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Red Tide Still Looms Along Florida’s Gulf Coast

A major red tide bloom extends more than 100 miles along Florida's Gulf coastline, and reaches more than 30 miles off shore in this NASA true-colour image

A major red tide bloom extends more than 100 miles along Florida's Gulf coastline, and reaches more than 30 miles off shore in this photo provided by Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on Dec. 22, 2001. The largest red tide bloom seen in Florida in nearly a decade has killed thousands of fish in the Gulf of Mexico and may pose a greater health threat if it washes ashore as expected in the next two weeks, researchers said on Aug. 7. Jacques Descloitres/NASA/MODIS via Reuters, file

A red tide that has threatened Florida’s Gulf Coast since earlier this summer is being kept offshore by slowing ocean currents and favorable winds, scientists involved in tracking such algae blooms said Monday.

The bloom of Karenia brevis — an algae that produces the phenomenon called red tide because of its reddish-brown color — appeared far offshore in early July. Wildlife officials were worried because a smaller bloom last year led to the deaths of 276 of the state’s 5,000 manatees. And tourism officials were alarmed at the prospects that the bloom could come onshore and could drive visitors away.

Such blooms happen nearly every year, but this one was spotted unusually early, said Jason Lenes, a University of South Florida researcher studying the modeling of red tides. Blooms typically begin 20 to 40 meters below the surface and move close to shore in late August or early September before rising near enough to the surface to be seen in aerial or satellite photos.

Rescued manatee released in Fla.

This one was identified nearly two months earlier — with fish kills first reported July 9 and sampling confirming the bloom a couple of weeks later, Brandon Basino, spokesman for the state’s Fish and Wildlife Research Institute, told NBC News in an email.

This bloom is also fairly large and began farther north than usual, Lenes said. Right now it’s 5 to 30 miles offshore from Dixy to Pasco counties and 5 to 15 miles off Pinellas County, home of St. Petersburg, Basino said.

Small fish kills and some reports of respiratory distress in humans have been reported in northern Pinellas County off Honeymoon Island, said Alina Corcoran, a research scientist with the state institute. The island is home to a popular state park.

The algae harm fish and animals by producing brevetoxins. Surf action can break up the algae cells and release the toxins into the air, causing problems for people with chronic respiratory trouble, Corcoran said. The toxins also can accumulate in oysters and clams and poison people who eat them.

Right now, scientists can predict the movement of a red tide about 3.5 days out with 150-meter accuracy using the West Florida Coastal Ocean Model, Lenes said. Beyond that is still pretty iffy. “The problem with this type of modeling is that you’re dependent on the forecast for the wind,” he said, similar to the issues in predicting hurricane tracks.

Still, he said, scientists are experimenting with combinations of physics and ecological models that might push the limit out to seven to 14 days — though such calculations require a lot of computer crunching time.

And this bloom? For now, it’s showing little movement, Lenes and Corcoran said (you can check the forecast here). That gives manatees and tourists a little breathing room — at least for the next 3.5 days.