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