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2013 manatee deaths highest in recorded history

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By Mark Scohier, Staff writer

As the cold weather sets in, so do some of Florida's most notable characters: manatees.

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The mammals, protected by both federal and state law, have been using places such as Manatee and Fanning springs as warm-water refuges for millennia, and their presence is a vital part of the state's economy, drawing tourists from all over the world to partake in their chubby magnificence.

But 2013 was a hard year for manatees, the hardest on record.

While only four manatee deaths were recorded in Levy County for the last year, according to the Florida Fish and Wildlife Conservation Commission, a total of 813 deaths happened throughout the state.

"The deaths, obviously, are awful," said Dr. Katie Tripp, director of science and conservation with Save the Manatee Club.

The two biggest die offs happened when an unknown illness killed hundreds of animals. including manatees, dolphins and pelicans, at Indian River Lagoon and then when 276 manatees died from red tide in the Gulf, according to Tripp.

The red tide incident caused the biggest single die off of manatees by such a happening on record, according to FWC. The previous record for red tide deaths of manatees happened in 1996 when 152 died. 

"I think all Floridians should be concerned about what we put into our waterways," Tripp said, referring to the red tide incident.

Florida red tide is caused by a single-celled algae known as Karenia brevis and, according to accounts as far back as the 1700s, is not a new occurrence. The algae, when it dies, produces a deadly toxin that compromises the nervous systems of vertebrate animals — such as manatees, fish, turtles and even humans — when it is introduced into the food chain or churned into airborne particles that can be breathed. And the phenomenon is getting worse.

Scientists aren't sure what causes the blooms, which can cover up to 10,000 square miles and often stretch from the sea bottom to the surface of the water, though some point to the ever-growing use of fertilizers and wastes that inevitably find their way into Gulf waters. 

The red tide algae blooms, typically, originate 10 to 40 miles offshore, which has caused some to suggest that their blooming has nothing to do with nitrogen and phosphorous levels in the Gulf.

But there is increasing evidence to suggest that once the blooms are drawn closer in on wind or water currents that the algae is sustained, and even bolstered, by those contaminants indirectly.

"When things blow it to shore, it's about what's here for it to eat," Tripp said.

A 2011 study performed by marine biologists at the University of Maryland and North Carolina State University demonstrated that Karenia brevis feeds on a type of green algae known as synechococcus in the Gulf that has proliferated because of elevated levels of nitrogen and phosphorous.

"The following research into the sustaining near shore of  red tide blooms provides scientific evidence that the red tide algae is capable of  finding  a food source to sustain itself  near shore," the researchers wrote.

Last year's manatee die off is frightening, Tripp said, because, despite the manatee's protected status, there just aren't that many left in the wild. The last count in Florida was in 2011, she said, and it revealed 4,834 manatees. But nobody has a truly accurate count, she said.

Other factors to consider include things such as exposure to cold. 

In 2010, the previous record holder, 766 manatee deaths were recorded by the state, 282 attributed to cold stress.

"It's the last thing we want to see is cold weather," she said, an issue that is complicated by the continuing degradation of Florida springs and the threat that some artificial warm water refuges, such as those created by power plants, are expected to close in the next 20 years.

Some think manatees are resilient, Tripp said. "But were finding that some things in the environment are just too much. Their future is a lot more tenuous."

And then there are other things, too. While only 34 cold-stress-related deaths were recorded for 2013, 71 died from injuries associated with watercraft, a constant threat which can be seen on the backs of surviving manatees in the form of scars on their backs.

Last year, after months of rehabilitation from being hit by a boat, a manatee rescued near Fanning Springs was released back into the wild into the Suwannee River. The manatee was nicknamed Bolt because of the lightning-bolt-shaped scars on its back.

This issue, as well, is complicated by people, for various reasons, wanting to downlist manatees from endangered to threatened, a move that would reduce protection zones in Florida waters.

In December of 2012, Save Crystal River Inc. filed a petition to have the manatee downlisted because the U.S. Fish and Wildlife Service, in essence, shuts King's Bay down for several months while manatees are there during the winter. Representatives from Save Crystal River Inc. claim the practice hurts business.

Ironically, according to Tripp, it's the manatee that draws more than 100,000 tourists to the area each year.

"They're iconic," Tripp said about manatees. "No one else has them. It's one of the reasons so many people come to Florida."