Science
7:01 am
Mon March 18, 2013

Red Tide Claims 170 Manatees, But South Florida Population Should Be Spared

One of Florida's most beloved endangered species is facing a tough end to the winter. State wildlife officials have confirmed the deaths of more than 170 manatees in Southwest Florida as red tide impacts regional populations of the gentle water-dwelling mammals.

Red tide, according to the Florida Fish and Wildlife Conservation Commission (FWC), is a "higher-than-normal concentration of microscopic alga." The species most associated with Florida's red tide blooms is Karenia brevis

Manatees that winter in Southeast Florida are unlikely to be impacted by the red tide blooms killing dozens of manatees on the Southwest side of the state.
Credit Tricia Woolfenden

The current outbreak of Karenia brevis has led to the deaths of 174 manatees as of March 11. Kevin Baxter of FWC said the bloom is confined to Southwest Florida. Manatees that have been sickened by the red tide toxin are unlikely to travel to parts of South Florida -- like Everglades National Park, Biscayne Bay, or the Intracoastal Waterway -- that are popular with manatees. 

Additionally, the east and west coast populations of manatees have "limited exchange" making it "very unlikely" for the red tide to affect local manatees. 

The FWC's red tide status report for March 15 showed a persisting bloom in the central portion of Southwest Florida, particularly off the coast of Lee County, with lower-level concentrations in Charlotte County. 

Red tide is a naturally-occuring event, but it presents health risks to marine life and some humans with compromised respiratory systems. The organism responsible for the bloom produces a toxin that can affect a manatee's central nervous system. An NBC News story on the bloom says "particles seep into sea grass, which manatees also eat. So the killing will probably continue for two months after the red tide dissipates." A Tampa-area animal care expert quoted in the story says the toxin can cause paralysis and "comatose" behavior, which can cause the manatees to drown in as little as two inches of water.

Baxter, of the FWC, said regardless of there being very little chance of coming across a red-tide-affected manatee in Southeast Florida, the public should always contact authorities in the event of finding "a manatee in distress."

"It's an ongoing message, whether there's a red tide or not," Baxter said. "If you see a manatee in distress, regardless of the cause, report it."

In addition to red tide deaths, there have been 12 deaths in 2013 related to watercraft collisions and 20 reported deaths in connection with "cold stress," plus dozens more related to a variety of factors including natural and undetermined factors. So far this year, there have been a total of 296 reported deaths. There were a total of 86 deaths in 2012 and 176 in 2011. The worst of recent years was 2010, when a cold snap helped to contribute 202 fatalities to the year's total of 389. (Find the FWC preliminary 2013 manatee mortality report here.)

To report a sick, injured, or dead manatee, call the FWC at 1-888-404-3922, or by dialing *FWC or #FWC on a cellphone. Be ready to answer questions about the exact location of the animal, whether the manatee is alive or dead, the size of the manatee, and contact information for follow-up reporting.   

The manatee is currently listed as endangered under the U.S. Fish and Wildlife Service's Endangered Species Act.