From aquatic food webs to our tables: the influence of exotic invasion on nutritional provisioning and contaminants in sport fish

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The project goal is to integrate food web analytical tools and ecosystem modelling to understand the trophic role of the invasive round goby fish on aquatic food web quality and Hg bioaccumulation in the St. Lawrence River (SLR). The project is a partnership with the St. Lawrence River Institute of Environmental Sciences ('The River Institute'; non-government organisation) and it will train 1 PhD student + several BSc students. We will address the ecosystem-level problem in the Upper SLR using food web tracers: stable isotopes, fatty acids, and MeHg trophic transfer, at 8 trophic levels of the food web per site, across 9 to 30 sites. These metrics will be measured at sites that span spatial environmental gradients in dissolved organic carbon, nutrients, and invasion load across three fluvial lakes of the Upper SLR (Lake St. Francis, Lac St. Louis, et Lac des Deux Montagnes), and will be related with round goby invasion. In Lake St. Francis, ecosystem models will be applied to address how dressenid mussel and round goby invasion have modified the biological and physicochemical properties from primary producers to aquatic birds, using both historical and contemporary data. The partner will provide expertise and infrastructural support on fish ecology and mercury transfer in the food web, as well as share historical data on the eastern Ontario section of Lac St. Francis. The Upper SLR has an economically important sportfish industry, and the Alliance research project will provide information about how the interplay of multiple stressors plays out for contaminant loads and fitness of sportfish in this ecosystem. The research outcomes will strengthen community partnership of The River Institute with founders of the organisation and core stakeholders in the SLR, such as The Mohawks of Akwesasne. More generally, the project will provide insight into how the interplay of exotic invasion and other environmental stressors play out for contaminant loads and nutrient provisioning of sportfish for people. The Alliance research project could impact government policy on guidelines for sportfish consumption for balancing the risks of mercury exposure with the benefits of nutritional provisioning in the Great Lakes and the SLR.