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Toxic Red Tide Kills 60 Florida Manatees

-April 17, 2003

‹ MIAMI (Reuters) - A toxic "red tide" has killed at least 60 endangered manatees along the southwest Florida coast in the last two months, the second-largest mass death of sea cows blamed on the deadly algae bloom, state biologists said on Thursday.

The deaths, caused by a huge red tide stretching from Venice to Marco Island, represent about 2 percent of the Florida manatee population.

In 1996 a red tide was blamed for 149 manatee deaths, most of them in a six-week period in March and April.

The Florida manatee, a leathery aquatic mammal averaging about 10 feet in length and 1,000 pounds, dates back at least 45 million years. It has hovered on the edge of extinction for years, despite having no natural enemies.

Population surveys done in January indicated there were about 3,000 manatees in Florida coastal waters. According to state statistics, 305 died in 2002 and about 120 died in the first three months of this year.

The Florida Marine Research Institute said 60 manatee deaths between Feb. 27 and April 15 were caused by red tide. The animals were all found along the southwest Florida coast.

The one-celled organism that causes red tide contains a brevetoxin released into the water when the algae dies.

"They can ingest the toxins when they eat or they can inhale the toxins when they come to the surface to breathe," said Tom Pitchford, a wildlife biologist with the Florida Fish and Wildlife Conservation Commission. "Once the toxin is in the animal, it affects their coordination and causes a paralysis."

Six manatees that scientists know of survived the red tide. Two were helped by people who held their heads above water as they recovered from the effects of paralysis while four others were being treated at marine sanctuaries.

Pitchford said the red tide this year was unlikely to cause as many deaths as the one in 1996 because manatees had already started to disperse from warm-water areas where they concentrate in the winter by the time the algae bloom began.

Florida's population of beloved sea cows has long been the focus of battles between conservationists and the boating industry. Dozens of manatees are killed each year by boats, which crush or gash the slow-moving animals as they rise to the surface to breathe.

The state has enacted restricted speed zones in Florida waterways and other protection measures fought by the industry.