HR: 0800h
AN: B51D-0241    [Abstracts]
TI: Soil Geochemical Control Over Nematode Populations in Bull Pass, McMurdo Dry Valleys, Antarctica
AU: * Poage, M A
EM: mpoage@iup.edu
AF: Indiana University of Pennsylvania, Geoscience Department, Indiana, PA 15705 United States
AU: Barrett, J E
B51D-0241 AF: Dartmouth College, Environmental Studies Program, Hanover, NH 03755 United States
AU: Virginia, R A
B51D-0241 AF: Dartmouth College, Environmental Studies Program, Hanover, NH 03755 United States
AU: Wall, D H
B51D-0241 AF: Colorado State University, Natural Resource Ecology Laboratory, Fort Collins, CO 80523 United States
AB: The McMurdo Dry Valleys occupy the largest ice-free region of Antarctica and are characterized by climatic conditions among the most extreme on Earth. Despite the harsh environmental conditions, some soils of the dry valleys host simple low-diversity ecosystems dominated by microbes and several taxa of metazoans, predominantly nematodes. Distributions, abundance, and diversity of these biota appear to be related to the highly variable soil geochemistry (pH, conductivity, nitrate, sulfate, chloride) of the dry valleys. Bull Pass is a glacially carved valley within the dry valleys. An ancient lake margin near the valley floor creates a continuous gradient spanning the full range of geochemical parameters found across the entire McMurdo Dry Valleys system. This unique setting provides the opportunity to systematically investigate the soil geochemical control on local biodiversity and establish, on the spatial scale of hundreds of meters, correlations between nematode populations and individual geochemical parameters that have application at the regional scale. We measured soil geochemistry and nematode population data from a 1500-meter transect across this ancient lake margin. There were significant negative correlations between live nematode abundance and concentrations of soil nitrate, sulfate and chloride as well as total soil salinity, consistent with recent laboratory experiments showing strong salinity inhibition of nematode survival. A logistical regression analysis based on a compilation of published datasets from across the dry valleys was designed to calculate the probably of live nematode populations occurring given a particular soil chemistry, using the dataset from the Bull Pass transect as a case study to field-test the model. Small-scale chemical and biological gradients can provide insights on the distribution of soil biota at much larger regional scales.
DE: 0410 Biodiversity
DE: 0456 Life in extreme environments
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: Fall Meeting 2005