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Florida’s Manatees Are Dying at an Alarming Rate

Experts say starvation appears to be the main cause of death. Polluted waters are likely smothering the manatees’ favorite food: seagrass

A Florida manatee swimming near the surface. (Jim Reid, USFWS via Flickr under CC BY 2.0)
smithsonianmag.com

Florida’s manatees are dying in droves. So far this year, a total of 782 manatees died between January 1 and June 4, according to a recent report from the state’s Fish and Wildlife Conservation Commission. That’s more than ten percent of the docile marine mammal’s entire Florida population, which has come back from near extinction, reports Johnny Diaz for the New York Times.

Last year, Florida lost 637 manatees, a total that 2021 has well surpassed barely halfway through the year. At this rate, 2021 will likely see the highest level of manatee mortality since 2018 when 824 individuals were recorded dead.

“We’ve never seen anything like this before,” Jaclyn Lopez, Florida director at the nonprofit Center for Biological Diversity, tells Derek Hawkins of the Washington Post. “I think it’s fair to call it a crisis. It’s not hyperbole when you see hundreds of manatees dying like this.”

Experts say the likely cause of the die off is starvation. The bulbous, slow-moving mammals need to eat large quantities of seagrass to survive and that critical food source has been virtually erased by years of pollution. This pollution comes primarily in the form of nutrient runoff from fertilizer as well as leaks from sewers and septic tanks. Excessive levels of nutrients such as nitrogen and phosphorus can fuel runaway blooms of algae which can in turn smother the seagrass.

“The algal blooms are clouding the water and cutting off light, so the seagrass can’t photosynthesize and sustain themselves," Jon Moore, a marine biologist and oceanographer at Florida Atlantic University, tells Denis Chow of NBC News.

In particular, a 156-mile estuary on Florida’s Atlantic coast called the Indian River Lagoon, a favorite feeding ground of manatees, has lost an estimated 58 percent of its seagrass since 2009, according to NBC News.

“The lagoon is like a desert,” Martine de Wit, a veterinarian with the Florida Fish and Wildlife Conservation Commission (FWC), tells the Times.

“This past winter, it was hardly growing anything… If there is no sea grass for the manatees, there is also no sea grass for other species,” she adds. “The fact that manatees are dying from starvation signals there is something very wrong with the water quality.”

Apart from starvation, deaths from boat collisions remain a serious issue for the less-than-maneuverable manatees. The FWC report indicates that 52 of this year’s deaths have been caused by watercraft.

A federally protected endangered species since 1973, Florida’s manatee population has come back from just 1,200 remaining individuals in 1991 to its current population of around 6,300 animals. In 2017, the manatee was downgraded by the United States Fish and Wildlife Service (USFWS) from endangered to threatened as a result of this recovery. But as reports of this year’s heightened death toll have rolled in, U.S. Rep.Vern Buchanan has urged USFWS to reconsider, reports Ryan Callihan for the Bradenton Herald.

“It was very ill-advised for the Fish and Wildlife Service to weaken the Manatee’s protections in 2017,” wrote Buchanan in a letter to Martha Williams, the principal deputy director for USFWS, quoted by the Bradenton Herald. “Given the alarming surge in manatee deaths this year, upgrading their (Endangered Species Act) designation is critical.”

Patrick Rose, an aquatic biologist and the executive director of the nonprofit Save the Manatee Club, tells the Times that manatees are key members of Florida’s coastal fauna, calling them “gardeners of the aquatic ecosystem” because of their seagrass grazing. Rose tells the Times that the manatee is a “sentinel species telling us that the ecosystem is in a catastrophic state of decline.”

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