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McMurdo Dry Valleys Upper Pond Nematode Survey Experiment
In January 2001, we surveyed streams and ponds above 300 m asl in Taylor Valley, South Victoria Land, Antarctica. One pond was examined in detail. Organic materials covered nearly 100% of the adjacent soil to 5-20 m from the shore, with intermittent patches to 80 m. Organic matter averaged 257 gC/m2, and totaled 1388 kg organic C on the soil around the pond. Soil moisture content (0.56 to 12.41%) decreased with distance from shore, whereas pH (7.8 to 10.8) increased with distance. Electrical conductivity was lowest in the soils less than 10 m from the pond (416 +- 94 uS/cm). Mineral soil organic C and total N concentrations were greatest between 10-30 m from the edgeof the pond (1.21 +- 0.37 and 0.13 +- 0.05 mg/g soil, respectively). Soil invertebrates were present in only 50% of samples and included tardigrades, rotifers and two nematodes, Scottnema lindsayae and Plectus antarcticus. A non-parametric, discriminant function analysis based on soil moisture, soil organic carbon and electrical conductivitycorrectly predicted 87.0% of sites that had invertebrates and 70.8% of sites for which invertebrates were absent. Tardigrades, rotifers and Plectus were found only in the wettest soils nearest the pond whereas Scottnema was restricted to drier soils farther from shore. Other ponds and streams also showed substantial accumulations of organic matter, suggesting that upland wetlands serve as resource islands in these polar deserts that provide a source of organic matter to nearby soils.
McMurdo Dry Valleys Airborn Sediment Traps / Aeolian Distribution of Soil Biota
Dispersal of soil organisms is crucial for their spatial distribution and adaptation to the prevailing conditions of the Antarctic Dry Valleys. This study investigate the possibility of wind dispersal of soil invertebrates within the dry valleys. Soil invertebrates were evaluated in wind-transported dust particles in collection pans (Bundt pans) 100 cm above the soil surface. Three species of nematode were recovered and Scottnema lindsayae was the most dominant. There were more juveniles (71%) in the transported sediments than adults (29%). The abundance of immobile (dead) nematodes in the Bundt pans was three times higher than active (live) nematodes. Anhydrobiosis constitutes a survival mechanism that allows wind dispersal of nematodes in the McMurdo Dry Valleys.
McMurdo Dry Valleys Soils Snowfence Nematode and Metazoa Survey Experiment
Increases in soil moisture from snow packs may influence distribution and abundances of soil invertebrates. In this study, two snow fences were erected in Lake Fryxell and Lake Bonney basins to trap snow and examine the effects of increased snow pack on soil physical, chemical and biological properties.
McMurdo Dry Valleys Soil Long Term Manipulation Experiment - Soil Temperatures Hourly
A long-term soil manipulation experiment has been conducted as part of the McMurdo Dry Valleys Long Term Ecological Research (LTER) project. This table contains hourly soil temperature measurements associated with the long-term manipulation experiment on the south side of Lake Hoare, Taylor Valley, Antarctica.
McMurdo Dry Valleys LTER: Stoichiometry Experiment in Taylor Valley, Antarctica from 2007 to 2016
Soil communities in the McMurdo Dry Valleys are subject to many limitations, including resource limitations. However, the nutrients that are predominantly limiting to growth and diversity of soil biota are not known. Additionally, landscape history (N deposition, P weathering) and native N and P content (glacial till provenance) may influence the ability of soil communities to respond to nutrient additions or changes in nutrient availability associated with environmental change. Long-term experiments in the Bonney and Fryxell basins have been established with yearly application of aqueous nutrient additions: C, N, P, CN, and CP. Multiple nutrients additions were made at the Redfield Ratio of 106:16:1 (C:N:P). Responses of soil chemistry, CO2 flux, and biota are reported.
McMurdo Dry Valleys Stoichiometry Experiment - CO2
Soil communities in the McMurdo Dry Valleys are subject to many limitations, including resource limitations. However, the nutrients that are predominantly limiting to growth and diversity of soil biota are not known. Additionally, landscape history (N deposition, P weathering) and native N and P content (glacial till provenance) may influence the ability of soil communities to respond to nutrient additions or changes in nutrient availability associated with environmental change. Long-term experiments in the Bonney and Fryxell basins have been established with yearly application of aqueous nutrient additions: C, N, P, CN, and CP. Multiple nutrients additions were made at the Redfield Ratio of 106:16:1 (C:N:P). Responses of soil chemistry, CO2 flux, and biota are reported.
McMurdo Dry Valleys Moss nutrient plasticity and stoichiometry
  The McMurdo Dry Valleys of Antarctica is one of the coldest and driest habitats on the planet. As vascular plants are absent in this region, moss is the main form of above-ground primary production with a potentially important contribution to biogeochemical cycling, yet little is known about their ecological role. To determine the relationship between moss and soil properties relevant to biogeochemistry, we sampled both from a variety of locations in the Dry Valleys. Moss presence was compared to soil properties, and we measured the plasticity of moss stoichiometry (C:N:P) across gradients in nutrient availability. Results demonstrate that many soil properties significantly differed with moss presence, particularly conductivity and pH, but there is no strong evidence that this is caused by the  moss presence and not the conditions inherent to the microsites where moss was found. There is great variability in moss stoichiometry, with some significant differences between sites, but generally variability within sites is larger than variation among sites. Results suggest that the main source of moss nutrients is from the soil, rather than water, but correlations with any one nutrient source are weak, suggesting a great deal of plasticity in moss stoichiometry and nutrient uptake.      Related Publication citation: Ball, B. and R. Virginia. 2014. The ecological role of moss in a polar desert: implications for aboveground-belowground and terrestrial-aquatic linkages. Polar Biology 37:651-664.   Â
McMurdo Dry Valleys Community Respiration Rates : Quantifying the Activity of the Electron Transport System (ETS)
An important part of the McMurdo Long Term Ecological Research (LTER) is monitoring of spatial and temporal patterns, and processes that control net primary production (carbon dynamics) in perennial ice-covered lakes. One of the primary losses of carbon fixed by phytoplankton is through respiration, directly by the phytoplankton themselves and secondarily through the metabolic contributions of heterotrophic organisms such as bacterioplankton and protozoa. The coupling of low metabolic activity and supersaturated gases in the water column prohibits a direct measurement of respiration. Therefore, we measure the respiratory electron transport system (ETS) activity which drives oxidative phosphorylation, and hence oxygen consumption in all aerobic organisms (Packard 1985). This data set addresses this core area of research and estimates a community-wide respiration rate at specific depths in McMurdo Dry Valley lakes (Hoare, Fryxell and Bonney).
McMurdo Dry Valleys Chlorophyll-A Concentrations in Lake Hoare Benthic Mats 1996-97
As part of the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, the growth of benthic cyanobacteria-dominated mats in the lakes have been monitored. This dataset shows chlorophyll-a levels associated with the benthic mats. Values are provided for various depths of Lake Hoare during the 1996-97 field season, both with and without correction for phaeopigments.
McMurdo Dry Valleys Summer Phytoplankton Densities 1992-2001
 Phytoplankton were collected over four austral summers (1991-92 through1994-95) to examine seasonal and annual fluctuation in species composition and biovolume in Lakes Fryxell, Hoare, West Lake Bonney, and East Lake Bonney. All of these lakes are perennially ice-covered lakes located in the Dry Valleys of South Victoria Land, Antarctica.     The phytoplankton consisted primarily of cryptophyte and chlorophyte flagellates, and filamentous cyanobacteria. Some common taxa were vertically stratified (Oscillatoria limnetica, Phormidium angustissimum, Pyramimonas sp., Oscillatoria sp.), while others showed no distinct vertical stratification (Chlamydomonas subcaudata, Cryptomonas sp.). The stratification of the phytoplankton reflects the gradients of nutrients and light, and the stability of the water column.
McMurdo Dry Valleys Winter Phytoplankton Densities during the 1990-1991 season
Using automated overwinter sampling devices, preserved phytoplankton samples were collected from multiple depths in Lake Fryxell, a permanently ice-covered lake in southern Victoria Land, Antarctica. Photosynthetic algae (i.e. algae possessing chloroplasts) are maintained in a stable water column throughout winter darkness. The algal taxa "overwinter" in different ways, in a species specific manner. Typical vegetative cells were the most abundant form for all species found in the water column. Populations of one chlorophyte, Stichococcus sp., and two cryptophyte species increased during winter. We interpret the increase in algal population size as evidence of wintertime heterotrophic growth, and mixotrophic behavior in the context of the entire year. For two chlorophyte species some portion of the population had distinct morphology, e.g. akinetes for Chlamydomonas subcaudata and cells containing a large amount of starch or other storage material for Chlorella sp.. During winter, vegetative cells of the most abundant species of cyanobacteria, Phormidium angustissimum, occurred at the depth of the summertime maximum and at depths below the oxycline, which may represent a "false bottom". Other than this false bottom and the absence of diatoms, settling did not appear to influence the overwinteringalgal community.
McMurdo Dry Valleys Summer vs Winter Phytoplankton Presence 1989-1991
Using automated overwinter sampling devices, we collected preserved phytoplankton samples from multiple depths in Lake Fryxell, a permanently ice-covered lake in southern Victoria Land, Antarctica. Photosynthetic algae were maintained in a stable water column throughout winter darkness. The algal taxa overwintered in different ways in a species-specific manner. Typical vegetative cells were the most abundant form for all species found in the water column. Populations of one chlorophyte, Stichococcus sp., were observed in winter, but the species was absent in both summers. Two cryptophyte species were more abundant in winter than in summer. We interpret the increase in algal population size as evidence of heterotrophic growth in winter and of mixotrophic behavior throughout the year. For two chlorophyte species, some portion of the population had a distinctive morphology, for example, many Chlamydomonas subcaudata Wille. formed akinetes, whereas many Chlorella sp. contained a large amount of starch or other storage material. During winter, vegetative cells of the most abundant cyanobacterial species, Phormidium angustissimum West et West, occurred at the depth of the summer maximum and at depths below the oxycline. The presence of P. angustissimum below the oxycline may have resulted from the accumulation of settling cells at a depth with a greater density. In contrast to the settling of P. angustissimum, the general absence of the other algal species below the oxycline in winter indicated that these species were not influenced by overwinter settling.
McMurdo Dry Valleys Microzooplankton Species Found in Lake Fryxell
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows microzooplankton species found in Lake Fryxell.
McMurdo Dry Valleys Microzooplankton : Lake Fryxell Ciliates, Bacteria, Nanoflagellates
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows numbers of ciliates, bacteria, heterotrophic nanoflagellates, and phototrophic nanoflagellates found at various depths in Lake Fryxell.
McMurdo Dry Valleys Microzooplankton : Cryptophyte, Ciliate, and Heterotrophic Nanoflagellate Abundances
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows the abundance of heterotrophic nanoflagellates, cryptophytes, and ciliates found at various depths in Lake Fryxell and Lake Hoare.
McMurdo Dry Valleys Microzooplankton : Flagellate Grazing in Lakes Hoare and Fryxell
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows grazing rates of heterotrophic and mixotrophic flagellates found in Lakes Hoare and Fryxell at various depths and dates.
McMurdo Dry Valleys Microzooplankton : Ciliate Grazing Rates
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows grazing rates of ciliates feeding on cryptophytes between November 1997 and January 1998. The sample for this micro dataset was gathered at the Lake Fryxell.
McMurdo Dry Valleys Dissolved Inorganic Nitrogen Concentrations in Lakes
The McMurdo Long Term Ecological Research (LTER) project monitors patterns of inorganic material transport in perennial ice-capped lakes. This data set addresses this core area of research and quantifies dissolved inorganic nitrogen concentrations at specific depths in McMurdo Dry Valley lakes.
McMurdo Dry Valleys Halogen chemistry and isotopic composition in McMurdo lake waters and pore fluids
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file are the dissolved halogens :chloride, bromide, and total iodine in lake waters and pore waters. The isotopic composition of I-129 and Cl-36 are also presented for these same samples, as are the molar ratios of I-129/I-127, and Cl-36/Cl-37.  Alkalinity was also determined in order to subsequently investigate the relationship between the oxidation of organic matter and the release of iodine into the lake waters.
McMurdo Dry Valleys Iodine content and I-129 isotopic composition in McMurdo lake-bottom sediments
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file is the total iodine content and I-129 isotopic composition of lake-bottom sediments from Lakes Joyce and Fryxell. An attempt was made to determine the  iodine and chlorine isotopic content  of gypsum cored from the bottom of Lake Vanda, but the total iodine content was below detection.       Â
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