Biochemical responses and environmental contaminants in breams (Abramis brama L.) caught in the river Elbe.

Adult breams (Abrama brama L.) were caught in October 1992 at seven stations in the river Elbe and at one nonpolluted reference site, the Belauer See. The locations of the sampling stations extended from the city of Steti (Tschechien Republic) to the city of Hamburg. Indices of biochemical effects in microsomal and cytosolic fractions of livers were studied by measuring cytochrome P450-dependent monooxygenases and glutathione-S-transferase (GST) activities. In addition, levels of mercury and 35 polychlorinated biphenyl (PCB) congeners were analyzed in livers of breams. Fish caught in the River Elbe exhibited a significant increase of cytochrome P450-mediated monooxygenase activities and the detoxifications enzyme GST compared to the reference site. At two stations of the river Elbe (Steti and Dresden) elevated activities of ethoxyresorufin-O-deethylase (EROD) were analyzed. These effects were discussed as effects from the pulp mill industries at station Steti and high concentrations of PCBs in the livers of breams at station Dresden. A significant reduction of GST activities was observed at station Dresden compared to those at Steti. These findings were probably a synergistic effect of high mercury concentrations at Dresden. The results presented in this study suggest that breams can be successfully employed for monitoring biological effects in the river Elbe.