Arctic Marine Biogeochemistry

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The Arctic Ocean plays an important role in the global climate system as a sink for atmospheric CO2. However, the Arctic marine system is changing rapidly and unpredictably in response to global climate change, with potential consequences for its CO2 uptake potential, and its sensitivity to ocean acidification. Over the past few decades, observed changes in sea ice, river discharge, and coastal permafrost have altered both the Arctic freshwater system and the marine carbon cycle. Unfortunately, our understanding of the influences of these changes is still limited in certain sectors, including the Canadian Arctic Archipelago, hindering our ability to assess their present and future impacts on the coastal ecosystem. Overall, understanding the influences of Arctic warming on freshwater and the marine carbon cycle will be crucial to predicting the impacts of ocean acidification on coastal ecosystem dynamics and the long-term changes in the Arctic Ocean's ability to act as an important CO2 sink. The proposed research will investigate the influences of freshwater source (sea ice melt, rivers), location (regional variability), and timing (seasonal and inter-annual variability) on carbon cycle processes along the Canadian Arctic Archipelago coastline. In particular, the objectives of this research are to: (i) characterize carbon and nutrient exchanges across the river-ocean mixing zone and identify the key processes that modify carbon along this gradient; (ii) determine the seasonal roles of different sources of freshwater (sea ice melt, river runoff) in setting the CO2 sink-source status of the coastal ocean and sensitivity to ocean acidification; and (iii) examine how local carbon-cycle processes cascade in scale to affect regional carbon-dynamics. These objectives will be achieved by tracking freshwater along the land-to-sea mixing gradient at strategic locations throughout the southern Canadian Arctic Archipelago and will be carried out in close collaboration with northern communities. Engaging northern community members as a core component of this research will generate opportunities to integrate local Indigenous Knowledge, providing a unique understanding of the long-term drivers of coastal ecosystem change. Insights generated through these collaborations will support the development and application of ecosystem models that will be used to predict future ocean acidification states and changes to the CO2 sink-source status of Arctic coastal seas.