Impacts on zooplankton of ongoing changes in the physics,
chemistry and biota of South-central Canadian lakes
Presenta: Norman Yan - (York University, Department of Biology, Toronto, ON, Canada)
New environmental issues are arising, even for the relatively remote, visually pristine, soft-water lakes of Canada. Using large scale (300 lakes) and long-term (35 year) data sets, Yan will show that while progress has been made on past environmental issues (eg. lake acidification and shoreline development), there are new widespread challenges, including rising temperatures, Natural Organic Matter (NOM) and Cl levels, falling Ca levels, and the spread of new predators including Bythotrephes. Yan will demonstrate that Canadian zooplankton: i) are threatened by Bythotrephes, Ca decline and road salt; ii) that native species differ enormously in their sensitivity to these threats; iii) that interactions of the stressors worsen the threat, eg., interactions of Bythotrephes with Ca decline, and oligotrophication with road salt; iv) and that rising levels of NOM have real but poorly understood effects on daphniid growth rates. We have made enormous strides in solving past environmental problems, but will likely not solve the current ones without understanding interactions of these emerging stressors.
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