State scientists are blaming a harmful algal bloom rarely found in
Researchers with the Florida Fish and Wildlife Research Institute in
The organisms, once called Gymnodinium
pulchellum, were to blame for fish kills in the same area
of the lagoon in 1990 and 1996, the only other times the algae have been identified
in
"There's still very much that we don't know about it," she said. "But we've experienced this one before in the same area, so it leads us to suspect there's something particular to the lagoon that helps it bloom."
The algae, possibly transported to the area in a ship ballast, could live in the lagoon all the time, she said, but only become visible when they bloom.
Scientists don't know exactly why the bloom is associated with fish kills.
It could simply soak up oxygen in the water, denying it to fish. Or the bloom could be toxic. Some of the scientists collecting samples in the lagoon noted a stinging sensation in their eyes and around their mouths, Landsberg said.
Researchers will be testing the toxicity of the algae for several weeks.
St. Lucie County officials first noticed dead fish Aug. 15 at Blind Creek and Little Mud Creek, north of the St. Lucie Nuclear Power Plant, and at Pete Stone Creek, near Bear Point.
By Wednesday night, the bloom reached south, almost to the the Jensen Beach Causeway, Mosquito Control Director Jim David said.
"It's worse than any bloom conditions I've ever seen out there," he said. "This is bad, and it's getting worse, and it might kill more fish."
The bloom covers mostly backwater areas and water around mangroves, where nutrients tend to accumulate. It has turned the water grayish brown, with white scum on the surface, and has caused an unpleasant odor, which led county officials to first suspect waste water.
Tuesday night, officials with the Florida Department of Environmental Protection ruled that out after inspecting the waste-water facilities of St. Lucie County and the Fort Pierce Utilities Authority. They found no leaks.
Scientists identified the culprit as Takayama Wednesday in the
Scientists ruled out algae in that case, "but it's possible that these fish encountered a bloom somewhere else and just happened to die there," said Heather Porter, a scientist with the Fish and Wildlife Research Institute.
Results from toxin tests, available later this week, may link the two fish kills.
Local environmentalists say they noticed diminished water quality in the lagoon in the days leading up to the fish kill.
"You can't see two inches into the water," Kevin Stinnette of Indian Riverkeeper said. "It's just a soup."
Boats leave white streaks in their wake, a sure sign of dirty water, said Mark Perry, executive director of the Florida Oceanographic Society.
"In the summer months, periodically, the dissolved oxygen gets low and the water is shallow because we get extra low tides," he said. "But this is unusual."
He said recent releases into the lagoon from storm-water canals may have added more nutrients to the water, helping algae bloom. Water managers have released about 500 cubic feet, or 3,740 gallons, per second from the C-23 and C-24 canals in the past two days, said Randy Smith, spokesman for the South Florida Water Management District.
But Stinnette said the bloom might have been caused by years of runoff of residential and commercial fertilizer. Residents, he said, should start to limit how much they use on their yards.
County officials will keep circulating water in the mosquito impoundment areas but will wait until after Labor Day to make any releases into the lagoon, David said. They don't want to spread the algae.
In the meantime, Jim Moses, environmental health director with the St. Lucie County Health Department, urged residents to avoid swimming or fishing in affected areas.
"And if you have any doubts, just don't go near it," he said.
Takayama pulchella
What is it?
A harmful alga that often blooms in estuaries, causing fish kills and respiratory
irritation in humans.
Where is it found? Typically, it is found in the
How did it get here? Scientists aren't sure, though it might have
been transported in the ballast of a ship.