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 bioindicator since its recent reintroduction. Some environmental and physiological variables influencing accumulation processes of organochlorine compounds in Dreissena were investigated because climatic factors may affect life cycle, reproductive stage and age. PCB levels were highest in the soft tissues of Dreissena close to the industrialized area of Como (2298 ng g(-1) of lipids) and slowly decrease going north, reaching approximately half this value at the closing section of the lake branch. Nonetheless, the PCB concentrations are well below the dangerous levels for the aquatic environment.