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Beaches Mostly Free Of Red Tide

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By KATE SPINNER

Sarasota Herald-Tribune

Published: December 26, 2008

Tourism may be down. Real estate has sunk. And unemployment is surging. But for Southwest Florida, one major indicator has been nothing but positive.

Red tide has largely disappeared from area beaches.

Entering what is expected to be an unseasonably warm holiday weekend, coastal waters are free of the toxic blooms that in the past left beaches covered with dead fish and sent choking tourists fleeing to their hotels.

Indeed, it has been more than two years since a significant outbreak hit the area.

Red tide still exists in Gulf waters. But scientists theorize that a combination of factors, including drought, wind patterns, ocean currents and water temperature, has prevented the massive blooms that made beach days miserable through much of 2004, 2005 and 2006.

A red tide bloom is a gigantic cluster of single-cell algae. When the algae dies, their cell walls burst, releasing toxic gasses that cause humans to cough and wheeze. In high concentrations, the gas kills all forms of sea life, including creatures as large as manatees.

Red tide is "a complex organism," said Kellie Dixon, a senior scientist at Mote Marine Laboratory in Sarasota. "It has a complex life history and it may just need several different coinciding things to occur at the same time to trigger the massive bloom that effects everyone."

Drought, beginning in late 2006, is the biggest factor preventing red tide outbreaks in recent years, theorized Brian Lapointe, a Florida Atlantic University research professor.

The severe blooms of 2004-06 followed torrential hurricane seasons.

"That was record rainfall and we had one of the largest red tide events in history," Lapointe said.

Water samples showed the red tide blooms were thriving in fresh water plumes that fanned into the Gulf of Mexico from the Caloosahatchee, Peace and other rivers. Those plumes were rich with algae-feeding nutrients, such as nitrogen and phosphorus, both from natural decay and man-made pollution, Lapointe said.

This year, a few blooms of red tide have formed, but none grew to a size large enough to effect people or produce noticeable fish kills, said Cindy Heil, a leading red tide scientist for the state Fish and Wildlife Research Institute.

Heil said runoff from rivers is a factor for red tide growth, but wind, ocean currents and water temperatures also play a major role in how the algae accumulate into blooms and spread.

In 2007 and '08, winds blew northeast more frequently, carrying the blooms away from Southwest Florida, Heil said. Water temperatures in the Gulf have also been cooler than in 2005.

The most persistent bloom of this year formed at the mouth of Charlotte Harbor in early October, about a month after Hurricane Ike passed through the region.

The minor bloom is still present, but has traveled south to the Florida Keys.

Around the same time last year, a bloom also formed near Charlotte Harbor, but a month of northeasterly winds shoved the bloom north and south, Heil said. The algae traveled to the Panhandle and south to the tip of the state, where currents transported it to the Jacksonville area.

"We're so shallow here that the winds have a huge influence on where the water moves," Heil said.

Aside from its toxicity, red tide is mysterious because it is very slow-growing, compared with other algae. It also has the ability to tap nutrient sources that other algae have a difficult time absorbing.

Heil said correlating rainfall and stormwater runoff with blooms is tricky because the algae do not use the nutrients immediately or directly. There is a lag, she said.

"People want to make that link, but we know these blooms are so complex that it's not a straightforward cause and effect," Heil said. "One of the worst red tides, in the 1970s, was during a big drought."

Most scientists agree, however, that stormwater runoff delivers the nutrients in the form of lawn fertilizers and other pollution that red tide needs to form a sustaining bloom.

After heavy rains and high river flows started to ease off in late 2006, "the incidence of red tide declined a bit," Dixon said.

Frequent beachgoers such as Steve Graham, 63, of Bradenton Beach, said red tide was so bad in 2005 that it drove he and his friends and their metal detectors back home.

"There were thousands of dead fish washed up on the tide, and the whole place was stinking," he said. "When it's like that, I won't even go down there. I'm grateful it hasn't been here for sure, because it's a big difference."

Herald-Tribune Manatee Bureau Chief Bart Pfankuch contributed to this story.

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