Lake Huron Ecosystem

• Category: Inland Aquatic Biomes.
• Geographic Location: North America.
• Summary: Lake Huron, the second-largest of the Great Lakes, has seen dramatic changes in its fish species mix, and climate change could accelerate the process.

Lake Huron, in terms of surface area, is the second-largest of the Great Lakes of North America, and the fourth-largest freshwater lake in the world. Lake Huron has a surface area of approximately 23,000 square miles (60,000 square kilometers). The lake contains a volume of 850 cubic miles (3,540 cubic kilometers). Lake Huron has the longest shoreline of any of the North American Great Lakes, at 3,827 miles (6,157 kilometers), including the shorelines of its islands, which number more than 30,000. The surface of Lake Huron is situated 577 feet (176 meters) above sea level.

The average depth of the lake is 195 feet (59 meters); its greatest depth is 750 feet (229 meters). Lake Huron is 206 miles (332 kilometers) in length, and it has a breadth of 183 miles (295 kilometers) at its greatest width. The total area of the Lake Huron drainage basin is 51,700 square miles (133,900 square kilometers).

Regional Geography

Along the northeast end of Lake Huron is Georgian Bay, separated from the main part of Lake Huron by Bruce Peninsula and Manitoulin Island. Georgian Bay is so large that it is sometimes referred to as the sixth Great Lake; it is bordered by the Canadian province of Ontario. The shoreline of Georgian Bay is strikingly similar to the shoreline of Lake Superior, possessing rugged, rocky cliffs above relatively unspoiled waters. Manitoulin Island is the largest freshwater lake island in the world and in turn, contains its own lakes. A smaller bay, Saginaw Bay, extends southwest from Lake Huron into the state of Michigan.

At the northwest corner of Lake Huron are the Straits of Mackinac, a deep trench of water that connects Lake Michigan with Lake Huron. The Straits of Mackinac equalize the water levels of the two Great Lakes, making them essentially two parts of the same lake, in a geological sense as well as hydrologically. Because of these connections between Lakes Michigan and Lake Huron, the two are sometimes collectively referred to as Lake Michigan-Huron. Taken together in this way, Lake Michigan-Huron, with a surface area of 45,300 square miles (117,000 square kilometers), qualifies as the world's largest freshwater lake by area.

Lake Superior is at a slightly greater elevation than both Lake Michigan and Lake Huron. Lake Superior drains into the St. Marys River at Sault Ste. Marie; the St. Marys then empties into Lake Huron. Lake Huron itself empties into the St. Clair River at its southernmost point; the St. Clair flows into Lake St. Clair, a very shallow lake with a surface area of 430 square miles (1,114 square kilometers), which in turn sends water south into Lake Erie.

Lake Huron, as well as the other Great Lakes, was formed by the melting and retreating of continental glaciers at the end of the last ice age. Before the last glaciation event, Lake Huron emptied into what is currently the Ottawa River Valley and then into the St. Lawrence River, close to present-day Montreal. Lake Huron's drainage shifted to the south when the land surface rebounded with the retreat of the glaciers. In some areas around Lake Huron, the land surface is still rising by approximately 13 inches (350 millimeters) per century.

When the first French explorers saw Lake Huron, they named it La Mer Douce, which means sweetwater sea. A map published in 1656 called the Lake Karegnondi, an Indigenous Wendat word that is translated generally as Freshwater Sea, or Lake of the Hurons, referring to the Indigenous Huron people who lived along the shores. The Huron had established trading networks across the region, and the French fur trade accelerated the founding of settlements at many points around the lake.

Ecology

The ecology of Lake Huron has been subjected to numerous major changes and disturbances during the 20th and 21st centuries. The lake formerly was home to a robust deepwater fish community, with the lake trout being the dominant top predator. The lake trout consumed cisco, sculpin, and other native prey. However, invasive fish species, such as alewife, rainbow smelt, and the parasitic sea lamprey, became quite numerous in the lake during the early 20th century, arriving via shipping lanes from the Atlantic Ocean via the St. Lawrence River. Already weakened by overfishing, then devastated by the sea lamprey, the lake trout population disappeared in the lake by 1950. Except for the bloater, all native species of deepwater cisco also were extirpated here.

Since the 1960s, the Pacific salmon, which is exotic to the Great Lakes region, has been stocked in Lake Huron. Lake trout have also been the focus of restocking programs, in an attempt to restore this species and rebuild its population in the lake, but a significant amount of natural reproduction of lake trout in Lake Huron has not been observed since the restocking and release programs have been initiated.

More recently, other nonnative species have been introduced into Lake Huron and the other Great Lakes; these new invaders are having devastating impacts on the regional ecology. The invasive species include the zebra and quagga mussels, the round goby, and the spiny water flea. The deepwater fish community of Lake Huron was on the verge of collapse by 2006; there have also been a number of documented changes to the zooplankton community here. Catches of chinook salmon have declined precipitously in recent years, and lake whitefish are less abundant and generally in poor condition. Most or all of these negative changes in the ecology of Lake Huron may be due in large part to these newer invasive species disrupting the structure and function of the native aquatic communities. However, in 2020, rehabilitation efforts began to increase the population of native fish such as lake trout.

Lake Huron has many wetlands that supply nesting and gathering areas for thirty species of wading and shoreline birds, and twenty-seven species of ducks, geese, and swans. Enormous numbers of birds visit these habitats during migrations through the region. Large numbers of fens and bogs, together with other wetland types, sustain diverse plant and animal communities throughout the shoreline areas.

Most of the more than 30,000 islands in the lake are relatively undisturbed habitats, some hosting rare species of plants and insects. Saginaw Bay is the largest freshwater coastal wetland in the United States, at 1,143 square miles (2,961 square kilometers). A large proportion of Lake Huron's fish species use this wetland during their growth and development periods.

Two of the unique ecosystems of Lake Huron are the alvars and the Pinery, an Ontario Provincial Park. Alvars are extremely rare, hostile environments, consisting of exposed limestone bedrock and very thin, poorly drained soils. Because temperatures fluctuate dramatically in alvars, these ecosystems are populated by species of very rare, specifically adapted plants and lichens. A few species of conifers live on alvars, and some of these individual trees are among the oldest living trees in the Great Lakes region. Alvars are fragile and easily disturbed by even minimal human activities.

The Pinery Provincial Park, on the shoreline in southern Ontario, includes a black oak savanna, a type of ecosystem that combines sand dunes and oak meadows. Oak savanna ecosystems are extremely rare; one other such habitat in the region can be found at the western end of Lake Erie, in the Oak Openings Toledo Metropark.

The Pinery offers protection to the sand dunes, meadows, and oak trees; it is a critical habitat for the five-lined skink, the only known lizard species in Ontario, and the blueheart flower, a plant that is extinct everywhere with the exception of the Pinery. In total, 300 species of birds and 700 species of plants have been identified and recorded in this unusual, endangered ecosystem.

Threats

Climate change effects are evident in Lake Huron and the other Great Lakes. Higher average water temperatures, already sustained for years, are projected to lead to mostly ice-free winters in the future, an extreme departure from seasonal patterns that have built and integrated many habitat niches here. Another key natural cycle, that of stratification of water levels during summer, has been occurring two weeks earlier in the year than during the mid-20th century average time of onset. This, too, is pressuring the nutritive load and food web vigor in the lakes—and could lead to a spread of oxygen-depleted zones.

The overall water volume seems to be declining as well, likely due to faster rates of evaporation caused by higher air and water surface temperatures combined with lower precipitation rates. These rising temperatures are attributed to climate change. Some scientists predict an increase in such fish species as smallmouth bass and yellow perch here—at the expense of lake trout and other species that favor colder water.

The Canadian energy company Ontario Power Generation has been seeking approval since 2013 to bury nuclear waste near Lake Huron; an environmental assessment conducted by a federal panel in 2015 found that this was likely to be safe, but the plan has drawn criticism from citizens and politicians in both the United States and Canada due to concerns that the nuclear waste might pollute the lake. In 2017, thirty-two members of the US Congress signed a petition against the plan, including thirteen of Michigan's fourteen delegates to the House of Representatives. Many municipalities in the United States and Canada have also passed resolutions opposing the plan. However, after intense pressure from environmentalists and communities who believed the threat to drinking water was too great, in 2020, Ontario Power Generation announced that it no longer wished to proceed with the project.

Bibliography

Beckett, Harry. Lake Huron. Rourke Corporation, 1999.

Bowie, Taylor. "EPA Drafts New Plan Addressing Threats to Michigan's Great Lakes." Michigan Public, 14 Aug. 2023, www.michiganpublic.org/environment-climate-change/2023-08-14/epa-drafts-new-plan-addressing-threats-to-michigans-great-lakes. Accessed 4 Nov. 2024.

Grady, Wayne, et al. The Great Lakes: The Natural History of a Changing Region. Greystone Books, 2011.

Lake Huron Lakewide Action and Management Plan Annual Report 2017. Binational.net, 2017, binational.net/2017/10/23/lhar2017/. Accessed 4 Nov. 2024.

Perkel, Colin. "Ontario Power Generation Pulls Plug on Plan to Bury Nuclear Waste Near Lake Huron Shoreline." The Canadian Press, 26 June 2020, globalnews.ca/news/7113241/opg-pulls-plug-nuclear-waste-burial-lake-huron/. Accessed 4 Nov. 2024.

Roseman, Edward F., et al. "Diet and Bathymetric Distribution of Juvenile Lake Trout Salvelinus namaycush in Lake Huron." Aquatic Health & Management, vol. 23, no. 3, July 2020, scholarlypublishingcollective.org/msup/aehm/article-abstract/23/3/350/168667/Diet-and-bathymetric-distribution-of-juvenile-Lake. Accessed 4 Nov. 2024.

Spangler, Todd. "Nuclear Waste Storage near Lake Huron? Congress Pushes Back." Detroit Free Press, 7 June 2017, www.freep.com/story/news/2017/06/07/tillerson-canadian-waste-lake-huron/377006001/. Accessed 4 Nov. 2024.

Ylvisaker, Anne. Lake Huron. Capstone Press, 2004.