Document: DOR-3-58-9

How stable are nematode populations in the Antarctic Dry Valley soil ecosystem?

PORAZINSKA, D.L.* ¹, D.H.WALL ¹ and R.A.VIRGINIA ²

Colorado State University, Ft. Collins, CO 80523-1499, USA ¹
Dartmouth College, Hanover, NH 03755-3560, USA ²

Abstract:
The McMurdo Dry Valleys allow study of patterns of nematode population dynamics in an extreme environment. Nematode populations are sensitive to soil disturbance and are useful indicators of environmental change. We hypothesized that the pristine soil environments of Antarctica would support stable nematode populations on spatial and temporal scales. We established three sampling sites across an elevation gradient in Taylor Valley, during the 1993-1994 austral summer. We sampled each site at larger (10 x 10 m) and smaller (1 x 1 m) scales three times during six years (1993, 1995, and 1999). Nematode abundance, diversity, and soil moisture varied only with elevation, not spatial scale over the six years. Scottnema lindsayae was more abundant at the highest elevation and dominated all sites, while Eudorylaimus antarcticus was more abundant at the lowest elevation. Plectus antarcticus was present only at the lowest elevation and declined sharply in numbers during the study (as did soil moisture) suggesting it could be subject to local extinction. Soil moisture was greater at the lowest elevation. Year of sampling had a significant effect on the density and diversity of nematode species and on soil moisture. While Scottnema was negatively correlated with soil moisture, Eudorylaimus and Plectus showed a positive relationship. Narrow niche requirements and sensitivity to small changes in soil moisture characterize nematode species in the Dry Valley soil ecosystem. Interannual variation in Antarctic soil nematode communities suggests they respond to short-term climate variation and may be affected by climate change.

Keywords: Antarctica, Dry Valley soil ecosystem, Eudorylaimus, nematode, Plectus, Scottnema, spatial and temporal scales

This abstract is being presented at: 8:45 AM in session:
Oral Session #23: Soil Ecology.