Evidence for endocrine disruption in perch (Perca fluviatilis) and roach (Rutilus rutilus) in a remote Swedish lake in the vicinity of a public refuse dump

A two-year study on perch (Perca fluviatilis) in Lake Molnbyggen, Sweden, l ocated in a pristine area but with a public refuse dump in the vicinity, ha s been conducted. The mechanistic approach through a set of biomarkers duri ng the first year included age, condition, somatic growth, liver, gonad, an d spleen weights, and a number of other physiological variables, in additio n to ethoxyresorufin O-deethylase, glutathione-S-transferase, glutathione r eductase, catalase, and the formation of DNA adducts in the liver. Perch fr om the uncontaminated Lake Djursjon, located in a neighboring drainage area , were used as reference fish. The most pronounced effect was a 80% reducti on in the gonadosomatic index (GSI) for females and a corresponding 36% red uction in males. Fin erosion and shallow open sores were also frequently ob served. Biomarkers and later chemical analysis employed indicated that expo sure to well-known environmental pollutants was low, suggesting that less w ell-known antrophogenic substances are responsible for the effects observed in perch from Lake Molnbyggen. During the second year, roach (Rutilus ruti lus) of both sexes were also included in this study. In addition, aromatase (P450arom) activity in the brain and testosterone and 17 beta -estradiol l evels in blood plasma were analyzed. Only one-fourth of the female perch we re found to be sexually mature, which was associated with decreased GSI, lo wer P450arom activity, and reduced circulating levels of steroids. The repr oductive disorders observed indicates disturbed endocrine function(s), arre sting the majority of the female perch in a sexually nonreproducible immatu re stage. This novel study is the first to report evidence for endocrine di sruption in wild populations of fish living in a lake exposed to leakage wa ter from a public refuse dump. (C) 2001 Academic Press.