Mercury Bioaccumulation and Adverse Reproductive Effects in Snapping Turtles Inhabiting a Historically Contaminated River

Mercury (Hg) is a global pollutant that has received much attention due to its ability to persist within the environment and biota. Currently, most ecotoxicology studies euthanize animals to quantify the concentrations of Hg bioaccumulation. The development of nondestructive sampling techniques is a critical step for sustainable spatial and temporal monitoring of Hg accumulation because it eliminates adult sacrifice, enables repeated sampling of the same individual over time, and allows the collection of larger sample sizes. In this study, we collected blood, nail, muscle, and egg tissues from snapping turtles (Chelydra serpentina) inhabiting an Hg contaminated gradient at a historically contaminated river located in central Virginia and formulated mathematical models describing relationships between tissues. From these tissues, we also describe important demographic, spatial, and temporal factors that influence Hg bioaccumulation in turtles. Additionally, in order to validate our mathematical models, we sampled two additional Hg contaminated locations in Virginia. As predicted, turtles inhabiting contaminated areas accumulated higher levels of Hg in their tissues than reference individuals. However, all Hg tissue concentrations were strongly and positively correlated with each other (in all cases: p < 0.001). Body size significantly influenced bioaccumulation of Hg in muscle but the nature of this effect was dependent upon site, with muscle Hg concentrations increasing with body size within contaminated individuals but did not change with size within the two reference sites. After correcting for body size, females had on average 93.9%, 6.3%, and 15.3% higher Hg in muscle than males from the two reference sites along the Middle and South River and the