Factors affecting the use of Dreissena polymorpha as a bioindicator: The PCB pollution in Lake Como (N. Italy)

The aim of this study was to assess the PCB pollution of the South-Western branch of Lake Como by using the zebra mussel (Dreissena polymorpha) as a b ioindicator since its recent reintroduction. Some environmental and physiol ogical variables influencing accumulation processes of organochlorine compo unds in Dreissena were investigated because climatic factors may affect lif e cycle, reproductive stage and age. PCB levels were highest in the soft ti ssues of Dreissena close to the industrialized area of Como (2298 ng g(-1) of lipids) and slowly decrease going north, reaching approximately half thi s value at the closing section of the lake branch. Nonetheless, the PCB con centrations are well below the dangerous levels for the aquatic environment .