Details

Autor(en) / Beteiligte

• Bhatia, Maya P.
• Waterman, Stephanie
• Burgess, David O.
• Williams, Patrick L.
• Bundy, Randelle M.
• Mellett, Travis
• Roberts, Megan
• Bertrand, Erin M.

Titel

Glaciers and Nutrients in the Canadian Arctic Archipelago Marine System

Ist Teil von

• Global biogeochemical cycles, 2021-08, Vol.35 (8), p.n/a

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2021

Quelle

Wiley Blackwell Single Titles

Beschreibungen/Notizen

• 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. Plain Language Summary The Canadian Arctic Archipelago (CAA) contains many glaciers that are vulnerable to global warming. Many of these glaciers terminate in the ocean, meaning that as they melt, they deliver materials directly into the coastal ocean, often below the sea surface. This glacier meltwater can deliver nutrients that may enhance marine productivity, but this has not yet been systematically examined in the CAA. Here, we compare concentrations of essential macronutrients (nitrogen, silica, phosphorus), and micronutrients (iron, manganese) in areas with glaciers and without, in the Jones Sound region of the CAA. We find elevated concentrations of nutrients in marine waters surrounding areas with glaciers. The source of macronutrients are deeper marine waters that are carried to the surface by rising glacier meltwater entering the ocean below the sea surface, while the source of micronutrients is glacier meltwater itself. Much of the water that flows from the Arctic Ocean into the North Atlantic does so through CAA passageways that receive this glacier input. Understanding how glacier‐driven nutrient delivery is likely to change as the climate continues to warm will help us predict changes in marine productivity both locally in the CAA and in regions of the North Atlantic that receive CAA water. Key Points Marine waters fed by tidewater glaciers in the Canadian Arctic have elevated macro‐ and micro‐nutrient concentrations Upwelling of deeper marine waters drives macronutrient enrichments, while micronutrient enrichments are driven directly by glacial discharge As Canadian Arctic glaciers melt, local and regional marine productivity may be impacted by changes in nutrient delivery