An examination of mercury concentrations in white perch, yellow perch, and white sucker in Cumberland and Guysborough Counties in Nova Scotia.

Abstract

Mercury concentrations in the environment have been a growing concern globally due to the inherent health risks associated with mercury exposure. Concentrations are of importance due to the impacts on the natural environment and the eventual impact on human and wildlife health. An organic form of mercury, methylmercury, is able to easily bioaccumulate and biomagnify in tissues of organisms. In Nova Scotia, much research has been done in the Kejimkujik National Park on fish and waterfowl; however, relatively little has been done to further an understanding of mercury concentrations in aquatic food webs throughout the rest of the province. For this study, we focused on mercury concentrations in three species of freshwater fish from four lakes which were Gilbert and Mattatall (Cumberland County), and Lochiel and Pringle (Guysborough County). Perca flavescents (yellow perch), Morone americana (white perch), and Catostomus commersoni (white sucker), were analyzed to determine the mercury concentrations of these species and compare how they differed among species and lakes. Mercury concentrations in all three species exceeded Health Canada’s marketing limit of 0.5 ng/g. The trends for white perch and yellow perch remained fairly consistent with significant and positive correlation between length and THg concentrations. These trends occur as the species grows and begins consuming other fish and elevating its position in the food chain. However, white sucker did not show a significant relationship between length and THg concentrations which may be due to consistent diet throughout its life regardless of its size. The THg-length trends differed significantly among lakes, meaning that other variables, such as the complexity of the food web and availability of food, could play a role.