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Regional Overview & Fact Sheet
This is perhaps one of the most unusual marine systems in North America. The primary characteristic of this ecoregion is its Arctic water mass with seasonal ice regimes. Except for the Hudson Bay area, vast and open seascapes are rare in this region. The habitats of this ecoregion are generally comprised of a patchwork of interconnecting bays, fjords, channels, straits, sounds, basins, shoals, sills and gulfs. Its northwestern most border includes Prince Regent and Peel Sounds. The ecoregion encompasses part of Lancaster Sound and waters to the west of Baffin Island, including Foxe Basin, most of the Gulf of Boothia (except its southernmost part), Queen Maud and Coronation Gulfs and extends south into Canada’s most prominent geographical features, Hudson Bay and James Bay. The ecoregion is one of the richest areas for marine mammals in the world. It is also an important habitat for several species at risk, like the beluga whale and polar bear.
Fact Sheet
Arctic water mass and seasonal ice regimes.
minus 2 - 4°C
North Water Polynya in Baffin Bay
shelf (roughly 0–200 m): 89%
slope (roughly 200–2,500/3,000 m): 11%
abyssal plain (3,000+ m): 0%
Note that water depths of 150–400 m are typical. In Hudson and James Bays the waters are shallow (50–150 m).
rocky to muddy
estuaries and mud flats
Moderately high productivity ecosystem (150-300 gCm-2yr-1). Productivity is enhanced in coastal waters, near embayments and estuaries, and near islands with upwelling of nutrient-rich water.
beluga whale, polar bear, Atlantic walrus, narwhal, bowhead whale, peregrine falcon, polar bear
Polynyas of northern Foxe Basin support high densities of bearded seals and walrus
High-density polar bear denning areas of Southampton Island and Churchill, Manitoba
The region supports most of world’s narwhal as well as one-third of North America’s beluga—high density along the west coast of Hudson Bay, particularly Nelson River estuary, in summer; whales in high density are found in North Water Polynya in Baffin Bay in winter.
Adjacent tidal flats and inland marshes are key area for shorebirds and waterfowl.
Hunting and fishing by indigenous peoples, mining on adjacent lands, hydroelectric development on adjacent rivers, deposition of long-range transported pollutants (e.g., PCBs, DDT, mercury).
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Physical and Oceanographic Setting
The coastline in this ecoregion varies considerably. Precipitous fjords and cliffs are common around the coasts of Baffin Island, Lancaster Sound and Nares Strait, whereas Foxe Basin has flat to rolling coastal plains. Massive glaciers along the backbone of Baffin and Ellesmere islands often reach from the mountaintops and into the sea. On the eastern side of Ellesmere Island, glaciers extending into the sea calve (break off) huge icebergs into Nares Strait.
During the long winter, sea ice is jammed fast to the land (“landfast ice”) and extends over the seas as a solid sheet. Polynyas occur throughout the ecoregion and are critically important to wildlife. The ice cover reaches its maximum thickness in May. In the brief spring and summer periods, the ice breaks up. In the northwestern part of the ecoregion, the sea ice normally shatters into massive sheets that are separated by narrow channels of open water; the sea ice persists throughout the summer. In the rest of the ecosystem, the ice is more seasonal. In summer, the massive sheets of ice fracture, drift, and melt away. The process can be very dramatic. Shorelines can be markedly scoured by drifting fragments of ice, or huge ice jams can be driven up on the beaches. As the summer period proceeds, open water can be found further and further north. From year to year, ice conditions are so variable and unpredictable; however, that mariners and navigators of even the most technologically advanced ships can still find themselves blocked. By September, most of the sea ice in the southeasterly parts has either melted or drifted away on southerly currents.
Foxe Basin itself is rarely ice-free until late August or early September; open pack ice is common throughout the short summer. Vigorous tidal currents and strong winds keep the pack ice in constant motion and contribute to the numerous polynyas and shore leads which are found throughout the region. This same motion, combined with the high sediment content of the water makes the sea ice of Foxe Basin dark and rough, easily distinguishable from other ice in the Canadian Arctic. In Hudson Bay, the ice cover season is shorter lasting from October to June. Shore leads along the entire inner edge of the bay are often kept open through the winter by strong prevailing winds, separating the land fast ice along the coast from the pack ice which predominates in most of the bay.
Long periods of daylight in the short summer help stretch the short productive season, but air temperatures remain chilly. Even in July, mean daily air temperatures average just 10ºC. In winter, air temperatures average about -30ºC, and often much lower. In the southern range of the ecosystem lie Hudson and James bays, where the waters are amongst the shallowest (50–150 m) and the climates are the most temperate.
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Biological Setting
During the brief Arctic summer, dozens of species of migrating birds make use of the unpredictable sections of open water that appear in the ecosystem. As the pack ice breaks up, ice edges become vital areas for mammals and seabirds. The region provides an example of marine and terrestrial ecosystems that are intricately linked—species like polar bear and Arctic tern, for example, roam between land and sea. Although relatively little is known about the Hudson Bay/Boothian Ecoregion, recent studies are proving it to be both biologically rich and diverse. The numerous polynyas in the northern Foxe Basin support high densities of bearded seals and the largest walrus herd in Canada (over 6,000 individuals). Ringed seal and polar bear are common, with north Southampton Island and Churchill, Manitoba bearing two of the highest density polar bear denning areas in Canada. This region is also one of the richest in marine mammals in the world. Most of the world's narwhal and a third of North America's beluga, as well as the endangered eastern population of bowhead whale, spend the summer in these waters; many whales winter in the North Water Polynya in Baffin Bay. Upwards of 20,000 belugas spend their summers along the west coast of Hudson Bay, with the densest concentrations in the larger estuaries, notably that of the Nelson River. Polar bears' annual autumn concentrations along the Cape Churchill coast are also quite exceptional as they gather to await the return of the ice and good feeding. Walrus tend to concentrate around the major polynyas. Some 20,000 to 50,000 harp seals spend the summer in these waters. This region also has one of the highest population densities of polar bear in the Canadian Arctic.
The Hudson Bay tidal flats and inland marsh areas harbor some of the world’s largest concentrations of breeding, moulting and migrating shorebirds and waterfowl. About one-third of eastern Canada’s colonial seabirds breed and feed in Lancaster Sound, including more than 700,000 pairs of thick-billed murres, black-legged kittiwakes and northern fulmars. There are also several thousand pairs of black guillemot; Arctic tern; and glaucous, Iceland and ivory gulls; many of these species use the ecoregion to breed. Large colonies of greater snow goose are located in the region as well. Thousands of waterfowl, notably tundra swan, brant, greater white-fronted, Ross’s, snow geese and Canada geese, common eider, oldsquaw, and yellow-billed loon breed, moult and stage in the area.
The largest bird concentrations are within the Queen Maud Gulf Migratory Bird Sanctuary, including most of the world’s population of Ross's goose. Several shorebird species are also abundant nesters. The region is the main North American stronghold of the Sabine’s gull, with some 10,000 pairs nesting here. The Great Plain of the Koukdjuak on Baffin Island is the world’s largest goose nesting colony, with upwards of 1.5 million birds, 75 percent of which are lesser snow geese and the remainder Canada geese and brant. Shorebirds and ducks are also abundant, and more than a million cliff-nesting seabirds breed throughout the region, notably thick-billed murres, black-legged kittiwakes and northern fulmars. The region harbors some of the most important North American breeding sites for the Hudsonian godwit and whimbrel, as well as one of the world’s largest breeding concentrations of peregrine falcon.
Although some 30 fish species have been reported for the northern portion of the region, one species—Arctic cod—makes up most of the diet of various seabirds and marine mammals. Large schools of this species have been observed in the region. Greenland cod and Arctic char are also common. Some 40 to 50 freshwater, anadromous and Arctic and subarctic marine fish species are found in the waters of the southern portion of the region, with Arctic char, capelin, Arctic cod, Greenland cod, sculpins and blennies being the most abundant.
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Human Activities and Impacts
The ecoregion is located mostly in the Nunavut Territory, although it also encompasses parts of the coasts of Quebec, Ontario and Manitoba. Canada’s Inuit find most of their traditional food in this region—hunting and fishing therefore remain significant human activities. As mineral prospectors gain more experience in northern latitudes, large mineral deposits may be found, raising questions about mine waste and tailings that could find their way into the sea (MEQAG 1994; Wiken et al.1996). To the south, hydroelectric development will likely continue on the rivers draining into James Bay. Changes in water flow, salt content, and the presence of heavy metals leached from the soil will have unpredictable consequences for the southern portion of the region. The long-range transport of pollutants—such as PCBs, DDT and mercury—from distant places has impacts on the region and adjacent areas as well. Moreover, the possibility that climate change may influence the regimes of ice formation raises concerns about the possibility of commercial shipping routes opening in the future (Wiken et al.1996; WHC 2001), as well as long-term changes to the ecology of the region.
Level II and Level III Descriptions
Level II captures the break between neritic (near shore) and oceanic areas and is determined by large-scale physiography (continental shelf, slope, and abyssal plain, as well as areas of oceanic islands and major trenches, ridges and straits). This level reflects the importance of depth as a major determinant of benthic marine communities as well as the importance of major physiographic features in determining current flows and upwelling. Like Level I, it extends from the coasts to the EEZ.
Level III captures differences within the neritic realm and is based on more locally significant variables (local characteristics of the water mass, regional landforms, as well as biological community type). Level III is limited to the continental shelf, since only this area has sufficient information for finer-scale delineation.
Level II and Level III Ecoregions
Other Marine Ecoregions
Marine ecoregions are areas of general similarity in terms of physiographic, oceanographic and biological characteristics, which fall within the Exclusive Economic Zones of the North American countries. There are 24 marine ecoregions in North America.
