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Research article - Peer-reviewed, 2019

Municipal wastewater effluent affects fish communities: A multi-year study involving two wastewater treatment plants

McCallum, Erin S.; Nikel, Kirsten E.; Mehdi, Hossein; Du, Sherry N. N.; Bowman, Jennifer E.; Midwood, Jonathan D.; Kidd, Karen A.; Scott, Graham R.; Balshine, Sigal


Although effluent from municipal wastewater treatment plants (WWTPs) is a major stressor in receiving environments, relatively few studies have addressed how its discharge affects natural fish communities. Here, we assessed fish community composition over three years along a gradient of effluent exposure from two distinct WWTPs within an International Joint Commission Area of Concern on the Great Lakes (Hamilton Harbour, Canada). We found that fish communities changed with distance from both WWTPs, and were highly dissimilar between sites that were closest to and furthest from the wastewater outfall. Despite differences in the size and treatment technology of the WWTPs and receiving habitats downstream, we found that the sites nearest the outfalls had the highest fish abundances and contained a common set of signature fish species (i.e., round goby Neogobius melanostomus, green sunfish Lepomis cyanellus). Non-native and stress tolerant species were also more abundant near one of the studied WWTPs when compared to the reference site, and the number of young-of-the-year fish collected did not vary along the effluent exposure gradients. Overall, we show that fish are attracted to wastewater outfalls raising the possibility that these sites may act as an ecological trap. Crown Copyright (C) 2019 Published by Elsevier Ltd. All rights reserved.


Water quality; Anthropogenic impacts; Great lakes; Ecotoxicology; Contaminants

Published in

Environmental Pollution
2019, Volume: 252, pages: 1730-1741

    Sustainable Development Goals

    SDG6 Clean water and sanitation

    UKÄ Subject classification

    Fish and Aquacultural Science
    Environmental Sciences

    Publication Identifiers


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