National Geographic 
Warm water in the discharge canal at Tampa Electric Company—and at other power plants in the state—provides manatees with an unexpected winter haven when the ocean becomes too cold.
Photograph by Jason Gulley, National Geographic
Over 60 percent of the Sunshine State’s iconic manatees have a surprisingly codependent relationship with power plants—and many of the beloved mammals could die if they shut down.
Stop by one of Florida’s power plants in the winter and you’ll likely find hundreds—or even thousands—of manatees, lazily bobbing in nearby coastal water. While tourists may coo at the congregation of these charismatic animals, their presence at these industrial sites is alarming.
In the last 70 or so years, the state’s rapidly growing population, expanding industry, and rising sea levels have re-engineered the Florida manatee’s natural habitat, limiting their access to food and the waters that kept them warm during cold winter months.
In search of new warm water habitats, manatees have developed a generations-strong dependence on warm water discharges from the state’s coal-fired power plants, using them as a refuge during the winter.
But in the next 30 years, Florida aims to pivot away from these industrial sites and toward renewable energy, and the animals are poised to lose one of their primary warm water refugia. If action isn’t taken soon, it could trigger cataclysmic losses in the state’s population.
Manatees need warm water to survive
Manatees become vulnerable to cold stress syndrome when water temperatures drop below 68°F. While they may look round and chubby, they lack the insulating blubber found in whales and seals and have difficulty regulating their body temperature—their size is due to their large digestive tracts.
When water temperatures drop during the coldest months of the year, the animals pull warmth to their cores and away from their extremities, explains Monica Ross, the director of manatee research and conservation at Clearwater Marine Aquarium. This cold water causes their skin and portions of their tail to die, she adds.
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Historically, manatees would seek refuge in the winter by migrating to southern Florida, where temperatures are generally more tropical, or to passive thermal basins and natural spring systems in northern Florida. When power plants began popping up in the state between the 1940s and 1970s, manatees began wintering near these industrial areas, some of which are farther north than their historic range.
“Manatees are very opportunistic, and from what we’ve seen they’re capable of finding a one-degree Celsius difference in water temperature and will hone in on it,” says Ross.
Recent population surveys conducted by the Florida Fish and Wildlife Conservation Commission (FWC) in 2020 and 2021 estimate that the current manatee population is in the high 8,000s—for now.
In 2017, manatees were downgraded from an endangered to a threatened species, a move that was criticized by environmental groups.
But in 2021, hundreds of manatees starved to death after a harmful algal bloom depleted seagrass beds; and a 2020 study revealed that 96 percent of the population has some kind of scar on their bodies from boating collisions, which account for about 25 percent of their mortalities.
Manatees gather on the sandy bottom near Homosassa Springs, where the water is warm in winter. Naturally forming warm water inlets were where manatees used to spend the winter, but urban development destroyed their natural hydrology.
Photograph by Jason Gulley, National Geographic Image Collection
A generations-strong dependence on power plants
Power plants take in water to cool internal mechanical equipment. The water is heated into steam, which turns turbines to create power, and is then released at a higher temperature than it came in. The discharges’ quality is regulated by the Clean Water Act and the Environmental Protection National Pollutant Discharge Elimination System (NPDES).
“Power plants that produce ‘meaningful biological warm water’ are required to have an NPDES permit and a manatee protection plan in place,” says conservationist Katherine Sayler of Defenders of Wildlife.
There are currently 67 warm-water sites used by manatees in Florida, including 10 power plants, 23 springs, and 34 thermal basins, explains Michelle Pasawicz, the manatee management program lead at the FWC.
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“More than 60 percent of manatees utilize Florida’s industrial power plants during the cold season with six of 10 of those sites offering reliable and consistent sources of warm-water,” she says. Water temperatures at these areas vary but tend to hover around 68°F.
Natural springs, by comparison, almost always stay between 70°F and 73°F, but as Florida’s human population grew by over 20 million people since the 20th century, many of the state’s natural springs were drained for agriculture and drinking water or destroyed by urban development.
Now, the warm temperatures responsible for climate change are causing seas to rise along the Florida coast. Overall sea levels across Florida have risen by eight inches since 1950, and that rate is only accelerating. This is a problem for manatees because the vegetation they rely on cannot withstand salt water.
Power plants may provide refuge during the winter months, but they don’t offer many foraging options. This means that manatees must travel from discharge sites to access seagrass beds. During the absolute coldest times of the year, they’ll hunker down at a site and fast, sometimes for as long as a week.
This reliance on power plant discharges is exacerbated by the fact that manatees exhibit what scientists refer to as strong site fidelity. Satellite telemetry tracking studies and research on manatee behavior suggest that mothers teach their calves, during the roughly two-year period they’re together, to return to the same site year after year.
“Manatees are very resilient and highly adaptable. These are animals that learn where to seek refuge from each other,” explains Ben Prater, a conservationist and manatee expert at the non-profit Defenders of Wildlife. “They’re closely related to elephants, which also demonstrate similar behaviors in having mental maps that they share through generations for resources.”
Conservationists fear that when the state’s power plants eventually go offline, manatees will continue returning to the same sites for refuge. Population models indicate that there’s a nearly 50 percent chance “that as power plants go offline, we’ll see a decline of at least 30 percent over the coming century of the manatee population in Florida in the southwest and Atlantic regions,” says Sayler.
What are the solutions?
Site fidelity, while part of the problem, could be part of the solution. By digging deep water basins heated via solar or gas power, conservationists can create new warm water spots along a manatee’s migratory path.
On their regular trek to these industrial sites, the animals could find these new areas, remember them, and teach them to their offspring, explains Patrick Rose, the executive director of the Save the Manatee Club.
He emphasizes that it’s an effort that’s going to take a considerable amount of time and funding.
“We can’t just turn off [the power plants] and then expect the manatees to find these new places in time,” says Rose, who has been studying manatees since the 1970s. “I suspect even under the best scenario, we’re still going to have manatees that suffer as a result of this. I don’t think we can eliminate that, and that’s why we need to put these efforts in place soon.”
The main priority for both the state and conservationists, however, is to restore and maintain the integrity of the state’s natural springs. Doing so would provide manatees with reliable access to both healthy seagrass beds and winter habitat. This approach requires removing barriers to springs, ensuring that springs are not drained, preventing shore erosion, and managing pollutants that lead to harmful algal blooms.
While the task is a daunting one, there have already been some triumphs.
In a 2020 report, the FWC and the federal Fish and Wildlife Service highlighted the restoration of several natural manatee habitats at Fanning Springs, Three Sisters Springs, and Port of the Isles. The FWC also successively created a passive warm water site in Collier County, in southwest Florida, that has been consistently used by manatees since work was completed in 2016.
For conservationists like Prater, protecting Florida’s manatees is just one step in maintaining the integrity of the state’s natural ecosystems: “By [helping] a species like the manatee, we’re helping to sustain a protected, connected, and wild Florida for future generations.”
