What’s Killing the Manatees?

Posted by: Kelsey Schueler

There are only about 5,000 manatees remaining in Florida. According to the Florida Fish and Wildlife Conservation Commission, have already died this year. This mortality rate exceeds last year’s loss of . Why are so many manatees dying? A powerful, persistent red tide that has been lingering off the lower west coast since the fall. The red tide, aka Harmful Algal Bloom or “HAB,” contains a nerve poison toxic to both humans and animals.

Red Tides are a type of Harmful Algal Bloom (HAB).  Algal blooms can occur naturally, but human activities have greatly increased the frequency, intensity and duration of HAB events in recent years.  If a bloom is large enough, its sheer biomass can choke coral reefs and clog fish gills.  When these large blooms die, they are eaten by bacteria in a process that consumes oxygen, creating dead zones where marine animals cannot live.  If that weren’t bad enough, many harmful algal blooms also emit different toxins that can kill fish, birds, marine mammals (including manatees) and even humans.

Causes of Harmful Algal Blooms vary region by region and are not always well understood.  That said, scientists have established a fairly clear link between algal blooms and nutrient runoff from farms and lawns.  In Florida, the Caloosahatchee River carries this agricultural runoff from Florida’s productive farmland to the ocean near Fort Meyers, feeding the toxic red tide that has killed hundreds of manatees and driven humans from the beach with respiratory issues. Of course, the solution is not as simple as dealing with agricultural runoff. Global warming also increases sea surface temperature which is like tossing gasoline on a flame where HABs are concerned.

While the red tide dissipates, the toxins persist in seagrasses, shellfish, and other critters consuming the algae. Manatees may be the most obvious charismatic megafauna impacted by the red tide. However, the red tide can also shut down fisheries, reduce tourism, and impact other species. The problem is complex, but the solutions all start in the same place – Congress. In past years we’ve worked with our champions to move a good bill addressing toxic algae and dead zones, coming closer each year.  With more strong ocean champions in Washington D.C. than ever before, we can pass HABs legislation and continue the fight for healthy ocean ecosystems and the critters (like Manatees and people) who need them to survive.

 

Date Posted: June 26, 2013 @ 4:08 pm Comments Off

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