Hurricane Michael could end — or strengthen — Florida's Red Tide

The strong storm could dissipate the toxic algae in the Gulf of Mexico, or heavy rain could cause runoff that would feed the bloom with more pollutants.

Red Tide has been affecting beaches across Florida, like Madeira Beach shown here in September 2018, for months on end. [Luis Santana | Florida Beach Insider photo]
Red Tide has been affecting beaches across Florida, like Madeira Beach shown here in September 2018, for months on end. [Luis Santana | Florida Beach Insider photo]

As it charges north through the Gulf of Mexico this week, Hurricane Michael could finally dissipate the Red Tide algae bloom that’s been the bane of Florida beach communities.

Or it could make it worse.

"In the past, it’s gone either way," said Tracy Fanara, a staff scientist at Mote Marine Laboratory in Sarasota.

Oceanographer Richard Stumpf of the National Oceanic and Atmospheric Administration predicted the hurricane will just push the Red Tide around.

"It is most likely that Hurricane Michael will move some of the bloom northward," he said. Because the Panhandle already has some Red Tide affecting its beaches, "we might not notice a difference."

READ MORE: Answers to questions about Red Tide.

As of Friday, the Red Tide bloom stretched 145 miles along the state’s Gulf coast from northern Pinellas County down to Collier County, as well as touching several Panhandle counties and a few beaches on the state’s Atlantic coast from St. Lucie County to Miami-Dade County. Fish kills and reports of beachgoers with respiratory problems followed at each location.

The bloom has hurt the state’s tourism industry for months, but no one can say for sure whether the hurricane will finally knock it out. A lot depends on the direction and wind speed of the storm.

Sometimes, Fanara said, a hurricane can "dissipate a bloom due to turbulent wind and water." And sometimes the heavy rainfall a storm brings can fuel a bloom with nutrient pollution running off the land, she said.

READ MORE: Forecasts for Red Tide air quality are on the way.

For instance, she said, look at what happened in 2004 when four hurricanes clobbered the state in quick succession. Charley, Frances, Ivan and Jeanne may have had a hand in causing an algae bloom, she said.

That 2004-05 bloom, deemed one of the worst Red Tide outbreaks in Florida history, spent more than a year killing fish and shutting down beach tourism from the Alabama border to the Florida Keys. The impact on sea life was so catastrophic that it created a dead zone — an area of the Gulf devoid of oxygen and sea life — that stretched from New Port Richey south to Sarasota.

Then along came Hurricane Katrina, sweeping across the Florida peninsula and then the Gulf to devastate New Orleans. As it passed over the water, it broke up that dead zone, Stumpf said, but also pushed some of the algae bloom north to the Panhandle.

READ MORE: Red Tide also can affect birds along the shore.

Fanara said Hurricane Irma, which slammed into Florida in September last year, brought such massive amounts of rain that it helped fuel the algae bloom first detected offshore in November.

To keep growing, a Red Tide algae bloom needs a steady flow of nutrients, not unlike a crop that requires repeated fertilization. That’s why a Red Tide bloom, which starts up to 40 miles offshore, can be prolonged when it moves inshore and is fueled by leaky septic tanks and sewage systems, as well as fertilizer in stormwater runoff.

READ MORE: Is Red Tide affection Florida's seafood?

Normally, a Red Tide bloom begins in the late summer or early fall and lasts through the winter until February or March, when it dissipates on its own. But the current bloom has lasted so long, and become so deadly for marine life, that scientists have dubbed it the worst in a decade.

Stay tuned on whether Michael makes it better — or far worse.

This article was originally published in the Tampa Bay Times on Oct. 9, 2018.

Craig Pittman is the environmental reporter at the Tampa Bay Times. A native Floridian, he is the author of several books about the state.