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(W/EH040) Bioassays with fish bile can detect new pollutants in the Baltic Sea. Ek, Helene1, Larsson, Åke1, Dave, Göran1, 1 ABSTRACT- Since 1988 annual field studies on perch (Perca fluviatilis) have been conducted in two coastal areas of the Baltic Sea, Kvadofjarden and Holmoarna. Most variables used as bioindicators have been stable, with the exception of an increasing trend in the detoxification enzyme EROD in the liver of perch from Kvadofjarden, in the Baltic proper. No corresponding increase in induced hepatic EROD activity was found at Holmoarna, in the Bothnian Bay. Both Kvadofjarden and Holmoarna are presently used as reference sites. The increasing EROD activity in perch living in the Kvadofjarden indicates that the fish are presently being exposed to one or several inducing substances. In order to investigate this further, bioassays were conducted with stored (1989, 1996, 1997) and fresh (1999) perch-bile from the Kvadofjarden. The toxicity of bile to the crustacean Daphnia magna showed that bile from 1989 was less toxic to Daphnia than bile from 1996, 1997 and 1999. Furthermore, bile from Kvadofjarden in 1999 was more toxic to Daphnia than bile from Holmoarna in 1999. Samples of bile were analyzed for pollutants by GC/MS revealing that also exposure to some chemicals had increased since 1989. Substances detected in bile, which may contribute to the higher EROD activity in recent years, are anthraquinone and tetrachlorinated pyridine. The concentrations of some PAH-metabolites and phenols were also significantly lower in the bile from 1989 than in the bile from 1996, 1997 and 1999. Therefore, the results from both the bile bioassay and the chemical analysis suggested that aquatic organisms in parts of the Balitic are more heavily exposed to new contaminants when compared to the conditions prevailing when the first field studies were conducted. Key words: Baltic Sea, fish bile, toxicity, Daphnia |
