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Study Says Toxic Algae Blooms May Be Contributing To Own Survival In Ohio Lakes

Satellite view of toxic algal bloom on Lake Erie
NASA Earth Observatory

Toxic blue-green algae blooms, or cyanobacteria, are a growing problem in Ohio’s lakes, and grabbed the attention of the whole country after the bacteria shut down Toledo’s water system last summer.

A new study funded by the National Science Foundation and published today in the journal Ecosphere shows that what creates good conditions for the blue-green bacteria might sometimes be the bacteria themselves. Past research has already shown that cyanobacteria can essentially process and create nitrogen and phosphorous; the nutrients then become available to other organisms by leaking or when the bacteria die off and release them.

Nitrogen and phosphorous might already be in excess in lakes because of fertilizer and sewer runoff, but as cyanobacteria create even more, that in turn encourages more of the toxic green slime to grow. Some cyanobacteria are capable of processing nitrogen from the air, or phosphorous from underwater sediments, into forms that are available to other organisms.

“We’ve kind of been ignoring this but we can’t do that anymore,” says Kathryn Cottingham, an ecologist at Dartmouth and a lead author on the study. She says new modeling in this study show that once there’s a bloom of toxic algae even in a relatively clear, clean lake, the problemcan keep getting worse no matter what we do.

But Cottingham says we should still address what we can control—runoff and pollution, as well as climate change. Blue-green algae blooms thrive in late summer, and the warmer the water, the better.

The explosion of the problem in 2014 led to the creation of a statewide protocol for testing for cyanobacteria in drinking water, and an Ohio law passed earlier in the year will eventually require all farmers using commercial fertilizers to get certified. Although that doesn’t go into effect until 2017, some Ohio farmers are already taking the certification classes.

Lewis Wallace is WYSO's managing editor, substitute host and economics reporter. Follow him @lewispants.