Carbon Sinks and Ocean Acidification in Canadian Coastal Waters

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Oceans absorb a significant amount of carbon dioxide (CO2) from the atmosphere. This slows the rate of climate change, but causes ocean acidification. Ocean acidification has negative impacts on certain marine organisms, including some economically important species of shellfish and crustaceans. The cycling of CO2 in seawater is complex, and often involves other greenhouse gases like methane (CH4). This project uses complementary tools and approaches focused on coastal community engagement to study all three aspects (CO2, CH4, and ocean acidification) in both Arctic and southern Canadian seas. In the Arctic, marine CO2 and CH4 cycles are poorly understood. Sea ice is thought to play an important role, but we lack the fundamental studies to properly include gas exchange in models of icy oceans. Rivers are also important, but it is uncertain how much CO2 and CH4 they deliver to the coastal ocean. This project will study gas exchange in the presence of sea ice using an innovative weather station we have built in collaboration with community partners on a small island near Cambridge Bay (Nunavut, Canada). By directly measuring CO2 exchange at this station, we can assess the sea ice and ocean conditions that drive gas transport. Using a community-based sampling approach, we will collect measurements of dissolved CO2 and CH4 beneath Arctic lakes, in rivers, and in estuaries. These studies will allow us to investigate the movement of greenhouse gases from freshwater systems to the ocean, and what happens once they arrive there. This project will also investigate ocean acidification on southern Canadian coasts. Although in a very different environment, this research is linked to our Arctic work through a common topic (CO2 absorption in seawater), common tools, and a common focus on coastal communities. We will work with aquaculture operators and other harvesters to test the ability of low-cost sensors to detect dangerous ocean acidification events. We will also develop new methods of sample collection that will enable "citizen scientists" to collect high quality ocean acidification data. By linking high quality measurements with mortality events observed by harvesters, we will investigate the emerging risks to aquaculture and wild fisheries in Canada. The impacts of this research will be: 1) improved budgets of greenhouse gas cycles in Arctic seas, a critical component of Canada's Paris Agreement obligations; 2) new methods for modeling gas exchange in the presence of sea ice that can be applied to the circumpolar Arctic and Antarctic; 3) new strategies for monitoring and mitigating the effects of ocean acidification. All aspects of this research program rely on coastal communities, and provide space for meaningful collaborations. The project is designed to learn from Indigenous (particularly Inuit) communities to find ways for natural science to advance community priorities and build local capacity for environmental monitoring and research.