That means agricultural discharge and sewage leaks have jacked up the levels of nutrients like phosphorus and nitrogen in nearby waters. This extra fertilizer drives microalgae blooms, which block sunlight from reaching seagrass. The dead seagrass can fertilize blooms further. This cascade of pollution has destabilized Florida’s ecosystem for plants and herbivores; scientists estimate that about 95 percent of seagrasses have died off in parts of the Indian River Lagoon. Without them, the manatees are dying too.
Manatees are instead relying on red algae (which is different from the plentiful algal blooms), but it’s not a good replacement for seagrass because it lacks the fiber of vegetation. One study this year suggests that manatees’ low-fiber diets cause digestive issues and infection. The lettuce being thrown to them as a substitute is better because of its fiber content—it’s what manatees in captivity are fed.
Allen recently led a study that examined the stomach contents of manatees that died for unknown reasons between 2013 and 2015. He compared those samples with some from between 1977 and 1989, when the lagoon was healthier. He found that the animals’ diet shifted from 62 percent seagrass to only 34 percent; the share of algae rose from 28 percent to 50 percent. And manatee health is unequivocally worse now than it was in 2015. “So it's like they've gone from seagrass to algae,” Allen says, “to actually being emaciated.”
Scientists hope that restoring Florida’s Everglades will help protect natural habitats. Comprehensive restoration, overseen by federal agencies like the Army Corps of Engineers and the Department of the Interior, plus Florida’s state government, began in 2000. Its associated projects aim to restore the flow of water from the central Lake Okeechobee to South Florida after a century of diversion that parched the wetland. But that project will run through 2050, at least, and environmental advocates believe that more can be done in the meantime at the government level.
In 2013, the US Environmental Protection Agency approved the State of Florida’s annual limits—which are still in place today—on nitrogen and phosphorus in the Indian River Lagoon. “They stated that it would not adversely modify the Indian River Lagoon and affect any listed species,” says Ragan Whitlock, a staff attorney with the Center for Biological Diversity. “That clearly has turned out not to be the case.”
In a bid to get the EPA to lower those limits, and to cut pollution, in August 2021, the US Fish and Wildlife Service sent a letter to the agency recommending that it reinitiate its process for approving this “numeric nutrient criteria,” or NNC. The EPA declined, saying that the limits were not the problem.
In May 2022, the nonprofits Save the Manatee Club, Defenders of Wildlife, and the Center for Biological Diversity sued, arguing that the EPA’s inaction is neglecting the environment during a period of “catastrophic mortality” for manatees. “If they choose to be a productive player in this space, they can help,” says Whitlock.
An EPA representative declined an interview but provided WIRED a statement via email. “The EPA recognizes that manatees are a keystone species for the coastal ecosystem, and their health and behavior are alerting us to water quality changes,” the spokesperson wrote. “The EPA is concerned about this environmental crisis and is working to find solutions with our partner agencies that will improve water quality, which contributes to the long-term survival of the manatee population.”
However, the statement argued that the problem isn’t the need to recalibrate the numeric criteria—it’s that the nutrient levels in the waters are’t meeting the existing regulations. Therefore, the agency has no plans to reevaluate those criteria.
Meanwhile, a group of environmental advocates is petitioning the US Fish and Wildlife Service to reverse a 2017 decision to delist manatees as an “endangered” species, a designation that increases their priority for government funding and attention. That agency also declined an interview but provided an email to WIRED stating: “The US Fish and Wildlife Service is aware of the petition. Service staff will review the petition through our normal petition processes.”
Because restoration efforts, petitions, and lawsuits are slow going, in the meantime members of the public have stepped up to help their state’s unofficial mascot. (“You think of Florida, you think of manatees,” says Allen. “It’s kind of synonymous.”) For example, that supplemental feeding program relies on tons of donated lettuce. People also call the state wildlife agency’s hotline to rescue sick and injured manatees. In places like Alachua County, residents report sightings to the Save the Manatee Club to help gather data about the species. People avoid using fertilizers, herbicides, and pesticides on their lawn. And a big one, says Silverstein, is simply being willing to accept infrastructure upgrades, like septic-to-sewer conversions or sewage upgrades, “even though they can be inconvenient because there's construction going on.”
There are some signs of hope for manatees. In 2008, nonprofits petitioned the USFWS to revise manatees’ critical habitat designations, which identify the areas essential to their survival and recovery. Those areas had originally been identified in 1976—in July, the agency agreed to an update based on decades of study. And in November, Florida’s Fish and Wildlife Conservation Commission voted to amend its boater safety course with information about protecting manatees, like slow zones. “It’s a huge step,” Whitlock says. “This information does resonate.”
Allen, who has been monitoring seagrass throughout the year, says the Indian River Lagoon is seeing a minor rebound. He thinks the work people have done to curb the release of fertilizers and sewage into the water system “could definitely be having an impact.” And most important to the manatees’ supporters, as of December, rescue efforts throughout Florida had saved 103 sick and injured manatees.
“I think we can bring the seagrass back. We can remove these pollution pressures,” agrees Silverstein. But there’s a long road ahead, she says. “It's very difficult and expensive to put nature back together once it’s been broken.”
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