Factors determining nematode distributions at Cape Hallett and Gondwana station, Antarctica

The distribution of nematodes at Cape Hallett and Gondwana station was found to be patchy but consistent, broad-scale habitat preferences were identified. These had been previously noted in McMurdo Dry Valleys soils and on Ross Island, indicating that habitat preferences are consistent across large scales and may play a role in determining range limits. Soil geochemistry, especially salinity, has a strong impact on distribution patterns. The distinct distribution patterns of the four species indicate different niches. Panagrolaimus davidi Timm is the only nematode that can survive within penguin rookeries, where salinity is high but bacterial food is plentiful. Scottnema lindsayae Timm was found across the greatest range of habitats, including the driest sites and largest salinity range. Plectus sp. was found in the wettest sites, with high organic content and low salinity. Eudorylaimus antarcticus Steiner (Yeates) was found at low densities and with other nematodes indicating a dependence on prey availability, an example of a biotic interaction structuring even these simplest ecosystems. Field-identifiable features could be used to identify probable nematode habitats, providing useful information for sampling and the selection of conservation areas.