Will northern fish populations be in hot water because of climate change?

Authors

  • SAPNA SHARMA,

    1. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3G5,
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  • DONALD A. JACKSON,

    1. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3G5,
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  • CHARLES K. MINNS,

    1. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3G5,
    2. Great Lakes Laboratory for Fisheries and Aquatic Sciences, Department of Fisheries and Oceans Canada, Burlington, ON, Canada L7R 4A6,
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  • BRIAN J. SHUTER

    1. Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3G5,
    2. Aquatic Research, Ontario Ministry of Natural Resources, c/o Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3G5
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Sapna Sharma, e-mail: ssharma@zoo.utoronto.ca

Abstract

Predicted increases in water temperature in response to climate change will have large implications for aquatic ecosystems, such as altering thermal habitat and potential range expansion of fish species. Warmwater fish species, such as smallmouth bass, Micropterus dolomieu, may have access to additional favourable thermal habitat under increased surface-water temperatures, thereby shifting the northern limit of the distribution of the species further north in Canada and potentially negatively impacting native fish communities. We assembled a database of summer surface-water temperatures for over 13 000 lakes across Canada. The database consists of lakes with a variety of physical, chemical and biological properties. We used general linear models to develop a nation-wide maximum lake surface-water temperature model. The model was extended to predict surface-water temperatures suitable to smallmouth bass and under climate-change scenarios. Air temperature, latitude, longitude and sampling time were good predictors of present-day maximum surface-water temperature. We predicted lake surface-water temperatures for July 2100 using three climate-change scenarios. Water temperatures were predicted to increase by as much as 18 °C by 2100, with the greatest increase in northern Canada. Lakes with maximum surface-water temperatures suitable for smallmouth bass populations were spatially identified. Under several climate-change scenarios, we were able to identify lakes that will contain suitable thermal habitat and, therefore, are vulnerable to invasion by smallmouth bass in 2100. This included lakes in the Arctic that were predicted to have suitable thermal habitat by 2100.

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