Do humans add to red tide woes?


Published: Saturday, October 1, 2005 at 6:01 a.m.
Last Modified: Friday, September 30, 2005 at 11:06 p.m.
Answers about red tide are as murky as the water it clouds.
The state this week lifted red-tide-related closures of clam farms in Horseshoe Beach, the last remaining closures in Dixie and Levy counties.
But this is the second closure for Cedar Key since 2003. And since a lingering red tide has affected southwest Florida and the Panhandle since the beginning of this year, some are questioning whether human activities are contributing to the problem.
The toxic algae bloom discolors water, kills aquatic life and makes shellfish dangerous for human consumption.
State workers found thousands of dead fish and detected red tide in water samples off the shores of Cedar Key more than three weeks ago, forcing area clam harvesting to be closed for only the second time in recent memory.
The reasons for increasing red tide blooms are unclear.
A University of Miami professor says his research shows red tide events have increased with coastal development and pollution, but the state's pre-eminent expert on red tide says recent blooms have just gotten more attention than events in the past.
"Some years you get bad blooms and some years you don't," said Cindy Heil, senior research scientist with the Florida Fish and Wildlife Research Institute.
Red tide is a natural phenomenon in the Gulf of Mexico, she said, that was first documented by Spanish explorers. New residents sometimes assume the problem is a new occurrence, she said.
"A lot of us have not been here that long," she said.
But she agrees this year's event has been the worst in decades and doesn't look to be ending any time soon. The bloom has littered beaches off Southwest Florida with dead fish, killed endangered sea turtles and caused coastal residents to have respiratory problems. In recent months, it expanded to the Panhandle, killing fish and closing oyster farms there.
While most red tide blooms begin in the fall and last a few months, this bloom started in January and continues today.
"We don't have an end in sight," Heil said.
Larry Brand, a marine biology professor at the University of Miami, said his research shows the event continues a trend of off-season red tides. That spells trouble for spring and summer tourism, he said, as well as manatees and sea turtles that migrate in those times.
Studying data taken over 50 years, Brand said he found red tides in recent years have become 10 times more abundant, occur during a longer period of time and affect a larger area than before.
Human activities may be contributing nutrients to the water that cause those changes, he said.
But Heil said red tide has naturally evolved in the Gulf. The red tide that affected Cedar Key could have been brought near the shore by higher-than-normal temperatures in the Gulf, she said.
Those temperatures altered circulation patterns, she said, blowing the tide closer to the coast than usual.
Mike Kuhan, a state environmental specialist studying the red tide near Cedar Key, said the good news is winds now appear to be blowing in the other direction.
"We should be good to go unless we get a west wind," he said.
Nathan Crabbe can be reached at 352-338-3176 or crabben@gvillesun.com.

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