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Hurricane Michael may have disrupted Florida's red tide

"It's like the ocean water in the hurricane is going thorough one big blender," said Tom Frankovich, a biologist at Florida International University.
Image: Red Tide Warnings Have Closed Some Miami Area Beaches
A Lake Worth lifeguard wearing a protective mask asks a surfer to exit the ocean as Palm Beach County officials announced that all county beaches are closed due to red tide affecting coastal areas on Oct. 4, 2018, in Lake Worth, Florida.Joe Raedle / Getty Images

For the last year, Florida has been plagued with red tide, a hazardous algae bloom that kills sea life and turns typically crystal-blue water brown and smelly.

But after Hurricane Michael tore through the Gulf Coast, large portions of the state may be getting a break from the algae, which had caused droves of fish, birds, dolphin and more to wash up dead on Florida's shores.

The Florida Fish and Wildlife Conservation Commission (FWC) tracks the amount of Karenia brevis cells, the microorganism that causes red tide, in the water. The group reported low or no traces of it in many parts of the Gulf Coast where red tide recently existed. The data used represents the most recent eight days of sampling.

Image: Toxic Red Tide
Fish are washed ashore the Sanibel causeway after dying in a red tide on Aug. 1 in Sanibel, Florida.Joe Raedle / Getty Images file

It was not immediately clear if Hurricane Michael was the cause of the sharp decline in red tide, but Tom Frankovich, a biologist at Florida International University, said storms can contribute to breaking the algae up.

"It's like the ocean water in the hurricane is going thorough one big blender and gets spread over a larger area," Frankovich said.

Frankovich said the hurricane also creates turbidity in the water, which means the amount of light that penetrates the water decreases, and some of the colder lower-level ocean water is also brought to the surface. Both factors make it harder for red tide to survive.

With the exception of two areas that show "low" or "very low" detection of Karenia brevis cells, FWC's daily sample map shows no detectable red tide conditions on the west coast from Collier County in southwest Florida to Manatee County, approximately 174 miles north.

It's unclear if levels of red tide were decreasing prior to the storm, but NBC News affiliate WFLA published a FWC map on Oct. 5 that showed the stretch of land between Collier County and Manatee County littered with indicators of low, medium and high concentrations of Karenia brevis cells.

One point on the map that remains unchanged is Pinellas County, just north of Manatee County, which still showed a red dot and two orange dots on the map on Saturday, indicating a medium and high levels of Karenia brevis cells.

Frankovich said the red tide in Pinellas has the potential to spread across the coast.

"It moves around with currents and those are driven by wind," Frankovich said, adding that red tide has spread from one area to another "in the past, and we would expect that to continue in the future."

Much of the red tide also appears to have subsided in Florida's panhandle, where only one point on the map near Santa Rosa Island indicated a medium level of Karenia brevis cells. On the east coast, from Broward County to St. Lucie County, the concentration of Karenia brevis cells is overwhelming "low" to "very low."

While parts of Florida might have a break from red tide, Frankovich warned that Hurricane Michael could trigger another bloom down the line.

Frankovich pointed to 2004, when an active hurricane season triggered a particularly brutal red tide the following year.

"Hurricane comes through mix things up … and the cell counts go down. But when a hurricane dumps water on land, and the water drains off of the land, it brings more nutrients into the Gulf," Frankovich said. "If it reaches areas where there are blooms, it could fuel it back up again."