VAJDA, Alan M. ; LOPEZ, Elena M.; WOODLING, John D.; MALDONADO, Tammy A.; NORRIS, David O. ; Univ. of Colorado, Boulder; Univ. of Colorado, Boulder; Colorado Division of Wildlife; Univ. of Colorado, Boulder; Univ. of Colorado, Boulder: Reproductive disruption and intersex in white suckers (Catostomus commersoni) downstream of a Colorado wastewater treatment plant

We have identified gonadal intersex and other forms of reproductive disruption in white suckers (Catostomus commersoni) collected downstream of wastewater treatment plant (WWTP) effluent in the Colorado Front Range stream, Boulder Creek. This effluent contains many known endocrine-disrupting chemicals including estrogenic surfactant metabolites (alkylphenols and alkylphenolethoxylates), plasticizers (bisphenol A), and the steroid 17&alpha-estradiol. Fish were obtained by electroshocking during stream surveys conducted by the Colorado Division of Wildlife. Intersex fish were present downstream of WWTP effluent but not at upstream reference sites. The male to female ratio was skewed toward females downstream of the WWTP effluent. Abnormalities in gross gonadal morphology, smaller ovaries, and increased asynchrony of oocyte development were noted in female white suckers downstream of the Boulder Creek WWTP. The reproductive potential of native fishes may be compromised in stream reaches of western states where large volumes of treated wastewater are discharged into relatively small-sized streams. This research was funded by a grant from the US EPA Region 8.