@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 {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 {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 {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 {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 {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} } @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} }