Saskatchewan River ecosystem
The Saskatchewan River ecosystem is a significant freshwater biome in Canada that supports diverse habitats for a wide array of plants and animals. Originating from the Columbia ice fields in British Columbia, the river system comprises the North and South Saskatchewan Rivers, which converge near Prince Albert, Saskatchewan, and flow into Lake Winnipeg in Manitoba. Spanning about 800 miles (1,300 kilometers) for the North branch and 865 miles (1,400 kilometers) for the South, the river's watershed covers approximately 130,000 square miles (336,000 square kilometers), featuring a variety of landscapes including forests, agricultural lands, and marshes.
The ecosystem is characterized by rich biodiversity, with numerous invertebrates, fish species, and avian populations that rely on the river for sustenance and habitat. However, human activities such as agriculture, urbanization, and industrial development have led to environmental challenges, including pollution and habitat disruption. Additionally, changes in climate patterns pose threats to the water supply, which is crucial for both ecological balance and human use. The Saskatchewan River ecosystem represents a vital resource, not only for indigenous peoples and local communities but also for the broader biodiversity that depends on its health and stability.
Subject Terms
Saskatchewan River ecosystem
Category: Inland Aquatic Biomes.
Geographic Location: North America.
Summary: This major freshwater body spans the Canadian prairies; the biome incorporates a broad scope of habitats and species, many now threatened by human activity.
The Saskatchewan River is a major freshwater biome in Canada, sustaining a variety of ecosystems and providing habitat for a rich diversity of plants and animals. Originating in the Columbia ice fields of British Columbia, the glacial water combines with snowfall meltwater and drains in two main branches that flow east across Alberta and Saskatchewan, then empty into Lake Winnipeg, Manitoba.
Geography and Climate
The North Saskatchewan River is 800 miles (1,300 kilometers) long, and the South Saskatchewan River is 865 miles (1,400 kilometers) long. The two branches merge, forming the Saskatchewan River, about 25 miles (40 kilometers) east of Prince Albert, Saskatchewan. The confluence is known as the Saskatchewan River Forks. The Plains Cree (nēhiyawēwin) refer to the river as kisiskaciwani-sipiy, meaning swift flowing river, describing the speed and power of the stream. The volume of this river averages about 22,400 cubic feet (634 cubic meters) per second.
Natural features of the river include shifting sandbars (both exposed and submerged), gravel, large stones, oxbows, lakes, rapids, islands, tree and shrub roots along shorelines, and fallen logs, all providing habitat for invertebrates, fish, birds, small and large mammals, and a variety of plant life. While a river brings to mind a body of water flowing along a channel, it is much more than that. The Saskatchewan River system is part of a watershed covering approximately 130,000 square miles (336,000 square kilometers) and filled with tributaries, forests, agricultural lands, delta areas, and marshes.
Most of the watershed is within a temperate, continental climate zone. The mean annual temperature ranges from approximately 36 to 43 degrees F (2 to 6 degrees C). Total annual precipitation ranges from 11 to over 32 inches (28 to over 80 centimeters) as one moves westward into the mountains.
Biodiversity
Invertebrates are important parts of the Saskatchewan River biome because they are food sources for fish and birds and are a good measure of the health of an ecosystem. The diversity and numbers of invertebrates is usually a better indicator of water quality than random water sampling. Invertebrates found in the Saskatchewan River system include water boatmen, roundworms, caddisfly larvae, stonefly nymphs, mayfly nymphs, bristle worms, midge larvae, and damselfly nymphs, as well as various clams, leeches, snails, beetles, crayfish, dragonflies, black flies, water fleas, fairy shrimp, and numerous other small organisms. Mosquitoes lay their eggs in standing water and are abundant in this ecoregion as an important food source for many birds and bats.
Minnows occupy lakes and rivers across Canada. Some common types found in the Saskatchewan River system are fathead minnows and brassy minnows. Larger fish, such as sauger, rainbow trout, and northern pike, feed on minnows. Like invertebrates, minnows are sensitive to water quality and changes in their environment. Increased pollution from prairie agriculture, wastewater effluent from human habitation, and other chemical releases are known to adversely affect minnow reproductive systems.
The Saskatchewan River biome is home to brook trout, burbot, cisco, goldeye, lake sturgeon, lake whitefish, longnose sucker, mooneye, northern pike, rainbow trout, sauger, shorthead redhorse, walleye, white sucker, yellow perch, and Atlantic salmon. The fish vary in number and habitat preference along the river, with some preferring shallower waters, some occupying deeper waters, and still others occupying pools of less turbulent water. The shorthead redhorse, for example, is sensitive to water quality and favors clear shallow water with a good sand or gravel bottom, whereas suckers are able to thrive in poor-quality water. Suckers are among the most prolific species in the ecoregion.
The river valleys of the Saskatchewan River system provide rich habitat for a great variety of birds. Some of the larger species include the peregrine falcon, Swainson’s hawk, bald eagle, ruffed grouse, great horned owl, great blue heron, osprey, American white pelican, common merganser, Canada goose, Franklin’s gull, and trumpeter swan. Smaller birds include the pileated woodpecker, blue-headed vireo, blue jay, magpie, crow, raven, swallow, black-capped chickadee, white-breasted nuthatch, house wren, American robin, Swainson’s thrush, gray catbird, European starling, and cedar waxwing.
Some birds that typically migrate to warmer wintering grounds may stay in areas where the river does not freeze, mainly as a result of human influences. The Canada goose, for example, can sometimes be found year round in urban areas. In the Saskatchewan River delta, an estimated half-million breeding waterfowl make their way from the Arctic and northern boreal areas to renew the life cycle of their species. Other birds migrate from parts of North, Central, and South America each year to their particular territory along the river.
Large mammals that live in the watershed include the moose, white-tailed deer, mule deer, elk, black bear, and wolf. The animals are not easily seen during warm seasons, preferring to keep away from human habitations. Fruit and berry supplies growing along the river provide a source of food for bears in late summer, requiring extra caution for humans hoping to collect the same harvest. Smaller mammals—such as beavers, otters, fishers, minks, and coyotes—occupy small territories in and around the river.
The ecology of the Saskatchewan River system changes as it crosses through various zones. The mid-boreal lowland ecoregion occupies the northern section of the Manitoba Plain, from the eastern shore of Lake Winnipeg to the Cumberland Lowlands in Saskatchewan. The boreal transition ecoregion extends from southern Manitoba to central Alberta. The aspen parkland ecoregion extends in a broad arc from southwestern Manitoba, and northwestward through Saskatchewan to its northern apex in central Alberta. Moist mixed grassland is an ecoregion comprising the northern extension of open grasslands in the interior plains of Canada.
Each of these ecoregions has variations in climate, precipitation, vegetation, soils, and wildlife. The boreal transition ecoregion, for example, encompasses the area where the North Saskatchewan and South Saskatchewan rivers meet. Here is found a mix of deciduous boreal forest area and agricultural lands. Tall trembling aspen and balsam poplar provide thick canopy, with smaller shrubs filling in the understory. White spruce and balsam fir are the climax species, but have been reduced because of fires.
Human Impact
Traditionally, many indigenous peoples relied on native flora and fauna for survival. Many native plant and animal species of the biome are no longer found, however, having been replaced by imported, invasive, or stocked species. The Saskatchewan River is an important source of freshwater that humans and all other living things rely on.
The river is also an important source of agricultural irrigation, power generation, and recreation for people in Canada. Two hydroelectric power plants in Saskatchewan and one in Manitoba provide electricity. Hydroelectric dams have changed some areas and upset some habitats through the creation of reservoirs that flood large tracts of land. Silt and sediments removed at the dam sites reduce deposits on the downstream side, creating deeper channels and faster water flow. Chemical pollutants and wastes make consumption of resident fish risky. Intensive agriculture over many generations has depleted soil nutrients; farmers now use nontraditional methods of farming with greater amounts of fertilizer that eventually wash into the river, upsetting balanced ecosystems.
Changing climate conditions will bring changes to the Saskatchewan River system, also. Less annual snowfall in mountain valleys and less precipitation across the prairies will mean the bodies of water forming the Saskatchewan River will be drawn down more to support crops, urban landscaping, golf courses, industrial development, and human populations. This will challenge habitats deprived of their life-currents. Simultaneously, more precipitation in some areas of the watershed and earlier spring snowmelt will bring flooding and temporarily higher river levels that will also challenge watershed ecosystems with greater erosion, stream turbidity, and habitat disruption. Eventually, if the glaciers that feed the river system melt, the water flowing into the North and South Saskatchewan rivers will lessen. This could potentially impact large cities such as Edmonton that depend on the river for their water supply.
Bibliography
Casey, Alan. “Climate Prosperity.” Canadian Geographic, October 2010. http://www.canadiangeographic.ca/magazine/oct10/south‗saskatchewan‗river.asp.
Hallstrom, Tim and Chris Jordison. Fish Species of Saskatchewan. Regina, Canada: Saskatchewan Watershed Authority, Fish and Wildlife Development Fund, 2007.
Rasche, Teagan. “The Impact of Climate Change on the South Saskatchewan River.” Chat News Today, 18 Oct. 2021, chatnewstoday.ca/2021/10/18/the-impact-of-climate-change-on-the-south-saskatchewan-river/. Accessed 2 Sept. 2022.
University of Saskatchewan. “Ecoregions of Saskatchewan.” http://www.usask.ca/biology/rareplants‗sk/root/htm/en/researcher/4‗ecoreg.php.