Study may predict how climate change fosters Great Lakes dead zones

Study may predict how climate change fosters Great Lakes dead zones

Sep 19 2012 An algal bloom on Lake Erie. Photo: National Oceanic and Amospheric Administration

Scientists are studying how extreme weather associated with climate change may produce more of the algae that creates dead zones in the Great Lakes and elsewhere.

Figuring it out may help them manage the threat algae poses with projected climate changes.

Climate change presents a “perfect storm” for the Great Lakes because the sequence and intensity of extreme weather creates just the right conditions for blooms to flourish, said R. Jan Stevenson, co-director for Michigan State University’s Center for Water Sciences and the study’s principal investigator.

Algal blooms are rapid increases in algae caused by an excess of nutrients like the phosphorus and nitrogen often used in farm fertilizers. Harmful blooms can produce natural toxins. And when they die and decompose they use up dissolved oxygen, creating a “dead zone” that suffocates fish and other organisms.

They are a persistent problem in the Great Lakes region, especially Lake Erie.

Blooms typically grow in stable, low wind conditions and in warm water – the kind of climate during a drought, Stevenson said.  Climate change can prompt such droughts, but may also cause more intense storms.  Such storms produce runoff that washes nutrients from land into the lakes.

Those nutrients then exacerbate the growth of algae during the droughts, he said.

The study attempts to quantify the relationship between blooms and the extreme weather associated with climate change. Once the researchers gather data on nutrient flow and compare it to other regions, they will develop mathematical models to predict the influence of climate change on algal blooms.

The researchers will do this in part by looking at satellite images of blooms going back to 1972.

They will look at the relationship between extreme weather and blooms first around the Great Lakes and then elsewhere in the country. Then they will compare each region to see how they differ in blooms’ reactions to extreme weather, said Nathan Moore, professor of geography at Michigan State University and a co-worker on the project.

The research prompts questions of how to respond to problems affected by climate change.

Among them is what will we have to do in land use management in order to lower the heightened risk caused by climate change? Stevenson said. By studying regions where blooms respond differently to extreme weather, researchers will provide information tailored to each specific case. That will make it easier for policy makers and land managers to decide how best to control algae problems.

The study is funded by a $749,801 grant from the U.S. Environmental Protection Agency.

It will be conducted over the next three years and include modeling of Muskegon Lake in Muskegon County, Mich., Saginaw Bay in Lake Huron, Grand Traverse Bay in northwest Michigan and Michigan’s Grand River, which is one of the biggest sources of nutrients that flow into Lake Michigan,  Stevenson said.

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