CHEEK*, AO; FENTRESS, JA; STEELE, SL; BART, HL, Jr.; Southeastern Louisiana Univ., Hammond; Southeastern Louisiana Univ., Hammond; Southeastern Louisiana Univ., Hammond; Tulane Univ., New Orleans, LA: Reproductive disruption in wild longear sunfish (Lepomis megalotis)

Endocrine disruption is the alteration of normal hormone function by man-made chemicals in the environment. The goal of this project was to estimate the extent of hormone disruption in a wild population of longear sunfish Lepomis megalotis spawning in a river receiving paper mill effluent. To estimate mobility of adult longear, we marked 697 fish at four sites. We recaptured 18 fish (2.6%), 83% of which were recaptured at the site of initial capture. This suggests that adults do not migrate up or downstream very much, so fish downstream of the paper mill outfall are probably receiving long term exposure to potential endocrine disrupting compounds. We took blood samples bimonthly during the spawning season (Apr – Jul) and monthly in the late summer, fall and winter (Aug – Mar), then analyzed the levels of testosterone (T), estrogen (E2), 11-ketotestosterone (11KT), and vitellogenin (VTG) in males and females. VTG and E2 were elevated in females during the spawning season and declined in September. T and 11KT profiles in males paralleled each other and showed two to three peaks during the spawning season, suggesting that males have bouts of spawning and nest guarding. 11KT in females was elevated at the same time as in males. Male reproductive parameters were unaffected by paper mill effluent. However, females downstream had significantly lower T levels and VTG levels declined steadily throughout the spawning season, rather than remaining elevated as occurred in upstream females. Female E2 and 11KT were unaffected. We conclude that subtle alterations in endocrine function are occurring in female, but not male longear in the Pearl River due to paper mill effluent.