According to the results of a new study, Lakes Erie and Ontario are the most threatened of the five Great Lakes, while Lake Superior remains in the est health. A team of 22 U.S. and Canadian scientists collected data for 3 years, and analyzed 34 stressors to the world's largest supply of fresh water, including zebra mussels, toxins, light pollution, and more.
The study also came to the conclusion that any restoration effect that focuses on a single, high-profile threat may have minimal effect unless other threats are also addressed at the same time. Peter McIntyre, one of the study's co-authors and a professor at the University of Wisconsin-Madison's Center for Limnology, says:
"It's almost a death-by-a-thousand-cuts syndrome."
The Great Lakes provide 1.5 million jobs and $62 billion in paychecks each year, according to a 2010 study. The lakes also provide recreational activities for swimmers, anglers, boaters, and other outdoor enthusiasts.
The study, which was published on monday in the journal Proceedings of the National Academy of Sciences, charts out the "cumulative stress" on the lakes.
22 scientists collected and then layered data and reports from satellite images to compile a single map that charts' the impact of humans on the Great Lakes. The results of their efforts is a multicolored map in which red highlights areas of the lakes that are facing multiple problems, and blue areas in which fewer threats exist.
McIntyre said that the lakes' red zones were like a sick patient with multiple organ failure, commented:
"It's not going to do a lot of good to have a heart transplant if their kidneys and liver aren't working."
The reddest areas tend to hug the shorelines of urban areas. A large swath of red runs along southern Lake Erie's shoreline beginning near the Pennsylvania-New York border, going westward through Ohio and turning north to the Detroit area. The reason behind this large area of red is the predominance of agriculture in those areas, and the resulting runoff from fertilizer.
The study's authors say that the map confirms that the more than $1 billion federal Great Lakes Restoration Initiative is targeting the most acutely threatened regions.
The two lakes facing the greatest threats are Lake Erie and Lake Ontario.