Current climate models predict significant future warming in polar regions. Climate warming in the McMurdo Dry Valleys, Antarctica is expected to increase snow and glacial melt resulting in higher stream discharge and rising lake levels, but the potential influence of this warming and associated changes in hydrology on the soil in this sensitive environment remain unknown. To examine the potential effects of soil warming and changes in the availability of liquid water on populations of soil animals and their habitat we established a full-factorial experiment in three sites occurring in distinct lake basins of Taylor Valley, Antarctica. Since 1999, ITEX chambers have been used to experimentally warm the soil and additional water has been added annually to each experimental plot. We hypothesized that an increase in temperature and moisture would increase the microbial resource base, thus influencing abundance, biomass and species composition of the soil animal communities that feed upon them. 

Results/Conclusions

Variation in populations of soil biota was strongly related to experimental warming, lake basin, and sampling date. Warming treatments had a significant negative effect on density, mortality and body size of Scottnema lindsayae, the dominant nematode in the dry valleys. Melting of ground ice in one basin (unrelated to experimental treatments) significantly altered soil communities; mortality of S. lindsayae increased and densities decreased following this melting event. This same event resulted in an increase in micro-algae and populations of Eudorylaimus sp., a nematode species that prefers moist to wet habitats and feeds on soil micro-algae. These results suggest that regional warming in the dry valleys could significantly affect nematode populations and alter soil species composition.