Mercury content in roach (Rutilus rutilus L.) in circumneutral lakes - effects of catchment area and water chemistry

The environmental influence on the mercury content in roach (Rutilus rutilu s L.) is investigated using partial least square regression on 46 environme ntal variables describing the land use in the catchment area, various catch ment area and lake characteristics, lake water chemistry, and fish stock. T he Hg content in the fish from the 78 investigated circumneutral lakes is h eavily influenced by the land use in their surroundings. The boreal forest lakes possessed the highest Hg levels in roach, whereas fish from lakes sur rounded by arable land had lower levels. The Hg levels also showed a negati ve relationship to the amount of dissolved ions and the total amount of nut rients in lake water. Lake pH did not have any significant influence on the Hg content in roach in these non-acidified lakes. The Hg levels in lakes i nfluenced by large amounts of wetland were less well explained by the prese ntly investigated environmental variables, which implies that the Hg burden in fish from this kind of lake is governed by other factors. (C) 2001 Else vier Science Ltd. All rights reserved.