Central Arctic Coastal
Mary Burridge and Nicholas Mandrak
Major Habitat Type
Drainages flowing into
All drainages flow north into the Arctic Ocean.
Main rivers to other water bodies
Great Bear Lake (30 764 km2), lies in the NWT and straddles the Arctic Circle. The Great Bear River drains the lake from its southwest corner into the Mackenzie River. The Coppermine River (845 km) begins in Lac de Gras in the Barren Lands of NWT and flows northwest through Point Lake, Nunavut, into Coronation Gulf on the Arctic Ocean. The Back River (974 km) begins in Contwoyto Lake and flows northeast through Garry Lake and the Barren Lands of Nunavut to Chantrey Inlet in the Arctic Ocean. Smaller rivers in this ecoregion include the Horton, Hood, Burnside, Ellice, and Hayes rivers.
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.
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.
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.
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.
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
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