Mercury Bioaccumulation in Lacustrine Fish Populations Along a Climatic Gradient in Northern Ontario, Canada
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Mercury Bioaccumulation in Lacustrine Fish Populations Along a Climatic Gradient in Northern Ontario, Canada A. W. Sumner,1 T. A. Johnston,2* G. L. Lescord,1 B. A. Branfireun,3 and J. M. Gunn1 1
Cooperative Freshwater Ecology Unit, Biology Department, Vale Living with Lakes Centre, Laurentian University, Sudbury, Ontario P3E 2C6, Canada; 2Ontario Ministry of Natural Resources and Forestry, Cooperative Freshwater Ecology Unit, Vale Living with Lakes Centre, Laurentian University, Sudbury, Ontario P3E 2C6, Canada; 3Department of Biology and Centre for Environment and Sustainability, Western University, London, Ontario N6A 5B7, Canada
ABSTRACT Climate change is predicted to alter many processes in boreal aquatic ecosystems, including mercury (Hg) bioaccumulation in fish. We investigated current patterns in fish Hg across a climatic gradient in northern Ontario, Canada, to assess the possible influence of further climate change. Cohabiting populations of walleye (a piscivore) and white sucker (a benthivore) were sampled from lakes spanning over 9.0 of latitude (45 24¢ N–54 20¢ N). Latitudinal trends were evident in climatic conditions, as well as several other ecosystem characteristics over this range. Muscle total Hg concentration ([THg]) was modelled with respect to climatic variables as well as other physical, chemical, and biological variables, and all models were ranked by Akaike information criterion. Neither long-term mean temperature nor precipitation was a strong predictor of current muscle [THg] in either species across this region. Instead, drainage basin
Received 10 March 2019; accepted 4 November 2019 Electronic supplementary material: The online version of this article (https://doi.org/10.1007/s10021-019-00464-9) contains supplementary material, which is available to authorized users. Author’s Contributions AWS, TAJ, and JMG designed study; AWS, TAJ, and GLL performed research and analysed data; AWS, TAJ, GLL, BAB, and JMG wrote the paper. *Corresponding author; e-mail: [email protected]
characteristics (for example, mean slope) and lake water chemistry (for example, [DOC], [SO4]) were the strongest predictors, followed by fish biological traits (for example, muscle d13C). Walleye [THg] was more strongly related to water chemistry, and white sucker [THg] was more strongly related to drainage basin physical characteristics. For both species, muscle [THg] showed unimodal relationships with several predictors (for example, latitude, [SO4], [DOC]), peaking in their mid-ranges. Fish [THg] is not strongly associated with current climatic conditions across northern Ontario but may be influenced by climate change in future through indirect effects on water chemistry and food web structure. Key words: freshwater; limnology; climate; contaminants; landscape; latitude.
HIGHLIGHTS Fish mercury concentrations do not increase monotonically with latitude in Ontario. Variation in fish mercury among Ontario lakes is
A. W. Sumner and others not strongly related to climate. Variation in fish mercury is
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