Effect of polychlorinated biphenyls and mercury on the common snapping turtle (Chelydra serpentina serpentina)

Snapping turtles are a good bioindicator of aquatic contaminants. Two contaminants of concern in aquatic environments are polychlorinated biphenyls (PCBs) and mercury. Snapping turtles are capable of surviving high levels of PCBs in their tissues. Females pass contaminants to their eggs, thereby exposing embryos prior to development. The effects of PCBs through maternal exposure on the developing embryo and neonate hatchling are poorly understood. My study addressed techniques to mimic maternal exposure, the change in PCBs from egg to hatchling, and the effects of PCBs on neonate hatchling respirations. My study also addressed estimating mercury levels in snapping turtles through a non-invasive technique. Snapping turtle eggs were collected, injected with oil or a low (1 ppm) or high (10 ppm) PCB solution, and incubated under low and high temperature and moisture treatments. Upon hatch, neonate hatchlings were measured in a respirometer for CO2 production. In adult snapping turtles, the claw, liver, muscle, and adipose tissues were sampled and analyzed for mercury concentration. Hatching success in PCB injected eggs was 61% overall. A comparison of congener specific profiles from egg to hatchling indicated an increase in higher chlorinated congeners and a decrease in lower chlorinated congeners. The interaction of high PCB treatment and high incubation temperature resulted in a lower total PCB concentration in the hatchling. Data did not support the relationship of PCB treatment and CO2. In modeling mercury contaminants in internal tissues, the claw alone was not a good indicator. The model to estimate mercury in the liver required the mercury in the claw and the weight of the turtle. Future contaminant studies should continue attempts with egg injection techniques to mimic maternal transfer. Understanding the toxicokinetics of PCBs during embryonic development is still in its infancy. My study revealed that PCBs are mobile and dynamic during embryonic development. Although effects were not observed in respiration measurements, other physiological effects should continue to be examined. Contaminant monitoring should be limited to non-invasive techniques when possible. Predictive models should continue to be developed to limit impacts to stable populations and to infer contaminants in threatened or endangered populations of turtles.