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2C (2) - Biomarkers (WE7/5) Feminisation effects of a municipal effluent to the freshwater mussel Elliptio complanata. Gagné, Francois1, Blaise, Christian1, Trottier, Sylvain1, Salazar, Michael2, Douville, Mélanie1, 1 St.-Lawrence Centre, Montreal, Quebec, Canada2 Applied biomonitoring, Kirkland, Washington, USA ABSTRACT- Municipal effluents are known to contain estrogenic substances that can induce vitellogenesis in both male and female fish species.We tested the hypothesis that mussels exposed to xeno-estrogens discharged from a municipal effluent over a complete cycle of reproduction (1 year) could alter their sex ratio in favor of females. Elliptio complanata mussels were exposed with two different cage designs: one cage was designed to hold mussels in a benthic pen while the other consisted of individualized mussels in nets attached to a PVC frame. The cages were firmly attached to the bottom with spikes and placed upstream (2 km) and downstream of the municipal effluent plume (7 and 10 km) in June 2001. The cages were collected in June 2002 for sex ratio and growth determinations. The results showed that the benthic pen was a superior design because most mussels survived the long-term exposure period because mussels in these cages were able to rise over the accumulated sediments. Mussels collected at both downstream sites had an increased condition factor (i.e., g wet weight/length3) and the proportion of females were significantly (p<0.05) increased at 7 km downstream (64 % females) and 12 km downstream (64 %) with respect to the upstream site (42 % females). Our results suggest that prolonged exposure of freshwater mussels to municipal effluent discharges skews the sex ratio in favor of females and may have adverse effects on bivalve reproduction performance in the long term. Key words: municipal estrogens, vitellin-like proteins, feminization |
