Freshwater

Great Lakes Eco-Region

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Multimedia

Lessons and Activities

Real World Data

Background Information

The Great Lakes system is a series of five large connected lakes, one small lake, four connecting channels, and the St. Lawrence Seaway. The five large lakes are: Superior, Michigan, Huron, Erie, and Ontario. The lake system contains the largest supply of freshwater in the world. They hold about 18% of the world's freshwater and about 90% of the freshwater in the United States. Forty million U.S. and Canadian citizens depend on this system for clean drinking water.

Satellite image of Great Lakes
A satellite view of the Great Lakes, including the turbid waters of Lake Erie. Source: NASA Visible Earth

During the last ice age, a mile-thick ice sheet covered the area. The massive weight and movement of this glacier gouged out the earth to form the lake basins. About 20,000 years ago the climate warmed and the ice sheet retreated. Water from the melting glacier filled the basins and the Laurentian Great Lakes were formed. Approximately 3, 000 years ago, the Great Lakes had formed into their present shapes and sizes. Today, the Great Lakes eco-region contains a wide variety of habitats including: aquatic, forest, marsh, wetland, and dune ecosystems. Widely varying climate, soils, and topography of the region, in combination with these diverse ecosystems, support more than 3,500 species of plants and animals.

Humans are also a part of the Great Lakes system. Commercial and sport fishing, agriculture, recreation and tourism, manufacturing, and shipping are all important to the region. These activities create jobs, and provide needed goods and services . The fishing industry extracts over 65 million pounds of fish per year from the lakes, contributing more than one billion dollars to the region's economy. Agriculture produces corn, soybeans, hay, milk, and other food products. The area is also known for its heavy industry which produces steel, chemicals and other products that people use. A long and dangerous history of shipping on the Great Lakes played a critical role in settlement of the region and development of industry. Today more than 200 million tons of cargo pass through its water's each year.

There are a number of threats to the Great Lakes' ecosystems, including: invasive species, climate change, pollution, and habitat destruction. Climate change affects water temperatures, weather patterns and lake levels. Pollutants from residential, agricultural, and industrial areas reduce water quality. Land development decreases the amount of wildlife habitat. Fish populations have been declining in recent years as a result of these threats and increased fishing pressure.

Education Connection
"The Great Lakes are socially, economically, and environmentally significant to the region, the nation, and the planet." This an essential principle for Great Lakes literacy. The Great Lakes Literacy Principles and Fundamental Concepts provide a framework for educators teaching about the Great Lakes, helping teachers and students think, teach and learn of the Great Lakes as a system, rather than a set of unrelated parts. Thinking systemically can provide for a greater understanding and can help provide solutions to the issues threatening the region.

Adapted from: About Our Great Lakes, NOAA Great Lakes Environmental Research Laboratory
Last updated: 11/1/2010

Features
Snow at NEW forecast office.
The Science Behind Lake-Effect Snow

January 2010 (NOAA)
Suddenly, a "wall of white" appears several hundred yards ahead and a blizzard of heavy snowfall obscures everything in your path. You inch forward through the blizzard until you arrive on the other side.... Read More

Zebra and Quagga mussels
Zebra Mussels Hang On While Quagga Mussels Take Over

July 2009 (UW Sea Grant)
Zebra and Quagga mussels have permanently changed the Lake Michigan ecosystem. Before the mussels invaded, Lake Michigan water was mostly cloudy, and millions of tiny microorganisms provided a food base for fish.... Read More

Map of proposed estuary research reserve.
Lake Superior Estuarine Reserve EIS

September 2010 (NERRS)
The proposed Lake Superior National Estuarine Research Reserve is a diverse complex of terrestrial and aquatic habitats that form a unique freshwater estuary where the St. Louis River empties into Lake Superior.... Read More