Mercury contamination in fishes of Mount Desert Island and a comparative food chain mercury study

Burgess, John

From the abstract: "To assess the scope of mercury contamination in lakes within and surrounding Acadia National Park, mercury concentrations were determined in fish species of ten lakes on Mount Desert Island, Maine, USA. Five fish of the most common predatory species were collected from each lake. Skinless and boneless fillets of each fish, and the remaining carcass, were homogenized separately and analyzed for total mercury. Mean size-adjusted fillet concentrations for each lake ranged from 0.17 μg g-1 to 1.71 μg g-1 (wet wt.). Smallmouth bass (Micropterus dolomieu) from Hodgdon Pond had a mean fillet concentration of 1. 71 μg g-1, which is 2.5 times higher than the statewide average (0.67 μg g-1) for this species. Hodgdon Pond and Seal Cove Pond, an adjacent pond with a significantly lower mean mercury concentration (0.85 μg g-1, P=0.0008) in smallmouth bass, were chosen for a comparative food chain mercury study. Food organisms in the chain leading to smallmouth baa and in prey fish species were determined by stomach content analysis. Water, sediment, plankton, macroinvertebrates, and prey fish species were collected seasonally from both ponds and analyzed for total and methylmercury. In Hodgdon Pond, warmer, low-dissolved oxygen hypolimnetic water is probably contributing to the enhanced bioavailability of mercury, as seen by higher methylmercury concentrations in plankton at the base of the food chain. An extra trophic link in the food chain leading to smallmouth bass, as evidenced by the presence of larval fish and isopods in the diet of yellow perch, is also contributing to the increased biomagnification of mercury in Hodgdon Pond."

Mercury contamination in fishes of Mount Desert Island and a comparative food chain mercury study

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