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Researcher Says Test Results Identify Red Tide Cause

The bulrushes rimming Lake Okeechobee. Photo by Amy Green

During the height of this past summer’s toxic algae bloom, a team of researchers from Florida Gulf Coast University took water samples from the Gulf of Mexico, the Caloosahatchee River and Lake Okeechobee to try and identify a common source of pollution.

The samples were sent to a lab across the country to have their nitrogen compounds analyzed to find where tested nitrates originated from.

Dr. William Mitsch is leading FGCU’s research efforts and announced the test results during a lecture series discussion Thursday night at the Everglades Wetland Research Park in Naples.

“Take it to the bank: red tide is mostly caused on our coastline by nitrate fertilizer,” he said.

Mitsch said the highest reading for nitrates came from the Caloosahatchee River sample.

The second highest reading came from collected rainwater, which Mitsch said could explain how nitrates end up in the Gulf, where they feed the red tide algae present in the water.

“It could be polluted rainfall that’s causing red tide, or at least accelerating it or maybe starting it,” he said.

Mitsch said he and his team will continue their research on toxic algae and water quality.

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