Scientists link climate, Great Lakes `dead zones'

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Capital News Service
LANSING — Scientists are studying how extreme weather associated with climate change may produce more of the algae that create dead zones in the Great Lakes.
Figuring it out may help government agencies manage the threat algae poses in light of further projected changes in climate.
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 of Michigan State University’s Center for Water Sciences. He heads a research team studying the situation.
Over the next three years, the work will include modeling of Muskegon Lake in Muskegon County, Saginaw Bay in Lake Huron, Grand Traverse Bay on Lake Michigan and the Grand River – the state’s longest river — which is one of the biggest sources of nutrients that flow into Lake Michigan, Stevenson said.

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, especially Lake Erie.
Blooms typically grow in stable, low-wind conditions and in warm water – the kind of climate evident 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, he said.
Those nutrients then exacerbate the growth of algae during the droughts, he said.
The study attempts to measure 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’ll develop mathematical models to predict the influence of climate change on algal blooms.
They’ll do that in part by looking at satellite images of blooms going back to 1972.
MSU geography Professor Nathan Moore said the research team will first look at the relationship between extreme weather and blooms around the Great Lakes, and then elsewhere in the country. Then they’ll compare each region to see how they differ in blooms’ reactions to extreme weather.
Stevenson said the research prompts questions of how to respond to environmental conditions affected by climate change.
Among them is what should be done in land use management to lower the heightened risk, he said.
By studying regions where blooms respond differently to extreme weather, researchers will provide information tailored to each case. That will make it easier for policymakers 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.
Matt Hall writes for Great Lakes Echo.

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