MANATEES FELLED BY MYSTERY ILLNESS.

Byline: The New York Times

Just as scientists thought the endangered manatee was rebounding from one of the species' most disastrous years, 221 of the gentle sea mammals have been found dead in Florida's coastal waters so far this year. Of these deaths, 128 have been attributed to a mysterious ailment that is confined to the state's southwest coast.

The worst year on record for manatees was 1990, when 206 were found dead, according to state Department of Environmental Protection scientists.

``It's very troublesome,'' said Joy Mills, a spokeswoman for the agency, said Wednesday. ``I want to make it clear, however, we're not talking about an extinction situation at this point.''

Marine mammal biologists say they have identified no culprit or cause, but are divided about the effect these deaths might have on the wild manatee population, which numbers roughly 2,600.

The 128 mysterious deaths, all recorded on the southwest coast of the state since March 5, are marked by no obvious behavioral or physical abnormalities, scientists say.

What is interesting, Mills said, is that no young manatees have been found dead among the 128. ``It's just not affecting the young, for whatever reason,'' she said.

But the presence of red tide, a toxic microorganism, along the south Gulf Coast of Florida has led some to believe that there is a connection.

Scientists had earlier believed that the West Indian manatee, which during the winter months is found almost exclusively in Florida's near-shore waters, was bound for a recovery after 201 animals were found dead last year. But after the recent spate of deaths, the number of manatees found dead this year already equals roughly 8 percent of the known wild population.

Although many state scientists remain optimistic, professing that long-term trends indicate a healthy, growing manatee population, others are less optimistic. ``Until they determine a cause, I don't know how DEP can conclude there's no epidemic,'' said Patti Thompson, a marine mammal biologist with the Save the Manatee Club, a private group founded in 1981.

Red tide was linked to the deaths of 39 manatees two decades ago, but symptoms like behavioral abnormalities are not shared by the latest casualties. However, some experts believe the seaborne toxin is somehow related to the recent deaths.

``We have not ruled that out yet,'' Mills said, while also raising the possibility that an unknown virus could be responsible.

Red tide is the common name for an abundance of flagellates, microorganisms that gather in blooms. Toxic to fish and marine life but mainly just a nuisance to humans, red tide was given its name because of the way it colors sea water reddish-brown. The red tide now floating off Florida's south Gulf Coast stretches beyond the typical affected area to encompass 150 miles of coastline, said Scott Willis, a spokesman for the environmental agency.

``If this is one single outbreak, it would be the longest on record,'' said Beverly Roberts, a red tide specialist at the agency, noting that this latest bloom could date as far back as September 1994.

Researchers say the sea grasses that manatees depend on for a large part of their diet may be contaminated by red tide toxins.

Whatever the cause, many believe the species cannot tolerate any more natural or man-made threats. ``My concern, I think everyone's, is man has so compromised the health of the species already that any natural mortality is unacceptable for the health and well-being of the manatee species as a whole,'' Roberts said. ``It can't tolerate this scenario.''