TITLE: RED TIDE CULPRIT IN MANATEE DEATHS

BYLINE: Stephen G. Reed STAFF WRITER

EST. PAGES: 1

DATE: 12/11/97

DOCID: SSTA73450301

SOURCE: Sarasota Herald-Tribune; SSTA

EDITION: Venice; SECTION: LOCAL/STATE; PAGE: 1B

(Copyright 1997)

Red tide was responsible for the deaths of 16 manatees in Southwest Florida last month, the state Department of Environmental Protection announced Wednesday.

After analyzing tissue samples and studying the carcasses of the stricken marine mammals, scientists concluded that the microscopic alga was the culprit, said Wendy Quigley, a spokeswoman for the DEP's Florida Marine Research Institute in St. Petersburg.

This is the second year in a row that red tide has been blamed for a rash of manatee deaths. Last year, a severe outbreak killed 149 manatees and helped make 1996 a record year for manatee deaths overall.

This year's fatalities were discovered Nov. 6 through 26, mostly in Lee and Collier counties. One animal was found in Charlotte County on Nov. 14 in a canal off Ainger Creek.

Tissue samples taken from the manatees were tested at the University of Miami. There, scientists detected toxins associated with red tide.

"They exhibited a range of conditions, generally in the area of the liver, kidneys, lungs and in the brain," Quigley said.

Red tide generates a neurotoxin that affects the nervous systems of fish and other creatures. Scientists still aren't sure how the manatees absorb enough to kill them, or exactly what it does to them, Quigley said.

In the past, investigators have suspected that the animals ate contaminated sea creatures - such as sea squirts - or inhaled airborne toxins near the water surface.

Research "is still ongoing to try to understand those mechanisms," Quigley said.

Red tide is a natural phenomenon that occurs when Gymnodinium breve, a one-celled dinoflagellate, blooms in large numbers. The blooms usually begin several miles offshore in the Gulf of Mexico, and cause obvious problems only when they drift ashore.

That's when dead fish turn up on the beach and beachgoers report irritation to their noses and throats - a symptom caused when toxins are released into the air by crashing waves.

Before last year, scientists suspected that red tide might kill manatees. In 1982, according to the DEP, 37 manatees in Lee County were believed to have been killed by red tide.

But until last year, when massive numbers of the endangered animals began dying and tests were done to detect red tide toxins, scientists could only be suspicious.

"In terms of data to support it, it's a relatively new thing," said Beverly Roberts, a DEP research administrator. Modern testing methods were not available in earlier years, she said.

Although most of this year's outbreak has cleared up, red tide continues to linger in areas south of Fort Myers. Quigley said it is present only in very low quantities.

OTHER TERMS: TAG: 9712110301