Boundaries

This expansive ecoregion of the Arctic complex falls entirely along the extreme northern mainland coast of Canada within the Northwest Territories (NWT) and Nunavut. It is bounded by the Arctic Ocean to the north, the Coppermine and Back river drainages to the south and east, and Great Bear Lake to the west.

Topography

The northern part of the ecoregion is underlain by horizontal sedimentary rock and is nearly flat to gently rolling. Broad lowlands and plateaus are incised by rivers. Great Bear Lake lies between two major physiographic regions: the Canadian Shield and the Interior Plains. Since the last glacial periods the lake has undergone changes resulting from rebound following the melting of the ice. Further east, the ecoregion is underlain by flat-lying Paleozoic and Mesozoic sedimentary bedrock, with lowland plains of glacial moraine, marine deposits and bedrock outcrops. To the south, the ecoregion is underlain by Precambrian granitic bedrock with broadly rolling uplands and lowlands. The rolling landscape is studded with numerous lakes, ponds, and wetlands. Virtually the entire area is underlain by continuous permafrost with moist or wet layers throughout the summer.

Freshwater habitats

Great Bear Lake is cold and deep, causing fish species to grow very slowly. Its northern shores are treeless tundra, whereas short spruce trees grow on the southern shores. Great Bear Lake is ice-bound for eight months of the year. The Horton River once flowed north and west into Harrowby Bay on the Cape Bathurst Peninsula. However, a few hundred years ago it broke through a barrier of low alluvial hills to the east, and now empties into Franklin Bay. This has left a series of oxbows in its former path. The valley floor of the Coppermine River lies in a wide, deep valley. Fifteen km upstream of its mouth, it goes through a series of rapids, and then flows over a narrow gorge of volcanic rock into the Arctic Ocean. The Back River has rapids in the upper reaches, but broadens onto a plain and forms Pelly, Garry, and Upper and Lower Macdougall lakes. Near its mouth, it narrows and cuts through rock to the coast.

Terrestrial habitats

This ecoregion is transitional between the boreal forests in the south and treeless arctic tundra in the north. To the north, vegetation is sparse and dwarfed due to a harsh climate and shallow soil. Stands of  black spruce (Picea mariana), tamarack (Larix laricina), white spruce (P. glauca), dwarf birch (Betula spp.), Labrador tea (Ledum decumbens) and willow (Salix spp.) occur. Understory species include bearberry, mosses and sedges. Arctic willow (Salix arctica), saxifrage (Saxifraga spp.) and lichens. Vegetation is greater on wet sites in sheltered valleys and along rivers and streams.

Description of endemic fishes

There are no known endemic species within the ecoregion.

Ecological phenomena

Most fish species in this ecoregion exhibit anadromy, including the Pacific salmons (Oncorhynchus spp.), chars (Salvelinus spp.), and whitefishes (Coregonus spp.).

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 Central Arctic Coastal ecoregion is comprised of relatively small, isolated watersheds draining directly into the central Arctic Ocean. As a result, this ecoregion has a depauparate freshwater fish fauna primarily comprised of species with some saltwater tolerance.

Level of taxonomic exploration

Poor