Red tide, mysterious ailment killing Florida manatees

MELBOURNE, Fla. - Even as a Red Tide algae bloom is wiping out a record number of manatees in southwest Florida, a mysterious ailment is killing off dozens more manatees on the state's East Coast. So far, state biologists have been unable to pinpoint what killed them.

Pat Rose, a former government manatee biologist who is now executive director of the Save the Manatee Club, said he could not recall another time when manatees were being killed under similar circumstances on both coasts at the same time.

Since last July, 55 manatees have died of similar symptoms in the Indian River Lagoon area -- 25 of them in just the past month, according to Kevin Baxter, a spokesman for the state's Fish and Wildlife Research Institute in St. Petersburg.

"They have not been able to determine what the cause is," Baxter said Monday.

There is no Red Tide bloom on the East Coast, and the winter has not been cold enough to kill off more than a few manatees.

They suspect the deaths are connected to back-to-back blooms of a different kind of harmful algae, one that has stained the Indian River Lagoon a chocolate brown.

Over the past two years the blooms wiped out thousands of acres of sea grass in the 156-mile-long lagoon. Manatees eat sea grass, but with the sea grass gone, they may have turned to other, less healthful sources of nutrition.

The manatees that have turned up dead on the East Coast all appeared to have gone into shock and drowned after they "ingested large amounts of macroalgae," Baxter said. "Our researchers are thinking the deaths are related to some kind of dietary change."

"A big part of it is that there's just not that much left for them to feed on," Rose said. "The system is way out of balance."

Rose blamed the Indian River Lagoon's toxic algae blooms on nutrient pollution from storm runoff. The runoff carries into the waterways excess fertilizer, sewage and animal waste that fuels the growth of some kinds of algae.

Although scientists suspect something similar fuels Red Tide blooms too, they lack the evidence to prove it. Red Tide, an algae bloom that turns the water the color of rust and releases toxins that kill fish, dolphins and manatees, has killed more than 180 manatees so far this year in Lee County. That breaks the 1996 record of 151.

State biologists estimate the total Florida manatee population to be between 4,000 and 5,000. Manatees have been on the federal endangered species list since the list was created in 1967. They have been protected by state law since 1893.

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 Information from: Tampa Bay Times (St. Petersburg, Fla.), http://www.tampabay.com.
 

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