M9 AM Ecotoxicology of Reptiles
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 339-340

(BLA-1116-857270) Using Diamondback terrapins, Malaclemys terrapin, as sentinel species for monitoring mercury pollution in estuarine systems.

Blanvillain, G¹, Schwenter, J¹, Day, R², Christopher, S², Roumillat, W³, Owens, D¹, ¹ College of Charleston, Charleston, SC, 29412² NIST, Charleston, SC, 29412³ Department of Natural Resources, Charleston, SC, 29412

ABSTRACT- Contamination of aquatic ecosystems from anthropogenic sources of mercury is one of our most important environmental pollution concerns. The life history of the diamondback terrapin may make this species susceptible to mercury bioaccumulation, which may be measured in their blood and scutes for biomonitoring. Mercury concentrations were measured in terrapin blood and scutes collected from four sites in South Carolina and at a superfund site in Purvis Creek (Brunswick, GA). There was a strong correlation between mercury concentrations in the two terrapin body compartments (tau=0.78, p<0.001). Mercury concentrations in keratin and blood were significantly higher in Purvis Creek than at all other sites (p<0.001). Mercury was also higher in salt marsh periwinkles, Littorina irrorata, from Purvis Creek, suggesting that concentrations in terrapin tissues reflect the levels of contamination in other resident members of the local ecosystem. We also investigated seasonal fluctuations of total mercury in the blood and scutes of terrapins collected in the Ashley River, Charleston Harbor, SC. Mercury concentrations in blood were significantly lower in August than in April, June or October (p<0.001), but scute mercury concentrations did not vary seasonally (p=0.7596). One hypothesis is that terrapins might be eliminating mercury from blood into growing scutes at a faster rate in the summer when they are thought to forage heavily and grow. Overall, we also found higher concentrations of mercury in the scutes of females than males (n=32, p<0.05). This may be because females are significantly larger than males and tend to eat larger prey items, and the energetic demand associated with female reproduction requires higher foraging rates. Overall, these findings show that terrapin scutes in particular are good predictors of mercury pollution, and that this species could indeed be used as a bioindicator for assessing mercury contamination of estuarine systems.

Key words: diamondback terrapin, mercury, sentinel species, estuaries