In this study it has been examined to which level bioaccumulated pesticides in transplanted zebra mussels can give an indication of trends in environmental pesticide pollution. In addition, it was investigated if pesticide body residues could be related to ecological responses (alternation in macroinvertebrate community composition). The study was conducted by measuring pesticide accumulation in translocated zebra mussels as well as assessing macroinvertebrate community structure by calculating biological water quality indices (BBI, MMIF, BMWP, total macroinvertebrate taxa and EPT). The results indicated that high body burdens of dimethoate, terbutylazine, chlorpyrifos and hexachlorobenzene were related to low biological water quality. Therefore for above mentioned pesticide threshold values of accumulated levels could be derived, above which ecological quality, as expressed by macroinvertebrate communities, were always low. The results suggest that zebra mussel body burdens can be used to predict the ecological impacts of pesticide contamination on the macroinvertebarte communities and to measure pesticides bioavilability. However, it should mentioned that the quantile regression analysis did not show negative significant relationship between calculated pesticides and the calculated biological water quality indices with the exception of hexachlorobenzene, indicating that other factors than the accumulated pesticides affect the community structure as well.