A New Ecological Framework for Adverse Outcomes of Contaminants on Ecosystems: Microplastics as a Case Study

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Plastic pollution is now recognized as a global issue. Scientists have found plastic debris virtually everywhere they have looked, from densely populated cities to remote ecosystems. Most plastics found in the environment are microplastics, which primarily come from the breakdown of larger pieces of litter. Microplastics are challenging our scientific understanding of contaminants because they are both particles and a complex mix of chemicals. High doses of microplastics can harm animals in various ways, such as obstructing the gut or releasing toxic chemicals. However, we don't know if current levels of microplastic pollution are causing harm to the environment. Our knowledge of this issue in Canada is limited, despite microplastics being recently found in rivers and lakes across the country. With funding from NSERC, I will examine the effects of microplastics on structure and function of freshwater ecosystems. More simply, my research will give us new insights into how microplastics change which species thrive in lakes, as well as how quickly critical processes happen in these ecosystems. This work is timely and relevant because virtually every scientific review written about microplastics points to the lack of information on how these contaminants impact higher levels of biological organization. Notably, this was echoed in the recently released Canadian Plastics Science Agenda. My research directly addresses this high-priority research need. In this grant, I propose to add microplastics to `mini-lakes' of increasing complexity. Starting with water only, subsequent experiments will phase-in microscopic plants, followed by small invertebrates, and culminating in the addition of vertebrates. This elegant design allows what we learn at one level of complexity to inform the next. In our model ecosystems, we will monitor how the community, as well as rates of critical ecosystem functions, respond to different levels of pollution. My research will contribute to environmental science and policy in Canada. My research will generate scientific evidence as to if, and if so how, microplastics negatively impact freshwater lakes and the characteristics of these ecosystems we most value as a society. I expect my research to generate intriguing hypotheses that will drive future research in ecology and ecotoxicology and support evidence-based policy decisions for managing potential threats posed by microplastic pollution. More broadly, my program is pioneering a new ecological framework for an established toxicological approach to link contaminant exposure with adverse outcomes. Doing so would be a significant advance because my field has been struggling for decades to put the `eco' into ecotoxicology. Such a framework has strong potential to be adopted internationally to assess environmental risks of toxic chemicals.