page_title: Lake Ontario
section_title: Ecology and environmental concerns
hierarchical_section_title: Lake Ontario / Ecology and environmental concerns
caption_attribution_description: English: Wetland profile for Great Lakes
context_page_description: Lake Ontario is one of the five Great Lakes of North America. It is surrounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the American state of New York, whose water boundaries meet in the middle of the lake. Ontario, Canada's most populous province, was named for the lake.
  The Canadian cities of Toronto, Kingston, and Hamilton are located on the lake's northern and western shorelines, while the American city of Rochester is located on the south shore. In the Huron language, the name Ontarí'io means "great lake". Its primary inlet is the Niagara River from Lake Erie. The last in the Great Lakes chain, Lake Ontario serves as the outlet to the Atlantic Ocean via the Saint Lawrence River. It is the only Great Lake not to border the state of Michigan.
context_section_description: The Great Lakes watershed is a region of high biodiversity, and Lake Ontario is important for its diversity of birds, fish, reptiles, amphibians, and plants.  Many of these special species are associated with shorelines, particularly sand dunes, lagoons, and wetlands. The importance of wetlands to the lake has been appreciated, and many of the larger wetlands have protected status.  However, these wetlands are changing in part because the natural water level fluctuations have been reduced.  Many wetland plants are dependent upon low water levels to reproduce. When water levels are stabilized, the area and diversity of the marsh is reduced.  This is particularly true of meadow marsh (also known as wet meadow wetlands); for example, in Eel Bay near Alexandria Bay, regulation of lake levels has resulted in large losses of wet meadow.  Often this is accompanied by the invasion of cattails, which displace many of the native plant species and reduce plant diversity. Eutrophication may accelerate this process by providing nitrogen and phosphorus for the more rapid growth of competitively dominant plants. Similar effects are occurring on the north shore, in wetlands such as Presqu'ile, which have interdunal wetlands called pannes, with high plant diversity and many unusual plant species.
  Most of the forests around the lake are deciduous forests dominated by trees including maple, oak, beech, ash and basswood.  These are classified as part of the Mixedwood Plains Ecozone by Environment Canada, or as the Eastern Great Lakes and Hudson Lowlands by the United States Environmental Protection Agency, or as the Great Lakes Ecoregion by The Nature Conservancy. Deforestation in the vicinity of the lake has had many negative impacts, including loss of forest birds, extinction of native salmon, and increased amounts of sediment flowing into the lake. In some areas more than 90 percent of the forest cover has been removed and replaced by agriculture.  Certain tree species, such as hemlock, have also been particularly depleted by past logging activity. Guidelines for restoration stress the importance of maintaining and restoring forest cover, particularly along streams and wetlands.
  The open water is less-affected by shoreline features, such as wetlands, and more affected by nutrient levels that control the production of algae. Algae are the basis of the open water food web, and the source of primary production that ends up as Lake Trout and Walleye at the top of the open water food web.
  Like the other Great Lakes, Lake Ontario used to have an important commercial fishery. It has been largely destroyed, mostly by over-fishing.  Consider the Lake Sturgeon as but one example. Lake sturgeon are huge fish—they can grow up to three meters long and exceed 190 kg in weight.  The females mature slowly and require decades to reach sexual maturity. It was once an abundant species in Lake Ontario. "In 1860, this species, taken on incidental catches of other fishes, was killed and dumped back in the lake, piled up on shore to dry and be burned, fed to pigs, or dug into the earth as fertilizer." It was even stacked like cordwood and used to fuel steamboats.  Once its value was realized, "They were taken by every available means from spearing and jigging to set lines of baited or unbaited hooks laid on the bottom to trapnets, poundnets and gillnets." Over 5 million pounds were taken from adjoining Lake Erie in a single year. The fishery collapsed, largely by 1900. They have never recovered. Like most sturgeons, the lake sturgeon is rare now, and is protected in many areas. Populations in the Oswego River are being actively managed for recovery.
  This food web has been damaged not only by over-fishing, and changes in nutrient levels, but also by other types of pollution from industrial chemicals, agricultural fertilizers, untreated sewage, phosphates from laundry detergents, and pesticides. Some pollutant chemicals that have been found in the lake include DDT, benzo[a]pyrene and other pesticides; PCBs, aramite, chromium, lead, mirex, mercury, and carbon tet
caption: Wetlands on a lakeshore
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