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MERCURY IN MINK IN RHODE ISLAND
Citation:
Lake, J L., F Osterman, S Ryba, AND J R. Serbst. MERCURY IN MINK IN RHODE ISLAND. Presented at 10th Annual Conference of the Wildlife Society, Burlington, VT, September 6-10, 2003.
Description:
Tissues of mink (Mustela vison) collected from Rhode Island sites during winters of 1999-2002 were analyzed for mercury and stable isotopes of nitrogen and carbon to determine the extent of Hg contamination in these aquatic dependent wildlife, and to evaluate whether stable isotopic techniques were useful for delineating home ranges for these animals. The mink were divided into an upland group and a salt pond group based on the habitat in which they were collected. The mean concentrations of total Hg in liver and muscle tissues from upland sites (1.60 ug Hg/g liver (ww), sd = 1.25, n = 54, and 1.14 ug Hg/g muscle (ww), sd = 0.69, n = 23) were significantly greater than those found in salt pond sites (0.54 ug Hg/g liver (ww) sd = 0.28, n = 53, and 0.46 ug Hg/g muscle (ww) sd = 0.30, n = 23) (p < 0.05). The two groups of sites were proximate and the probable source of the Hg input was atmospheric. Therefore, we believe the Hg concentration differences in mink groups may have been caused by differences in availability of Hg in upland and salt pond sediments, or by differences in the fraction of Hg laden fish in mink diets. The mean Hg concentrations of the upland group agreed closely with literature values for mink in adjacent states in New England and providences of Canada, but the values from the salt pond sites were below the literature values. The Hg concentrations in liver from the present study were below those that have been associated with adverse effects in laboratory dosing studies with mink. The highest liver Hg concentration in the present study was 26% of the value found in livers of impacted animals, and the overall mean liver Hg concentration was 5% of the value. Carbon and nitrogen stable isotopes were measured in a subset of these samples (the 1999-2000 samples) and showed significant differences between upland and salt pond sites. These results suggest differences in carbon fixation at the base of the upland and salt pond food chain, and differences in denitrification and/or input of human wastewater at sites comprising the groups. Overall, stable isotopes were useful for delineating mink groups.