The Great Lakes have been facing growing numbers and levels of threats to their ecosystems and to the human-use of their resources in recent years. Large-scale toxic blue-green algae blooms, high-levels of mercury and PCB pollution, invasive species, etc, have been doing significant damage to the lakes. A newly released report by the Great Lakes Environmental Assessment and Mapping Project has detailed these problems and found that Lake Ontario is currently the most-threatened of the five Great Lakes, followed closely by Lake Erie.
The report’s conclusions were based on over 3 years of collected data, on 34 different lake ‘stressors’. The research has resulted in the “first-of-its-kind computer-generated map of the lakes that paints the biggest problem areas in red.”
“I think it’s great to call it a Great Lakes threat map,” said Peter McIntyre, a mapping-project researcher with the University of Wisconsin’s Center for Limnology.
“Although no one wants a particular Great Lake to be the ‘worst,’ the one that has that status could attract more money to fight problems. Most of the funding would come from the federal Great Lakes Restoration Initiative, which has spent about $1 billion since 2010. Lake Ontario landed its ‘worst’ status because of widespread mercury and PCB pollution, and problems stemming from invasive sea lampreys and zebra and quagga mussels.”
Lake Erie, though, has some significant issues of its own. “In the summer of 2011, researchers tracked a record-size ‘bloom’ of toxic algae in Lake Erie. The algae, also called cyanobacteria, can sicken people and kill pets. NASA satellite photos snapped in October 2011 showed the algae stretching from Toledo to Cleveland.”
“Decomposing algae create a vast, oxygen-depleted ‘dead zone’ in the lake. Research indicates that Lake Erie has the biggest dead zone, although a sudden shift in Lake Ontario’s zone is suspected in the deaths of thousands of fish that washed up on that lake’s beaches in September.”
Large portions of Lake Erie are contaminated with large quantities of phosphorus and nitrogen run-off from agriculture located in the area. These nutrients are potent triggers for the massive and toxic algae blooms.
“Erie also appears to lead other lakes in sediment problems from erosion; an invasive shoreline reed called phragmites; and one invasive fish species, round gobies. Zebra and quagga mussels are in Erie but are more concentrated in Lake Ontario.”
Climate change has also been having an impact. “The Great Lakes maps show a large loss of winter ice cover in Erie and in Lake Superior. Ice is important because it helps to slow the warming of the water in the spring and summer.”
“The ice levels are just dropping significantly over time, year after year,” Bihn said.
Source: Columbus Dispatch
Image Credits: University of Michigan; Jeff Schmaltz, LANCE/EOSDIS MODIS Rapid Response. Caption by Mike Carlowicz and Jeff Schmaltz