Manatees Are Dying in Droves, Florida Says ‘Too Bad’

‘Red tide’ and a loss of sea grass account for some manatee deaths, but researchers believe undiscovered factors are also at play.

Red tide is killing off Florida manatees.
The NOAA is launching a study to investigate the factors behind the recent rash of manatee deaths. (Photo: Kallista/Getty Images)
A staff writer for LiveScience, Doug has written for the NYTimes.com. He lives in New York City.

A record number of endangered manatees are dying in Florida's algae-choked waterways. So far this year, 582 manatees have died, more than any year on record, according to preliminary numbers from the Florida Fish and Wildlife Conservation Commission (FWC).

Pat Rose is an aquatic biologist and the executive director of the Save the Manatee Club, an organization devoted to preserving the animal. In his interview with TakePart, Rose reports the estimated minimum population of these gentle beasts is only 3,100 adults. That means their population has decreased by more than 10 percent in just four months.

A total of 247 of these have died in the southwest of the state due to an explosion of a red-hued algae called Karenia brevis, also known as a red tide.

This pesky microorganism produces neurotoxins that can kill manatees by causing them to seize to the point where they can't make it to the surface—or even lift their head out of the water—to breathe.

The large marine mammals are also dying in the eastern part of the state, in Brevard County near Orlando. Rose says a gradual die-out of sea grass, upon which the manatees feed, has combined with blooms of brown algae and likely other unknown factors to kill nearly 150 more manatees. Since 2010, about 30,000 acres of sea grass have been wiped out.

Luckily, it appears that both events are winding down, and the rate of manatee deaths appears to be slowing. But that's cold comfort for Rose, since the number of threats to manatees appears to be growing, and little is being done to address the problem.

Traditionally, boat collisions have been the biggest killer of manatees; they're vulnerable since they're large, slow-moving and often hang out on the surface. Until this year, at least 41 percent of all manatee deaths resulted from these collisions, and likely more, because not all of these deaths are reported or detected.

The threat of algal blooms could be reduced if Floridians and others throughout the country could reduce nutrient runoff.  These nutrients, from fertilizers and wastewater, feed algae blooms like red tide. When these proliferations of algae die, they also consume massive amounts of oxygen, creating dead zones that kill fish, coral and just about anything that happens to be in the wrong place at the wrong time.

Unfortunately, the Florida State Senate is considering a bill that would prevent local governments from water quality laws that are stricter than that of the state—which aren't strict enough, according to Rose. "The Legislature is doing everything it can to further pair down our water-quality laws," he says.

Called HB 999, the bill will be voted on by the Senate this week. According to an editorial in the Tampa Bay Times, this legislature "would make it easier to pollute waterways, destroy flood protection areas, squander the drinking water supply and extend even more leverage to developers over when and where they build."

Rose says it's unclear exactly why this red-tide event killed more manatees than any on record. It certainly didn't help that the bloom persisted through the winter months. But this has happened before; there was a persistent bloom of Karenia brevis that lasted from June 2002 until February 2004, for example, but far fewer manatees were killed, according to the FWC.

Quay Dortch, a scientist with the National Oceanic and Atmospheric Administration, says that the NOAA just commissioned a study to help find out why red tide may be killing more manatees than usual.

"I'm actually quite worried about the future of manatees because it's so tied to health of water bodies," Rose explains.

When manatees come into contact with red tide toxins, they often move to shallow water so they can keep their heads above water. Rose reports that if rescued, they can survive.

For that reason, it's important to report any sick or distressed animals to the FWC by calling 1-888-404-3922.

What measures would you like to see taken to protect the manatees? Let us know in the Comments.

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