Boundaries

This ecoregion covers the Canadian islands of Nunavut north of the Arctic Circle. It is bounded by the Beaufort Sea to the west; the Arctic Ocean to the north; Greenland, Baffin Bay, and Davis Strait to the east; and the Canadian mainland and Hudson Bay to the south. The larger islands include Baffin, Prince of Wales, Victoria, Banks, Ellesmere, Axel Heiberg, and Devon islands. These islands are separated from each other and the mainland by waterways known as the Northwestern Passages.

Topography

The western part of the Canadian Arctic Archipelago ecoregion is underlain by sedimentary bedrock. Lowland plains are covered with glacial moraine, marine deposits, and bedrock outcrops. Much of Victoria Island, the northeastern portion of Banks Island, and the Dundas Peninsula on Melville Island are composed of Ordovician and Silurian sediments that are 400-500 million years old. Steep, high cliffs have formed from uplifts along fault lines. Glacial landforms, including drumlins, moraines, and raised beaches, also characterize the landscape. The north and west coasts of Ellesmere and Axel Heiberg islands are rugged and mountainous, with ice-covered mountains reaching 2500 m in elevation. To the east and south, the landscape is comprised of granite bedrock outcrops with glacial moraine and marine deposits. The Davis Highlands contain massive rocks that form peninsulas and fjords. The permafrost is continuous and may extend to depths of several hundred meters (ESWG 1995). The Soper River drainage on Baffin Island has intrusions of crystalline limestones, schists, and quartzite. It also contains small deposit of Lapis lazuli (a blue gemstone), which is one of the few known occurrences in the world.

Freshwater habitats

The islands of the Canadian Arctic Archipelago experience a variety of conditions. For example, the north is covered in ice fields and glaciers even through the summer, whereas to the south river sources are generally formed from snow melt. The rivers  travel across rolling tundra, often gaining speed through basalt cliffs and canyons. Some low, lush wetlands occur where rivers meander through valleys.

Low annual precipitation and permafrost play a major role in the formation of rivers and lakes in this ecoregion. Frozen ground cannot absorb water during spring thaw so a large amount of runoff occurs at this time. Because much of the landscape is fairly flat, summer rainfall is channeled into shallow lakes by permafrost.  These ecosystems are extremely fragile, and regeneration of damaged habitats is extremely slow.  

Uplifting of the land surface in coastal areas due to isostatic rebound has created saltwater pools. Over time, saltwater has been replaced by rainfall and species trapped in the pools have become adapted to freshwater.

Terrestrial habitats

Because of low precipitation, high winds, harsh climate, and shallow, poor soils, vegetation in this ecoregion is sparse and dwarfed. Purple saxifrage (Saxifraga spp.), cottongrass (Eriophorum spp.), Arctic willow (Salix arctica), wood-rush (Luzula spp.), lichens, and mosses dominate the vegetation. In the southeast, the dominant vegetation is similar, but because of a milder climate, wet areas may develop wood-rush, wire rush (Juncus spp.), and saxifrage with a nearly continuous cover of mosses. In some valleys, sedges (Carex spp.), cottongrass, sphagnum moss (Sphagnum spp.), yellow mountain saxifrage (Saxifraga aizoides), Arctic willow, dwarf birch (Betula nana), Arctic heather (Cassiope tetragona), Arctic poppy (Papaver radicadum), and Labrador tea (Rhododendron groenlandicum)  may be present.

Description of endemic fishes

There are no known endemic species within the ecoregion.

Other noteworthy fishes

Landlocked, freshwater populations of the marine Atlantic cod (Gadus morhua) and fourhorn sculpin (Myoxocephalus quadricornis) are found on several islands of this ecoregion.

Ecological phenomena

Most species in this ecoregion exhibit anadromy, including the chars (Salvelinus spp.) and whitefishes (Coregonus spp.). In the spring the islands become a major breeding ground for migratory birds. Banks Island and the east coast of Baffin Island were not glaciated during the last Ice Age and, hence, acted as refugia for many freshwater species as well as other Arctic flora and fauna.

Justification for delineation

The ecoregions of Canada were identified based on the faunal similarity of 166 major watersheds based on a cluster analysis of freshwater fish occurrences in these watersheds. The Canadian Arctic Archipelago ecoregion is comprised of all of the Canadian islands found in the Arctic Ocean. As a result of its extreme remoteness, climate and isolation by saltwater, this ecoregion has the most depauparate freshwater fish fauna of North America.

Level of taxonomic exploration

Poor