Nutrient and Carbon Export From a Tidewater Glacier to the Coastal Ocean in the Canadian Arctic Archipelago

A range of glacially driven processes modify and export freshwater and sediments to the ocean. This glacial runoff may influence biological productivity in coastal ecosystems by supplying essential nutrients and labile carbon. Previous studies of glacial meltwater export to the ocean have primarily been conducted on rivers draining land‐terminating glaciers, or in fjords with large tidewater glaciers. These studies speculate about downstream effects (river studies) or upstream causes (fjord studies) of differing carbon and nutrient availability and biological productivity, but do not measure them. Here, we conduct the first ice‐to‐ocean study at a marine‐terminating glacier in the Canadian Arctic Archipelago (CAA). We characterize the nutrient and carbon content of ice and meltwater collected on the glacier surface, at its margins, and in the near‐shore coastal ocean, all within 1 to 25 km of the glacier terminus. Results demonstrate that while meltwater from a shallow tidewater glacier did not directly increase downstream carbon and nutrient concentrations, it induced upwelling of deeper nutrient‐rich marine water. Although carbon concentrations in meltwater were low, results show that this carbon is potentially more bioavailable than marine carbon. Glacially mediated delivery of labile carbon and upwelling of nutrient‐rich water occurs in summer, when surface waters are nutrient‐limited. Collectively, these processes could benefit surface marine plankton, potentially stimulating production at the base of the food web. Shallow tidewater glaciers are commonly retreating in Arctic regions like the CAA and Svalbard, and understanding how increased meltwater output from these systems impacts marine ecosystems is critical. Plain Language Summary As glaciers melt, nutrients and carbon contained in runoff may impact recipient marine ecosystems. The last study to explore the relationship between tidewater glaciers and nutrient availability in the Canadian Arctic Archipelago (CAA) was in the 1970s. Here, we measure nutrient and carbon concentrations in ice, glacial melt, and marine waters in front of a shallow tidewater glacier in the CAA. We find that nutrient and carbon concentrations in glacial melt are not high enough to augment downstream marine concentrations, but the composition of glacial dissolved organic matter indicates it is more bioavailable than marine carbon. Additionally, with the release of submarine discharge at the terminal ice front, glacial me