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Research article - Peer-reviewed, 2021

Municipal wastewater as an ecological trap: Effects on fish communities across seasons

Mehdi, Hossein; Lau, Samantha C.; Synyshyn, Caitlyn; Salena, Matthew G.; McCallum, Erin S.; Muzzatti, Melissa N.; Bowman, Jennifer E.; Mataya, Kyle; Bragg, Leslie M.; Servos, Mark R.; Kidd, Karen A.; Scott, Graham R.; Balshine, Sigal

Abstract

Municipal wastewater treatment plant (WWTP) effluents are a ubiquitous source of contamination whose impacts on fish and other aquatic organisms span across multiple levels of biological organization. Despite this, few studies have addressed the impacts of WWTP effluents on fish communities, especially during the winter-a season seldom studied. Here, we assessed the impacts of wastewater on fish community compositions and various water quality parameters during the summer and winter along two effluent gradients in Hamilton Harbour, an International Joint Commission Area of Concern in Hamilton, Canada. We found that fish abundance, species richness, and species diversity were generally highest in sites closest to the WWTP outfalls, but only significantly so in the winter. Fish community compositions differed greatly along the effluent gradients, with sites closest and farthest from the outfalls being the most dissimilar. Furthermore, the concentrations of numerous contaminants of emerging concern (CECs) in the final treated effluent were highest during the winter. Water quality of sites closer to the outfalls was poorer than at sites farther away, especially during the winter. We also demonstrated that WWTPs can significantly alter the thermal profile of effluent-receiving environments, increasing temperature by as much as similar to 9 degrees C during the winter. Our results suggest that wastewater plumes may act as ecological traps in winter, whereby fish are attracted to the favourable temperatures near WWTPs and are thus exposed to higher concentrations of CECs. This study highlights the importance of winter research as a key predictor in further understanding the impacts of wastewater contamination in aquatic ecosystems. (C) 2020 Elsevier B.V. All rights reserved.

Keywords

Wastewater treatment plant effluent; Great Lakes; Hamilton Harbour; Biodiversity; Seasonality

Published in

Science of the Total Environment
2021, Volume: 759, article number: 143430
Publisher: ELSEVIER

    Sustainable Development Goals

    SDG6 Clean water and sanitation
    SDG14 Life below water

    UKÄ Subject classification

    Ecology
    Environmental Sciences

    Publication identifier

    DOI: https://doi.org/10.1016/j.scitotenv.2020.143430

    Permanent link to this page (URI)

    https://res.slu.se/id/publ/110506