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TISSUE MERCURY CONCENTRATIONS AND POTENTIAL NEUROGPATHOLOGICAL CHANGES IN COMMON LOONS (GAVIA IMMER)
Citation:
Murray, M. J., R Haebler, R. Miconi, C. Perkins, M. Pokras, AND R. Poppengay. TISSUE MERCURY CONCENTRATIONS AND POTENTIAL NEUROGPATHOLOGICAL CHANGES IN COMMON LOONS (GAVIA IMMER). Presented at American Waterbird Society, Plymouth, MA, November 2-5, 2000.
Description:
Common loons (Gavia immer) in New England are exposed to high levels of mercury through their diet. Mercury bioaccumulates through the food chain as methylmercury, a neurotoxin which has been shown in controlled feeding studies to have detrimental effects on the health and behavior of birds. This study examines liver total mercury concentrations of common loons found dead on freshwater breeding lakes in New England (predominantly New Hampshire and Maine) in relation to potential indicators of loon behavior: body condition and incidence of sternal punctures. Loons in thin or emaciated condition are found to have significantly higher liver total mercury concentrations than loons in good body condition. As no difference in mercury concentration is found between loons that died of anthropogenic and nonanthropogenic causes, poor body condition can be viewed as a potential indicator of foraging success. Significantly higher mercury concentrations are also found in birds that were discovered to have one or more sternal punctures upon necropsy. Sternal punctures are a potential indicator of aggressive interactions between individuals of this territorial species and may reflect an alteration in the signaling behavior that would be expected to prevent most territorial conflicts from becoming physical encounters. These results suggest the need for further research into the role that mercury toxicity may play in contributing to behavioral changes that could have direct negative impacts on loon survival.