages = {25-45}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Martyn Tranter and Thomas H. Nylen and Booth, D and Karen J. Lewis} } @article {1319, title = {Denitrification and hydrologic transient storage in a glacial meltwater stream, McMurdo Dry Valleys, Antarctica}, journal = {Limnology and Oceanography}, volume = {49}, year = {2004}, month = {09/2004}, pages = {1884-1895}, keywords = {LTER-MCM}, doi = {10.4319/lo.2004.49.5.1884}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel and John H. Duff} } @article {1349, title = {Detritus, trophic dynamics and biodiversity.}, journal = {Ecology Letters}, volume = {7}, year = {2004}, pages = {584-600}, keywords = {LTER-MCM}, doi = {LTER}, author = {Moore, J and Morin, P and Nadelhoffer, K and Rosemound, A and Post , D and Sabo, J and Scow, K and Michael J. Vanni and Diana H. Wall and Berlow, E and David C. Coleman and Peter C. De Ruiter and Dong, Q and Hasting, A and Johnson, N and McCann, K and Melville, K} } @mastersthesis {1350, title = {Development of large supraglacial channels in the polar environment}, volume = {M.S.}, year = {2004}, school = {Portland State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Johnston, R} } @article {1328, title = {The distribution of microplankton in the McMurdo dry valley lakes, Antarctica: Response to ecosystem legacy or present-day climate controls?}, journal = {Polar Biology}, volume = {27}, year = {2004}, pages = {238-249}, keywords = {LTER-MCM}, doi = {LTER}, author = {Emily C. Roberts and John C. Priscu and Craig F. Wolf and W. Berry Lyons and Johanna Laybourn-Parry} } @inbook {1329, title = {Earth{\textquoteright}s Icy Biosphere}, booktitle = {Microbial Diversity and Bioprospecting}, year = {2004}, publisher = {American Society for Microbiology}, organization = {American Society for Microbiology}, keywords = {LTER-MCM}, doi = {LTER}, url = {http://mcm.lternet.edu/reports/lakes/PriscuChristner2004IcyBiosphere.pdf}, author = {John C. Priscu and Brent C. Christner}, editor = {Bull, Alan T.} } @article {1351, title = {Ecological linkages between aboveground and belowground biota.}, journal = {Science}, volume = {304}, year = {2004}, pages = {1629-1633}, keywords = {LTER-MCM}, doi = {LTER}, author = {Wardle, D and Richard D. Bardgett and Klironomos, J and Setala, H and van der Putten, W and Diana H. Wall} } @article {1330, title = {Elevated levels of dimethylated-sulfur compounds in Lake Bonney, a poorly ventilated Antarctic lake}, journal = {Limnology and Oceanography}, volume = {49}, year = {2004}, pages = {1044-1055}, keywords = {LTER-MCM}, author = {Lee, P and John C. Priscu and G R DiTullio and Riseman, S and Tursich, N and DeMora, S} } @article {1321, title = {Evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, month = {01/2004}, pages = {35-45}, keywords = {LTER-MCM}, doi = {10.3189/172756504781830312}, author = {Andrew G Fountain and Martyn Tranter and Thomas H. Nylen and Karen J. Lewis and Derek R. Mueller} } @article {1331, title = {Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice.}, journal = {Hydrological Processes}, volume = {18}, year = {2004}, pages = {379-387}, keywords = {LTER-MCM}, author = {Martyn Tranter and Andrew G Fountain and Christian H. Fritsen and W. Berry Lyons and John C. Priscu and Stathan, P and Kathleen A. Welch} } @inbook {1332, title = {Geochronology of high latitude lake sediments}, booktitle = {Long-Term Environmental Change in Arctic and Antarctic Lakes}, year = {2004}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, keywords = {LTER-MCM}, author = {Wolf, A and Miller, G and Olsen, C and Forman, S and Peter T. Doran and Holmgren, S}, editor = {Pienitz, R and Douglas, Marianne S. V. and J.P. Smol} } @article {1333, title = {Geomicrobiology of Blood Fall: An iron-rich saline discharge at the terminus of the Taylor Glacier, Antarctica}, journal = {Aquatic Geochemistry}, volume = {10}, year = {2004}, pages = {199-200}, keywords = {LTER-MCM}, author = {Jill A. Mikucki and Christine M. Foreman and Sattler, B and W. Berry Lyons and John C. Priscu} } @article {1353, title = {Gradient analysis of cryoconite ecosystems from two Polar glaciers}, journal = {Polar Biology}, volume = {27}, year = {2004}, pages = {66-74}, keywords = {LTER-MCM}, author = {Derek R. Mueller and Pollard, W} } @article {1334, title = {Identification of a psychrophilic green alga from Lake Bonney, Antarctica: Chlamydomonas raudensis ETTL. (UWO 241) (Chlorophyceae)}, journal = {Journal of Phycology}, volume = {40}, year = {2004}, pages = {1138-1148}, keywords = {LTER-MCM}, author = {Pocock, T and Lachance, M and Proschold, T and John C. Priscu and Kim, S and Norman P.A. Huner} } @article {1354, title = {The impact of anhydrobiosis on the persistence of Scottnema lindsyae (Nematoda): a modeling analysis of population stability thresholds}, journal = {Polar Biology}, volume = {27}, year = {2004}, pages = {507-512}, keywords = {LTER-MCM}, author = {Weicht, T and Daryl L. Moorhead} } @article {1320, title = {Impact of episodic warming events on the physical, chemical and biological relationships of lakes in the McMurdo Dry Valleys, Antarctica}, journal = {Aquatic Geochemistry}, volume = {10}, year = {2004}, month = {09/2004}, pages = {239-268}, type = {Journal}, keywords = {LTER-MCM, Climate Response, stoichiometry}, doi = {10.1007/s10498-004-2261-3}, url = {http://link.springer.com/article/10.1007\%2Fs10498-004-2261-3}, author = {Christine M. Foreman and Wolf, C and John C. Priscu} } @article {1335, title = {Inorganic nitrogen and phosphorus dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities}, journal = {Journal of the North American Benthological Society}, volume = {23}, year = {2004}, pages = {171-188}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Robert L. Runkel and John H. Duff and Cathy M. Tate and Daryl L. Moorhead} } @article {1336, title = {Microplankton dynamics in a perennially ice-covered Antarctic lake-Lake Hoare}, journal = {Freshwater Biology}, volume = {27}, year = {2004}, pages = {238-249}, keywords = {LTER-MCM}, author = {Emily C. Roberts and John C. Priscu and Johanna Laybourn-Parry} } @inbook {1337, title = {The need for understanding how biodiversity and ecosystem functioning affect ecosystem services in soil and sediments}, booktitle = {Sustaining Biodiversity and Ecosystem Services in Soils Sediments}, year = {2004}, publisher = {Island Press}, organization = {Island Press}, keywords = {LTER-MCM}, author = {Diana H. Wall and Richard D. Bardgett and Covich, A and P.V.R. Snelgrove}, editor = {Diana H. Wall} } @article {1338, title = {The Occurrence of Lysogenic Bacteria and Microbial Aggregates in the Lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Microbial Ecology}, volume = {47}, year = {2004}, pages = {427-439}, keywords = {LTER-MCM}, author = {John T. Lisle and John C. Priscu} } @inbook {1339, title = {Paleolimnology of extreme cold terrestrial and extraterrestrial environments.}, booktitle = {Long-Term Environmental Change in Arctic and Antarctic Lakes}, year = {2004}, pages = {475-507}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, address = {Dordrecht, The Netherlands}, keywords = {LTER-MCM}, isbn = {978-1-4020-2125-1}, author = {Peter T. Doran and John C. Priscu and W. Berry Lyons and Powell, R and Robert J. Poreda and Dale T. Andersen} } @inbook {1340, title = {Paleolimnology of Ice-covered Environments}, booktitle = {Long-term environmental change in Arctic and Antarctic lakes}, year = {2004}, pages = {475-507}, publisher = {Kluwer Academic Publishers}, organization = {Kluwer Academic Publishers}, keywords = {LTER-MCM}, author = {Peter T. Doran and John C. Priscu and W. Berry Lyons and Powell, R and Robert J. Poreda}, editor = {Pienitz, R and Douglas, Marianne S. V. and John Smol} } @article {1341, title = {Reach-scale cation exchange controls on major ion chemistry of an Antarctic glacial meltwater stream}, journal = {Special issue of Aquatic Geochemistry on the McMurdo Dry Valleys}, volume = {10}, year = {2004}, pages = {221-238}, keywords = {LTER-MCM}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel} } @article {1342, title = {Soil carbon dioxide flux from Antarctic Dry Valley soils}, journal = {Ecosystems}, volume = {7}, year = {2004}, pages = {286-295}, keywords = {LTER-MCM}, author = {Andrew N. Parsons and John E. Barrett and Diana H. Wall and Ross A. Virginia} } @thesis {1355, title = {Soil phosphorus dynamics in Taylor Valley, Antarctica}, volume = {B.S.}, year = {2004}, school = {Dartmouth College}, type = {bachelors}, keywords = {LTER-MCM}, doi = {LTER}, author = {D. Brad Bate} } @article {1343, title = {Stable carbon and nitrogen isotopic compositions of benthic and pelagic organic matter in four polar lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Aquatic Geochemistry}, volume = {10}, year = {2004}, pages = {269-301}, keywords = {LTER-MCM}, author = {Lawson, J and Peter T. Doran and Kenig, Fabien and David J. DesMarais and John C. Priscu} } @book {1344, title = {Sustaining Biodiversity and Ecosystem Services in Soil and Sediments.}, series = {Scientific Committee on Problems of the Environment (SCOPE) Series Vol. 64}, year = {2004}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall}, editor = {Diana H. Wall} } @article {1345, title = {Thermodynamic constraints on microbially mediated processes in lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Geomicrobiology Journal}, volume = {21}, year = {2004}, pages = {1-17}, keywords = {LTER-MCM}, doi = {LTER}, author = {Lee, P and Jill A. Mikucki and Christine M. Foreman and John C. Priscu and G R DiTullio and Riseman, S and DeMora, S and Craig F. Wolf and Kester, L} } @article {1356, title = {Trophic interactions in a changing world: modelling aboveground-belowground interactions}, journal = {Basic and Applied Ecology}, volume = {5}, year = {2004}, pages = {515-528}, keywords = {LTER-MCM}, doi = {LTER}, author = {Schroter, D and Brussaard, L and De Deyn, G and Proveda, K and Brown, V and Berg, M and Wardle, D and Moore, J and Diana H. Wall} } @inbook {1346, title = {Understanding the functions of biodiversity in soils and sediments will enhance global ecosystem sustainability and societal well-being}, booktitle = {Sustaining Biodiversity and Ecosystem Services in Soils Sediments}, year = {2004}, pages = {249-254}, publisher = {Island Press}, organization = {Island Press}, keywords = {LTER-MCM}, author = {Diana H. Wall and Richard D. Bardgett and Covich, A and P.V.R. Snelgrove}, editor = {Diana H. Wall} } @article {1347, title = {Variation in biogeochemistry and soil biodiversity across spatial scales in a polar desert}, journal = {Ecology}, volume = {85}, year = {2004}, pages = {3105-3118}, abstract = {
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.
}, keywords = {LTER-MCM}, doi = {10.1890/03-0213}, author = {John E. Barrett and Ross A. Virginia and Diana H. Wall and Andrew N. Parsons and Powers, Laura E. and Melody B. Burkins} } @inbook {1348, title = {Vulnerability to global change of ecosystem goods and services driven by soil biota}, booktitle = {Sustaining Biodiversity and Ecosystem Services in Soil and Sediments}, year = {2004}, pages = {101-136}, publisher = {Island Press}, organization = {Island Press}, keywords = {LTER-MCM}, isbn = {1-55963-760-9}, author = {Wardle, D and V.K. Brown and Valerie Behan-Pelletier and St. John, M and Wojtowicz, T and Richard D. Bardgett and Brown, G. G. and Ineson, P. and Lavelle, P and van der Putten, W and Anderson, J. M. and Brussaard, L and H. William Hunt and E. A. Paul and Diana H. Wall}, editor = {Diana H. Wall} } @article {1358, title = {Biochemistry of Si in the McMurdo Dry Valley lakes, Antarctica}, journal = {The International Journal of Astrobiology}, volume = {1}, year = {2003}, pages = {737-749}, keywords = {LTER-MCM}, author = {Pugh, H and Kathleen A. Welch and W. Berry Lyons and John C. Priscu and Diane M. McKnight} } @inbook {1359, title = {Century to millennial scale climate change and ecosystem response in Taylor Valley, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long-Term Ecological Research Sites}, series = {Long-Term Ecological Research Network}, year = {2003}, pages = {319-340}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York City}, keywords = {LTER-MCM, Climate Response}, isbn = {0195150597}, author = {Andrew G Fountain and W. Berry Lyons}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} } @inbook {1360, title = {Chemistry and lake dynamics of the Taylor Valley lakes, Antarctica: The importance of long-term monitoring.}, booktitle = {Antarctic Ecosystems: Models for Wider Ecological Understanding}, year = {2003}, publisher = {Caxton Press}, organization = {Caxton Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and Klaus Neumann and W. Berry Lyons and Diane M. McKnight}, editor = {Clive Howard-Williams and W. Davidson and P. Broady} } @article {1361, title = {Determining long time-scale hyporheic zone flow paths in Antarctic streams}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, pages = {1691-1710}, keywords = {LTER-MCM}, author = {Michael N. Gooseff and Diane M. McKnight and Robert L. Runkel and Bruce H. Vaughn} } @mastersthesis {1362, title = {Distribution of 210Pb and 137Cs in the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2003}, school = {University of Illinois, Chicago}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Olsen, C} } @article {1357, title = {Formation and character of an ancient 19 m ice cover and underlying trapped brine in an}, journal = {Proceedings of National Academy of Sciences}, volume = {100}, year = {2003}, month = {01/2003}, pages = {26-31}, type = {Journal}, keywords = {LTER-MCM}, doi = {10.1073/pnas.222680999}, url = {http://www.pnas.org/content/100/1/26.short}, author = {Peter T. Doran and Christian H. Fritsen and Christopher P. McKay and John C. Priscu and Edward E. Adams} } @article {1363, title = {Fourier-transform raman spectroscopic studies of organic and inorganic chemical components in stromatolitic cores from Antarctic lake sediments}, journal = {International Journal of Astrobiology}, volume = {1}, year = {2003}, pages = {325-331}, keywords = {LTER-MCM}, author = {Edwards, H and Wynn-Williams, D and Ellis-Evans, J and Newton, E and Little, S and de Oliveira, L and Hodgson, D and Peter T. Doran} } @article {1364, title = {Glaciers of the McMurdo Dry Valleys: terrestrial analog for Martian polar sublimation}, journal = {Journal of Geophysical Research}, volume = {108}, year = {2003}, pages = {5031}, keywords = {LTER-MCM}, author = {Karen J. Lewis and Andrew G Fountain and Kargel, J and MacAyeal, D} } @article {1370, title = {Long-term perspectives on biodiversity-ecosystem function.}, journal = {Bioscience}, year = {2003}, pages = {89-98}, keywords = {LTER-MCM}, author = {Symstad, A and Chapin III, F and Diana H. Wall and Gross, K and Huenneke, L and Mittelbach, G and Debra P. C. Peters and Tilman, D} } @article {1365, title = {Map-based methods for estimating glacier equilibrium-line altitudes}, journal = {Journal of Glaciology}, volume = {49}, year = {2003}, pages = {329-336}, keywords = {LTER-MCM}, doi = {LTER}, author = {Leonard, K and Andrew G Fountain} } @article {1371, title = {Organic matter and soil biota of upland wetlands in Taylor Valley, Antarctica}, journal = {Polar Biology}, volume = {26}, year = {2003}, pages = {1009-1019}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and John E. Barrett and Ross A. Virginia and Diana H. Wall and Porazinska, D} } @mastersthesis {1372, title = {Phosphorus in Taylor Valley, Antarctica: the connection between landscape age and nutrient limitation in aquatic ecosystem components}, volume = {M.S.}, year = {2003}, school = {The Ohio State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Gudding, J} } @inbook {1373, title = {Polar Limnology - the past, the present, and the future. Review in the SCAR VIII International Biology Symposium Proceedings}, booktitle = {Antarctic Biology in a global context}, year = {2003}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry} } @mastersthesis {1367, title = {Spatial and temporal variations of phytoplankton populations in Lake Bonney}, volume = {M.S.}, year = {2003}, school = {Montana State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Turish, N} } @article {1368, title = {Strontium isotopic signatures of the streams and lakes of Taylor Valley, southern Victoria Land, Antarctica: chemical weathering in a polar climate}, journal = {Aquatic Geochemistry}, volume = {8}, year = {2003}, pages = {875-895}, keywords = {LTER-MCM}, author = {W. Berry Lyons and C. A. Nezat and Benson, L and Bullen, T and Graham, E and Kidd, J and Kathleen A. Welch and Thomas, J} } @article {1369, title = {Surface glaciochemistry of Taylor Valley, southern Victoria Land, Antarctica and its relationship to stream chemistry.}, journal = {Hydrological Processes}, volume = {17}, year = {2003}, pages = {115-130}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Andrew G Fountain and Gayle L. Dana and Bruce H. Vaughn and Diane M. McKnight} } @article {1377, title = {Antarctic climate cooling and terrestrial ecosystem response}, journal = {Nature}, volume = {415}, year = {2002}, month = {01/2002}, pages = {517-520}, type = {Journal}, keywords = {LTER-MCM, Climate Response}, doi = {10.1038/nature710}, author = {Peter T. Doran and John C. Priscu and W. Berry Lyons and John E. Walsh and Andrew G Fountain and Diane M. McKnight and Daryl L. Moorhead and Ross A. Virginia and Diana H. Wall and Gary D. Clow and Christian H. Fritsen and Christopher P. McKay and Andrew N. Parsons} } @article {1385, title = {The balance between photosynthesis and grazing in Antarctic mixotrophic cryptophytes during summer}, journal = {Freshwater Biology}, volume = {47}, year = {2002}, pages = {2060-2070}, keywords = {LTER-MCM}, author = {Marshall, W and Johanna Laybourn-Parry} } @thesis {1386, title = {The biogeochemistry of Si in the McMurdo Dry Valley Lakes}, volume = {B.S.}, year = {2002}, school = {The Ohio State University}, type = {bachelors}, keywords = {LTER-MCM}, doi = {LTER}, author = {Pugh, H} } @mastersthesis {1387, title = {The chemical evolution of Canada Glacier melt: supraglacial and proglacial waters in Taylor Valley, Antarctica}, volume = {M.S.}, year = {2002}, school = {The Ohio State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Tegt, S} } @mastersthesis {1388, title = {Climatic controls on interannual variation in streamflow in Fryxell Basin, Taylor Valley}, volume = {M.S.}, year = {2002}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Chris Jaros} } @article {1378, title = {Direct observation of aluminosilicate weathering in the hyporheic zone of an Antarctic Dry Valley stream}, journal = {Geochimica et Cosmochimica Acta}, volume = {66}, year = {2002}, pages = {1335-1347}, keywords = {LTER-MCM}, author = {Maurice, P and Diane M. McKnight and Leff, L and Fulghun, J and Michael N. Gooseff} } @article {1379, title = {Distribution and life cycle of Scottnema lindsayae (Nematoda) in Antarctic soils: A modeling analysis of tempaerature responses}, journal = {Polar Biology}, volume = {25}, year = {2002}, pages = {118-125}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Diana H. Wall and Ross A. Virginia and Andrew N. Parsons} } @inbook {1380, title = {Extremophiles: ice ecosystems and biodiversity}, booktitle = {Knowledge for Sustainable Development: an Insight into the Encyclopedia of Life Support Systems.}, year = {2002}, pages = {573-598}, publisher = {UNESCO Publishing-Eolss Publishers}, organization = {UNESCO Publishing-Eolss Publishers}, address = {Oxford}, keywords = {LTER-MCM}, author = {Psenner, R and Felip, M and John C. Priscu and Wagenbach, D and Willie, A and Sattler, B} } @article {1389, title = {Field and microcosm studies of decomposition and soil biota in a cold dessert soil}, journal = {Ecosystems}, volume = {5}, year = {2002}, keywords = {LTER-MCM}, author = {Amy M Treonis and Diana H. Wall and Ross A. Virginia} } @article {1390, title = {Flux of eolian sediment in the Mcmurdo Dry Valleys, Antarctica: a preliminary assessment}, journal = {Arctic Antarctic and Alpine Research}, volume = {34}, year = {2002}, pages = {318-323}, keywords = {LTER-MCM}, author = {Lancaster, N} } @mastersthesis {1391, title = {Interannual variation in phytoplankton dynamics in Lake Fryxell}, volume = {M.S.}, year = {2002}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Van Matre, E} } @article {1392, title = {Invertebrates in ornithogenic soils at Ross Island, Antarctica.}, journal = {Polar Biology}, volume = {25}, year = {2002}, pages = {569-574}, keywords = {LTER-MCM}, author = {Porazinska, D and Diana H. Wall and Ross A. Virginia} } @mastersthesis {1381, title = {Linkages between soils and lake ice sediments biogeochemistry: Taylor Valley, southern Victoria Land, Antarctica}, volume = {M.S.}, year = {2002}, school = {Montana State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Konley, S} } @article {1393, title = {Modeling the effects of loss of soil biodiversity on ecosystem function}, journal = {Global Change Biology}, volume = {8}, year = {2002}, pages = {32-49}, keywords = {LTER-MCM}, author = {Hunt , H and Diana H. Wall} } @article {1394, title = {Population age structure of nematodes in the Antarctic Dry Valleys: perspectives on time, space, and habitat suitability}, journal = {Arctic,Antarctic, and Alpine Research}, volume = {34}, year = {2002}, pages = {159-168}, keywords = {LTER-MCM}, author = {Porazinska, D and Diana H. Wall and Ross A. Virginia} } @article {1382, title = {Recent Temperature Trends in the Antarctic}, journal = {Nature}, volume = {418}, year = {2002}, pages = {291-292}, keywords = {LTER-MCM}, author = {John E. Walsh and Gary D. Clow and Christian H. Fritsen and Christopher P. McKay and Andrew N. Parsons and Peter T. Doran and John C. Priscu and W. Berry Lyons and Andrew G Fountain and Diane M. McKnight and Daryl L. Moorhead and Ross A. Virginia and Diana H. Wall} } @article {1383, title = {Satellite-Derived Indices of Stream Discharge in Taylor Valley,Antarctica.}, journal = {Hydrological Processes}, volume = {16}, year = {2002}, pages = {1603-1616}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Davis, R and Andrew G Fountain and Robert A. Wharton Jr.} } @article {1376, title = {Snow patch influence on soil biogeochemical processes and invertebrate distribution in the McMurdo Dry Valleys, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {35}, year = {2002}, month = {02/2003}, pages = {91-99}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1657/1523-0430(2003)035[0091:SPIOSB]2.0.CO;2}, url = {http://instaar.metapress.com/content/r086455ju7213711/}, author = {Michael N. Gooseff and John E. Barrett and Peter T. Doran and Andrew G Fountain and W. Berry Lyons and Andrew N. Parsons and Porazinska, D and Ross A. Virginia and Diana H. Wall} } @article {1395, title = {Survival mechanisms in Antarctic lakes}, journal = {Philosophical Transactions of the Royal Society B}, volume = {357}, year = {2002}, pages = {863-869}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry} } @article {1384, title = {Synthetic aperture radar detection of the snowline on Commonwealth and Howard Glaciers, Taylor Valley, Antarctica}, journal = {Annals of Glaciology}, volume = {34}, year = {2002}, pages = {177-183}, keywords = {LTER-MCM}, author = {Bardel, P and Andrew G Fountain and Hall, D and Kwok, R} } @article {1396, title = {Trends in resin and KCl-extractable soil nitrogen across landscape gradients in Taylor Valley, Antarctica}, journal = {Ecosystems}, volume = {5}, year = {2002}, pages = {289-299}, keywords = {LTER-MCM}, author = {John E. Barrett and Ross A. Virginia and Diana H. Wall} } @article {1374, title = {Valley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-2000}, journal = {Journal of Geophysical Research}, volume = {107}, year = {2002}, month = {12/2002}, pages = {4772-4784}, type = {Journal}, abstract = {

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.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2001JD002045}, author = {Peter T. Doran and Christopher P. McKay and Gary D. Clow and Gayle L. Dana and Andrew G Fountain and Thomas H. Nylen and W. Berry Lyons} } @article {1375, title = {Weathering reactions and hyporheic exchange controls on stream water chemistry in a glacial meltwater stream in the McMurdo Dry Valleys}, journal = {Water Resources Research}, volume = {38}, year = {2002}, month = {12/2002}, pages = {1279-1296}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2001WR000834}, url = {http://www.agu.org/pubs/crossref/2002/2001WR000834.shtml}, author = {Michael N. Gooseff and Diane M. McKnight and W. Berry Lyons and Blum, A} } @article {1409, title = {519-529A model for nematode locomotion in soil}, journal = {Nematology}, volume = {3}, year = {2001}, pages = {705-716}, keywords = {LTER-MCM}, author = {Hunt , H and Diana H. Wall and DeCrappeo, N and Brenner, J} } @article {1410, title = {Absorption and utilization of low irradiance by cyanobacterial mats in two ice-covered Antarctic lakes}, journal = {Journal of Phycology}, volume = {37}, year = {2001}, pages = {5-15}, keywords = {LTER-MCM}, author = {Ian Hawes and Schwartz, A-M} } @article {1398, title = {Bacterial dissolved organic carbon demand in antarctic dry valley lakes}, journal = {Limnology and Oceanography}, volume = {46}, year = {2001}, month = {07/2001}, pages = {1189-1194}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.4319/lo.2001.46.5.1189}, url = {http://www.jstor.org/stable/2671031}, author = {Cristina D. Takacs-Vesbach and John C. Priscu and Diane M. McKnight} } @inbook {1411, title = {Basic Principles in ecosystem functioning}, booktitle = {Encyclopedia of Biodiversity}, volume = {2}, year = {2001}, pages = {345-352}, publisher = {Academic Press}, organization = {Academic Press}, keywords = {LTER-MCM}, author = {Ross A. Virginia and Diana H. Wall}, editor = {S. Levin} } @article {1412, title = {Benthic primary production in two perennially ice-covered Antarctic lakes: comparisons of annual accumulation predicted from photosynthesis models with estimates from internal growth markers}, journal = {Antarctic Science}, volume = {13}, year = {2001}, pages = {18-27}, keywords = {LTER-MCM}, author = {Ian Hawes and Daryl L. Moorhead and Sutherland, J and Schmeling, J and Schwartz, A} } @article {1399, title = {Biodiversity in critical transition zones between terrestrial freshwater and marine soils and sediments: processes, linkages, and management implications.}, journal = {Ecosystems}, volume = {4}, year = {2001}, pages = {418-420}, keywords = {LTER-MCM}, author = {Diana H. Wall and M.A. Palmer and P.V.R. Snelgrove} } @article {1400, title = {Chemical weathering in streams of a polar desert (Taylor Valley, Antarctica).}, journal = {GSA Bulletin}, volume = {113}, year = {2001}, pages = {1401-1408}, keywords = {LTER-MCM}, author = {C. A. Nezat and W. Berry Lyons and Kathleen A. Welch} } @article {1401, title = {CO2 concentrations in perennially ice-covered lakes of Taylor Valley, Antarctica}, journal = {Biogeochemistry}, volume = {56}, year = {2001}, pages = {27-50}, keywords = {LTER-MCM}, author = {Klaus Neumann and W. Berry Lyons and John C. Priscu and Donahoe, R} } @article {1414, title = {Determining habitat suitability for soil invertebrates in an extreme environment: The McMurdo Dry Valleys, Antarctica.}, journal = {Antarctic Science}, volume = {13}, year = {2001}, pages = {9-17}, keywords = {LTER-MCM}, author = {Courtright, E and Diana H. Wall and Ross A. Virginia} } @phdthesis {1415, title = {Energy balance of a rough glacier surface, Canada Glacier, McMurdo Dry Valleys, Antarctica}, volume = {Ph.D.}, year = {2001}, school = {Portland State University}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Karen J. Lewis} } @article {1416, title = {Glacial cryoconite ecosystems: a bipolar comparison of algal communities and habitats}, journal = {Nova Hedwigia}, volume = {123}, year = {2001}, pages = {173-197}, keywords = {LTER-MCM}, author = {Derek R. Mueller and Warwick F. Vincent and Pollard, W and Christian H. Fritsen} } @mastersthesis {1417, title = {The influence of mixotroph growth on DOM chemistry in Pony Lake, a eutrophic coastal pond in Antarctica}, volume = {M.S.}, year = {2001}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Brown, A} } @article {1402, title = {The influence of soil biodiversity on hydrological pathways and the transfer of materials between terrestrial and aquatic ecosystems}, journal = {Ecosystems}, volume = {4}, year = {2001}, keywords = {LTER-MCM}, author = {Richard D. Bardgett and Anderson, J. M. and Valerie Behan-Pelletier and Brussaard, L and David C. Coleman and Ettma, C and Moldenke, A and Schimel, J and Diana H. Wall} } @article {1403, title = {Luminescence zeroing tests in Lake Hoare, Taylor Valley, Antarctica}, journal = {Journal of Paleolimnology}, volume = {25}, year = {2001}, pages = {519-529}, keywords = {LTER-MCM}, author = {G. W. Berger and Peter T. Doran} } @article {1404, title = {The McMurdo Dry Valleys Long-Term Ecological Research Program: new understanding of the biogeochemistry of the Dry Valley lakes: a review.}, journal = {Polar Geography}, volume = {25}, year = {2001}, pages = {202-217}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and John C. Priscu and Johanna Laybourn-Parry and Daryl L. Moorhead and Diane M. McKnight and Peter T. Doran and Martyn Tranter} } @article {1405, title = {Mineralogical 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 Mars}, journal = {Geochimica et Cosmochimica Acta}, volume = {65}, year = {2001}, pages = {2875-2897}, keywords = {LTER-MCM}, author = {Bishop, Janice L. and Lougear, A and Newton, J and Peter T. Doran and Froeschl, H and Krner, W and Koeberl, C and Trautwein, A} } @phdthesis {1366, title = {Modeling hyporheic exchange influences on biogeochemical processes in dry valley streams, Antarctica}, volume = {Ph.D.}, year = {2001}, school = {University of Colorado}, type = {doctoral}, abstract = {

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.

}, keywords = {LTER-MCM}, author = {Michael N. Gooseff} } @article {1418, title = {Organic carbon cycling in Taylor Valley, Antarctica: Quantifying soil reservoirs and soil respiration}, journal = {Global Change Biology}, volume = {7}, year = {2001}, pages = {113-125}, keywords = {LTER-MCM}, author = {Melody B. Burkins and Ross A. Virginia and Diana H. Wall} } @article {1397, title = {Phytoplankton phosphorus deficiency and alkaline phosphatase activity in the McMurdo Dry Valley lakes, Antarctica.}, journal = {Limnology and Oceanography}, volume = {46}, year = {2001}, month = {09/2001}, pages = {1331-1346}, type = {Journal}, keywords = {LTER-MCM}, author = {John E. Dore and John C. Priscu} } @mastersthesis {1419, title = {Regrowth of cyanobacterial mats in Greek Creek and the impact of ecotourism}, volume = {M.S.}, year = {2001}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Ethan Chatfield} } @article {1406, title = {Retrospective simulation of lake level rise in Lake Bonney based on recent 21-year record: indication of recent climate change in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Paleolimnology}, volume = {25}, year = {2001}, pages = {477-492}, keywords = {LTER-MCM, Climate Response}, author = {Bomblies, Arne and Diane M. McKnight and Edmund D. Andrews} } @mastersthesis {1413, title = {Sensitivity of carbon dynamics to changing light availability of benthic microbial mats in Lake Hoare, Antarctica}, volume = {M.S.}, year = {2001}, school = {University of Toledo}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Schmeling, J} } @inbook {1407, title = {Soil Biodiversity}, booktitle = {Global Biodiversity in a Changing Environment}, year = {2001}, pages = {47-82}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {New York}, keywords = {LTER-MCM}, author = {Diana H. Wall and Gina A. Adams and Andrew N. Parsons}, editor = {F. S. Chapin and Osvaldo E. Sala and E. Huber-Sannwald} } @article {1408, title = {Spectrofluorometric characterization of aquatic fulvic acid for determination of precursor organic material and general structural properties.}, journal = {Limnology and Oceanography}, volume = {46}, year = {2001}, pages = {38-48}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Elizabeth W. Boyer and Paul K. Westerhoff and Peter T. Doran and Thomas Kulbe and Dale T. Andersen} } @mastersthesis {1420, title = {Synthetic aperture radar imagery of polar glaciers}, volume = {M.S.}, year = {2001}, school = {Portland State University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Bardel, P} } @mastersthesis {1424, title = {Active layer dynamics and hyporheic zone storage in three streams in the McMurdo Dy Valleys, Antarctica}, volume = {M.S.}, year = {2000}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Peter A. Conovitz} } @article {1425, title = {Biodiversity above and below the surface of soils and sediments: linkages and implications for global change}, journal = {Bioscience}, volume = {50}, year = {2000}, pages = {1043-1048}, keywords = {LTER-MCM}, doi = {10.1641/0006-3568(2000)050[1043:BAABTS]2.0.CO;2}, author = {Gina A. Adams and Diana H. Wall} } @inbook {1426, title = {Climate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long Term Ecological Research Sites}, year = {2000}, pages = {174-195}, publisher = {Oxford University Press}, organization = {Oxford University Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Andrew G Fountain and Thomas H. Nylen and Peter T. Doran and Clive Howard-Williams}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} } @article {1427, title = {Distribution and phylogeny of bacterial communities associated with mineral particles in Antarctic lake ice.}, journal = {Microbial Biology}, volume = {39}, year = {2000}, pages = {197-202}, keywords = {LTER-MCM}, author = {Douglas A. Gordon and John C. Priscu and Stephen J. Giovannoni} } @article {1428, title = {Distribution of organic carbon and nitrogen in surface soils in the McMurdo Dry Valleys, Antarctica.}, journal = {Polar Biology}, volume = {23}, year = {2000}, pages = {121-128}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and Grue, A and John C. Priscu} } @mastersthesis {1440, title = {Dynamics of the deep chlorophyll maximum within the lakes of the McMurdo Dry Valleys, Antarctica}, volume = {M.S.}, year = {2000}, school = {University of Toledo}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Burnett, L} } @inbook {1429, title = {Experimental Approaches to Investigate Belowground Animal Diversity}, booktitle = {Methods in Ecosystem Science}, year = {2000}, pages = {318-329}, publisher = {Springer Verlag}, organization = {Springer Verlag}, address = {New York}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Reichman, O}, editor = {Osvaldo E. Sala and Jackson, R and Mooney, H and R. Howarth} } @article {1430, title = {Fossil fuel burning in Taylor Valley, southern Victoria Land, Antarctica: estimating the role of scientific activities on carbon and nitrogen reservoirs and fluxes}, journal = {Environmental Science and Technology}, volume = {34}, year = {2000}, pages = {1659-1662}, keywords = {LTER-MCM}, author = {W. Berry Lyons and C. A. Nezat and Kathleen A. Welch and Kottmeier, S and Peter T. Doran} } @article {1441, title = {Global biodiversity scenarios for the year 2100}, journal = {Science}, volume = {287}, year = {2000}, pages = {1770-1774}, keywords = {LTER-MCM}, doi = {LTER}, author = {Osvaldo E. Sala and Kinzig, A and Leemans, R and Lodge, D and Mooney, H and Oesterheld, M and Poff, N and Sykes, M and Walker, B and Walkder, M and Diana H. Wall and F. S. Chapin and Armesto, J and Berlow, E and Bloomfield, J and Dirzo, R and Huber-Sanwald, E and Huenneke, L and Jackson, R} } @article {1431, title = {Global change effects on above and below ground biodiversity in terrestrial ecosystems: interactions and implications for ecosystem functioning}, journal = {Bioscience}, volume = {50}, year = {2000}, pages = {1089-1099}, keywords = {LTER-MCM}, doi = {LTER}, author = {Wolters, V and Wardle, D and Brussaard, L and J. Mark Dangerfield and Brown, V and Giller, K and Hooper, D and Osvaldo E. Sala and Tiedje, J and van Veen, J and Silver, W and Bignell, D and David C. Coleman and Lavelle, P and van der Putten, W and DeRuiter, P and Josef Rusek and Diana H. Wall} } @article {1432, title = {The importance of landscape position and legacy: The evolution of the Taylor Valley Lake District, Antarctica.}, journal = {Freshwater Biology}, volume = {43}, year = {2000}, pages = {355-367}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Andrew G Fountain and Peter T. Doran and John C. Priscu and Klaus Neumann and Kathleen A. Welch} } @article {1433, title = {Interactions between above and belowground biodiversity in terrestrial ecosystems: patterns, mechanisms and feedbacks}, journal = {BioScience}, volume = {50}, year = {2000}, pages = {1049-1061}, keywords = {LTER-MCM}, author = {Hooper, D and Lavelle, P and van der Putten, W and DeRuiter, P and Josef Rusek and Silver, W and Tiedje, J and Wolters, V and Bignell, D and Brown, V and Brussaard, L and J. Mark Dangerfield and Diana H. Wall and Wardle, D and David C. Coleman and Giller, K} } @inbook {1434, title = {The Lions of the Dry Valleys}, booktitle = {Antarctica}, year = {2000}, pages = {313}, publisher = {Lonely Planet Publications}, organization = {Lonely Planet Publications}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall and Andrew N. Parsons} } @inbook {1435, title = {Mixotrophy as a survival strategy among planktonic protozoa in Antarctic lakes}, booktitle = {Antarctic Ecosystems: Models for Wider Ecological Understanding}, year = {2000}, publisher = {Caxton Press}, organization = {Caxton Press}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry and Emily C. Roberts and Elanor R. Bell}, editor = {Clive Howard-Williams and W. Davidson and P. Broady} } @inbook {1436, title = {Nematodes - Pervading The Earth and Linking All Life}, booktitle = {Nature and Human Society: The Quest for a Sustainable World}, year = {2000}, pages = {176-191}, publisher = {Committee for the Second Forum on Biodiversity, National Academy of Sciences and National Research Council}, organization = {Committee for the Second Forum on Biodiversity, National Academy of Sciences and National Research Council}, keywords = {LTER-MCM}, author = {Baldwin, J.G. and Nadler, S and Diana H. Wall}, editor = {Tania Williams and Peter H. Raven} } @article {1442, title = {Nuclear and mitochondrial DNA sequence diversity in the Antarctic nematode Scottnema lindsayae}, journal = {Journal of Nematology}, volume = {322}, year = {2000}, pages = {143-153}, keywords = {LTER-MCM}, author = {Courtright, E and Diana H. Wall and Ross A. Virginia and Vida, J and Frisse, L and Thomas, W} } @article {1437, title = {The Origin of Soil Organic Matter in Taylor Valley, Antarctica: A Legacy of Climate Change}, journal = {Ecology}, volume = {81}, year = {2000}, pages = {2377-2391}, keywords = {LTER-MCM, legacy}, author = {Melody B. Burkins and Ross A. Virginia and C. Page Chamberlain and Diana H. Wall} } @article {1422, title = {Phytoplankton dynamics in a stably stratified Antarctic lake during winter darkness}, journal = {Journal of Phycology}, volume = {36}, year = {2000}, month = {10/2000}, pages = {852-861}, type = {Journal}, keywords = {LTER-MCM, Biggie, winter}, doi = {10.1046/j.1529-8817.2000.00031.x}, author = {Diane M. McKnight and B. L. Howes and C. D. Taylor and D. D. Goehringer} } @article {1443, title = {Protozoan growth rates in Antarctic lakes}, journal = {Polar Biology}, volume = {23}, year = {2000}, pages = {445-451}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry and Elanor R. Bell and Emily C. Roberts} } @inbook {1438, title = {Soil Biodiversity and Ecosystem Functioning}, booktitle = {Biological Resource Management. Connecting Science and Policy}, year = {2000}, pages = {283-290}, publisher = {Springer}, organization = {Springer}, address = {Heidelberg}, keywords = {LTER-MCM}, author = {Diana H. Wall and J.M. Lynch}, editor = {E. Balazs and E. Galante and J.M. Lynch and J.S. Schepers} } @inbook {1444, title = {Soil Conservation}, booktitle = {Encyclopedia of Biodiversity}, volume = {5}, year = {2000}, pages = {315-326}, publisher = {Academic Press}, organization = {Academic Press}, keywords = {LTER-MCM}, author = {Porazinska, D and Diana H. Wall}, editor = {S. Levin} } @article {1421, title = {Stratification and dynamics of microbial loop communities in Lake Fryxell, Antarctica}, journal = {Freshwater Biology}, volume = {44}, year = {2000}, month = {12/2001}, pages = {649-661}, type = {Journal}, keywords = {LTER-MCM, Biggie, protozoa}, doi = {10.1046/j.1365-2427.2000.00612.x}, url = {http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2427.2000.00612.x/abstract}, author = {Emily C. Roberts and Johanna Laybourn-Parry and Diane M. McKnight and Novarino, G} } @article {1423, title = {The use of anhydrobiosis by soil nematodes in the Antarctic Dry Valleys}, journal = {Functional Ecology}, volume = {14}, year = {2000}, month = {08/2000}, pages = {460-467}, type = {Journal}, keywords = {LTER-MCM, Biggie, survival strategies}, doi = {10.1046/j.1365-2435.2000.00442.x}, url = {http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2435.2000.00442.x/full}, author = {Amy M Treonis and Diana H. Wall and Ross A. Virginia} } @article {1445, title = {UV radiation and potential biological effects beneath the perennial ice cover of an antarctic lake}, journal = {Hydrobiologia}, volume = {427}, year = {2000}, pages = {155-165}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr. and Collier, R and Cockell, C and Jeffrey, W} } @inbook {1449, title = {Arctic and Antarctic lakes: contrast or continuum?}, booktitle = {Poles Apart: A Study in Contrasts}, year = {1999}, pages = {59-68}, publisher = {University of Ottawa Press}, organization = {University of Ottawa Press}, keywords = {LTER-MCM, Biggie}, author = {Peter T. Doran and Peter Adams and Ecclestone, M} } @article {1475, title = {Biodiversity and Ecosystem Functioning}, journal = {Bioscience}, year = {1999}, pages = {107-108}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall} } @phdthesis {1476, title = {Carbon dynamics in lakes and streams of Taylor Valley, Antarctica}, volume = {Ph.D.}, year = {1999}, school = {University of Alabama, Tuscaloosa}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {Klaus Neumann} } @article {1450, title = {Carbon transformations in a perennially ice-covered Antarctic lake}, year = {1999}, keywords = {LTER-MCM}, author = {John C. Priscu and Craig F. Wolf and Cristina D. Takacs-Vesbach and Christian H. Fritsen and Johanna Laybourn-Parry and Emily C. Roberts and Birgit Sattl} } @article {1451, title = {Chlorine-36 in the waters of the McMurdo Dry Valley lakes, southern Victoria Land, Antarctica: revisited}, journal = {Geochimica et Cosmochimica Acta}, volume = {62}, year = {1999}, pages = {185-191}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Pankaj Sharma} } @article {1452, title = {Ciliated protozoa of two antarctic lakes: analysis by quantitative protargol staining and examination of artificial substrates}, journal = {Polar Biology}, volume = {21}, year = {1999}, pages = {285-294}, keywords = {LTER-MCM}, author = {Kepner, R.L. and D.W. Coats and Robert A. Wharton Jr.} } @article {1453, title = {Controls on soil biodiversity: insight s from extreme environments}, journal = {Applied Soil Ecology}, volume = {13}, year = {1999}, pages = {137-150}, keywords = {LTER-MCM}, author = {Diana H. Wall and Ross A. Virginia} } @article {1448, title = {Dating quaternary lacustrine sediments in the McMurdo Dry Valleys Antarctica}, journal = {Palaeography, Palaeoclimatology, Palaeoecology}, volume = {147}, year = {1999}, month = {03/1999}, pages = {223-239}, type = {Journal}, keywords = {LTER-MCM, sediments}, doi = {10.1016/S0031-0182(98)00159-X}, author = {Peter T. Doran and G. W. Berger and W. Berry Lyons and Robert A. Wharton Jr. and M. L. Davisson and J. Southon and J. E. Dibb} } @mastersthesis {1454, title = {Diatoms of the McMurdo Dry Valleys, Antarctica: A taxonomic appraisal including a detailed study of the genus Hantzschia.}, volume = {M.S.}, year = {1999}, school = {University of Michigan}, type = {masters}, address = {Ann Arbor, Michigan}, keywords = {LTER-MCM}, author = {Alexander S. Alger} } @article {1455, title = {The distribution and relative abundance of ammonium-oxidizing bacteria in lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Hydrobiologia}, volume = {401}, year = {1999}, pages = {113-130}, keywords = {LTER-MCM}, doi = {LTER}, author = {Mary A. Voytek and John C. Priscu and Bess B. Ward} } @article {1456, title = {Dry Valley streams in Antarctica: ecosystems waiting for water}, journal = {Bioscience}, volume = {49}, year = {1999}, pages = {985-995}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Dev K. Niyogi and Alexander S. Alger and Bomblies, Arne and Peter A. Conovitz and Cathy M. Tate} } @article {1477, title = {Ecological legacies: production, persistence and influence on soil and lake ecosystems of the Antarctic dry valleys}, journal = {Bioscience}, volume = {49}, year = {1999}, pages = {1009-1019}, keywords = {LTER-MCM} } @article {1457, title = {Effects of research diving on a stratified antarctic lake}, journal = {Water Research}, year = {1999}, keywords = {LTER-MCM}, author = {Kepner, R.L. and A. Kortyna and Robert A. Wharton Jr. and Peter T. Doran and Dale T. Andersen and Emily C. Roberts} } @phdthesis {1478, title = {Environmental controls of the diversity, activity, and function of soil nematodes in the McMurdo Dry Valleys of Antarctic}, volume = {Ph.D.}, year = {1999}, school = {Colorado State University}, type = {doctoral}, keywords = {LTER-MCM}, author = {Amy M Treonis} } @phdthesis {1458, title = {Factors Affecting the Distribution and Dynamics of Bacterioplankton Biomass and Diversity in Taylor Valley Lakes, Antarctica}, volume = {Ph.D.}, year = {1999}, school = {Montana State University}, type = {doctoral}, keywords = {LTER-MCM}, author = {Cristina D. Takacs-Vesbach} } @article {1459, title = {Geomicrobiology of sub-glacial ice above Vostok Station}, journal = {Science}, volume = {286}, year = {1999}, pages = {2141-2144}, keywords = {LTER-MCM}, doi = {10.1126/science.286.5447.2141}, author = {John C. Priscu and Edward E. Adams and W. Berry Lyons and Mary A. Voytek and David W. Mogk and Robert L. Brown and Christopher P. McKay and Cristina D. Takacs-Vesbach and Kathleen A. Welch and Craig F. Wolf and Julie D. Kirshtein and Recep Avci} } @article {1460, title = {History of McMurdo Dry Valley Lakes, Antarctica, from stable chlorine isotope data}, journal = {Geology}, volume = {27}, year = {1999}, keywords = {LTER-MCM}, doi = {LTER}, author = {W. Berry Lyons and Frape, S and Kathleen A. Welch} } @article {1479, title = {How soils structure communities in the McMurdo Dry Valleys, Antarctica}, journal = {Bioscience}, volume = {48}, year = {1999}, pages = {973-983}, keywords = {LTER-MCM} } @article {1461, title = {The importance of terminus cliff melt on stream flow, Taylor Valley, McMurdo Dry Valleys}, journal = {Global and Planetary Change}, volume = {22}, year = {1999}, pages = {105-115}, keywords = {LTER-MCM}, doi = {LTER}, author = {Karen J. Lewis and Andrew G Fountain and Paul Langevin} } @article {1462, title = {Interactions underground: soil biodiversity, mutalism and ecosystem processes}, journal = {Bioscience}, volume = {49}, year = {1999}, pages = {109-119}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall and John C. Moore} } @article {1463, title = {Invertebrate biodiversity in Antarctic Dry Valley soils and sediments}, journal = {Ecosystems}, volume = {2}, year = {1999}, pages = {482-492}, keywords = {LTER-MCM}, author = {Amy M Treonis and Diana H. Wall and Ross A. Virginia} } @article {1464, title = {Lake ice microbial communities in alpine and Antarctic lakes}, year = {1999}, keywords = {LTER-MCM}, author = {Psenner, R and Sattler, B and Willie, A and Christian H. Fritsen and John C. Priscu and Felip, M and J. Catalan} } @article {1446, title = {Life in the valley of the dead}, journal = {Bioscience}, volume = {49}, year = {1999}, month = {12/1999}, pages = {959-960}, keywords = {LTER-MCM}, doi = {LTER}, author = {John C. Priscu} } @proceedings {1465, title = {McMurdo Dry Valley Lakes: Impacts of Research Activities.}, year = {1999}, publisher = {Desert Research Institute, University and Community College System of Nevada, USA, special publication}, keywords = {LTER-MCM}, doi = {LTER}, author = {Robert A. Wharton Jr. and Peter T. Doran} } @article {1466, title = {McMurdo LTER: Photosynthesis in an extreme shade habitat: benthic microbial mats from Lake Hoare, Antarctica}, journal = {Journal of Phycology}, volume = {35}, year = {1999}, pages = {448-459}, keywords = {LTER-MCM}, author = {Ian Hawes and Anne-Maree Schwarz} } @article {1467, title = {Mercury in aquatic systems in Antarctica}, journal = {Geophysical Research Letters}, volume = {26}, year = {1999}, pages = {2235-2238}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Jean-Claude Bonzongo} } @article {1468, title = {Mixotrophic cryptophytes and their predators in the Dry Valley lakes of Antarctica}, journal = {Freshwater Biology}, volume = {41}, year = {1999}, pages = {737-745}, keywords = {LTER-MCM}, doi = {10.1046/j.1365-2427.1999.00401.x}, author = {Emily C. Roberts and Johanna Laybourn-Parry} } @article {1447, title = {Physical controls on the Taylor Valley Ecosystem, Antarctica}, journal = {BioScience}, volume = {49}, year = {1999}, month = {12/1999}, pages = {961-972}, type = {Journal}, keywords = {LTER-MCM, Water availability}, author = {Andrew G Fountain and W. Berry Lyons and Melody B. Burkins and Gayle L. Dana and Peter T. Doran and Karen J. Lewis and Diane M. McKnight and Daryl L. Moorhead and Andrew N. Parsons and John C. Priscu and Diana H. Wall and Robert A. Wharton Jr. and Ross A. Virginia} } @article {1470, title = {Seasonal change in the optical properties of the permanent ice cover on Lake Bonney, Antarctica: Consequences for lake productivity and phytoplankton dynamics}, journal = {Limnology and Oceanography}, volume = {44}, year = {1999}, pages = {447-454}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and John C. Priscu} } @inbook {1471, title = {Soil Biodiversity: life in soil}, booktitle = {The Living Planet in Crisis}, year = {1999}, pages = {124-128}, publisher = {Columbia University Press}, organization = {Columbia University Press}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana H. Wall}, editor = {J. Cracraft and F. Griffo} } @inbook {1472, title = {Soil invertebrates}, booktitle = {Standard Soil Methods for Long Term Ecological Research}, year = {1999}, pages = {349-377}, publisher = {Oxford University Press}, organization = {Oxford University Press}, address = {New York}, keywords = {LTER-MCM}, doi = {LTER}, author = {David C. Coleman and J.M. Blair and Elliot, E and Diana H. Wall} } @article {1480, title = {Spatial and climatic variations and its control on glacier equilibrium line altitude in Taylor Valley, Antarctica}, journal = {Global and Planetary Change}, volume = {22}, year = {1999}, pages = {1-10}, keywords = {LTER-MCM} } @inbook {1474, title = {The world beneath our feet: Soil biodiversity and ecosystem functioning}, booktitle = {Nature and Human Society: The Quest for a Sustainable World}, year = {1999}, publisher = {National Academy of Sciences Press}, organization = {National Academy of Sciences Press}, keywords = {LTER-MCM}, author = {Diana H. Wall and Ross A. Virginia} } @article {1485, title = {The 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, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {217-228}, keywords = {LTER-MCM}, author = {Mary A. Voytek and Bess B. Ward and John C. Priscu} } @article {1481, title = {Analysis of transient storage subject to unsteady flow: diel flow variation in an Antarctic stream}, journal = {Journal of the North American Benthological Society}, volume = {17}, year = {1998}, month = {06/1998}, pages = {143-154}, keywords = {LTER-MCM}, url = {http://www.jstor.org/stable/1467958}, author = {Robert L. Runkel and Diane M. McKnight and Edmund D. Andrews} } @article {1486, title = {Antarctic lake-ice microbial consortia: Origin, distribution, and growth physiology}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {223-224}, keywords = {LTER-MCM}, author = {John C. Priscu and Christian H. Fritsen} } @article {1483, title = {Antarctic paleolake sediments and the search for extinct life on Mars}, journal = {Journal of Geophysical Research-Planets}, volume = {103}, year = {1998}, month = {05/1998}, pages = {28481-28493}, keywords = {LTER-MCM}, doi = {10.1029/98JE01713}, author = {Peter T. Doran and Robert A. Wharton Jr. and David J. DesMarais and Christopher P. McKay} } @article {1487, title = {Bacterioplankton dynamics in the McMurdo Dry Valley lakes, Antarctica: Production and biomass loss over four seasons}, journal = {Microbial Ecology}, volume = {36}, year = {1998}, pages = {239-250}, keywords = {LTER-MCM}, author = {Cristina D. Takacs-Vesbach and John C. Priscu} } @phdthesis {1536, title = {Chemical Weathering in Taylor Valley, Antarctica: Quantity and Quality}, volume = {Ph.D.}, year = {1998}, school = {University of Alabama, Tuscaloosa}, type = {doctoral}, keywords = {LTER-MCM}, doi = {LTER}, author = {C. A. Nezat} } @mastersthesis {1537, title = {Climatic controls on streamflow generation from Antarctic glaciers}, volume = {M.S.}, year = {1998}, school = {University of Colorado Boulder}, type = {masters}, address = {Boulder, CO}, keywords = {LTER-MCM}, author = {Bomblies, Arne and Diane M. McKnight} } @inbook {1488, title = {Cobalt Cycling and Fate in Lake Vanda}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {205-215}, keywords = {LTER-MCM}, author = {William J. Green and Donald E. Canfield and Philip Nixon} } @article {1489, title = {The Composite Glacial Erosional Landscape of the Northern McMurdo Dry Valleys: Implications for Antarctic Tertiary Glacial History, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {Jan-38}, keywords = {LTER-MCM}, author = {Michael L. Prentice and Johan Kleman and Arjen P. Stroeven} } @article {1490, title = {Cyanobacterial assemblages in permanent ice covers on Antarctic lakes: distribution, growth rate, and temperature response of photosynthesis}, journal = {Journal of Phycology}, volume = {34}, year = {1998}, pages = {587-597}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and John C. Priscu} } @article {1491, title = {Cyanobacterial communities associated with mineral particles in antarctic lake ice}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {224-225}, keywords = {LTER-MCM}, author = {Douglas A. Gordon and Brian D. Lanoil and Stephen J. Giovannoni and John C. Priscu} } @article {1493, title = {Dissolved gases in perennially ice-covered lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, volume = {10}, year = {1998}, pages = {124-133}, keywords = {LTER-MCM}, author = {Dale T. Andersen and Christopher P. McKay and Robert A. Wharton Jr.} } @article {1494, title = {Distribution, Community Structure, and Microhabitats of Soil Invertebrates along an Elevational Gradient in Taylor Valley}, journal = {Alpine and Alpine Research}, volume = {30}, year = {1998}, pages = {133-141}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Mengchi Ho and Diana W. Freckman and Ross A. Virginia} } @inbook {1538, title = {Ecosystem dynamics in a polar desert: the McMurdo Dry Valleys, Antarctica (American Geophysical Union Antarctic Research Series. Volume 72)}, booktitle = {Ecosystem dynamics in a polar desert: the McMurdo Dry Valleys, Antarctica (American Geophysical Union Antarctic Research Series. Volume 72)}, year = {1998}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1495, title = {Energy balance studies of Canada Glacier, Taylor Valley, McMurdo Dry Valleys, Antarctica}, journal = {Annals of Glaciology}, volume = {27}, year = {1998}, pages = {603-609}, keywords = {LTER-MCM}, doi = {LTER}, author = {Karen J. Lewis and Andrew G Fountain and Gayle L. Dana} } @article {1496, title = {Evidence of deep circulation in two perennially ice-covered Antarctic lakes}, journal = {Limnol. Oceanogr.}, volume = {43}, year = {1998}, pages = {625-635}, keywords = {LTER-MCM}, author = {Scott W. Tyler and Peter G. Cook and Anya Z. Butt and James M. Thomas and Peter T. Doran and W. Berry Lyons} } @article {1497, title = {Fluorescence Quenching in Phytoplankton of the McMurdo Dry Valley Lakes (Antarctica): Implications for the Structure and Function of the Photosynthetic Apparatus, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {241-253}, keywords = {LTER-MCM}, author = {Patrick J. Neale and John C. Priscu} } @inbook {1498, title = {From the ground up: nematode ecology in bioassessment and ecosystem health}, booktitle = {Plant-Nematode Interactions(Agronomy Monograph)}, year = {1998}, keywords = {LTER-MCM}, author = {R. K. Niles and Diana W. Freckman} } @inbook {1499, title = {Geochemical Linkages Among Glaciers, Streams, and Lakes Within the Taylor Valley, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, volume = {72}, year = {1998}, pages = {77-92}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Klaus Neumann and Jeffrey K. Toxey and Robyn McArthur and Changela Williams and Diane M. McKnight and Daryl L. Moorhead} } @inbook {1500, title = {Glaciers of the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {65-75}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Gayle L. Dana and Karen J. Lewis and Bruce H. Vaughn and Diane M. McKnight} } @inbook {1501, title = {Hydrologic Processes Influencing Streamflow Variation in Fryxell Basin, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {93-108}, keywords = {LTER-MCM}, author = {Peter A. Conovitz and Diane M. McKnight and Lee H. MacDonald and Andrew G Fountain}, editor = {Harold R. House} } @article {1502, title = {Inorganic carbon-isotope distribution and budget in the Lake Hoare and Lake Fryxell basins, Taylor Valley, Antarctica}, journal = {Annals of Glaciology}, volume = {27}, year = {1998}, pages = {685-690}, keywords = {LTER-MCM}, author = {Klaus Neumann and W. Berry Lyons and D.J. Des Marais} } @article {1503, title = {A late holocene dessication of Lake Hoare and Lake Fryxell, McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Science}, volume = {10}, year = {1998}, pages = {247-256}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Scott W. Tyler and Robert A. Wharton Jr. and Diane M. McKnight and Bruce H. Vaughn} } @article {1539, title = {A lesson from the bottom of the earth}, journal = {Bioscience}, volume = {48}, year = {1998}, pages = {843-847}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1504, title = {Longitudinal Patterns in Algal Abundance and Species Distribution in Meltwater Streams in Taylor Valley, Southern Victoria Land, Antarctica, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {109-127}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Alexander S. Alger and Cathy M. Tate and Gordon H Shupe and Sarah A. Spaulding} } @article {1505, title = {The McMurdo Dry Valley Ecosystem: Organization, Controls, and Linkages, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {351-363}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and John C. Priscu} } @article {1506, title = {McMurdo Dry Valleys Long-Term Ecological Research (LTER): An overview of 1995-1996 research activities}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {187-188}, keywords = {LTER-MCM}, author = {Sherry E. Jennings-Mays and Robert A. Wharton Jr.} } @article {1509, title = {McMurdo Dry Valleys LTER: Characterization of protozoan communities in lakes Hoare and Fryxell using artificial substrates}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {201-202}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr.} } @article {1507, title = {McMurdo Dry Valleys LTER: Density-driven mixing in Lake Hoare?}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {205}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and Scott W. Tyler and Pankaj Sharma} } @article {1510, title = {McMurdo Dry Valleys LTER: Genetic diversity of soil nematodes in the McMurdo Dry Valleys of Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {203-204}, keywords = {LTER-MCM}, author = {Courtright, Ericha M and Diana W. Freckman and Ross A. Virginia and W. Kelley Thomas} } @article {1484, title = {McMurdo Dry Valleys LTER: Geophysical determination of bathymetry and morphology of Taylor Valley lakes}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, month = {01/1996}, pages = {198-200}, keywords = {LTER-MCM}, author = {Peter T. Doran and Robert A. Wharton Jr. and Jeffrey P. Schmok} } @article {1511, title = {McMurdo Dry Valleys LTER: Phosphorus deficiency and alkaline phosphatase activity in lakes of Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {206-208}, keywords = {LTER-MCM}, author = {John E. Dore and John C. Priscu} } @article {1512, title = {McMurdo Dry Valleys LTER: Solar radiation on glaciers in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {191-193}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Robert A. Wharton Jr. and Andrew G Fountain} } @article {1513, title = {McMurdo Dry Valleys LTER: Spatial variation of glacier mass balance in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {194-195}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Karen J. Lewis and Gayle L. Dana} } @article {1508, title = {McMurdo Dry Valleys LTER: Stream discharge as a function of ambient temperature and incoming shortwave radiation in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {196-197}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Diane M. McKnight} } @article {1514, title = {McMurdo Dry Valleys LTER: The role of terminus cliff melt in streamflow, Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {189-190}, keywords = {LTER-MCM}, author = {Karen J. Lewis and Andrew G Fountain and Paul Langevin} } @article {1515, title = {Mercury speciation and distribution in a polar desert lake (Lake Hoare, Antarctica) and two glacial meltwater streams}, journal = {Science of the Total Environment}, volume = {213}, year = {1998}, pages = {229-237}, keywords = {LTER-MCM}, author = {Vandal, G.M. and R.P. Mason and Diane M. McKnight and W. Fitzgerald} } @article {1516, title = {Microbial phototrophic, heterotrophic, and diazotrophic activities associated with aggregates in the permanent ice cover of Lake Bonney, Antarctica}, journal = {Microbial Ecology}, volume = {36}, year = {1998}, pages = {221-230}, keywords = {LTER-MCM}, author = {Hans W. Paerl and John C. Priscu} } @article {1517, title = {Modeling Nitrogen Transformations in Dry Valley Streams, Antarctica, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {141-151}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Diane M. McKnight and Cathy M. Tate} } @article {1518, title = {Natural abundance of carbon and nitrogen isotopes in potential sources of organic matter to soils of Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {209-210}, keywords = {LTER-MCM}, author = {Melody B. Burkins and C. Page Chamberlain and Ross A. Virginia and Diana W. Freckman} } @article {1519, title = {Nitrogen fixation within permanent ice covers on lakes in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {218-220}, keywords = {LTER-MCM}, author = {Amanda M. Grue and Christian H. Fritsen and John C. Priscu} } @inbook {1520, title = {Optical Properties of the McMurdo Dry Valley Lakes, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {189-203}, keywords = {LTER-MCM}, author = {Clive Howard-Williams and Anne-Maree Schwarz and Ian Hawes and John C. Priscu} } @article {1482, title = {Perennial Antarctic Lake Ice: An Oasis for Life in a Polar Desert}, journal = {Science}, volume = {280}, year = {1998}, month = {06/1998}, pages = {2095-2098}, type = {Journal}, keywords = {LTER-MCM, Biggie}, doi = {10.1126/science.280.5372.2095}, url = {http://www.sciencemag.org/content/280/5372/2095.short}, author = {John C. Priscu and Christian H. Fritsen and Edward E. Adams and Stephen J. Giovannoni and Hans W. Paerl and Christopher P. McKay and Peter T. Doran and Douglas A. Gordon and Brian D. Lanoil and James L. Pinckney} } @inbook {1521, title = {Permanent Ice Covers of the McMurdo Dry Valley Lakes, Antarctica: Bubble Formation and Metamorphism}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {281-295}, keywords = {LTER-MCM}, author = {Edward E. Adams and John C. Priscu and Christian H. Fritsen and Scott R.Smith and Steven L. Brackman} } @inbook {1522, title = {Permanent Ice Covers of the McMurdo Dry Valleys Lakes, Antarctica: Liquid Water Contents}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {269-280}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and Edward E. Adams and Christopher P. McKay and John C. Priscu} } @article {1523, title = {Photosynthetic characteristics of cyanobacteria in permanent ice covers on lakes in the McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {216-218}, keywords = {LTER-MCM}, author = {Christian H. Fritsen and John C. Priscu} } @article {1524, title = {Physical Limnology of the McMurdo Dry Valleys Lakes, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {153-187}, keywords = {LTER-MCM}, author = {Spigel, Robert H. and John C. Priscu} } @inbook {1525, title = {Pigment Analysis of the Distribution, Succession, and Fate of Phytoplankton in the McMurdo Dry Valley Lakes of Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {229-239}, keywords = {LTER-MCM}, author = {Michael P. Lizotte and John C. Priscu} } @inbook {1526, title = {Primary Production Processes in Streams of the McMurdo Dry Valleys, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {129-140}, keywords = {LTER-MCM}, author = {Ian Hawes and Clive Howard-Williams} } @inbook {1527, title = {Protozooplankton and Microzooplankton Ecology in Lakes of the Dry Valleys, Southern Victoria Land}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {255-267}, keywords = {LTER-MCM}, author = {Mark R. James and Julie A. Hall and Johanna Laybourn-Parry} } @article {1528, title = {The role of phytoplankton extracellular release in bacterioplankton growth of Taylor Valley Lakes, Antarctica}, journal = {Antarctic Journal of the United States - 1996 Review Issue (NSF 98-28)}, volume = {31}, year = {1998}, pages = {211-212}, keywords = {LTER-MCM}, author = {Cristina D. Takacs-Vesbach and John C. Priscu} } @inbook {1540, title = {Science and Environmental Management in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {337-350}, keywords = {LTER-MCM}, author = {Harris, Colin M.} } @article {1529, title = {Soil Biodiversity and Community Structure in the McMurdo Dry Valleys, Antarctica, in Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, journal = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {323-335}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @inbook {1530, title = {The Soil Environment of the McMurdo Dry Valleys, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {297-322}, keywords = {LTER-MCM}, author = {Iain B. Campbell and Graeme G.C. Claridge and David I. Campbell and Megan R. Balks} } @inbook {1531, title = {Solar Radiation in the McMurdo Dry Valleys, Antarctica}, booktitle = {Ecosystem Processes in a Polar Desert: The McMurdo Dry Valleys, Antarctica}, series = {Antarctic Research Series}, volume = {72}, year = {1998}, pages = {39-64}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Robert A. Wharton Jr. and R. Dubayah} } @mastersthesis {1541, title = {Spatial-temporal patterns of primary production in phytoplankton communities of Taylor Valley lakes, Antartica: A modelling synthesis}, volume = {M.S.}, year = {1998}, school = {Texas Tech University}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Davis, W} } @article {1532, title = {Structure and composition of the photochemical apparatus of the Antarctic green alga Chlamydomonas subcaudata}, journal = {Photosynthesis Research - Regular Paper}, volume = {56}, year = {1998}, pages = {303-314}, keywords = {LTER-MCM}, author = {Morgan, Rachael M. and Alexander G. Ivanov and John C. Priscu and Denis P. Maxwell and Norman P.A. Huner} } @article {1533, title = {Surface energy balance and meltwater production for a Dry Valley glacier, Taylor Valley, Antarctica}, journal = {Annals of Glaciology}, volume = {27}, year = {1998}, pages = {603-609}, keywords = {LTER-MCM}, author = {Karen J. Lewis and Andrew G Fountain and Gayle L. Dana} } @inbook {1439, title = {A Temperature area index of stream discharge in Taylor Valley, Antarctica}, booktitle = {Applications of Remote Sensing in Hydrology}, year = {1998}, pages = {29-39}, publisher = {National Water Research Institute , Environment Canada}, organization = {National Water Research Institute , Environment Canada}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Davis, R and Andrew G Fountain and Robert A. Wharton Jr.}, editor = {A. Pietroniro and R. Granger and T.J. Pultz} } @article {1534, title = {Transparency of Antarctic ice-covered lakes to solar UV radiation}, journal = {Limnol. Oceanogr.}, volume = {43}, year = {1998}, pages = {618-624}, keywords = {LTER-MCM}, author = {Warwick F. Vincent and Rowena Rae and Isabelle Laurion and Clive Howard-Williams and John C. Priscu} } @article {1535, title = {Viruses in antarctic lakes}, journal = {Limnol. Oceanogr.}, volume = {43}, year = {1998}, pages = {1754-1761}, keywords = {LTER-MCM, Biggie}, author = {Kepner, R.L. and Robert A. Wharton Jr. and C. Suttle} } @inbook {1544, title = {The abundance of planktonic virus-like particles in Antarctic lakes}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {241-250}, publisher = {Balkema Press}, organization = {Balkema Press}, address = {Rotterdam}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr. and Galchenko, V} } @article {1545, title = {Biodiversity and Ecosystem Functioning in Soil}, journal = {Ambio}, volume = {26}, year = {1997}, pages = {563-570}, keywords = {LTER-MCM}, author = {Brussaard, L and Valerie Behan-Pelletier and David E. Bignell and V.K. Brown}, editor = {W. Didden and P. Folgarait and C. Fragoso and Diana W. Freckman} } @article {1566, title = {The Biogeochemistry of Nitrous Oxide in Permanently Ice-Covered Lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Global Change Biology}, volume = {3}, year = {1997}, pages = {301-315}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1546, title = {Canada Stream: a glacial meltwater stream in Taylor Valley, South Victoria Land, Antarctica}, journal = {Journal of the North American Benthological Society}, volume = {16}, year = {1997}, pages = {14-17}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Cathy M. Tate} } @article {1547, title = {Carbon cycling in soils of the McMurdo Dry Valley region, Antarctica}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {78}, year = {1997}, pages = {230}, keywords = {LTER-MCM}, author = {Melody B. Burkins and Ross A. Virginia and Diana W. Freckman and C. Page Chamberlain} } @inbook {1548, title = {Carbon dynamics of aquatic microbial mats in the Antarctic dry valleys: A modelling synthesis}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {181-196}, publisher = {Balkema Press, Rotterdam}, organization = {Balkema Press, Rotterdam}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and W. Shane Davis and Robert A. Wharton Jr.} } @inbook {1549, title = {Chemical weathering rates and reactions in the Lake Fryxell Basin, Taylor Valley : Comparison to temperate river basins}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {147-154}, publisher = {Balkema Press, Rotterdam}, organization = {Balkema Press, Rotterdam}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch and C. A. Nezat and K. Crick and Jeffrey K. Toxey and J.A. Mastrine and Diane M. McKnight} } @inbook {1550, title = {Climate history of the McMurdo Dry Valleys since the last glacial maximum: A synthesis}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {155-162}, publisher = {Balkema Press, Rotterdam}, organization = {Balkema Press, Rotterdam}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Louis R. Bartek and Paul A. Mayewski and Peter T. Doran} } @article {1551, title = {Detection and Characterization of Denitrifying Bacteria from a Permanently Ice-Covered Antarctic Lake}, journal = {Hydrobiologia}, volume = {347}, year = {1997}, pages = {57-68}, keywords = {LTER-MCM}, author = {Bess B. Ward and John C. Priscu} } @inbook {1552, title = {Determination of rare earth elements in Antarctic lakes and streams of varying ionic strengths}, booktitle = {Plasma Source Mass Spectrometry: Developments and Applications}, year = {1997}, pages = {253-262}, publisher = {Royal Society of Chemistry}, organization = {Royal Society of Chemistry}, address = {London}, keywords = {LTER-MCM}, author = {Graham, E and Ramsey, L. A. and W. Berry Lyons and Kathleen A. Welch} } @article {1553, title = {Diatoms in sediments of perennially ice-covered Lake Hoare, and implications for interpreting lake history in the McMurdo Dry Valleys of Antarctica}, journal = {Journal of Paleolimnology}, volume = {17}, year = {1997}, pages = {403-420}, keywords = {LTER-MCM}, author = {Sarah A. Spaulding and Diane M. McKnight and E.F. Stoermer and Peter T. Doran} } @inbook {1554, title = {Ecological processes in a cold desert ecosystem: the abundance and species distribution of algal mats in glacial meltwater streams in Taylor Valley}, booktitle = {Institute of Arctic and Alpine Research}, series = {Occasional Paper}, volume = {51}, year = {1997}, pages = {108 pp}, publisher = {University of Colorado}, organization = {University of Colorado}, keywords = {LTER-MCM}, url = {http://instaar.colorado.edu/other/download/OP51-ECOLOGICAL-PROCESSES.pdf}, author = {Alexander S. Alger and Diane M. McKnight and Sarah A. Spaulding and Cathy M. Tate}, editor = {Gordon H Shupe and Kathleen A. Welch and R. L. Edwards and Edmund D. Andrews} } @article {1555, title = {Impact of Light Regimes on Productivity Patterns of Benthic Microbial Mats in an Antarctic Lake: A Modeling Study}, journal = {Limnology and Oceanography}, volume = {42}, year = {1997}, pages = {1561-1569}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Craig F. Wolf and Robert A. Wharton Jr.} } @article {1556, title = {Linking biodiversity and ecosystem functioning of soils and sediments}, journal = {Ambio}, volume = {26}, year = {1997}, pages = {556-562}, keywords = {LTER-MCM}, author = {Diana W. Freckman and T.H. Blackburn and Brussaard, L and P. Hutchings and M.A. Palmer and P.V.R. Snelgrove} } @article {1557, title = {Lithium in waters of a polar desert}, journal = {Geochimica et Cosmochimica Acta}, volume = {61}, year = {1997}, pages = {4309-4319}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Kathleen A. Welch} } @article {1558, title = {Low-diversity Antarctic soil nematode communities: distribution and response to disturbance}, journal = {Ecology}, volume = {78}, year = {1997}, pages = {363-369}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1567, title = {The measurement of reactive silicate in saline-hypersaline lakes: examples of the problem}, journal = {International Journal of Salt Lake Research}, year = {1997}, keywords = {LTER-MCM} } @inbook {1559, title = {The microbial loop in Antarctic lakes}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {231-240}, publisher = {Balkema Press}, organization = {Balkema Press}, address = {Rotterdam}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry} } @article {1560, title = {The microbial plankton of Lake Fryxell, southern Victoria Land, Antarctica during the summers of 1992 and 1994}, journal = {Polar Biology}, volume = {17}, year = {1997}, pages = {54-61}, keywords = {LTER-MCM}, author = {Johanna Laybourn-Parry and Mark R. James and Diane M. McKnight and John C. Priscu and Sarah A. Spaulding and Russell Shiel} } @article {1542, title = {Open-top Designs for Manipulating Field Temperature in High-Latitude Ecosystems}, journal = {Global Change Biology}, volume = {3}, year = {1997}, month = {12/1997}, pages = {20-32}, keywords = {LTER-MCM}, doi = {10.1111/j.1365-2486.1997.gcb136.x}, author = {G. M. Marion and G.H.R. Henry and Diana W. Freckman and J. Johnstone and G. Jones and M.H. Jones and E. Levesque and U. Molau and P. M{\O}LGAARD and Andrew N. Parsons and J. Svoboda and Ross A. Virginia} } @inbook {1561, title = {Satellite-derived surface temperatures in the McMurdo Dry Valleys, Antarctica}, booktitle = {IRS {\textquoteright}96 Current Problems in Atmospheric Radiation}, year = {1997}, pages = {530-533}, publisher = {Deepak}, organization = {Deepak}, keywords = {LTER-MCM}, author = {Gayle L. Dana and M.A. Wetzel and Robert A. Wharton Jr.} } @inbook {1563, title = {Sources and sinks of nutrients in a polar desert stream, the Onyx River, Antarctica}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {155-170}, publisher = {Balkema Press}, organization = {Balkema Press}, address = {Rotterdam}, keywords = {LTER-MCM}, author = {Clive Howard-Williams and Ian Hawes and Anne-Maree Schwarz and Julie A. Hall} } @inbook {1564, title = {Species composition and primary production of algal communities in Dry Valley streams in Antarctica: Examination of the functional role of biodiversity}, booktitle = {Ecosystem Processes in Antarctic Ice-free Landscapes}, year = {1997}, pages = {171-179}, publisher = {Balkema Press, Rotterdam}, organization = {Balkema Press, Rotterdam}, keywords = {LTER-MCM}, author = {Dev K. Niyogi and Cathy M. Tate and Diane M. McKnight and John H. Duff and Alexander S. Alger} } @phdthesis {1607, title = {Algal investigations at varying temporal scales in an extreme environment: McMurdo Dry Valley lakes, Antarctica}, volume = {Ph.D.}, year = {1996}, school = {Colorado State University}, type = {doctoral}, keywords = {LTER-MCM}, author = {Spaulding, S.A. and Diana H. Wall} } @article {1568, title = {Bacterial growth in Antarctic lakes: The role of phytoplankton extracellular release}, journal = {Bacterial growth in Antarctic lakes: The role of phytoplankton extracellular}, year = {1996}, keywords = {LTER-MCM}, author = {Cristina D. Takacs-Vesbach and John C. Priscu} } @article {1569, title = {Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography}, journal = {Journal of Chromatography A}, volume = {739}, year = {1996}, pages = {257-263}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Graham, E and Klaus Neumann and James M. Thomas and D. Mikesell} } @article {1570, title = {Effects of human disturbance on soil nematode populations in Taylor Valley, Antarctica}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {77}, year = {1996}, pages = {360}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Ross A. Virginia} } @booklet {3240, title = {Environmental Management of a Cold Desert Ecosystem}, year = {1996}, keywords = {LTER-MCM}, author = {Warwick F. Vincent} } @article {1571, title = {Evolution of Temperature and Salt Structure of Lake Bonney, a Chemically Stratified Antarctic Lake}, journal = {Hydrobiologia}, volume = {321}, year = {1996}, pages = {177-190}, keywords = {LTER-MCM}, author = {Spigel, Robert H. and John C. Priscu} } @article {1572, title = {Extreme Supersaturation of Nitrous Oxide in a Poorly Ventilated Antarctic Lake}, journal = {Limnol. Oceanogr}, volume = {41}, year = {1996}, pages = {1544-1551}, keywords = {LTER-MCM}, author = {John C. Priscu and Malcolm T. Downes and Christopher P. McKay} } @inbook {1573, title = {Food-web dynamics and applied problems}, booktitle = {Food Webs: Integration of patterns and dynamics}, year = {1996}, pages = {327-336}, keywords = {LTER-MCM}, author = {L.B. Crowder and D.P. Reagan and Diana W. Freckman} } @article {1574, title = {Geochemistry of aquatic humic substances in the Lake Fryxell Basin, Antarctica}, journal = {Biogeochemistry}, volume = {34}, year = {1996}, pages = {157-188}, keywords = {LTER-MCM}, author = {George R. Aiken and Diane M. McKnight and Richard A. Harnish and Robert Wershaw} } @article {1575, title = {Lakes Hoare, Fryxell and Bonney: Geophysical Determination of Bathymetry and Morphometry, Report Generated by Golder Associates Ltd, Burnaby, British Columbia}, year = {1996}, keywords = {LTER-MCM}, author = {Jeffrey P. Schmok and Brian S. Waddington} } @article {1576, title = {Microcosms and Soil Ecology: Critical Linkages Between Field Studies and Modelling Food Webs}, journal = {Ecology}, volume = {77}, year = {1996}, pages = {694-705}, keywords = {LTER-MCM}, author = {John C. Moore and Peter C. De Ruiter and H. William Hunt and David C. Coleman and Diana W. Freckman} } @phdthesis {1577, title = {Paleolimnology of Perenially Ice-Covered Antarctic Oasis Lakes}, volume = {Ph.D.}, year = {1996}, school = {University of Nevada Reno}, type = {doctoral}, address = {Reno, NV}, keywords = {LTER-MCM}, author = {Peter T. Doran and Robert A. Wharton Jr.} } @article {1578, title = {Phytoplankton Dynamics in the Stratified Water Column of Lake Bonney, Antarctica. I. Biomass and Productivity During the Winter-Spring Transition}, journal = {Polar Biology}, volume = {16}, year = {1996}, pages = {155-162}, keywords = {LTER-MCM}, author = {Michael P. Lizotte and Thomas R. Sharp and John C. Priscu} } @article {1580, title = {Reflectance spectroscopy and geochemical analyses of Lake Hoare sediments, Antarctica: Implications for remote sensing of the Earth and Mars}, journal = {Geochimica et Cosmochimica Acta}, volume = {60}, year = {1996}, pages = {765-785}, keywords = {LTER-MCM}, author = {Bishop, Janice L. and Koeberl, C and C. Kralik and H. Froschl}, editor = {P.A.J. Englert and Dale T. Andersen and C.M. Pieters and Robert A. Wharton Jr.} } @inbook {1581, title = {Soil invertebrates as indicators of soil quality}, booktitle = {Methods for assessing soil quality}, year = {1996}, publisher = {Soil Science Society of America}, organization = {Soil Science Society of America}, address = {Madison, WI}, keywords = {LTER-MCM}, author = {J.M. Blair and Patrick J. Bohlen and Diana W. Freckman}, editor = {J. W. Doran and A.J. Jones} } @mastersthesis {1610, title = {Soil nematode distribution and genetic diversity in the Dry Valleys of Antarctica}, volume = {M.S.}, year = {1996}, school = {Colorado State University}, type = {masters}, address = {Fort Collins, CO}, keywords = {LTER-MCM}, author = {Courtright, Ericha M and Diana H. Wall} } @article {1582, title = {Soil spatial variation along a toposequence in Taylor Valley, Antarctica}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {77}, year = {1996}, pages = {197}, keywords = {LTER-MCM}, author = {Mengchi Ho and Ross A. Virginia and Diana W. Freckman} } @article {1583, title = {Sources and distribution of abundance of organic matter in the Dry Valley soils of southern Victoria Land, Antarctica}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {77}, year = {1996}, pages = {56}, keywords = {LTER-MCM}, author = {Melody J. Brown and Ross A. Virginia and C. Page Chamberlain} } @mastersthesis {1586, title = {Surface energy balance and meltwater production for a dry valley glacier, Taylor Valley, Antarctica}, volume = {M.S.}, year = {1996}, school = {University of Colorado}, type = {masters}, keywords = {LTER-MCM}, doi = {LTER}, author = {Karen J. Lewis} } @article {1584, title = {Viruses in antarctic lakes: a first assessment of their distribution}, journal = {Bulletin of the Ecological Society of America Supplement}, volume = {77}, year = {1996}, pages = {230}, keywords = {LTER-MCM}, author = {Kepner, R.L. and Robert A. Wharton Jr. and Galchenko, V} } @article {1585, title = {A weather network in McMurdo Dry Valleys, Antarctica}, journal = {The Campbell Update}, volume = {7}, year = {1996}, pages = {3}, keywords = {LTER-MCM}, author = {Peter T. Doran} } @article {1587, title = {The influence of stream channel characteristics on streamflow and annual water budgets for lakes in Taylor Valley}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {284-287}, keywords = {LTER-MCM}, author = {Harold R. House and Diane M. McKnight and Paul Von Guerard} } @article {1608, title = {McMurdo Dry Valleys Long-Term Ecological Research (LTER): An overview of 1994-1995 research activities}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {275-276}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr.} } @article {1588, title = {McMurdo Dry Valleys Long-Term Ecological Research (LTER): LTER automatic weather network (LAWN)}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {276-280}, keywords = {LTER-MCM}, author = {Peter T. Doran and Gayle L. Dana and Hastings, Jordan Towner and Robert A. Wharton Jr.} } @article {1589, title = {McMurdo LTER: Algal mat distribution in glacial meltwater streams in Taylor Valley, southern Victoria Land, Antarctica}, journal = {Antarctic Journal of the United States}, volume = {30}, year = {1995}, pages = {287-289}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Cathy M. Tate} } @article {1590, title = {McMurdo LTER: Comparative limnology of the Taylor Valley lakes: The major solutes}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {292-293}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons} } @article {1591, title = {McMurdo LTER: Photosynthesis in benthic cyanobacterial mats from Lake Hoare, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {296-297}, keywords = {LTER-MCM}, author = {Ian Hawes and Anne-Maree Schwarz} } @article {1609, title = {McMurdo LTER: Progress with the Taylor Valley geographic information system}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {297-299}, keywords = {LTER-MCM}, author = {Hastings, Jordan Towner} } @article {1592, title = {McMurdo LTER: Relationships between vertical nutrient flux and phytoplankton biomass and productivity in lakes of the Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {294-295}, keywords = {LTER-MCM}, author = {R. L. Edwards and John C. Priscu} } @article {1593, title = {McMurdo LTER: Soil properties associated with nematode distribution along an elevational transect in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {282-283}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Mengchi Ho and Ross A. Virginia} } @article {1594, title = {McMurdo LTER: Species composition and spatial distribution of algal mats in Green Creek, Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U. S.}, volume = {30}, year = {1995}, pages = {289-291}, keywords = {LTER-MCM}, author = {Alexander S. Alger and Sarah A. Spaulding and Gordon H Shupe and Diane M. McKnight} } @article {1595, title = {McMurdo LTER: The surface-energy balance of the Canada Glacier, Taylor Valley}, journal = {Antarctic Journal of the United States}, volume = {30}, year = {1995}, pages = {280-282}, keywords = {LTER-MCM}, author = {Karen J. Lewis and Gayle L. Dana and Scott W. Tyler and Andrew G Fountain} } @article {1596, title = {Paleolakes on Mars}, journal = {Journal of Paleolimnology}, volume = {13}, year = {1995}, pages = {267-283}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr. and J. Crosby and Christopher P. McKay and J. Rice} } @article {1597, title = {The Photosynthetic Apparatus of Phytoplankton from a Perennially Ice-Covered Antarctic Lake: Acclimation to an Extreme Shade Environment}, journal = {Plant Cell Physiology}, volume = {36}, year = {1995}, pages = {253-263}, keywords = {LTER-MCM}, author = {Patrick J. Neale and John C. Priscu} } @article {1598, title = {Phototactic response of phytoplankton forming discrete layers within the water column of Lake Bonney , Antarctica}, journal = {Antarctic Journal of the US}, volume = {30}, year = {1995}, pages = {301-303}, keywords = {LTER-MCM}, author = {John C. Priscu and Patrick J. Neale} } @article {1599, title = {Phytoplankton Nutrient Deficiency in Lakes of the McMurdo Dry Valleys, Antarctica}, journal = {Freshwater Biology}, volume = {34}, year = {1995}, pages = {215-227}, keywords = {LTER-MCM, legacy}, author = {John C. Priscu} } @article {1600, title = {Profiles of electrode potential and dissolved oxygen in lakes of the McMurdo Dry Valleys}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {305-307}, keywords = {LTER-MCM}, author = {Malcolm T. Downes and John C. Priscu} } @article {1602, title = {Responses of bacterial growth to inorganic and organic nutrient enrichment in the lakes of the dry valleys, Antarctica}, journal = {Antarctic Journal of the US}, volume = {30}, year = {1995}, pages = {303-305}, keywords = {LTER-MCM}, author = {Cristina D. Takacs-Vesbach and John C. Priscu} } @article {1603, title = {Soil chemistry along a glacial chronosequence on Andrews Ridge, Taylor Valley}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {310-311}, keywords = {LTER-MCM}, author = {Mengchi Ho and Ross A. Virginia and Powers, Laura E. and Diana W. Freckman} } @article {1604, title = {Some metamorphic processes in the lake ice of the McMurdo Dry Valleys}, journal = {Antarctic Journal of the U.S.}, volume = {30}, year = {1995}, pages = {307-309}, keywords = {LTER-MCM}, author = {Edward E. Adams and John C. Priscu and Atsushi Sato} } @article {1605, title = {Spatial Distribution of Nematodes in Polar Desert Soils of Antarctica}, journal = {Polar Biology}, volume = {15}, year = {1995}, pages = {325-333}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Ross A. Virginia} } @article {1606, title = {Streamflow, water-temperature, and specific-conductance data for selected streams draining into Lake Fryxell, Lower Taylor Valley, Victoria Land, Antarctica, 1990-92}, journal = {U.S. Geological Survey. Open-File Report 94-545}, year = {1995}, keywords = {LTER-MCM}, author = {Paul Von Guerard and Diane M. McKnight and Richard A. Harnish and J. W. Gartner and Edmund D. Andrews} } @article {1611, title = {Aquatic fulvic acids in algal-rich antarctic ponds}, journal = {Limnology and Oceanography}, volume = {39}, year = {1994}, month = {07/1994}, pages = {1972-1979}, keywords = {LTER-MCM, Biggie}, author = {Diane M. McKnight and Edmund D. Andrews and Sarah A. Spaulding and George R. Aiken} } @article {1613, title = {Depth distribution of soil nematodes in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {175-176}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Ross A. Virginia} } @article {1612, title = {Light transmission and reflection in perennially ice-covered Lake Hoare, Antarctica}, journal = {Journal Geophysics Research}, volume = {99}, year = {1994}, month = {06/1994}, pages = {20427-20444}, keywords = {LTER-MCM}, doi = {10.1029/94JC01414}, author = {Christopher P. McKay and Gary D. Clow and Dale T. Andersen and Robert A. Wharton Jr.} } @article {1630, title = {McMurdo Dry Valleys LTER: An overview of 1993-1994 research activities}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {224-226}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr.} } @article {1614, title = {McMurdo LTER: Developing a geographic information system access system}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {246-247}, keywords = {LTER-MCM}, author = {Hastings, Jordan Towner and Anya Z. Butt} } @article {1615, title = {McMurdo LTER: Developing a geographic information system database}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {244-245}, keywords = {LTER-MCM}, author = {Anya Z. Butt and Hastings, Jordan Towner} } @article {1616, title = {McMurdo LTER: Glacier mass balances of Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {226-228}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Bruce H. Vaughn and Gayle L. Dana} } @article {1617, title = {McMurdo LTER: Inorganic geochemical studies with special reference to calcium carbonate dynamics}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {237-239}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and John C. Priscu and R. L. Edwards and Diane M. McKnight and Harold R. House and Robert A. Wharton Jr.} } @article {1618, title = {McMurdo LTER: Paleolimnology of Taylor Valley, Antarctica}, journal = {Antarctic Journal of the United States}, volume = {29}, year = {1994}, pages = {234-237}, keywords = {LTER-MCM}, doi = {LTER}, author = {Peter T. Doran and Robert A. Wharton Jr. and Sarah A. Spaulding and J. S. Foster} } @article {1631, title = {McMurdo LTER: Phytoplankton nutrient deficiency in lakes of the Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {239-241}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1619, title = {McMurdo LTER: Primary production model of benthic microbial mats in Lake Hoare, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {241-243}, keywords = {LTER-MCM}, author = {Daryl L. Moorhead and Robert A. Wharton Jr.} } @article {1620, title = {McMurdo LTER: Streamflow Measurements in Taylor Valley}, journal = {Antarctic Journal of the United States}, volume = {29}, year = {1994}, pages = {230-232}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Harold R. House and Paul Von Gerard} } @article {1621, title = {McMurdo LTER: Using narrow band spectroradiometry to assess algal and moss communities in a dry valley stream}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {232-234}, keywords = {LTER-MCM}, author = {Gayle L. Dana and Cathy M. Tate and Sharon L. Dewey} } @article {1622, title = {McMurdo LTER:Soil and nematode distribution along an elevational gradient in Taylor Valley, Antarctica}, journal = {Antarctic Journal of the U.S.}, volume = {29}, year = {1994}, pages = {228-229}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Mengchi Ho and Ross A. Virginia} } @article {1623, title = {Natural Fluorescence and Quantum Yields in Vertically Stationary Phytoplankton from Perennially Ice-Covered Lakes}, journal = {Limnol. Oceanogr.}, volume = {39}, year = {1994}, pages = {1399-1410}, keywords = {LTER-MCM}, author = {Michael P. Lizotte and John C. Priscu} } @article {1624, title = {Nematode biodiversity and community structure in Antarctic Polar Desert Soils}, journal = {Bulletin of the Ecological Society of America}, volume = {75}, year = {1994}, pages = {186}, keywords = {LTER-MCM, Biggie}, author = {Powers, Laura E. and Diana W. Freckman and Ross A. Virginia} } @inbook {1625, title = {Nematode biodiversity and survival in Antarctic Dry Valley soils}, booktitle = {SCAR 6th Biology Symposium}, year = {1994}, address = {Venice, Italy}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia and Powers, Laura E.} } @article {1626, title = {Paleolimnology of the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Paleolimnology}, volume = {10}, year = {1994}, pages = {85-114}, keywords = {LTER-MCM}, doi = {10.1007/BF00682507}, author = {Peter T. Doran and Robert A. Wharton Jr. and W. Berry Lyons} } @article {1627, title = {Phytoplankton population dynamics in perennially ice-covered Lake Fryxell, Antarctica}, journal = {Journal of Plankton Research}, volume = {16}, year = {1994}, pages = {527-541}, keywords = {LTER-MCM}, author = {Sarah A. Spaulding and Diane M. McKnight and Richard L. Smith and Richard Dufford} } @inbook {1628, title = {Stromatolite mats in Antarctic lakes}, booktitle = {Phanerozoic Stromatolites II}, year = {1994}, publisher = {Kluwer, Netherlands}, organization = {Kluwer, Netherlands}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr.} } @article {1629, title = {Survival of Scottnema lindsayae under extreme osmotic conditions}, journal = {Society of Nematologists}, year = {1994}, keywords = {LTER-MCM}, author = {Powers, Laura E. and Diana W. Freckman and Ross A. Virginia} } @article {1648, title = {Book Review: Physical and biogeochemical processes in Antarctic lakes}, journal = {Limnology and Oceanography}, volume = {39}, year = {1993}, pages = {1499-1500}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1632, title = {Dissolved Organic Material in Dry Valley Lakes: A Comparison of Lake Fryxell, Lake Hoare, and Lake Vanda, in Physical and Biogeochemical Processes in Antarctic Lakes}, journal = {Antarctic Research Series}, volume = {59}, year = {1993}, pages = {119-133}, keywords = {LTER-MCM}, author = {Diane M. McKnight and George R. Aiken and Edmund D. Andrews and E. C. Bowles and Richard A. Harnish} } @article {1633, title = {The ecology of nematodes in Antarctic Dry Valley soils}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {10-11}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1634, title = {Environmental regulators of microbial activity in continental antarctic lakes, in Physical and Biogeochemical Processes in Antarctic Lakes}, journal = {Antarctic Research Series}, volume = {59}, year = {1993}, pages = {165-195}, keywords = {LTER-MCM}, author = {Simmons, George M. and J. Robie Vestal and Robert A. Wharton Jr.} } @article {1635, title = {Extraction of nematodes from Dry Valley Antarctic soils}, journal = {Polar Biology}, volume = {13}, year = {1993}, pages = {483-487}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1636, title = {The geochemical evolution of terrestrial waters in the antarctic: the role of rock-water interactions, in Physical and Biogeochemical Processes in Antarctic Lakes}, volume = {59}, year = {1993}, pages = {135-143}, keywords = {LTER-MCM}, author = {W. Berry Lyons and Paul A. Mayewski} } @article {1637, title = {Influence of high salinity levels on ambient inorganic nitrogen and nitrogen-15 extraction efficiency in Lake Bonney}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {245-246}, keywords = {LTER-MCM}, author = {Richard D. Bartlett and John C. Priscu and Christopher D. Woolston} } @article {1638, title = {Life Cycle of the Microbivorous Antarctic Dry Valley Nematode Scottnema lindsaye Timm 1971}, journal = {Polar Biology}, volume = {13}, year = {1993}, pages = {151-156}, keywords = {LTER-MCM}, author = {A. Overhoff and Diana W. Freckman and Ross A. Virginia} } @article {1639, title = {Microbial communities in the permanent ice cap of Lake Bonney, Antarctica: Relationships among chlorophyll-a , gravel, and nutrients.}, journal = {Antarctic Journal of the U.S}, volume = {28}, year = {1993}, pages = {247-249}, keywords = {LTER-MCM}, author = {Wing, Kate T. and John C. Priscu} } @article {1640, title = {Microbial respiration potential in Lake Bonney using a novel tetrazolium-reduction method}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {244-245}, keywords = {LTER-MCM}, author = {Smith, James J. and John C. Priscu} } @article {1641, title = {Nitrifying and denitrifying bacteria in Lake Bonney}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {239-241}, keywords = {LTER-MCM}, author = {Bess B. Ward and Cockcroft, A.R. and John C. Priscu} } @article {1642, title = {Perennial ice covers and their influence on antarctic lake ecosystems, in Physical and Biogeochemical Processes in Antarctic Lakes}, journal = {Antarctic Research Series}, volume = {59}, year = {1993}, pages = {53-70}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr. and Christopher P. McKay and Gary D. Clow and Dale T. Andersen} } @article {1643, title = {Phytoplankton utilization of ammonium and nitrate in Lake Bonney: A preliminary assessment.}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {241-243}, keywords = {LTER-MCM}, author = {Christopher D. Woolston and John C. Priscu} } @article {1644, title = {Potential hydrologic and geochemical consequences of the 1992 merging of Lake Chad with Lake Hoare in Taylor Valley}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {249-251}, keywords = {LTER-MCM}, author = {Diane M. McKnight and Edmund D. Andrews} } @article {1645, title = {Stable isotopic biogeochemistry of carbon and nitrogen in a perennially ice-covered Antarctic lake}, journal = {Chemical Geology}, volume = {107}, year = {1993}, pages = {159-172}, keywords = {LTER-MCM}, author = {Robert A. Wharton Jr. and W. Berry Lyons and D.J. Des Marais} } @inbook {1646, title = {Terrigenous clastic sedimentation in antarctic dry valley lakes}, booktitle = {Physical and Biogeochemical Processes in Antarctic Lakes}, series = {Antarctic Research Series}, volume = {59}, year = {1993}, pages = {71-81}, publisher = {Wiley}, organization = {Wiley}, keywords = {LTER-MCM}, isbn = {9780875908304}, doi = {10.1029/AR059p0071}, author = {David W. Andersen and Robert A. Wharton Jr. and Steven W. Squyres} } @article {1647, title = {Water column transformations of nitrogen in Lake Bonney, a perennially ice-covered antarctic lake}, journal = {Antarctic Journal of the U.S.}, volume = {28}, year = {1993}, pages = {237-239}, keywords = {LTER-MCM}, author = {John C. Priscu and Bess B. Ward and Malcolm T. Downes} } @article {1649, title = {Nematodes and soil properties in the Dry Valleys of southern Victoria Land, Antarctica}, journal = {Bulletin of the Ecological Society of America}, volume = {73}, year = {1992}, pages = {179}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1650, title = {Nematodes in Antarctic Dry Valley soils: extraction and distribution}, journal = {Journal of Nematology}, volume = {24}, year = {1992}, pages = {591}, keywords = {LTER-MCM}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1651, title = {Photosynthesis-Irradiance Relationships in Phytoplankton From the Physically Stable Water Column of a Perennially Ice-Covered Lake (Lake Bonney, Antarctica)}, journal = {J. Phycol.}, volume = {28}, year = {1992}, pages = {179-185}, keywords = {LTER-MCM}, author = {Michael P. Lizotte and John C. Priscu} } @article {1652, title = {Spectral Irradiance and Bio-Optical Properties in Perennially Ice-Covered Lakes of the Dry Valleys (McMurdo Sound, Antarctica)}, journal = {Antarctic Research Series}, volume = {57}, year = {1992}, pages = {1-14}, keywords = {LTER-MCM}, author = {Michael P. Lizotte and John C. Priscu} } @article {3241, title = {McMurdo Dry Valleys: A cold desert ecosystem}, year = {1991}, month = {10/1991}, keywords = {LTER-MCM}, url = {https://mcm.lternet.edu/sites/default/files/MCM_1991_Report.pdf}, author = {Robert A. Wharton Jr.} } @article {1653, title = {Nematodes in the McMurdo Dry Valleys of Southern Victoria Land}, journal = {Antarctic Journal of the United States}, volume = {26}, year = {1991}, pages = {233-234}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1654, title = {Development and Application of a Technique for Estimating Nutrient Deficiency in Soft Sediments}, journal = {Hydrobiologia}, volume = {203}, year = {1990}, pages = {93-97}, keywords = {LTER-MCM}, author = {Walter K. Dodds and John C. Priscu} } @inbook {1655, title = {Glaciers of the southern hemisphere}, booktitle = {Global and Planetary Change}, volume = {22}, year = {1990}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andrew G Fountain} } @article {1656, title = {Nematode Ecology of the McMurdo Dry Valley Ecosystems}, journal = {Antarctic Journal of the United States}, volume = {25}, year = {1990}, pages = {229-230}, keywords = {LTER-MCM}, doi = {LTER}, author = {Diana W. Freckman and Ross A. Virginia} } @article {1657, title = {Inorganic Nitrogen Uptake and Regeneration in Perennially Ice-Covered Lakes Fryxell and Vanda, Antarctica}, journal = {Journal of Plankton Research}, volume = {11}, year = {1989}, pages = {335-351}, keywords = {LTER-MCM}, author = {John C. Priscu and Warwick F. Vincent and Clive Howard-Williams} } @article {1659, title = {Photon Dependence of Inorganic Nitrogen Transport by Phytoplankton in Perennially Ice-Covered Antarctic Lakes}, journal = {Hydrobiologia}, volume = {172}, year = {1989}, pages = {173-182}, keywords = {LTER-MCM}, author = {John C. Priscu} } @article {1658, title = {Temperature Dependence of Inorganic Nitrogen Uptake and Assimilation in Antarctic Sea-Ice Microalgae}, journal = {Polar Biology}, volume = {9}, year = {1989}, pages = {443-446}, keywords = {LTER-MCM}, author = {John C. Priscu and Anna C. Palmisano and Linda R. Priscu and Cornelius W. Sullivan} } @article {1660, title = {Diel Patterns of Photosynthate Biosynthesis by Phytoplankton in Permanently Ice-Covered Antarctic Lakes Under Continuous Sunlight}, journal = {Journal of Plankton Research}, volume = {10}, year = {1988}, pages = {333-340}, keywords = {LTER-MCM}, author = {John C. Priscu and Linda R. Priscu and Clive Howard-Williams and Warwick F. Vincent} } @article {1661, title = {Photosynthate Distribution by Microplankton in Permanently Ice-Covered Antarctic Desert Lakes}, journal = {Limnol. Oceanogr.}, volume = {32}, year = {1987}, pages = {260-270}, keywords = {LTER-MCM}, author = {John C. Priscu and Linda R. Priscu and Warwick F. Vincent and Clive Howard-Williams} }