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The Great Lakes and the Greatest Lake

The Great Lakes and the Greatest Lake. Characteristics and processes Physical and biological challenges Local and global relationships. The Great Lakes System. 18% of world’s fresh water [6 quadrillion gal] Spread over “lower 48” states = 9.5 ft. deep

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The Great Lakes and the Greatest Lake

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  1. The Great Lakes and the Greatest Lake Characteristics and processes Physical and biological challenges Local and global relationships

  2. The Great Lakes System • 18% of world’s fresh water [6 quadrillion gal] • Spread over “lower 48” states = 9.5 ft. deep • All among world’s top 20 lakes in surface area • Cover 94,000 sq mi • Drainage area (watershed) spans 100 of latitude and 180 of longitude (750 miles W-E) • Home to 10% of US population and 25% of Canadians

  3. http://www.on.ec.gc.ca/glimr/images/maps/glbasin.gif

  4. Formation of the Lakes • Geologically very young • Regional bedrock varies in hardness • Forces of mountain building, volcanoes, metamorphism active in Pre-Cambrian around Lake Superior [1-2 BYA] • Most of area sedimentary, Paleozoic age

  5. Permian Period, 285 MYA (shale, Limestone, coal); Carboniferous Period, 320 MYA) (sandstone, shale, coal) Devonian Period, 410 MYA (limestone, shale, sandstone) Silurian Period, 440 MYA (Dolostone, some limestone) Ordovician Period, 500 MYA (limestone, Cincinnati Arch)

  6. Ohio Bedrock

  7. Extent of glacial advance Pleistocene Events shaped Ohio’s topography

  8. Lake Superior • Largest surface area of any lake in world • Deepest of Great Lakes [1332 ft] • Volume = all other lakes + 3 more Eries • Retention time 191 years • Watershed mostly forested, water quality high except for airborne transport

  9. Lake Michigan • The only GL entirely in the United States • Cul-de-sac; water retention 99 years • Same level as Huron; they act as one lake • N is forested, S heavily urbanized (1/5 of basin population) • Green Bay: productive fishery but contaminated by paper mills • Home of world’s largest freshwater sand dunes

  10. Lake Huron • Includes Georgian Bay • 30,000 islands! Manitoulin Island largest freshwater island in world • Retention time 22 years • Saginaw Bay fishery very productive • Many shipwrecks, clear water for viewing

  11. Lake Ontario • 4x Lake Erie’s volume • Niagara Falls flows into it • Retention time 6 years • Hamilton & Toronto, Ontario; not as dense on US side

  12. Lake Erie • Shallowest, smallest volume • Retention time 2.6 years • Most agriculture and urban effects on water • Most productive in fish for human food • “Poster child” for environmental concerns in 60s & 70s

  13. Shipping importance • More ships through Lake Erie in 9-mo season than through Panama,Suez, Manchester, and Kiel Canals put together • Main commodities shipped: iron ore, grain, coal [bulk products] • Most fuel efficient, environmentally friendly mode for transporting goods • Seasonal [March 23-Dec 24, 2001] • Declining in recent years

  14. Regional environmental issues • Non-native species • Ecosystem balance issues • Water contamination • Bioaccumulation in food chain • GLWQA, Areas of Concern • Eutrophication • Habitat loss and species change • Urban sprawl • Fisheries changes

  15. Fishery importance • More fish from Lake Erie than all others together • Economic changes from commercial to sport (stocked) fish in US waters • Threatened by non-native species and environmental changes in watershed

  16. State of Lake Erie 2001 • Condition “mixed” to “mixed-deteriorating” • Contaminants • Nutrients • Non-native species • Habitat loss/alteration • Fisheries decline (walleye & perch)

  17. Contaminants • Toxic substances (PCBs, chlordane, DDT, dioxins, PAHs, pesticides, endocrine disruptors) • Heavy metals (Pb, Hg) • Nutrients (phosphates, nitrates) • Dead zone reappearing in recent years • NO3 concentration increasing

  18. Non-native species

  19. Habitat • Degraded wetlands, forests, beaches, dunes • Land use issues in tributaries • Open lake anoxic areas

  20. Other organisms... • Native unionid mussels • Abundance reflects ecosystem health • Absent from former habitats • ZM pressures, factory farms, herbicides • Lake trout • Scud • DELT (Deformities, eroded fins, lesions, tumors)

  21. Lake Erie water levels at Put-in-Bay, Ohio July 1999 June 1997

  22. Rich regional history & culture • War of 1812: 2nd war for independence • Civil War: John Brown, Johnson’s Island • First Nations tribes (Iroquois, Walpole Island) • Innovations in shipping: steamers, whalebacks, bulk carriers • Burning river, dead lake success stories

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