Study needed to understand red tide, says FWC official

FORT MYERS — The Florida Gulf Coast is once again suffering from red tide, according to the ecological conditions report presented by Florida Fish and Wildlife Conservation Commission Executive Director Eric Sutton at the Nov. 14 meeting of the South Florida Water Management District Governing Board. The meeting took place at Florida Gulf Coast University.

The marine algae Karenia brevis, commonly called “red tide,” is a natural event that occurs nearly every year, he said. Anecodotal reports from Spanish explorers noted reports of red tide in the 16th century. Mr. Sutton said red tide was first documented in Florida in 1844.

According to the FWC website Nov. 13 report, “in Southwest Florida over the past week, K. brevis was observed at background to very low concentrations in Pinellas County, background concentrations in Manatee County, background to low concentrations in Sarasota County, very low to high concentrations in and/or offshore of Charlotte County, background to high concentrations in and/or offshore of Lee County, and very low to high concentrations in and/or offshore of Collier County. Bloom concentrations (> 100,000 K. brevis cells per liter) persist in Charlotte, Lee and Collier, and high concentrations (>1 million cells per liter) were observed in 23 samples. These included coastal, inlet and estuarine sites in Charlotte and Lee Counties, as well as samples collected as far as 7 to 10 miles offshore of Lee and Collier counties.”

“The big question out there is are the nutrients occurring on land exacerbating the red tide. There are different theories on that,” said Mr. Sutton. Even if the nutrients in freshwater runoff are not significant to the increase in red tide, it’s a good idea to do everything we can to reduce the nutrient load going into the waterways, he explained. “Any removal of nutrients from the ground going into the water is going to benefit all of us,” he said.

“The bad news about red tide is that it can feed on itself,” he said. Red tide will use any nutrient in the water. “It is an opportunistic feeder,” he said.

“We are trying to understand what causes it, what causes it to expand, and if we can be more predictive,” he said.

Mr. Sutton said media coverage can make the situation look worse than it is. Even when red tide is present in some areas, other areas in the same waterway may be still be good areas for fishing. “When you see the media throw a blanket over the southwest coast, it is unfortunate,” he said.

“The red tide is something that is natural,” said board member Ron Bergeron. “The wind and currents bring it in to shore.

“One thing we can do is to reverse the nutrients that are created by us in our waterways that feed the red tide. There is probably nothing we can do about the red tide itself. It’s been here for centuries.”

Most of the flow — and most of the nutrient load — to the Caloosahatchee Estuary comes from local basin runoff. While that is true every year, the lower rainfall this year has made this even more apparent. According to the water conditions report presented at the Nov. 14 SFWMD meeting, since May, 69,600 acre-feet of water from Lake Okeechobee passed through the lock at Moore Haven. Of that flow, only about 41,000 acre-feet made it to the estuary. The rest of the lake water was used for irrigation and to maintain canal levels between the Moore Haven Lock and the Franklin Lock. In that same time frame, 677,000 acre-feet of water moved through the Caloosahatchee Estuary. That means that since May, less than 7 percent of the freshwater that flowed into the Caloosahatchee Estuary came from lake Okeechobee.

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