@article {4943, title = {Strong dispersal limitation of microbial communities at Shackleton Glacier, Antarctica}, journal = {mSystems}, volume = {8}, year = {2023}, month = {01/2023}, abstract = {

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

}, keywords = {LTER-MCM, community assembly, determinism, dispersal, niche, stochasticity}, doi = {10.1128/msystems.01254-22}, url = {https://journals.asm.org/doi/full/10.1128/msystems.01254-22}, author = {Lemoine, Nathan P. and Byron Adams and Melisa A. Diaz and Dragone, Nicholas B. and Franco, Andr{\'e} L. C. and Noah Fierer and W. Berry Lyons and Hogg, Ian D. and Diana H. Wall}, editor = {Lurgi, Miguel} } @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 {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} } @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 {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 {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} } @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 {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} } @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 {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 {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 {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 {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 {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 {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} } @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} } @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} }