Hurricane Michael may affect red tide and blue-green algae. Here's how.
Amy Bennett WilliamsAs Hurricane Michael lumbered toward Florida’s west coast, speculation swirled about what effect the storm might have on the persistent red tide and toxic blue-green algae blooms plaguing the region.
Michael is forecast to pass Cuba, entering the southeastern Gulf of Mexico by tonight, then move across the eastern Gulf by Tuesday night. The storm, which is expected to strengthen as it goes, will likely turn inland over the Florida Panhandle or Florida Big Bend area Wednesday.
Though scientists are loath to make detailed predictions at this stage, they agree that the hurricane’s winds and rain may bring a mixed bag of benefits and trouble.
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Serge Thomas, associate professor for environmental studies at FGCU doesn't expect the wind to blow the blue-green algae (cyanobacteria) up or down the Caloosahatchee much, but in areas with canals, if the wind is moving alongside the water, "It could have a significant impact ... potentially, it could stack up the algae into the back of canals, which could be a problem for some folks in Cape Coral," he said.
If the storm lowers the temperature, that could slow algae growth, Thomas said. "Lower temperatures do not favor cyanobacteria ... their metabolism responds negatively to temperature drops."
The dual toxic blooms, each with its own Gov. Rick Scott-declared state of emergency, have ravaged wildlife and the region's tourism-dependent economy. The National Oceanic and Atmospheric Administration first recorded the red tide last Oct. 16; the cyanobacteria bloom started flourishing once the U.S. Army Corps of Engineers began sending polluted Lake Okeechobee water down the river June 1.
Although Michael's not currently expected to bring huge amounts of rain, if it does, flooding could spur more algal growth as the water washes over the land and into the river, Thomas said. "If retention/detention ponds overflow, if septic tanks and sewage systems are overflowing ... that could fertilize the algae."
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Such nutrient-rich overflows might also revive the red tide bloom, which appeared to be dissipating near-shore last week. Then again, in 2005, Hurricane Katrina swept away a red tide that had lasted 18 months, but "I don't think we're going to get the Katrina effect," Thomas said.
The toxic tide may already have been on the way out. As of late last week, research scientist Rick Bartleson of the Sanibel-Captiva Conservation Foundation found no Karenia brevis, the microorganism that causes red tide at any of the beach locations his nonprofit samples, and testing he did this weekend offshore failed to show any as well.
“I sampled the causeway, a few Sanibel and Captiva beaches and offshore up to three miles from Captiva,” he said, “and no Karenia.”
Bartleson plans to sample offshore in the coming days.
Initially, a phenomenon called advection might shove any remaining bloom away from the island in the coming days. "The surface layer will be heading away from shore, at least at first," he said, "So if there's Karenia out there, it will be heading away."
Then, the water's lower layer will move toward shore, which should also help, because Bartleson found very little Karenia in that layer when he sampled two weeks ago. Also, he said that layer's lack of oxygen, hydrogen sulfide and darkness aren't conducive to red tide blooms either.
What's more, "The advection away from shore will also dilute and spread out the (Karenia) cells, so there's less chance of a dense patch," Bartleson said.
Plus, says Accuweather meteorologist Alyson Hoegg, the storm's wind could act to break up the red tide, 'depending on how it tracks as it comes north ... with the winds blowing counterclockwise you guys will get an offshore flow that will help pull it away from the beaches."