Glaciers and Nutrients in the Canadian Arctic Archipelago Marine System

The Canadian Arctic Archipelago (CAA) is vulnerable to climate warming, and with over 300 tidewater glaciers, is a hotspot for enhanced glacial retreat and meltwater runoff to the ocean. In contrast to Greenlandic and Antarctic systems, CAA glaciers and their impact on the marine environment remain largely unexplored. Here, we investigate how CAA glaciers impact nutrient delivery to surface waters. We compare water column properties in the nearshore coastal zone along a continuum of locations, spanning those with glaciers (glacierized) to those without (non-glacierized), in Jones Sound, eastern CAA. We find that surface waters of glacierized regions contain significantly more macronutrients (nitrogen, silica, phosphorus) and micronutrients (iron, manganese) than their non-glacierized counterparts. Water column structure and chemical composition suggest that macronutrient enrichments are a result of upwelling induced by rising submarine discharge plumes, while micronutrient enrichments are delivered directly by glacial discharge. Generally, the strength of upwelling and associated macronutrient delivery scales with the subglacial meltwater discharge. Glacier-driven delivery of the limiting macronutrient, nitrate, is of particular importance for local productivity, while metal delivery may have consequences for regional micronutrient cycling given Jones Sound's important role in modifying water masses flowing into the North Atlantic. Finally, we use the natural variability in glacier characteristics observed in Jones Sound to consider, how nutrient delivery may be affected as glaciers retreat. The impacts of melting glaciers on marine ecosystems through both these mechanisms will likely be amplified with increased meltwater fluxes in the short term, but eventually muted as CAA ice masses diminish.

Automated summary

The Canadian Arctic Archipelago is vulnerable to climate warming, with its glaciers impacting nutrient delivery to surface waters through upwelling and direct discharge. The strength of upwelling and nutrient delivery scales with subglacial meltwater discharge, with potential consequences for local productivity and regional micronutrient cycling. As glaciers retreat, the impacts on marine ecosystems are likely to be amplified initially but eventually muted as the ice masses diminish.