Science Advisory Report 2021/052
Identification of Ecological Significance, Knowledge Gaps and Stressors for the North Water and Adjacent Areas
- The North Water is a distinctive geographic and oceanographic region in northern Baffin Bay, characterized by one of the largest recurring polynyas in the Arctic. The importance of the region is attributed to:
- Patterns of atmospheric and oceanic circulation producing dominant north winds and ocean currents pushing sea ice from the Arctic Ocean south through Baffin Bay;
- Narrow channels that promote the formation of ice bridges in Nares Strait, Kane Basin, and Smith Sound, preventing the southward movement of sea ice, and leading to reduced sea ice cover south of Smith Sound;
- Nutrient rich waters that originate from both the Arctic (cold Pacific Water via the Bering Sea) and the North Atlantic (warm water via Davis Strait flowing north along west Greenland);
- Ocean circulation patterns and wind dynamics that encourage the upwelling or upward mixing of the nutrients imported at depth with the Pacific and Atlantic waters; and,
- Extended ice-free (or reduced ice cover) season that promotes a long productive period.
- Glaciers are important features in the vicinity of the North Water and meltwater from glaciers and ice caps likely comprise the greatest source of local freshwater runoff into the region. The mechanisms and overall input of freshwater by glaciers and ice caps into coastal/fiord environments are currently understudied, especially on the Canadian side of the North Water.
- The North Water is a highly biologically productive area, and the magnitude and timing of productivity is dependent on complex physical and biogeochemical controls (e.g., timing of the polynya formation, stratification and mixing, influence of different water masses), which vary across the region. The consequences of the magnitude and duration of productivity in the North Water are further enhanced by efficient energy transfers to the food web.
- The early phytoplankton blooms are supported by the reduced sea ice cover compared to surrounding areas, and the tight coupling between primary productivity and zooplankton provide early food for filter feeders, such as benthic species, and is fundamental in supporting fishes and birds.
- The North Water is an important site for gas exchange; this region is considered a sink for anthropogenic CO2, the magnitude of which is strongly impacted by regional forcing, including freshwater input, seawater properties (e.g., temperature), sea ice conditions, and biological processes, in particular photosynthesis and respiration.
- The North Water can be characterized by high regional biodiversity. Specifically, the Canadian side of the North Water is considered a hotspot for benthic community biodiversity. Functional diversity of the benthic community in the North Water is among the highest in the Canadian Arctic.
- Arctic Cod (Boreogadus saida) is a key species for the entire food web and potential changes in its abundance and/or distribution would result in cascading effects on the energetics of higher trophic levels.
- Two commercially important fish species in the Arctic are Northern Shrimp (Pandalus borealis) and Greenland Halibut (Reinhardtius hippoglossoides), yet there is limited information on their distribution and abundance in the North Water. Possible range expansion of a commercial trawl and longline fishery for these species represents both an opportunity for northern communities and a potential threat to the ecosystem (i.e., overfishing or bycatch).
- The North Water is a ‘hotspot’ for marine mammals in all seasons, and nine species occur regularly in the region. Endemic Arctic whales (i.e., Beluga [Delphinapterus leucas], Narwhal [Monodon Monoceros], and Bowhead Whale [Balaena mysticetus]) use the region for calving, foraging, and migration; the surrounding sea ice (floe edge) is important habitat for Walrus (Odobenus rosmarus), Ringed Seals (Pusa hispida), Bearded Seals (Erignathus barbatus), and Polar Bear (Ursus maritimus).
- The North Water is a vital feeding and nesting site for millions of migratory seabirds. Coburg Island (Nirjutiqavvik National Wildlife Area) is one of the most important seabird nesting areas in the Canadian Arctic. The Greenland side of the North Water hosts the world’s largest aggregation of Dovekie/Little Auk (Alle alle), and Greenland’s largest colonies of Thick-billed Murres (Uria lomvia) and Black-legged Kittiwakes (Rissa tridactyla). Other important colonies of birds include Common Eiders (Somateria mollissima), King Eiders (Somateria spectabilis), and Sabine’s Gull (Xema sabini).
- The last Canadian nesting site for the endangered Ivory Gull (Pagophila eburnean) is found on Ellesmere Island, close to the North Water. The Ivory Gull and Sabine’s Gull are particularly important species to monitor and protect, since both species have very small populations in Canada and Greenland.
- Coastal areas (i.e., river mouths, cliffs, fiords, and glacier edges) and the floe edge environment near communities are especially important for local hunting of subsistence species, such as Narwhal, Walrus, Ringed Seal, Polar Bear, and various seabirds. Arctic Char (Salvelinus alpinus) is an important subsistence species, and several rivers surrounding the North Water have stocks that utilize the marine environment during the summer months (July-September).
- It is anticipated that the most significant impacts on the North Water ecosystem will be from climate change. Local changes are already being observed, notably extreme weather events, a transition towards a thinner and mechanically weaker ice cover in Nares Strait (increasing sea ice movement through this region), less predictable polynya formation, changes to location and duration of phytoplankton blooms, melting glaciers, and increased water levels (shoreline erosion).
This Science Advisory Report is from the January 22–24, 2020 regional peer review meeting on the Biophysical and Ecological Overview of the North Water Polynya and Adjacent Areas. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.
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