Reproductive disorders in fish from Lake Molnbyggen and an adjacent stream contaminated by leakage water from a refuse dump

Fish were examined in Lake Molnbyggen, a remote Swedish lake with a refuse dump in the vicinity, and an adjacent stream which drains the refuse dump area. The results showed significantly decreased gonadosomatic index (GSI) in females of four teleost species: perch (Perca fluviatilis), northern pike (Esox lucius), roach (Rutilus rutilus) and brook trout (Salvelinus fontinalis). Results show that female perch and female brook trout with decreased GSI have a low brain aromatase activity (CYP 19), close to the activity found in juvenile fish. The testosterone levels in blood plasma were also significantly lower in female perch with decreased GSI values. A frequent occurrence of fin deformations and open wounds were also found on perch, pike and roach. The biomarkers ethoxyresorufin O-deethylase, glutathione reductase and hydrophobic DNA adducts indicated a low general exposure to anthropogenic substances, although glutathione-S-transferase and catalase were induced in female perch. In conclusion, these results suggest serious adverse impairment of endocrine functions caused by specific organic pollutants in leakage water from the refuse dump.