These trees are large enough to be used for construction of log buildings and are widely used as fuel. The delta is 80 km across, bordered by the Richardson Mountains in the west and the Caribou Hills in the east. Below Point Separation the river splits into three main, navigable channels: East Channel, which flows past Inuvik on the easterly edge of the delta; Peel Channel in the west, which flows past Aklavik ; and Middle Channel, which carries the main outflow into the Beaufort Sea.
With snowmelt and the break-up of ice in spring and summer, the Mackenzie River becomes laden with suspended sediments and dissolved solids. Year-round the river carries a greater load of such materials than any other circumpolar river.
Most of these solids originate in the mountain ranges that drain into the Mackenzie from the west including the Mackenzie Mountains, and the Pelly and Rocky Mountains in the Liard sub-basin. By contrast, the waters that flow into the Mackenzie from the Great Bear River to the east are clear. Fifty-four species of fish are found in the river, many of which move en masse between the Mackenzie and its tributaries.
Those that move from the sea to freshwater in order to spawn travel some of the farthest distances. The arctic cisco, for example, travels from the delta up the Mackenzie and into the Liard River. Lake whitefish, inconnu and long-nose suckers all migrate between the Liard and the Mackenzie. Migratory birds, including snow geese, tundra swans and sandhill cranes, use the Mackenzie River as a migration route and spend the summer months in the delta.
In the spring, the delta is also a calving ground for beluga whales. The maze of channels, cutoff lakes and circular ponds that make-up the delta are also home to a thriving muskrat population that has long sustained a fur-harvesting industry.
Moose , mink , beaver and wood frogs are all found along the riverbanks. Hazards resulting from climate change are already found along the Mackenzie, including unusual floods and thinner ice roads. There is concern that as permafrost thaws, drilling waste from oil and gas exploration will be exposed and could contaminate local environments.
Future changes in streamflow are also anticipated as a consequence of warming. Specifically, changes in the snowpack and melting will lead to lower water levels in spring and summer along the river, but higher levels in fall and winter. Climate change is interacting with contaminants like mercury and polychlorinated biphenyls PCBs that are found in the Subarctic and Arctic, but originate elsewhere. Levels of these toxins in burbot, a top predator in the Mackenzie River, and an important food source for local communities, have increased significantly since the mids.
Mercury is also flowing from the Mackenzie River into the Beaufort Sea and Arctic Ocean where it is consumed by beluga whales and other species. Its English name derives from Alexander Mackenzie , the first European to travel the length of the river to its mouth in Inuvialuit occupied a winter village, called Kuukpak, situated near the mouth of the Mackenzie River from the s until the late 19th century, when it was abandoned following epidemics of European-introduced diseases.
From Kuukpak, Inuvialuit could hunt caribou and beluga, and take advantage of the abundance of driftwood that floated down the river.
Fish camps that date back hundreds of years were situated on the banks of the main stem of the river. Families harvested fish from the river then moved inland to hunt caribou in the Mackenzie Mountains or on the tundra to the east, as summer changed to fall. Alexander Mackenzie and John Franklin both visited the fish camps on the river during their travels in and respectively. River fisheries increased in importance with the adoption of dog teams in the early fur trade period, as the main subsistence for the dogs during the winter months was dry fish.
Direct tributaries of the Mackenzie from the west such as the Liard and Peel Rivers carry runoff from the mountains of the eastern Yukon. The eastern portion of the Mackenzie basin is dominated by vast reaches of lake-studded boreal forest and includes many of the largest lakes in North America. By both volume and surface area, Great Bear Lake is the biggest in the watershed and third largest on the continent, with a surface area of 31, km2 12, sq mi and a volume of 2, km3 cu mi.
Great Slave Lake is slightly smaller, with an area of 28, km2 11, sq mi and containing 2, km3 cu mi of water, although it is significantly deeper than Great Bear.
The third major lake, Athabasca, is less than a third that size with an area of 7, km2 3, sq mi. Six other lakes in the watershed cover more than 1, km2 sq mi , including the Williston Lake reservoir, the second-largest artificial lake in North America, on the Peace River. During peak flow in the spring, the difference in discharge between the two halves of the watershed becomes even more marked. Breakup of ice jams caused by sudden rises in temperature — a phenomenon especially pronounced on the Mackenzie — further exacerbate flood peaks.
In full flood, the Peace River can carry so much water that it inundates its delta and backs upstream into Lake Athabasca, and the excess water can only flow out after the Peace has receded. As recently as the end of the last glacial period eleven thousand years ago the majority of northern Canada was buried under the enormous continental Laurentide ice sheet.
The tremendous erosive powers of the Laurentide and its predecessors, which at maximum extent completely buried the Mackenzie River valley under thousands of meters of ice and flattened the eastern portions of the Mackenzie watershed.
When the ice sheet receded for the last time, it left a 1, km mi -long postglacial lake called Lake McConnell, of which Great Bear, Great Slave and Athabasca Lakes are remnants. Significant evidence exists that roughly 13, years ago, the channel of the Mackenzie was scoured by one or more massive glacial lake outburst floods unleashed from Lake Agassiz, formed by melting ice west of the present-day Great Lakes. At its peak, Agassiz had a greater volume than all present-day freshwater lakes combined.
This is believed to have disrupted currents in the Arctic Ocean and led to an abrupt 1,year-long cold temperature shift called the Younger Dryas. There are fifty-three fish species in the basin, none of them endemic. Most of the aquatic species in the Mackenzie River are descendants of those of the Mississippi River and its tributaries.
This anomaly is believed to have been caused by hydrologic connection of the two river systems during the Ice Ages by meltwater lakes and channels. Further south the tundra vegetation transitions to black spruce, aspen and poplar forest.
Overall, the northern watershed is not very diverse ecologically, due to its cold climate — permafrost underlies about three-quarters of the watershed, reaching up to m ft deep in the delta region — and meager to moderate rainfall, amounting to about millimetres 16 in over the basin as a whole.
The southern half of the basin, in contrast, includes larger reaches of temperate and alpine forests as well as fertile floodplain and riparian habitat, but is actually home to fewer fish species due to large rapids on the Slave River preventing upstream migration of aquatic species. Migratory birds use the two major deltas in the Mackenzie River basin — the Mackenzie Delta and the inland Peace-Athabasca Delta — as important resting and breeding areas.
The latter is located at the convergence of four major North American migratory routes, or flyways. As recently as the mid-twentieth century, more than , birds passed through during the spring and up to a million in autumn. Through the trapping of animals such as beavers, lynxes, foxes, and martens for fur is still practiced by the indigenous Indians settled along the river, fur trading is no longer a dominant source of economic revenue for this region. Agriculture is not extensively practiced in this region, and is mainly limited to the warmer, southern reaches of the river and its tributaries, where grains and cereals are cultivated and animal ranching is practiced.
Oil and petroleum mining is the major profitable activity along the Mackenzie River, with the first oil field being discovered in at Norman Wells. Uranium, gold, diamond, lead, and zinc have also been mined in and along the Mackenzie River system. The Mackenzie River flows through a Boreal forest zone in the south, then into an extensive taiga vegetation zone in its middle reaches, and finally drains into the Arctic Ocean via the Arctic tundra zone in its northernmost reaches.
Alders, Trembling aspens, birches, Balsam firs, and spruces are some of the important plant species of the Taiga forests along the Mackenzie River system. Further north, cottongrass, feather-moss, bog cranberry, and sphagnum moss cover the landscape along the river basin. The caribou, lynxes, minks, beavers, and muskrats are some of the mammalian species inhabiting the taiga forests along the Mackenzie.
Beluga whales can often be spotted in the Mackenzie River Delta, while Mountain whitefish, Northern pike, minnows, Chinook salmon, Cutthroat trout, and other fish species thrive in the waters throughout the Mackenzie River system. The Osprey, geese, Sandhill cranes, Tundra swans, and other spectacular birds populate the watershed wetlands of the Mackenzie River system as well.
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