By Neal Lineback and Mandy Lineback Gritzner, Geography in the NewsTM
The Great Lakes’ Mounting Problems
Recent news about an algae bloom on Lake Erie leading to Toledo, Ohio’s municipal water plants closing is just one of the many problems affecting the Great Lakes. Toledo’s 400,000 people were forced to purchase bottled water for two days, focusing the attention of the region on the beautiful Great Lakes’ water quality and environmental issues.
The five Great Lakes contain an astonishing 20 percent of the world’s above-ground fresh water. The surface area of the five lakes is 95,000 square miles (246,050 sq. km.), or nearly twice the size of North Carolina. The lakes contain six quadrillion (or six followed by 15 zeros) gallons (23 quadrillion liters) of freshwater, representing 95 percent of the surface water of the United States.
Pleistocene glaciers, occurring between one million and 11,000 years ago, gouged the Great Lakes’ lakebeds as the glaciers moved southward from Canada, leaving huge reservoirs, some that are below sea level.
Historically, the Great Lakes’ water quality and use have been hotly debated. One of the major issues throughout the 1900s, continuing into the 21st Century, has been pollution. The lakes were both a source of water and a destination for industrial waste and municipal sewage in the 20th Century.
Over the years, major international environmental efforts between the United States and Canada cleaned up some of the worst problems. Some problems persist, however, including mercury and agricultural pesticide pollution. The latest issue with a major algae bloom on shallow Lake Erie was caused by nutrients from agricultural fertilizers and municipal waste.
One of the lakes’ additional, problems is invasive species — organisms found in ecosystems from which they did not originate. Many of these exotics out-compete, eat or otherwise harm native organisms.
Since the 1800s, more than 160 documented invasive species have entered the Great Lakes ecosystem from around the world, causing economic and ecological impacts. According to the Inland Seas Education Association, these non-natives deprive fish of food, cause blooms of toxic algae disrupt spawning areas and foul boats’ and drinking water intakes. On average one new invasive enters the Great Lakes every eight months.
Zebra mussel infestations in the Great Lakes illustrate the severity of the problems stemming from invasive species’ introduction and spread. This non-indigenous mollusk is an efficient filter feeder that competes with native mussels and impacts fish populations by reducing food and available spawning habitat.
The zebra mussel was inadvertently introduced into the lakes in the ballast water of ocean-going ships from the Black Sea as they traversed the St. Lawrence Seaway and the Great Lakes. Utility and manufacturing industries around the region, dependent on Great Lakes water for production, are expending substantial time and money cleaning intake and discharge pipes clogged by zebra mussels. The U.S. Fish and Wildlife Service officials estimate the economic impact to these industries will be $5 billion over the next decade.
Invasive plant and animal species enter new ecosystems in many ways, including some natural, but most are introduced with the help of humans. Invasive species stow away on every type of transport vehicle imaginable. Of course, these means are unintentional.
In other cases, humans may modify the environment in such a way that a species may be able to expand into new territories. When engineers built the Welland Canal in order to bypass Niagara Falls located between Lake Erie and Lake Ontario, the lamprey eel was able to migrate upstream into Lake Erie. Lamprey eels threaten Lake trout and whitefish fisheries by attaching themselves to adult fish and finally killing them.
Interestingly, however, some exotic species have been introduced intentionally into aquatic environments. Examples include pets that are released, involving aquatic fishes, snakes and turtles.
When native species disappear because of competition with or predation by invasive species, biodiversity in general declines. Loss of biodiversity can throw the entire ecosystem out of balance, causing disruptions that are likely to be permanent.
The range of problems impacting the Great Lakes is enormous, many of which are impossible to change. Nutrient pollution that created the latest algae bloom on Lake Erie, the shallowest and warmest of the Great Lakes, may be only partially controllable by controlling the nutrients entering the lakes. The algae problem, however, is further exacerbated by the warming of the Great Lakes’ water associated with global climate change, making total control even more difficult.
And that is Geography in the News.
Sources: GITN 914, “The Great Lakes’ Invasion,” Maps.com, Dec. 7, 2007; GITN #575, “The Greatest Lakes,” June 8, 2001; http://www.environmentreport.org/topten.php3; http://www.greatlakeseducation.org/about_isea/?id=204
Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.