@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 {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 {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 {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 {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} } @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 {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 {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 {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 {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 {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} } @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} } @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} } @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} } @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} } @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} } @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} } @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 {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} } @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} } @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} } @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 {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 {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 {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 {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} }