Large harmful algal bloom predicted for western Lake Erie

Posted at 1:21 PM, Jul 11, 2019
and last updated 2019-07-11 13:21:13-04

(WXYZ) — University of Michigan researchers and their partners are forecasting that western Lake Erie will experience a significant harmful algal bloom this summer.

Scientists expect this year’s bloom to measure 7.5 on the severity index, but it could possibly range between 6 and 9. An index above 5 indicates blooms having greater impact.

Last year's bloom had a severity index of 3.6, while 2017 was 8.0.

This year, researchers say the lake temperature has remained relatively cool due to the higher-than-average rainfall in the region, so the bloom is not expected to start until late July when the water temperature reaches 65 to 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,” said University of Michigan aquatic ecologist Don Scavia, a member of the forecast team, in a release.

“But bloom predictions—regardless of size—do not necessarily correlate with public health risk,” said Scavia, a professor emeritus at the School for Environment and Sustainability. “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,” Scavia said. “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.”

Researchers say the Lake Erie blooms consist of cyanobacteria, also called blue-green algae, that are capable of producing the liver toxin microcystin, which poses a risk to human and wildlife health. These blooms can result in higher costs for cities and local governments that need to treat drinking water, prevent people from enjoying fishing, swimming, boating and visiting the shoreline, and harm the region’s vital summer tourism economy.

“This extremely wet spring has shed light on the movement of nutrients from the land into Lake Erie,” said 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.

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