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Ecoregion Description


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Species Richness


# of Endemic Species


Threats

109: English - Winnipeg Lakes

Major Habitat Type:

large lakes

Author:

Mary Burridge and Nicholas Mandrak

Countries:

Canada; United States

Boundaries:

This ecoregion includes much of southeastern Saskatchewan, southern Manitoba, southern Ontario, northeastern North Dakota, and northern Minnesota. The major drainages of Lake Winnipeg, including the Saskatchewan River in the northwest, the Red and Assiniboine rivers in the southwest, and the Winnipeg and English rivers in the southeast, are found in this ecoregion.

Drainages flowing into:

This ecosystem drains into the Arctic Ocean via Hudson Bay.

Main rivers or other water bodies:

In this ecoregion, there are four large lakes within close proximity to each other: Lake Winnipeg (24,420 km2), Lake Winnipegosis (5370 km2), Cedar Lake (1350 km2), and Lake Manitoba (4624 km2). Two major tributaries, the Winnipeg and Saskatchewan rivers, account for 75% of the inflow into Lake Winnipeg. The Winnipeg River (813 km) receives water from Lake of the Woods, Lac Seul, Rainy Lake, and the English River, and flows into the southeast end of Lake Winnipeg. The Saskatchewan River (1939 km), formed by the confluence of the North Saskatchewan and South Saskatchewan rivers (part of the Middle Saskatchewan ecoregion [108]), flows into Lake Winnipeg via Cedar Lake. Other rivers that drain Lake Winnipeg include the Berens River and the Red River, which is formed from the Souris and Assiniboine rivers. The outflow of Lake Winnipeg drains by way of the Nelson River (part of the Southern Hudson Bay ecosystem).

Topography:

Flat-lying Paleozoic limestone bedrock covered with glacial till, silts and clays, and extensive peat deposits characterizes the northern and western portions of the ecoregion. Here, cretaceous shale with shallow depressions has caused a large number of small, shallow lakes, ponds, and sloughs to form. To the east, wetlands are extensive in the regions of the Lac Seul Upland, and undulating lacustrine deposits with occasional bedrock ridges are prevalent. To the southeast where glaciers once covered the region, the area now has thick deposits of glacial drift. Rock outcrops and glacial moraines are common features, providing a gentle rolling landscape.

Climate:

The ecoregion experiences a humid continental climate with cool summers. The mean January temperature around Lake Winnipeg is about -18 °C; the July average is about 20 °C. Mean annual precipitation around the lake is approximately 500 mm.

Freshwater habitats:

This ecoregion is on the Canadian Shield and has been covered by glaciers as recently as 10,000 to 15,000 years ago. The combination of glaciation, its landscape, and its geology provide a unique set of habitats, including many oligotrophic lakes and clear, cold streams. Lakes Winnipeg, Winnipegosis, and Manitoba are very large, shallow glacial lakes (once connected as glacial Lake Agassiz, the largest single lake ever to exist in North America).

Terrestrial Habitats:

Much of the ecoregion is mixed coniferous and deciduous forest, characterized by stands of quaking aspen (Populus tremuloides), balsam poplar (Populus balsamifera), black spruce (Picea mariana), and jack pine (Pinus banksiana). Cold and poorly drained fens and bogs are covered with tamarack (Larix laricina), and may also include an understory of sedges (Carex spp.), ericaceous shrubs (Ericaceae), and mosses. Toward the south-central portion of the ecoregion, the dominant grass species include big bluestem (Andropogon gerardii), switchgrass (Panicum virgatum), and Indian grass (Sorghastrum nutans).

Fish Fauna:

As a result of its coverage by glacial Lake Agassiz 11,000-8,000 years ago, the ecoregion\'s fish fauna consists largely of primary freshwater species originating from Mississippian and Beringian refugia. The low productivity of the Canadian Shield and harsh climate currently limit the fish diversity of this ecoregion. Characteristic fish species include northern pike (Esox lucius), lake trout (Salvelinus namaycush), lake whitefish (Coregonus clupeaformis), yellow perch (Perca flavescens), and walleye (Sander vitreus), all of which form important commercial or recreational fisheries.

Description of endemic fishes:

The area has no endemic fish, mussels, crayfish, or aquatic herpetofauna.

Other noteworthy fishes:

The lake sturgeon (Acipenser fulvescens) and the goldeye (Hiodon alosoides) have been severely over-fished and are currently very rare in this ecoregion.

Ecological phenomena:

Historically, the lake sturgeon likely undertook long spawning migrations, and the cisco (Coregonus artedi) and lake whitefish (Coregonus clupeaformis) likely formed large spawning schools in the larger lakes.

Evolutionary phenomena:

Morphological radiation related to depth and prey has been identified in cisco (Coregonus artedi) in some lakes.

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 extent of the English-Winnipeg Lakes ecoregion was determined by including fish occurrence data for watersheds in contiguous watersheds in the north-central United States. The English-Winnipeg Lakes ecoregion is comprised of watersheds that receive waters from the west and drain towards southern Hudson Bay. As a result of extensive coverage by glacial Lake Agassiz 11,000-8,000 years ago, the fish fauna of this ecoregion consists of freshwater species originating from Mississippian and Beringian refugia. The low productivity of the Canadian Shield and harsh climate currently limit the fish diversity of this ecoregion.

Level of taxonomic exploration:

Good / Fair

References/sources:

Abell, R., Olson, D., et al. (2000). "Freshwater ecoregions of North America" Washington, D.C.: Island Press.

Eswg (1995) "A national ecological framework for Canada". Ottawa/Hull, Ontario, Canada. Agriculture and Agri-food Canada, Research Branch, Centre for Land and Biological Resources Research; and Environment Canada, State of the Environment Directorate, Ecozone Analysis Branch..

Kuchler, A. W. (1975). "Potential natural vegetation of the conterminous United States" New York: American Geographical Society.

Mandrak, N. E.,Crossman, E. J. (1992). "A checklist of Ontario freshwater fishes annotated with distribution maps" Toronto, ON: Royal Ontario Museum Misc. Life Sci. Publ..

Ricketts, Taylor H. Dinerstein Eric Olson David M. Loucks Colby J. (1999). "Terrestrial ecoregions of North America: A conservation assessment" Washington, D.C.: World Wildlife Fund.

Scott, W. B.,Crossman, E. J. (1998). "Freshwater fishes of Canada" Fisheries Research Board of Canada Bulletin 184 966 + xvii..

Stewart, K. W.,Watkinson, D. A. (2005). "The freshwater fishes of Manitoba" Winnipeg, MB: University of Manitoba Press.

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