From ice to ocean: Understanding the impacts of melting glaciers on marine biogeochemical cycles

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Climate change is the defining challenge of our times, fundamentally reorganizing our planet's ecosystems and the human societies they support. Nowhere is this more evident than in Canada's Arctic, where melting glaciers define the landscape. While the contributions of these shrinking ice masses to sea level rise are undisputed, their role in broader biogeochemical cycling is just beginning to be revealed. When glaciers melt, they contribute large quantities of water, ice, sediments, and dissolved chemicals to the ocean. Recent work around Greenland and Antarctica shows that glacially-associated nutrients and carbon have the potential to stimulate production at the base of marine food webs with associated impacts up the food chain (e.g., enhanced local fish harvests) and on the broader carbon cycle via a more active marine biological pump. Yet, knowledge gaps remain about what life-essential elements are exported from glacial systems, what happens to this discharge in the ocean, and what the impacts are on marine microbial communities. Nowhere are these gaps in knowledge more prominent than in the Canadian Arctic Archipelago (CAA) - a region where the role of glacial meltwater in marine biogeochemical cycles is largely unexplored - despite the fact that the CAA is a hotspot for glacial retreat and meltwater runoff to the ocean. Over the next 5 years, my group and I will work to quantify contemporary export of nutrients and carbon from glacial systems, and the associated impact of this export on marine processes and ecosystems. Specifically we will ask: 1) What is the source of biogeochemical constituents (nutrients, carbon) leaving the ice system? 2)What is the fate of glacial meltwater and its associated constituents in the coastal ocean? and 3) How does glacial meltwater impact marine microbial community production, structure, and function? To answer these questions we will conduct novel ice-to-ocean studies, combining field measurements of chemical species with molecular biological assays and laboratory experiments. This approach will address the impact of meltwater interactions close to the glacier termini and at broader regional scales, and target unanswered mechanistic questions. My program will be achieved by HQP using interdisciplinary techniques, bridging oceanography, geochemistry and microbial ecology. Together we will do this work in Jones Sound in the CAA, a region surrounded by glaciers and home to Inuit hamlet of Grise Fiord. The termini of tidewater glaciers here are highly productive waters, serving as hunting grounds for the hamlet. Understanding the drivers of marine production at the base of the food web, and the susceptibility of these drivers to climate change, is important to the long-term health of this northern community, and to coastal Arctic ocean functioning. Collectively, this research is a critical step towards revealing the role of melting glaciers on the marine carbon cycle in the past, present, and future.