Researchers have put together a comprehensive map that reveals the greatest sources of stress on the Great Lakes. The map shows how “environmental stressors” are changing the future of an ecosystem that reportedly holds 20 percent of the world’s fresh water.
According to the Environmental Protection Agency, the Great Lakes constitute the largest surface freshwater system on the planet. More than 30 million people reside in the Great Lakes basin. The EPA notes that the impact of their daily activities directly affects the Great Lakes environment.
A group led by researchers at the University of Michigan created the most detailed map to date of Great Lakes’ stressors. The map is also the first to categorically take into consideration all significant types of stressors on the Great Lakes in a quantitative way.
“Despite clear societal dependence on the Great Lakes, their condition continues to be degraded by numerous environmental stressors,” said lead researcher David Allan, a professor of aquatic sciences at the University of Michigan’s School of Natural Resources and Environment, in a statement.
The group hopes that this map will serve as a valuable source of information for public officials to sustainably manage the Great Lakes.
To create the map, researchers pulled together the most recent data from federal and state agencies as well as non-governmental organizations and individual researchers.
Researchers studied 34 stressors, including coastal development, pollutants moved by rivers from agricultural and urban land, fishing pressure, climate change, invasive species and toxic chemicals. The map reveals the impacts of these stressors at the scale of half a mile.
The team utilized a new approach to assess the ecosystem health of the Great Lakes region. They ranked the relative importance of different stressors to ecosystem health by questioning 161 researchers and natural resource managers.
“Current efforts to conserve, manage and restore the Great Lakes often take a piecemeal approach, targeting threats one by one,” Mr. Allan said. “We need to recognize that the Great Lakes are affected by multiple environmental stressors, and devise strategies based on a full reckoning.”
Defining “stress” as human impacts like physical, chemical or biological issues that potentially have unfavorable effects on people, plants and animal, the researchers identified high and low “stress” in all five lakes. They also discovered that ecosystem stress is greatest closer to shores, but can also be found offshore in some areas. They found large sub-regions of moderate to high cumulative stress in lakes Erie and Ontario and along Lake Michigan’s shorelines. Offshore areas of lakes Superior and Huron, on the other hand, have relatively low stress.
According to the University of Michigan, the Great Lakes provide ecosystem services, such as recreational and commercial fishing, with economic values estimated in the tens of billions of dollars annually. Researchers found that areas providing ecosystem services were often excessively stressed.
“Basically, our work itemizes the laundry list of things that need to be fixed and where they occur,” said co-author Peter McIntyre, a professor at the University of Wisconsin-Madison’s Center for Limnology, in a statement. “This information can be used in any given location by local officials and citizen groups.”
This type of information will help planners recognize locations where ecosystem services are greatest, guaranteeing that all relevant stressors are taken into consideration.
“The Nature Conservancy and multiple partners are already working to attack many of these stressors in places like western Lake Erie, Green Bay and the coastal areas of Lake Ontario – the very places where nature and people are inexorably linked,” said co-author Patrick Doran, the director of conservation for Michigan and the Great Lakes at The Nature Conservancy, in a statement.
Researchers hope that the comprehensive map will help officials better plan Great Lakes-area investments like those under the Great Lakes Restoration Initiative, which is a federal effort that is funding hundreds of projects in areas where ecosystem stress is high.
“The cumulative impact map provides a quantitative perspective on how best to protect critical natural resources such as beaches, boating and fishing that support a vibrant tourism industry, as well as commercial fishing which remains important to local economies,” Mr. Allan said. “Conducting this analysis at the scale of the entire Great Lakes basin fills an important gap in strategic prioritization to protect the Great Lakes and the services they provide to society.”
Researchers will continue to map additional stress as new data become available. The Great Lakes Environmental Assessment and Mapping Project has a website that allows the public to see the results of the three-year-long project.
According to the EPA, a Presidential Executive Order was signed in May 2004 recognizing the Great Lakes as a national treasure.
The study’s findings were recently published online in the journal Proceedings of the National Academy of Sciences.