HOPKINS, W.A.*; WINNE, C.T.; Savannah River Ecology Laboratory; Savannah River Ecology Laboratory: Swimming performance of neonate black swamp snakes (Seminatrix pygaea) exposed to an acetylcholinesterase-inhibiting pesticide

Environmental contaminants have direct effects on organisms at the molecular, cellular, and tissue levels, but the net result of these sub-organismal effects are only consequential to exposed populations if they alter organism-level traits (i.e., growth, performance, reproduction, and survival) that ultimately influence fitness. Thus, studies focused on fitness-related traits provide the most insight into ecologically meaningful effects of environmental pollutants. Here, we explore the possibility that a fitness-related trait, swimming performance, may be useful for assessing the effect of environmental contaminants on aquatic organisms. We conducted two experiments where neonate black swamp snakes (Seminatrix pygaea paludis) were exposed for 48 hours to ecologically realistic concentrations of carbaryl (2.5 and 5 mg/L), an acetylcholinesterase-inhibiting pesticide that disrupts proper nerve signal transmission. Following exposure, snakes were raced three consecutive times down a 3 m swim track. In the first experiment, snakes exposed to carbaryl exhibited dose-dependent reductions in maximum swim velocities compared to controls. Moreover, the reduction in swimming performance was most pronounced during the third race, suggesting that snakes exposed to carbaryl exhaust more quickly than unexposed conspecifics. In our second experiment, we determined that recovery from the effects of carbaryl on swimming performance was slow; some carbaryl-exposed individuals had not recovered even after 96 hours. Taken together, our findings suggest that swimming performance may be a useful sublethal index of contaminant exposure in aquatic snakes and warrants further study.