Mercury Bioaccumulation and Adverse Reproductive Effects in Snapping Turtles Inhabiting a Historically Contaminated River
Hopkins, Brittney Cole
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Mercury (Hg) is a global pollutant that has received much attention due to its ability to bioaccumulate, biomagnify, and maternally transfers in humans and wildlife. In vertebrates, exposure to Hg can impair growth, alter behavior and morphology, decrease survival, and reduce reproductive success. Unfortunately, most ecotoxicology studies euthanize animals to quantify the concentrations of Hg bioaccumulation and in doing so eliminate the ability to relate Hg accumulation to observed effects. The development of non-destructive sampling techniques is a critical step for sustainable monitoring of Hg bioaccumulation and associated effects because it eliminates adult harvest, enables repeated sampling of the same individual over time, and allows the collection of larger sample sizes. My research aimed to develop and validate non-destructive sampling techniques for assessing Hg bioaccumulation, maternal transfer, and consumption risks in a long-lived aquatic omnivore, the common snapping turtle (Chelydra serpentina). I collected blood, nail, muscle, and egg tissues from turtles inhabiting an Hg contaminated gradient at a historically contaminated river, the South River, located in central Virginia. In my first chapter, I developed mathematical models describing relationships between the four tissues sampled and in doing so, described important demographic, spatial, and temporal factors that influence Hg bioaccumulation in turtles that may be important for ecological risk assessment and consumption. Additionally, I found that my mathematical models were applicable to other Hg contaminated locations in Virginia. In my second chapter, I examined the effects Hg bioaccumulation and maternal transfer has on turtle reproduction. I collected and incubated eggs from gravid females from reference and contaminated sites and quantified embryonic morality, infertility, and hatching success of each clutch, and assessed all hatchlings and dead embryos for gross morphological malformations. I found that Hg exposure negatively influenced hatching success through increased egg infertility and embryonic mortality. Taken together, my results are applicable to a wide array of systems where biomonitoring and assessing the ecological and consumption risk of contamination in turtles needs to be accomplished in a sustainable and conservation-minded fashion.
- Masters Theses