Hudson Bay ecosystem
The Hudson Bay ecosystem, located in northern Canada, is the second-largest bay in the world and plays a crucial role in supporting diverse marine and coastal environments. Covering approximately 450,000 square miles, it includes cold-water coastal areas and a mix of habitats ranging from wetlands to tundra, which are essential for many species. The bay is brackish, receiving significant freshwater inflow from rivers and precipitation, contributing to its unique ecological characteristics.
Home to a variety of marine mammals, including large populations of beluga whales and seals, Hudson Bay is vital for both Arctic and sub-Arctic species, as well as migratory birds that breed in the area. The ecosystem is intricately linked to the surrounding landscape, where terrestrial wildlife, such as polar bears and Arctic foxes, depend on the marine environment for sustenance. However, the Hudson Bay ecosystem faces challenges from climate change, leading to a reduction in sea ice, which is crucial for the survival of many ice-dependent species.
With increasing temperatures and shifting environmental conditions, stakeholders, including Indigenous communities, must navigate the complexities of conservation, resource management, and the impacts of human activities on this delicate ecosystem. As global warming accelerates, the future of the Hudson Bay ecosystem remains uncertain, emphasizing the need for collaborative efforts in its preservation.
Hudson Bay ecosystem
- Category: Marine and Oceanic Biomes.
- Geographic Location: North America.
- Summary: The second-largest bay in the world, Hudson Bay supports diverse cold-water coastal and marine ecosystems.
Named for the Dutch explorer Henry Hudson, Hudson Bay is the second-largest bay in the world after the Bay of Bengal. It is a marine bay and marginal sea in northern Canada that drains most of the central area of the country as well as parts of the upper Midwest of the United States, about 1.5 million square miles (3.9 million square kilometers) in all. Hudson Bay connects with the North Atlantic Ocean via the Hudson Strait, and to the Arctic Ocean via the Northwest Passages.
Hydrology and Geography
Many streams and rivers contribute to Hudson Bay's waters, but not nearly enough to offset its brackish salinity. Hudson Bay is surrounded by vast expanses of wetlands, shrubland steppes, taiga or boreal forest, and tundra ecosystems.
Hudson Bay is a relatively shallow saltwater body, with an average depth of 330 feet (100 meters). It is about 900 miles (1,450 kilometers) long north to south—including its southernmost lobe, James Bay—and about 650 miles (1,050 kilometers) across at its widest. Total surface area is approximately 450,000 square miles (1.16 million square kilometers). Hudson Bay is ice-covered for half the year; ice begins to form in early November, and the whole bay has very low year-round average temperatures. The ice cover begins to melt in mid-June, usually clearing from the eastern shores first. Water temperature rises to 46 to 48 degrees F (8 to 9 degrees C) on the western side of the bay by late summer.
While it is a saltwater or brackish body, Hudson Bay receives freshwater inflow at an annual volume of some 170 cubic miles (700 cubic kilometers); even more comes from precipitation and ice melt. Consequently, and also due to its limited hydraulic exchange with the Atlantic Ocean, the bay is less salty than the ocean.
Rich Base of Life
Because of its vast dimensions, the Hudson Bay marine ecosystem has many aquatic and coastal ecozones with varied habitats that are used year-round by Arctic and sub-Arctic species, as well as seasonally by migratory fish, marine mammals, and birds. The sea ice, for instance, supports the seals upon which polar bears depend. Millions of geese and shorebirds feed and breed in vast salt marshes. Productive submarine eelgrass beds provide food for waterfowl migrating to and from breeding habitat in the Arctic Islands, and shelter for crustacean and fish populations. Numerous estuaries provide habitat corridors for anadromous fish like salmon and Arctic char, and support beluga whales.
The Hudson Bay supports great numbers of large mammals, both aquatic and terrestrial. Migratory marine mammal species such as belugas, narwhals, and bowhead whales frequent the region as permitted by ice conditions across the northern channels. Other cetaceans, such as orca and minke whales, are rarer visitors. Large concentrations of up to 20,000 beluga whales are found in the estuaries of the Nelson and Churchill Rivers in July and August. Ringed seals, bearded seals, and harbor seals, as well as walruses, reside in the bay year-round, while harp and hooded seals visit seasonally. Subsistence harvesting of these marine mammals is important to the aboriginal peoples and the economy of the bay. Arctic foxes and polar bears reside on coasts in the summer, and on sea ice during the rest of the year; they, too, are hunters of the seals.
At least 130 species of birds migrate to the Hudson's waters each summer, and depart in late fall. Waders, water fowl, and raptors share pelagic, intertidal, and wetland habitats here. Most such species—at least 100—find breeding zones on shore. Cranes, plovers, herons, bitterns, loons, pelicans, ducks, geese, swans, osprey, falcons, eagles, and owls share the Hudson Bay.
Less is known about the prevalence and range of marine fish species here, due to the near-absence of commercial fisheries; even traditional subsistence fishing has been somewhat limited. Some sixty or so fish species are known in these waters, however, and many of these are adapted to the relatively shallow, brackish environment here. Of the recognized species, about two dozen stay in the marine environment all their lives. Half that many species are marine but frequent the estuaries as seasonal nursery grounds; another nine feed in the brackish coastal realm, but spawn in freshwater zones. As many as sixteen freshwater species have evolved salinity tolerances sufficient to spend some time here in brackish coastal reaches or estuaries. One species—the Atlantic salmon—winters in saltwater in between the freshwater spawn and final act of its anadromous life cycle.
Conservation and Climate Change
The governance of the Hudson Bay area is largely a series of compromise decisions and shared responsibilities between federal, provincial, local, and First Nations bodies. As global warming proceeds—and faster here in its effects than in many if not most other parts of the world—such organizations will have to work more closely in concert to help determine the growing number of issues. These will range from plans for hydroelectric dams and other water diversion schemes; new deepwater port facilities and related marine transport strategies; mining, agriculture, grazing, and aquaculture rights; tourism pursuits such as hunting; and real estate development. Encompassing all of these areas is the issue of environmental conservation.
There has already been considerable focus on the impact of climate change and transboundary contaminants on Hudson Bay. Historic commercial whaling, particularly for bowheads and belugas, depleted these populations, some of which have not entirely recovered. The steady increase in regional temperatures over the last 100 years has caused a lengthening of the ice-free period, and continues to jeopardize the sustainability of ice-dependent species such as polar bears and seals. These ice-dependent marine mammals are vulnerable to both airborne contaminants and global warming. Because these carnivorous animals are high in the food chain, they accumulate contaminants such as heavy metals, carcinogenic hydrocarbons, and radioactive materials in their fatty and other tissues.
Diminished sea-ice cover, decreasing flow from its tributary rivers, and increasing precipitation are some of the long-term trends already detected in the Hudson Bay. Each of these vectors is projected to intensify, along with other effects such as sea-level rise, which will have as yet undetermined but certainly serious impacts on the habitats here.
Bibliography
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