Meeting Abstract

P3.103  Monday, Jan. 6 15:30  Latent effects of multiple stressors on southern toads, Anaxyrus terrestris RUMRILL, C.T.*; FLYNN, R.W.; SCOTT, D.E.; LANCE, S.L.; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC rumrill@srel.uga.edu

Anthropogenic stressors cause lethal and sublethal effects that contribute to population declines in amphibians; however, few studies examine effects after metamorphosis. In natural habitats individuals are exposed to multiple stressors, making it difficult to extrapolate results from single-stressor laboratory studies. We used 24, 1000-L pond mesocosms to investigate the combined effects of anthropogenic (copper) and environmental (pond hydroperiod) stressors on egg, larval, and early post-metamorphic stages of the southern toad (Anaxyrus terrestris). We exposed embryos (4 clutches, ~100/clutch) and larvae (25/clutch) to three concentrations (0, 20, and 50 µg/L) of Cu, a wide-spread heavy metal contaminant, crossed with two simulated pond drying regimes. We measured embryo/larval survival, time to/size at metamorphosis, and assessed performance (hopping speed and endurance) in toads at 5 and 35 days post-metamorphosis. There were no treatment effects on embryo survival but larval survival was affected by hydroperiod, with long averaging ~70% survival vs. 20% in short. Metamorphosis was delayed in the 50 µg/L-long treatment. Both factors affected body size at metamorphosis, with some effects persisting one month later, and hopping performance correlated with body size. At metamorphosis, the 50 µg/L treatment reduced hopping sprint and endurance speeds, as well as endurance distance; endurance remained depressed one month later. Additionally, there was a Cu*hydroperiod effect on hopping sprint and endurance speed, with endurance speed remaining depressed after one month. The persistent effects of Cu and the delayed onset of a Cu*hydroperiod interaction emphasizes the importance of extending studies involving stressors beyond the larval period.