Seasonal and long-term variation in body-water content of an Antarctic springtail - a response to climate change?

Body-water content of field-fresh samples of the springtail, Cryptopygus an tarcticus Willem (Collembola, Isotomidae) was measured at monthly intervals over 11 years (1984-1995) at Signy Island, in the maritime Antarctic. A cl ear annual cycle of variation in water content was observed, with maxima in the austral spring and autumn, and minima in midwinter and midsummer. Ther e was no overall trend during the 11-year study, in contrast to an earlier analysis of the initial 1984-1987 period, which demonstrated a significant increase in body-water content (from 56.6 to 66.0% fresh weight). It is sug gested that, between 1984 and 1987, water stress on C. antarcticus in its e nvironment declined, and thereafter stabilised between 1988 and 1995. Sprin gtail body-water content between 1984 and 1995 showed significant increases in several months, particularly in autumn and early winter, with decreases in midsummer. This was consistent with the predicted consequences of the p attern of regional climatic warming in the maritime Antarctic, where small increments in temperature have effectively increased the length of the pote ntial biologically active period. C. antarcticus responds rapidly to local and short-term variations in environmental conditions and will be able to t ake advantage of increases in the thermal energy budget and growing season length. It is predicted that climate warming could lead to a reduction in l ife-cycle duration, an increase in population density and extension of geog raphical range.