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WP9 Endocrine Disruption: Fish Estrogenicity
(477) Relationship between changing effluent quality and reproductive effects in Eastern gambusia.
Noggle, J1, Bradley, W2, Smith, J3, Gross, T1, 3, 1 University of Florida, Gainesville, FL, USA2 NCASI/Southeastern Aquatic Biology Center, Vanceboro, NC, USA3 USGS/FISC Center for Aquatic Resource Studies, Gainesville, FL, USA
ABSTRACT- Over the past 4 years our laboratory has studied Eastern gambusia (Gambusia holbrooki) exposed to pulp and paper mill effluent. At our primary study site, Rice Creek in Palatka, FL, the discharging mill has installed several process modifications that have improved effluent quality. The current objective was to evaluate gambusia reproduction as effluent quality improved. Reproductive effects included secondary sex characteristics (anal fin morphology), sex steroids, gonadal histology, and brood size. For comparison, we evaluated additional collections of gambusia from two other effluent-receiving streams, Elevenmile Creek and Fenholloway River. These systems have historically contained females with anal fin elongation (development of a gonopodial-like structure typical of males). Neither mill was undergoing process changes at the time of collection, so exposure was considered relatively static. In response to process changes, female anal fin elongation was reduced but not eliminated. Significant elongation remained at effluent sites (average 1.15 ray 4÷ray 6), but disappeared further upstream compared to collections before process changes. At the Fenholloway, significant elongation occurred at all effluent-exposed sites, while there was a lack of elongation at Elevenmile. Collectively, these data indicate process changes ongoing at Rice Creek and already in place at Elevenmile Creek are removing effects on anal fin elongation. Similarly, hormone responses (E:T ratio<1) are no longer significant following process changes. Regardless of these effects, likelihood of reproduction (gonadal histology and brood counts) was not affected in all three systems. Current studies are expanding reproductive capacity endpoints to boost sample size and restrict brood counts to one female size range. In addition, fry production and population structure are being studied to begin addressing reproductive success.
Key words: reproduction, gambusia, pulp and paper mill effluent, chlorine dioxide substitution
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