Impacts of Calgary’s Municipal Wastewater Treatment Plant Effluents on Reproduction of Fish in the Bow River

Abstract

The purpose of this study was to investigate the reproductive impairment in fish exposed to treated municipal effluents in the Bow River. Adult fathead minnows were caged at five different sites along the Bow River for 26 days at upstream and downstream from the City of Calgary municipal wastewater treatment plants (WWTPs). The results provide evidence that exposure to treated municipal WWTP effluents discharged into the Bow River adversely affect reproduction in both male and female fish. The evidence is based on changes in gonadosomatic index, spermatogenesis by flow cytometry, gonadal morphology, caspase activity as a measure of apoptosis, measurement of transcripts for enzymes involved in the control of steroidogenesis, and gonadal steroid levels. The results provide evidence that treated WWWP effluents discharged in the Bow River from Bonnybrook and Fish Creek WWTPs contains contaminants of emerging concern with hormone-like activity and highlights a need to improve wastewater treatment process.