Mercury, polybrominated diphenyl ether, organochlorine pesticide, and polychlorinated biphenyl concentrations in fish from lakes along an elevation transect in the French Pyrenees

Concentrations of mercury and persistent organic pollutants in fish were examined in 11 lakes of the French Pyrenees spanning all elevation range of 2km. All lakes were confined to a relatively small area within a 50-km diameter. Most of the lakes were within the Pyrenees National Park, which is restricted to recreational hiking, angling, and seasonal grazing of livestock, and are not subject to any known point Sources of contaminants. Fish collected were mainly of 1 species (Salmo trutta fario), which is stocked regularly in the lakes. With increasing elevation, lake temperatures declined along with electrical conductivity and planktonic chlorophyll a. In contrast, water column nutrients (total phosphorus and total nitrogen) and epilithic periphyton biomass were not correlated with lake elevation. Of the global contaminants measured in fish, mercury, dicholorodiphenyltrichloroethane and its derivatives, and polybrorninated diphenyl ethers showed the strongest positive correlation with elevation. Hg levels in some fish exceeded health consumption guidelines in these mountain lakes. Variation in fish contaminant levels was not related to differences in growth rate or to Fish trophic position as determined using delta N-15 stable isotope measurements. This implies that the delivery and/or retention of many of these contaminants increase with lake elevation. (c) 2005 Elsevier Inc. All rights reserved.