Make us your home page

Today’s top headlines delivered to you daily.

(View our Privacy Policy)

Manatees that survive Red Tide may suffer immune problems

Lowry Park Zoo staff assess Cheer, a manatee exposed to Red Tide, in March. Mote scientists collected blood samples from 13 manatees Lowry treated and found immune system problems.


Lowry Park Zoo staff assess Cheer, a manatee exposed to Red Tide, in March. Mote scientists collected blood samples from 13 manatees Lowry treated and found immune system problems.

Manatees that survive exposure to Red Tide algae blooms may wind up with compromised immune systems, making them more susceptible to disease and other woes, a new study finds.

The discovery may alter the way the survivors are cared for at Tampa's Lowry Park Zoo and other rehabilitation facilities around the state.

Earlier this year, more than 270 manatees along the state's southwestern Gulf Coast died from the toxins in a Red Tide bloom — the worst die-off since records began being kept in the 1970s.

A handful of manatees that survived were tested by Mote Marine Laboratory in Sarasota. The Mote scientists collected blood samples from 13 manatees being treated for Red Tide exposure at Lowry Park Zoo, according to Cathy Walsh, manager of the marine immunology program at Mote Marine Laboratory.

For comparison purposes, the Mote researchers also collected blood samples from wild manatees in Crystal River, where the Red Tide bloom had not shown up at all.

The Mote scientists then tested the blood to see if one type of immune cells, called lymphocytes, multiplied the way they normally would when a manatee's body is challenged by infection.

They found that when the Red Tide toxins are still in the manatees' bloodstream, the lymphocytes did not multiply the way they normally would.

They also found that the manatees' blood plasma had higher levels of the types of molecules the body produces during stress. And they found increases in an enzyme that signifies stress on the immune system.

That means that even after the manatees appear to be recovered from exposure to the Red Tide, they remain more vulnerable to diseases and other problems, including cold, that could kill them. But no one knows yet how long that could last.

"We can't really answer how long the lingering effects go on," Walsh said. With sea turtles, though, scientists have found that Red Tide toxins may stay in their bodies for up to 80 days, she said.

The Mote study, unveiled at a recent conference at Mote, "provides some new insights into the long-term health and survival for rehabilitated manatees that have recovered from clinical Red Tide exposure," said Ray Ball, Lowry's director of medical services. "This may redirect the medical care while they are in rehab and also provide new criteria for release."

Red Tide is a higher-than-normal concentration of microscopic algae. The blooms stain the water a rusty tint and can kill fish, manatees, dolphins and other marine creatures. The algae contains at least 12 toxins that can also be harmful to humans, particularly those with respiratory problems.

Red Tide has plagued Florida's beaches for centuries. Spanish explorers recorded blooms in the 1500s. Karenia brevis — named for retired biologist Karen Steidinger, who spent decades studying its properties at the state's marine science laboratory in St. Petersburg — lives in the Gulf of Mexico all year long, usually without causing any problems.

But every now and then the algae population just offshore explodes into something called a bloom, staining the water a rust color and releasing large amounts of toxins. Pollution does not appear to affect the start of an offshore bloom, but can stimulate its growth and prolong it once it moves inshore.

The bloom that killed so many manatees this year appeared last fall along 70 miles of the southwest Florida coast, extending along the shores of Sarasota County south to Lee County, and hung on until March.

In the past, Red Tide has killed manatees because they breathed in its toxins when they surfaced for air. This year biologists said manatees had consumed the toxins after it settled onto sea grass they ate.

Craig Pittman can be reached at or on Twitter @craigtimes.

Manatees that survive Red Tide may suffer immune problems 11/17/13 [Last modified: Sunday, November 17, 2013 8:30pm]
Photo reprints | Article reprints

© 2017 Tampa Bay Times


Join the discussion: Click to view comments, add yours

  1. Rays send down Chase Whitley, Andrew Kittredge; add Chih-Wei Hu, acitvate Alex Cobb


    After having to cover more than five innings following a short start by Austin Pruitt, the Rays shuffled their bullpen following Wednesday's game, sending down RHPs Chase Whitley and Andrew Kittredge,

    The Kittredge move was expected, as he was summoned to add depth to the pen Wednesday in advance of RHP Alex …

  2. MLB commissioner Rob Manfred moves closer to wanting a decision on Rays stadium

    The Heater

    ST. PETERSBURG — Major League Baseball commissioner Rob Manfred called Wednesday for urgency from Tampa Bay area government leaders to prioritize and move quicker on plans for a new Rays stadium.

    MLB Commissioner Rob Manfred talks with reporters at Tropicana Field in St. Petersburg, Fla. on Wednesday, Aug. 23, 2017.
  3. Six home runs doom Rays in loss to Blue Jays (w/video)

    The Heater

    ST. PETERSBURG — A curve that didn't bounce was the difference Wednesday as the Rays lost 7-6 to the Blue Jays in front of 8,264, the smallest Tropicana field crowd since Sept. 5, 2006.

    Tampa Bay Rays shortstop Adeiny Hechavarria (11) greets center fielder Kevin Kiermaier (39) at the plate after his two run home run in the third inning of the game between the Toronto Blue Jays and the Tampa Bay Rays at Tropicana Field in St. Petersburg, Fla. on Wednesday, Aug. 23, 2017.
  4. Jones: Stop talking and start building a new Rays stadium

    The Heater

    ST. PETERSBURG — It was good to see Major League Baseball commissioner Rob Manfred at Tropicana Field on Wednesday, talking Rays baseball and the hope for a new stadium somewhere in Tampa Bay.

    Commissioner Rob Manfred is popular with the media on a visit to Tropicana Field.
  5. Ousted to political Siberia by Corcoran, Kathleen Peters sets sights on Pinellas Commission

    State Roundup

    TALLAHASSEE — The perks of power in Tallahassee are a coveted chairmanship, a Capitol office in a prime location and a prominent seat on the House floor. Now Rep. Kathleen Peters has lost all three, but here's the twist: Her trip to "Siberia" might actually help her reach the next step on the Tampa Bay political …

    Rep. Kathleen Peters, R-South Pasadena, has been relegated to the back row in the State House chamber, moved to a fouth floor office and stripped of her job as chairwoman of a House subcommittee after a series of disagreements with House Speaker Richard Corcoran. [SCOTT KEELER | Tampa Bay Times]