Climate change impacts on Canada's Northwest Atlantic Ocean ecosystem: observations, projections, and implications

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Coastal ecosystems are critical components of our biosphere and provide essential services to humans. Deeply transformed over historical times, they continue to be altered by changing human activities. My research program aims to quantify the magnitude of such changes in marine species, habitats, and ecosystems. Over the past 6 years, we have made substantial progress in understanding past and present consequences of exploitation, habitat alteration, pollution, and warming, and have advanced climate-change projection. Most climate-impact projections are employed on global scales with coarse resolution, and little is known how these compare to regional changes. This will be my work's focus over the next 5 years. Our goal is to provide a comprehensive understanding of current and expected changes in marine species, habitats, and ecosystems in Canada's Northwest Atlantic Ocean under different climate-change scenarios over the 21st century. We will build on our previous empirical and modeling studies, expand to other species and habitats, integrate new measures of community and ecosystem change, and contrast regional with global projections. Species-distribution models will project changes in selected commercial species, key habitats, species-at-risk, and invasive species, which will be combined to evaluate hotspots of biodiversity gains, losses, and turnover. Community-level changes with warming waters will be analysed from research trawl surveys and fisheries catch statistics to resolve changes among species, functional and taxonomic groups, and across management areas. Future changes in ecosystem structure and function will be assessed by contrasting regional with global climate and ecosystem models to evaluate shifts in primary and secondary production, food-web composition, and ecosystem indicators under different climate-change scenarios. We will employ multi-model ensembles to compare different approaches and compute model-averaged trends and uncertainty estimates. All results will be integrated to assess implications for management and conservation. For example, maps of shifting species, habitats, and ecosystems will be overlaid with marine protected areas to quantify which areas may serve as climate refugia or hotspots of change, and which may require adaptive measures to ensure effective biodiversity protection under climate change. The proposed research will advance our state of knowledge on climate-change impacts in Canada's ocean and provide insight into how mitigation efforts can halt or reverse projected changes. State-of-the-art ensemble modeling will evaluate the influence of different climate-change assessment approaches which is crucial for decision-making. Our work will inform future marine conservation planning, sustainable fisheries, ecosystem management, and climate-change adaptation for the benefit of Canadians.