Nutrient and Carbon Export from a Tidewater Glacier to the Coastal Ocean
in the Canadian Arctic Archipelago
Abstract
As glaciers melt, a range of glacier 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 can induce upwelling
of deeper nutrient-rich marine water. Also, 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.