Altered development and reproduction in mosquitofish exposed to pulp and paper mill effluent in the Fenholloway River, Florida USA.

Female mosquitofish exposed to pulp and paper mill effluent (PME) in the Fenholloway River, Florida, USA have masculinized secondary sex characteristics and altered aromatase enzyme activity. We and others have shown that the Fenholloway River PME contains androgenic and progestogenic substance(s). The present study was designed to test the hypothesis that the development and reproductive health of PME-exposed Fenholloway River mosquitofish are altered compared to mosquitofish living in Econfina River, which is the reference site. Fish were collected on a single day from both sites in June and August 1999 and January and June 2000. We compared standard length, anal fin length and segment number; body, liver, and gonad mass; and number of eggs and embryos from Fenholloway and Econfina River mosquitofish. The data were analyzed collectively for generalized site effect, for site effects during reproductive and nonreproductive seasons, and for repeatability of site effects between years. Mosquitofish exposed to PME in the Fenholloway River were generally smaller in length and mass, anal fin segment number was greater, and the number of embryos, but not oocytes, was significantly decreased compared to the reference site fish. Anal fin length and segment number and liver and testis masses were generally greater in Fenholloway compared to the Econfina River males. The importance of this study is that we have documented masculinized development and decreased embryo production in PME-exposed mosquitofish and that these site effects are generally consistent across seasons and between years.