Red tide, more common and concentrated, not expected to impact Southwest Florida this year

Chad Gillis
Fort Myers News-Press

More than four years have passed since a devastating and deadly red tide ravaged Southwest Florida, killing off millions of tons of marine life and shutting down the local tourism industry. 

And while late summer and early fall are when blooms typically initiate, red tide levels are at normal, background concentrations so far this year. 

A graphic from a University of Florida-led study shows the connectin between manmade pollution and red tide blooms in Southwest Florida.

"I remember the (sea) turtles," said Calusa Waterkeeper John Cassani of the 2018 outbreak. "That's the one that got me. That really bothered me a lot. These creatures are 20, 30, 40 years old and they're taken out of the subset of individuals and are not going to contribute anymore. I don't think you can put lipstick on that pig." 

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Red tide is a naturally occurring organism that sometimes takes over the eastern Gulf of Mexico, harming sea life while producing breathing irritation and coughing in humans. 

Blooms have occurred historically here and elsewhere in the Gulf of Mexico and Atlantic Ocean, but research out of the University of Miami shows that blooms are more frequent, intense and of longer duration today than they were just 50 years ago. 

"There's long been this narrative that what causes the blooms offshore is nutrient-rich deep water upwelling, but there's been this almost elephant in the room avoidance to any linkage to land-based runoff," Cassani said. "But now we know there is an empirical and derived link (with ride tide related) to nutrients." 

Pollution in the form of nutrients has been flowing down the Caloosahatchee River by the ton for decades. 

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For the most part, nutrients come from agriculture operations, although leaky sewage systems and ailing septic tanks add to the problem. 

Hurricane Irma in 2017 stirred up nutrients in the historic Lake Okeechobee system. A blue-green algae bloom broke out on the lake in the early summer of 2018, and soon the toxic algae was in the Caloosahatchee River. 

It blanketed canals and inlets, and some residents and visitors were forced to leave the area. 

Then-governor Rick Scott declared a state of emergency for Lee County for both the red tide and the blue-green algae impacts. 

"There are already legacy nutrients built up in the back bays. so when red tide gets here, whether it's a high density or not, it's going to acquire the needed nutrients," Cassani said. 

Mike Parsons is a professor and researcher at Florida Gulf Coast University. He's also a member of the state's Blue-Green Algae Task Force, and he monitors red tide here. 

"We collect samples pretty regularly and we haven't seen anything," Parsons said. "We saw some in the spring and it lurks, but there was no bloom concentrations. It's lurking but it's not blooming." 

Parsons said red tide blooms tend to initiate in October and end by the following February. 

That's been the historic pattern, but blooms like the one in 2018 lasted through the summer. 

"It was a late fall, early winter type phenomena," Parsons said. "What's been interesting and concerning is that it has been present over the summer the past couple of years. Why the change? It doesn't make sense that it would be responding to climate change because it typically likes cooler temperatures."

Parsons said he expects to see some red tide this fall but that a major bloom isn't likely in 2022.  

August is also the end of the ban on harvesting redfish that came from fish and wildlife managers in the wake of the 2018 bloom. 

Mike Westra's family owns Lehr's Economy Tackle in North Fort Myers, and he said the fisheries have largely recovered from the double-whammy blooms. 

The Florida Fish and Wildlife Conservation Commission closed several fisheries in 2018, and the redfish harvest will open again to licensed anglers on Sept. 1. 

Harvest regulations for snook, trout and redfish were changed then by FWC. Trout has since opened to harvest, but snook season, which typically takes place in the fall and spring, has remained closed. 

"Overall, for redfish, snook and trout, the closures did really, really well," Westra said. "I wouldn't be opposed to keeping any of them closed. They're going to open up redfish and I'm not opposed to that either." 

Connect with this reporter: @ChadEugene on Twitter.