Ann Arbor’s U-M Researchers Forecast Significant Algae Bloom this Summer

Researchers at the University of Michigan in Ann Arbor and their partners are forecasting that western Lake Erie will experience a significant harmful algae bloom this summer. This year’s bloom is expected to measure 7.5. An index above 5 indicates blooms having greater impact.
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algal bloom in Lake Erie
Researchers from U-M and other institutions predict a large algal bloom in Lake Erie this summer. // Photo courtesy of the University of Michigan

Researchers at the University of Michigan in Ann Arbor and their partners are forecasting that western Lake Erie will experience a significant harmful algae bloom this summer. This year’s bloom is expected to measure 7.5. An index above 5 indicates blooms having greater impact.

The forecast was released Thursday by the National Oceanic and Atmospheric Administration, which funds the research. The severity index is based on the bloom’s biomass, or the amount of algae, over a sustained period. The largest blooms occurred in 2011 with a severity index of 10 and in 2015 with a severity index at 10.5. Last year’s bloom had a severity index of 3.6, and 2017’s was 8.

The size of the bloom does not correlate with public health risk, according to Don Scavia, aquatic ecologist at U-M, member of the forecast team, and professor emeritus at the School for Environment and Sustainability.

The lake temperature has remained relatively cool this year due to higher-than-average rainfall, so the bloom is not expected to start until late this month when the water temperature reaches 65-70 degrees Fahrenheit. In 2018, warm weather at the beginning of June caused an early start.

“Because of the excessive spring precipitation, this year’s bloom is likely to be large,” says Scavia. “But bloom predictions, regardless of size, do not necessarily correlate with public health risk. Local weather conditions such as precipitation, wind direction and water temperature also play a role.

“Even so, we cannot continue to cross our fingers and hope that drier weather will keep us safe. These blooms are driven by diffuse phosphorus sources from the agriculturally dominated Maumee River watershed. Until the phosphorus inputs are reduced significantly and consistently so that only the mildest blooms occur, the people, the ecosystem, and the economy of this region are being threatened.”

Lake Erie blooms consist of cyanobacteria, also called blue-green algae, which are capable of producing the liver toxin microcystin, which poses a risk to human and wildlife health. Such blooms may result in higher costs for cities and local governments to treat drinking water, prevent people from fishing, swimming, boating, and going to the beach, and harm the region’s summer tourism. The effects will vary in location and severity due to winds that may concentrate or dissipate the bloom.

Calm winds in July, especially in western Lake Erie, tend to allow the algal toxins to concentrate, making blooms more harmful. They tend to peak in the western part of the lake in September. Most of the rest of the lake will not be affected.

“This extremely wet spring has shed light on the movement of nutrients from the land into Lake Erie,” says Christopher Winslow, director of Ohio Sea Grant and Stone Laboratory. “Despite the predicted size of this year’s bloom, portions of the lake will be algae-free during the bloom season, and the lake will remain a key asset for the state.

“Ongoing research continues to help us understand bloom movement and toxin production and remains vital to providing our water treatment facilities with the tools, technology, and training they need to keep our drinking water safe.”

The National Oceanic and Atmospheric Administration is developing tools to detect and predict toxic blooms and their conditions.

“This spring brought regular, heavy rainfall to the Maumee River watershed, which carried a lot of nutrients into the lake,” says Richard Stumpf, lead scientist for the seasonal Lake Erie bloom forecast for the administration’s National Centers for Coastal Ocean Science. “However, due to the amount of rain this year, farmers were unable to plant their fields, which reduced the nutrient concentration. That, combined with higher-than-normal lake levels, presents an opportunity to test the accuracy of our models.”

The forecast is part of an administration ecological forecasting initiative that aims to deliver accurate, relevant, timely, and reliable ecological forecasts directly to coastal resource managers and the public. The administration continues to expand the use of satellite data into its Lake Erie Harmful Algal Bloom Forecast System, which is helping improve the accuracy of bloom forecast products.

Nutrient load data for the forecasts came from Heidelberg University in Ohio. The forecast models are run by the administration, U-M, North Carolina State University, LimnoTech in Ann Arbor, Standford University in California, and the Carnegie Institute for Science in Washington, D.C.

Field observations used for monitoring and modeling are done in partnership with the administration’s Ohio River Forecast Center, its National Centers for Coastal Ocean Science, its Great Lakes Environmental Research Laboratory, the U-M-based Cooperative Institute for Great Lakes Research, Ohio Sea Grant and Stone Laboratory at Ohio State University, the University of Toledo, and Ohio Environmental Protection Agency.

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