Meeting Abstract
During ontogeny, organisms pass through critical developmental periods of heightened vulnerability to disruptive exogenous agents. In organisms with complex life cycles, these developmental windows result in variable susceptibility or differential effects across life stages. In addition, developmental anomalies that occur during early life can carry-over to affect later stages and ultimately individual fitness. In this study, we examine the stage specific and carry-over effects of exposure to presumably sub-lethal doses of endosulfan during two early life history stages — embryos and larvae. Endosulfan is a commonly used insecticide and a known neurotoxic endocrine disruptor that alters somatic and reproductive development in some taxa. We exposed green tree frog (Hyla cinerea) embryos and larvae, individually and across stages, to a gradient of environmentally relevant concentrations (0, 0.1, 1, 10, 100, and 1,000ng/L) of endosulfan. These concentrations range from low levels found in Artic meltwater to those measured in agricultural runoff, but are over an order of magnitude less than quantities found in human breast milk. We are examining how dose and the window of exposure affects tadpole growth, metamorphosis, and gonadal development. We will present results on larval stage duration and mass and length at metamorphosis, and effects on gonad length, width, developmental stage, and numbers of gametocytes (determined histologically). Because our endpoints are strong correlates of fecundity and overall fitness, our findings have important implications for understanding and mitigating amphibian population declines arising from sub-lethal exposures to endocrine disrupting environmental pollutants.
