Analyses of perch (Perca fluviatilis) bile suggest increasing exposure to PAHs and other pollutants in a reference area on the Swedish Baltic coast.

Kvädöfjärden on the Swedish Baltic coast has been used as a reference station in the Swedish National Marine Monitoring Programme since 1988. During this time an increasing trend in ethoxyresorufin-O-deetylase (EROD) activity and a decreasing trend in gonad size for female perch have been observed. It is known that EROD activity respond to exposure to certain groups of pollutants, including polycyclic aromatic hydrocarbons (PAHs). In the present study, perch bile from two years with high (2006) and low (2003) EROD levels, respectively, were analyzed. The concentration of PAH metabolites in bile was semi-quantified using fixed wavelength fluorescence. Furthermore, toxicity of the bile was tested on Daphnia magna. The total concentration of PAH metabolites and toxicity to D. magna was higher in 2006 than in 2003. Furthermore, there was a higher proportion of combustion-type PAHs in bile from 2006. The concentration of PAH metabolites in bile correlated to the EROD activity of the fish from which the bile was taken. There was no correlation between the concentrations of PAH metabolites and bile toxicity. Therefore, other pollutants than PAHs may also have been elevated in 2006. The results suggest that increasing exposure to PAHs can be causing the time trend in EROD activity. It is known that PAHs can have a negative effect on gonad development. Therefore, the decreasing trend in gonad size may also be caused by increasing exposure to PAHs.