RESIDUES OF POLLUTANTS IN SILURIFORMES FROM VARIOUS LOCALITIES OF THECZECH-REPUBLIC

Tissues (muscle, kidney, liver, gonads) were investigated for residues of pollutants in wels (Silurus glanis) from 6 large ponds (Bezdrev, S polsky, Kaclehy, Vrkoc, Novovesky, Bezruc), from Labe river and from t he Orlik reservoir and in brown bullhead (Ictalurus nebulosus) from th e river Labe. Thirty and 10 individuals of wels were investigated from ponds and the Orlik reservoir, respectively, and 2 individuals from t he river Labe. Thirty five individuals of bullhead were investigated f rom various localities of the Labe. Among pollutants, metals (Hg, Pb, Cd, Cu, Zn, Cr, Al), PCBs as amount of technical mixtures used in the Czech Republic (Delor 103 and Delor 106) and as 7 indicator congeners (K28, K52, K101, K118, K153, K138, K180), DDT and its metabolities, HC B, HCH isomers, triazines (atrazine, simazine, prometryne, desmetryne, terbutryne) were assessed. The values of individual pollutants found in tissues of wels from ponds were very low and corresponded to hygien ic limits in all cases. On the other hand, much higher values of pollu tant residues (Hg and PCB) were found in wels from the Orlik reservoir , and they exceeded the hygienic limit in some cases (PCB). Values of pollutant residues found in bullhead fished from various localities of the Labe were also increased. Above all, PCB and mercury values excee ded valid hygienic limit of the Czech Republic in some cases. Wels and brown bullhead proved to be important indicators of loading of variou s localities of surface waters with investigated pollutants. Wels as a predator and brown bullhead as an omnivorous and benthophagous fish a re important indicators of loading of surface waters with mercury. The muscles of wels are besides those of eel (Anguilla anguilla) one of t he most important indicators for the evaluation of surface waters load ing with polychlorinated biphenyls.