Organic pollutant contamination of the river Tichi Orlice as assessed by biochemical markers

This study used biochemical markers to assess contamination at two contaminated sites (Kraliky and Lichkov) and one control site (Cervena Voda) on the River Ticha Orlice, a left-side tributary of the River Elbe. The brown trout (Salmo trutta fario) was selected as an indicator species. Enzymes of the first stage of xenobiotic conversion, namely cytochrome P450 (CYP 450) and ethoxyresorufin-O-deethylase (EROD) in the liver were selected as biochemical markers. Blood plasma vitellogenin concentrations were used to evaluate xencrestrogenic effects of contamination. Results were compared with the most important inductors of these markers, i.e. with organic pollutants (PCB, HCH, HCB, OCS and DDT and their metabolites in fish muscle and with PAH concentrations in bottom sediments). The highest contamination with organic pollutants was at Kraliky, and this was reflected in increased cytochrome P450, EROD activity and vitellogenin concentrations. Significant differences were demonstrated in EROD activity and vitellogenin concentrations between Kraliky and Cervena Voda (P < 0.001). At the most contaminated site (Kraliky), a significant negative correlation (r(s) = -0.964) between EROD activity and vitellogenin concentrations was demonstrated. This relationship was discussed from the point of view of a possible induction or inhibition of the assessed biomarkers at persistently highly contaminated sites.