A Blue View is a weekly perspective on the life aquatic, hosted by National Aquarium CEO John Racanelli.
From the smallest plants and animals invisible to the human eye to entire ecosystems, every living thing depends on and is intricately linked by water.
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May 15, 2013: A Devastating Year for Manatees
Click here to listen to John discuss the issues
facing manatee populations in Florida.
Gentle giants with few enemies, manatee populations have nonetheless long been threatened. The species has been on the federal endangered species list since 1967, when the list was created, and has been protected by Florida state law since 1893. Thanks to this, manatee populations have grown in recent years.
Typically, manatee deaths and injuries are associated with boat strikes. In fact, you’d be hard-pressed to find a manatee without tell-tale propeller scars. But this year, a particularly aggressive red tide along Florida’s southwest coast has killed more than 265 manatees. Combined with other causes of death, more than 580 manatees have died out of an estimated population of 5,000—a staggering number that has erased those recent population gains.
Red tide is an algae bloom that occurs naturally every year, though the 2013 bloom has proven to be more deadly than any previous year on record. Characterized most often by a red discoloration of the water, the algae produces toxins that affect the nervous system of vertebrates. These toxins can settle on sea grass and blow through the air when waves break the algae apart. Since manatees eat up to 100 pounds of sea grass per day, this can have devastating effects.
Symptoms of red tide toxicity in manatees include muscle twitching, lack of coordination, difficulty breathing, and seizures, but they aren’t the only ones affected. It can also cause human respiratory distress, shellfish poisoning, and the deaths of other marine mammals, fish, and turtles.
So what can be done? The truth is, when red tide strikes, little can be done besides just waiting it out. Florida state wildlife officials believe that this year’s red tide is subsiding, but the effects of the bloom are likely to be seen over the next weeks and months, resulting in more deaths.
Several facilities in Florida are equipped to handle critical care of manatees, but the Lowry Park Zoo’s Manatee Hospital is the only one rehabilitating red tide patients. Not many have been rescued, though every life saved is a victory for this endangered species.
A manatee in rehabilitation at Lowry Park Zoo.
To date, 13 manatees with red tide toxicity have been admitted to the hospital for care. Staff members monitor each sick manatee around the clock until the danger has passed, holding up the manatee’s head so it can breathe. Once out of the red tide environment, manatees recover fairly quickly. Unfortunately, there really isn’t anywhere for them to go.
Manatees are migratory animals, and staff at the hospital don’t want to release their patients only to have them wind up in danger again. They are working with state and federal partners to determine when the manatees can be safely returned to the open waters.
Efforts are ongoing to understand why this year’s red tide bloom was so toxic and long-lasting. An uncommonly mild winter most likely contributed because the algae bloom didn’t die off as quickly as normal. Manatees swam right into the red tide in their search for warmer waters. There’s also speculation that phosphorus runoff from farms and lawns are been a factor in the red tide’s severity. The hope is that as scientists better understand the reasons behind this extraordinary red tide event, the lessons learned can better prepare us for the next time, and more manatees can be saved.