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A manatee swims in the turbid water of Florida’s Crystal River. Manatees lack insulating layers of blubber and must move to warmer waters when sea temperatures drop below 20C (68F). The spring-fed Crystal River is the largest natural winter thermal refuge for Florida’s manatees
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While manatees are often depicted as chubby, sedentary creatures, they are graceful swimmers. They normally swim at a leisurely 3-5mph (5-8km/h) but can accelerate to 20mph for short bursts, such as when trying to avoid fast boats
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Manatees rest where a warm spring runs into Florida’s Suwannee River
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A remote beach on Florida’s Merritt Island is a graveyard for manatees. This year has been the deadliest year on record for the state’s manatees. At least 905 manatees have died in Florida so far this year, compared with an annual average of 578 deaths from 2015-20. The National Oceanic and Atmospheric Administration termed it as an ‘unusual mortality event’
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A dead manatee floats in the Indian River Lagoon in March this year. Previous mass deaths were caused by ‘toxic red tides’, as algal blooms are known. But this year’s is largely caused by the loss of seagrass beds, a key food source for manatees. While toxic red tides typically dissipate within a year, seagrass beds can take years to recover. Biologists fear the lack of food will continue killing manatees this coming winter
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Florida Fish and Wildlife Conservation Commission (FWC) biologists haul a dead manatee on to the beach during a study on Merritt Island
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During most years, dead manatees would have been taken to a lab for an autopsy to find the cause of death. But Covid-19 restrictions and the sheer numbers of dead manatees have resulted in about 60% not being examined this year
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Outlines of propeller scars on dead manatees drawn by FWC biologists during a study in the Indian River Lagoon. While boats kill more than 100 manatees a year, this year’s huge rise in fatalities is due to environmental degradation
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Biologists return to their boat after examining manatee corpses in Indian River Lagoon in March
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A manatee and her calf swim past a mansion in the shallow water of the Homosassa River. Development has wiped out critical manatee habitat in Florida and fertilisers used to maintain lawns fuel algal blooms that choke native vegetation in nearby waterways
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Visitors to ZooTampa meet Citrine, a Florida manatee recovering from boat strike injuries and cold stress, caused by prolonged exposure to cold water. Cold stress can cause a manatee’s skin to break down and fall off – Citrine’s white sores are due to this condition. As seagrass beds deteriorate along Florida’s east coast, manatees are spending more time in cold water foraging for food
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When ocean temperatures dip below 20C, manatees must find warmer water or die. Historically, Florida’s springs, which have a constant temperature of 22C, provided natural refuges. As power plants were built across the state, manatees began to rely on the warm-water discharges to survive winter. As ageing power plants are shut down, the warm water will disappear and manatees will need to find new refuges
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A diver from Sea & Shoreline, a Florida-based aquatic restoration firm, scrubs algae from exclusion cages in the Crystal River. The cages allow seagrass to develop mature roots before manatees eat it. As in Indian River Lagoon, land development and pollution fuelled algal blooms that smothered the eelgrass manatees eat. A community organisation, Save Crystal River, has led a project to restore the area, which includes replanting 37 hectares (92 acres) of eelgrass
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A diver dredges thick layers of organic matter from the bed of Crystal River so eelgrass can be planted in the firmer substrate below
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Dr Lauren Smith, a vet at ZooTampa, and animal care specialist Jaime Vaccaro prepare an orphaned manatee calf for an X-ray. Opened in 1991, ZooTampa’s manatee critical care centre can provide medical care for about 25 manatees at a time. Manatee care centres across the state have reported a rise in orphaned calves this year
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Staff at the ZooTampa care centre bottle-feed an orphaned manatee. Orphaned calves require extensive care and are fed every four hours. Manatee mothers will continue nursing even if starving to death
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Chessie, known as the Wandering Manatee, is prepared for release on Palm Beach, Florida. Chessie was first rescued from the Chesapeake Bay in Maryland in 1994 after biologists feared he would not be able to return to Florida before ocean temperatures became dangerously cold. He was rescued again this February from Riviera Beach, Florida, and taken to SeaWorld for treatment, where he was diagnosed with pneumonia. Biologists fear that the loss of seagrass beds may cause many other manatees to migrate far from home in search of food and become trapped by cold water before they can return home
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Biologists conduct a release assessment on a Palm Beach boat ramp before Chessie is returned to the wild
