Red tide levels across Southwest Florida are falling in the wake of Tropical Storm Gordon, which brought heavy offshore winds that pushed the bloom away from beaches. Some Sanibel areas have tested below 1 million cells per liter for the first time in two months, which could be a sign that the bloom has moved offshore or is beginning to break up.

“The samples I looked at are way down in concentration,” said Rick Bartleson, a water quality scientist with the Sanibel-Captiva Conservation Foundation. “They were around 40 million cells per liter last Friday, and now they’re down to 40,000 cells at Beach Access 1. Algiers on Saturday was 41 million, and in three days it went down to 200,000. That’s basically a 99 percent drop.” 

Red tide was barely detectable this week in Collier County waters and fluctuating between background concentrations and 1 million cells per liter in Lee, according to a Florida Fish and Wildlife Conservation Commission report.

The National Weather Service also dropped its hazardous beach conditions advisory for several Southwest Florida counties.

The bloom is patchy but still stretches from the Tampa Bay area to around the Collier County line.

“Wind is helping disperse red tide cells and sending red tide concentrations offshore,” Bartleson said. “They’re getting disturbed. The wind can break up the cells, which are fragile and can rupture from too much turbulence.”

Onshore winds pushed the bloom to coastal areas in June, and Southwest Florida beaches have been largely void of humans and filled with dead wildlife since.

Counts since June have largely been at 1 million cells per liter and higher, according to Florida Fish and Wildlife Conservation Commission records.

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

Bartleson said counts in Pine Island Sound and San Carlos Bay may stay elevated because the barrier islands helped hold some of that water in the bays.

Conditions in Collier were already improving before Tropical Storm Gordon hit.

“The easterly winds we had a week prior to Tropical Storm Gordon had already helped minimize impacts at the beaches,” said Rhonda Watkins, an environmental specialist for Collier, in an email. “Bloom concentrations had already dropped to zero at all but one of our Collier County beaches prior to the storm. We won’t know if the storm had any further impact until we get results back.”

Bob Wasno, a Florida Gulf Coast University professor and researcher, said this is the worst red tide he’s seen in three decades.

“For the past 30 years and the red tide I’ve seen nothing has been this far ranging and devastating,” Wasno said. “I’ve never seen it this far before. Many of the episodes that I’ve seen in the past only lasted a few weeks.”

A University of South Florida College of Marine Science model shows the bloom moving out of the bays and to the north over the next three days.

That would help the situation even more for Lee.

“The water was very red, and it looks much more clear now,” Bartleson said.

— Published News-Press September 5, 2018