Feeding the manatees helps. Not feeding the algal blooms that kill seagrass would help them more.
CAPE CANAVERAL, Florida––The holiday season good news from the Indian River Lagoon region along the Florida east coast is that the U.S. Fish & Wildlife Service on December 7, 2021 at last approved a Florida Wildlife Commission plan to experimentally feed starving manatees this winter in waters south of the Kennedy Space Center.
The bad news is that the experimental feeding is to begin nine months after the Save the Manatee Club asked the federal and state governments to feed the manatees before the Florida manatee population crashed.
The manatees “are having a very hard time finding food,” Save the Manatee Club executive director Patrick Rose explained to Lori Rozsa of MSN News.
“The majority are quite malnourished”
“The majority are quite malnourished. The question is, how do we get them through this winter?” Rose asked rhetorically.
“Because there’s no reasonable amount of food available for them within the vicinity of the power plant where they go this time of year to stay warm,” huddling in the water discharged by the cooling pumps.
“So the manatees have this miserable choice,” Rose said, “between staying warm and forgoing food, or going out and trying to find food, only to die of cold stress.”
Rose pointed out that a 1,200-pound adult manatee needs to eat about 120 pounds of sea grass and other green forage per day.
Lately the Indian River manatees have been finding only sparse amounts of edible algae.
“They’re grazing on any low mangrove leaves they can find,” Rose said, “and if there’s a lawn somewhere near where they happen to be in a canal system, they’re trying to eat grass off the bank.”
Population crash since downlisting
Now the Florida manatee population has crashed. Political pressure from boaters and developers may prevent restoration of manatees to the U.S. endangered species list, but manatee numbers have fallen, in barely five years, from a record high of about 8,800 in 2016 to 5,700, according to the most recent aerial survey––about 3,100 fewer than on March 30, 2017, when the Donald Trump administration made removing manatees from endangered species protection a top priority.
The losses are equivalent to the entire estimated population when Florida manatees were first federally recognized as endangered, in 1967.
(See Favor to speedboaters: Trump administration downlists manatees.)
Floridians unwilling to slow down boats, quit using lawn chemicals, & keep septic tanks pumped
Feeding some of the starving manatees will temporarily relieve some manatee misery. Rescuing the population as a whole, however––and rescuing the entire Indian River ecosystem––would come at a price that Floridians have for more than 120 years again and again proved unwilling to pay, even at cost of losing much that attracted them to the state in the first place.
The emergency manatee feeding experiment, said Rozsa, “will target an area where more than 500 manatees have died this year,” approximately equal to the annual death toll throughout Florida in recent years before 2020.
Officially, 1,017 manatees died in the first 11 months of 2021. The actual toll, including manatees whose carcasses have not been found, may be far more.
Manatees lose 96% of their food supply
“The problem is especially acute in the northern Indian River Lagoon,” Rozsa summarized, “where roughly 96% of 77,000 acres of seagrass have disappeared.”
Elaborated Kimberly Miller of the Palm Beach Post, “A spiral of harmful algae blooms beginning in 2011 reduced the amount of light reaching the seagrasses, while, at the same time, nitrogen levels in the water got too high. Because the Indian River Lagoon does not get heavy ocean flushes, it becomes a trap for nutrients that are detrimental to seagrass.
“Little body fat”
“Although manatees look plump,” Miller continued, “they have very little body fat and can’t tolerate water temperatures below 68 degrees for prolonged periods.
“That’s why they are found in winter months huddled in the warm-water outflows of power plants, such as at Manatee Lagoon where the outflow is about 5 to 8 degrees warmer than the ambient water.”
Florida Wildlife Commission assistant executive director Thomas Eason told Miller that “Restoring the habitat, assuming we continue to accelerate that, is not a year or two proposition — it’s a longer-term thing,” meaning that manatees may need to be feed for several years, not just a few months.
“Problem decades in the making”
Detailed Catrin Einhorn for The New York Times. “The sea grass was killed off by algae blooms fueled largely by human waste and fertilizer runoff from lawns and farms, a problem decades in the making,” but becoming exponentially worse since 2011, coinciding with increasingly visible temperature extremes symptomatic of global warming.
Trying to save manatees with supplemental feeding “comes with risks,” Einhorn noted. “Boat strikes also kill manatees,” and in fact have been the biggest single cause of manatee deaths in almost every year before 2020, “so further habituating them to vessels or people could be deadly. The feeding program is expected to include measures to prevent that from happening,” Einhorn wrote, “and to clean up any uneaten produce so that it does not fuel further algal growth.”
(See COVID-19: speedboat toll on manatees soars, but large land mammals get a break.)
Officials say “Don’t feed. Clean up.”
“Wildlife officials urged the public to refrain from feeding manatees,” Einhorn finished. “To help the animals, they said, locals should take measures to improve water quality, such as avoiding using fertilizer and pesticides on their lawns, and switching from septic systems to a municipal sewer, or upgrading septic systems if that is not possible.”
That, unfortunately, is unlikely to happen through voluntary measures. Major fish kills occasioned by algal blooms were first documented in the 156-mile-long Indian River Lagoon in 1896 and 1902. This history did not deter the builders of the St. Lucie Canal from diverting nutrient-rich water from Lake Okeechobee into the southern part of the Indian River Lagoon as part of a 1916 flood control project.
The Florida legislature in 1990 passed the Indian River Lagoon Act, requiring most of the 46 sewage treatment plants in the region to stop discharging wastewater into the lagoon by 1996.
30,000 failing septic tanks
That helped to forestall the disaster that followed, but the 2011 phytoplankton bloom killed about a third of the Indian River Lagoon seagrass, and killed 135 manatees too.
A brown tide bloom followed in 2012.
By 2013, the third year in a row of drastically declining water quality, investigators found that approximately 10% of the estimated 300,000 septic tanks in the five-county Indian River Lagoon drainage basin were failing.
Little was done about it, though. The worst Indian River Lagoon fish kill to date hit in March 2016, originating in the no-motor zone of the Merritt Island National Wildlife Refuge that had been set aside specifically to protect manatees.
Loss of seagrass from the no-motor zone forced hungry manatees out into water frequented by speedboats, contributing to a record total of 104 documented collision deaths.
(See Snooty, 69, last Florida manatee without propeller scars, drowns in tank.)
As manatees go, so goes the Indian River Lagoon ecosystem
Logically, manatees should not have been downlisted after that, but the Trump administration accepted the boating lobby claim that more boat-killed manatees simply meant there were more manatees to be killed, never mind the seagrass losses.
(See Will more boat kills than ever stop proposal to ease manatee safeguards?)
Overlooked amid the soaring manatee death toll since then is that manatees are only the biggest and most emblematic of more than 2,200 animal species and 2,100 plant species known to inhabit the Indian River Lagoon.
As the manatees go, so goes the rest of the ecosystem.