Red tide numbers strong as fish kills reported throughout Naples, Collier County

Toxic red tide is blanketing the Southwest Florida coast at a time of year when it should actually be waning.

Levels from Tampa Bay south to Marco Island range from around 10,000 cells per liter to more than 1 million cells per liter, according to the Florida Fish and Wildlife Conservation Commission, or FWC.

Fish kills and breathing issues in humans can start when levels reach 10,000 cells per liter, according to the FWC.

Fish kills have been problematic in Collier County waters in recent weeks.

Rhonda Watkins, a pollution control environmental supervisor for Collier County, said reports of dead fish are widespread.

"Dead fish are being reported at every beach from Barefoot to South Marco and in the back bays including Naples Bay, Moorings Bay, and Cocohatchee River estuary," Watkins said in an email. "The red tide cell counts are higher north of Naples Pier.  Discolored water was reported (Monday) in Moorings Bay and cell counts there last week were around 26 million cells (per) liter."

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Red tide is a natural menace fed by humans

Red tide (Karenia brevis) occurs naturally here, but scientists say the blooms are fed along the coast by excess nutrients running of the landscape.

From the Cape Romano area of the Ten Thousand Islands National Wildlife Refuge north to Loudermilk Park, waters recently in the Naples-Marco Island area have measured between 10,000 and 1 million cell or more per liter, according to FWC reports.

Outbreaks tend to initiate in the late summer or early fall and disappear by the following winter or spring.

Cold fronts and heavy winds help break up blooms, while offshore winds help keep the airborne toxins away from local beaches and the nearby public.

Recent measurements have been high at Barefoot Beach, Vanderbilt Beach and Naples Pier, according to Collier County beach reports.

Red tide can be devastating to sea life

The Florida Department of Health in both Lee and Collier counties have issued red tide advisories in recent days and weeks.

A strong red tide hit Southwest Florida from the fall of 2017 until the spring of 2019, with the summer of 2018 being the worst of the conditions.

Sea turtles, dolphins, birds and even whale sharks washed up on local beaches that summer, and more than 1 million pounds of dead sea life was collected from Lee County beaches that year.

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The 2018 summer followed Hurricane Irma, which shot up the Southwest Florida coast and caused a massive release of pollution in the form of nutrients.

Some water quality advocates and researchers fear another strong bloom may be ahead for this area as Hurricane Ian, which hit in September 2022, may have a similar effect on local water quality.

Mike Parsons, a Florida Gulf Coast University professor, researcher and member of the state's Blue-Green Algae Task Force, said some researchers boating out of the Bonita Springs area have had to bail on recent water testing projects because the effects of red tide were so strong.

"We've had some folks on the water who had to come back in because it was so bad," Parsons said.

Parsons said Hurricane Irma in 2017 may not have necessarily been tied to the 2018 red tide outbreak.

Research from the University of South Florida, Parsons said, suggests there were two red tide blooms going on at once.

"There are some similarities, but it looks worse now than in March of 2018," Parsons said. "Typically it stops by the end of January or February, and it didn't do that in 2018. And right now it's worse than it was then. But it didn't get bad after Irma until the following summer."

Parsons said it's difficult to tell at this point how the 2023 red tide season will play out as there are many variables at play.

"It's really hard to say how it's going to project" Parsons said. "We'll have to wait until June, July and August to see."

These massive outbreaks are more frequent, longer lasting and more severe than they were just 50 years ago, scientists with the University of Miami and other institutions have found.

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