PARENT SESSION
Oral Session # 81: Soil Ecology II: Microorganisms and Mycorrhizae.
Presiding: SJ Hall
Thursday, August 7. 1:30 PM to 5:00 PM, SITCC Meeting Room 106.

Impacts of temperature and moisture regimes on Scottnema lindsayae population dynamics, an Antarctic soil nematode.

Weicht, Thomas^*,1, Moorhead, Daryl¹, ¹ University of Toledo, Toledo, Ohio

ABSTRACT- An earlier model of Scottenema lindsayae population growth was modified to include observed sex ratios and response to gravimetric soil moisture (data provided by the McMurdo Long-Term Ecological Research program). The sex ratio of field population approximated 63% ± 25 females, which altered the slope of the relationship between the coefficient of population growth () and cumulative annual degree-days (DD): =0.6 + 0.002DD, n = 17, r² = 0.97. The relationship between soil water content and the fraction of the resident nematode population that was inactive (anhydrobiosis) was approximated with a sigmoid curve: AN = 0.65² / (0.65² + M²) where An is the inactive portion of the population and M is the percent gravimetric water (n = 74 r² = 0.82). This model then was used to explore the combined impacts of temperature and moisture on population dynamics, given the observed sex ratio. Estimates of were found to be sensitive to both temperature and gravimetric moisture: = 0.68 + 0.0019DD + 0.025M - 8.18×10^-7DD² - 7.5×10^-4M², n = 213, R² = 0.68. In particular, the model was most sensitive to conditions found in the McMurdo Dry Valley soils (M < 10% and DD < 300).

Key words: lambda, LTER, Scottnema lindsayae, Antarctica