Manatees, the gentle giants of the seas, are perishing in unprecedented numbers.
As the TC Palm reports, Florida Fish and Wildlife Conservation Commission (FWC) data released last Friday shows that a record 841 West Indian manatees died during the first six months of 2021, with the deaths disproportionately clustered in Brevard County’s 251 km stretch of the Indian River Lagoon. That’s more than 2013, when an estimated 830 manatees died of exposure to red tide.
In Brevard County alone, a record 312 manatees died. The FWC’s Fish and Wildlife Research Institute attributed the surge in deaths to starvation resulting from mass die-off of sea grass, the manatee’s primary diet, in Indian River Lagoon. Warming temperatures as the summer months approached later caused the manatees to disperse, culminating in a spate of lethal collisions with boats and other watercraft in June.
To put this in context, the FWC estimated Florida’s manatee population at just 7,250 before the die-off, meaning a double-digit percentage could have been wiped out. As CNN noted, other estimates by the Fish and Wildlife Service and the nonprofit Save the Manatee Club have been considerably lower. Florida wildlife officials had declared an “unusual mortality event” regarding manatees back in March 2021.
“Unprecedented manatee mortality due to starvation was documented on the Atlantic coast this past winter and spring,” the FWC wrote in a report. “Most deaths occurred during the colder months when manatees migrated to and through the Indian River Lagoon, where the majority of seagrass has died off.”
“As temperatures warmed up and manatees on the Atlantic coast dispersed to other habitat for foraging, the numbers of malnourished carcasses and manatees in need of rescue decreased,” the institute added. “The recurrence of watercraft-related mortality as the leading cause of death in manatees necropsied in the Atlantic region in June, consistent with similar observations on the Gulf coast, underscores the need for previously identified threats such as watercraft-related mortality to continue to be recognised as a concern for the population. In addition, the long-term health effects of prolonged starvation in manatees that survived the Atlantic event to this point are not yet known.”
According to Phys.org, St. Johns River Management District officials say that water pollution has contributed immensely to algal blooms in the lagoon and the disappearance of an estimated 58% of its seagrass since 2009. Manatees eat about 5%-10% of their body weight in vegetation each day, translating to a potential consumption in the hundreds of pounds. The New Republic reported earlier this year that water quality has plummeted in the past decade due to neglected septic tanks and municipal sewer lines that spew raw sewage, as well as fertiliser runoff and other chemical pollutants like glyphosate, which is used in Bayer AG’s popular Roundup herbicide. The problem is worsened by the state’s increasingly severe hurricane seasons, during which heavy rains wash huge amounts of algae-fuelling pollution into waterways.
“The decline didn’t happen overnight. The stunning water views, the fishing and recreational opportunities that drew people to the area have resulted in the water quality conditions we see today,” the district’s executive director, Ann Shortelle, had warned in a March 2021 statement. “Too many nutrients, specifically nitrogen and phosphorus, are entering the lagoon from overfertilized lawns, faulty sewage treatment and leaching from septic tanks.”
The Fish and Wildlife Service removed the West Indian manatee from the endangered species list during the Trump administration in 2017, citing increased population numbers. The decision was heavily opposed by conservation groups and environmental activists. Manatees remain under extreme threat due to red tide and other algal blooms, boat collisions, cold snaps, and in some cases, harassment or attacks by humans. Other threats include developments and water pumps that have cut off natural springs in central and northern Florida that manatees use to overwinter, which can mean they take shelter in non-ideal environments like canals or areas where power plants discharge warm water, according to the Miami Herald.
The TC Palm reported that a coalition of 16 environmental groups and clean water-dependent businesses had pressured Republican Governor Ron DeSantis to declare a state of emergency for the Indian River Lagoon. A Florida Department of Environmental Protection spokesperson, Dee Ann Mill, told the TC Palm such an order was unnecessary as the state government is already responding and allocated $US8 ($11) million (double the usual amount) to manatee recovery such as habitat rehabilitation in 2021.
The TC Palm added that members of Congress are considering the bipartisan Marine Mammal Research and Response Act, which would allocate $US42 ($56) million over the course of six years to help with the recovery of marine mammal populations and create a database to track reports of sick or dead mammals.