Florida Manatees: Between a Rock and a Warm Place

Florida manatees are an iconic and extraordinarily popular attraction at
Crystal River each winter.
Since Florida manatees were added to the endangered species list in 1967, the population has been slowly growing. Once thought to number as few as 1,000, more than 5,000 were counted last year. The irony, according to Bob Bonde, a biologist with the U.S. Geological Survey, is that in the process of being saved, manatees have been thoroughly urbanized, and that transformation puts them in serious jeopardy.

Evidence of this urbanization is not difficult to find. Every winter manatees must find sources of warm water to survive. Historically, they congregated at warm springs found in abundance in Tampa Bay, the St. Johns River basin, the Crystal River/Kings Bay basin and other similar Florida locations. Unfortunately, access to many springs has been limited or eliminated through land development, and the flow of the manatee-friendly, warm freshwater in the springs has been reduced as we siphon off increasingly larger amounts of water for our own use. To make matters worse, as the freshwater flow declines, cooler saltwater intrudes, altering both the temperature and the biology of the springs. The manatees' urban solution is to seek the Jacuzzi-like warmth of power station cooling-water outflows. In 2005, Coastal Management reported that about 60 percent of manatees in Florida found their winter warmth at 10 power stations around the state.

Whether they choose the shrinking springs or the power plants, man's changes to the manatees' habitat force them to swim farther and farther to feed on the seagrasses that comprise their winter diet. The Florida Fish and Wildlife Conservation Commission reports that 279 manatees died from cold stress in 2010, although it is likely that cold temperatures contributed to many of the 214 deaths in the "undetermined" category and the 68 deaths in the "unrecovered" category. Some were killed by acute hypothermia, but others died from chronic cold-stress syndrome, symptoms of which may include emaciation, skin lesions or abscesses, fat depletion, dehydration, gastrointestinal disorders and secondary infections. Alex Costidis, a marine mammal biologist at the University of Florida, said most of the manatees killed by cold stress were younger, smaller animals lacking the body size and experience of the older animals. Boat strikes, infant mortalities and other causes brought the total manatee deaths to 767 in 2010. Costidis points out that it will take only a couple of years of similar cold temperatures to reverse more than 40 years of gains in the manatees' population numbers.

A happier indicator of the urbanization of manatees is their reaction to humans. Bonde calls Florida manatees the friendliest manatees on earth. "When you swim with the youngsters," he said, "it's like being in a room full of puppies. They go from snorkeler to snorkeler seeking attention." The problem is lots of people want to pet cute animals, whether they are puppies or manatees. Thousands of snorkelers and swimmers flock to Florida to interact with the manatees each winter. The sheer volume of visitors can be dangerously energy sapping. Katie Tripp, director of science and conservation for the Save the Manatee Club, likens it to a kind of celebrity/paparazzi relationship. The manatees have to leave the peace of their no-entry sanctuaries to feed, but they are forced to run a gauntlet of tourists both coming and going.

All of these problems are approaching their flash point in Florida's famous Crystal River. The clear waters of Three Sisters Springs are one of the last bastions of clear, warm water, attracting large numbers of both manatees and manatee-loving humans each winter. The stakes are high; the manatees bring about $20 million to the local economy. In 2010, a 59-acre parcel around Three Sisters slated for waterfront development was purchased with a combination of state, federal and private funds (Alert Diver, Fall 2009). The U.S. Fish and Wildlife Service (USFWS), which manages the Crystal River National Wildlife Refuge, took another key step with an emergency ruling establishing the Kings Bay Manatee Refuge. Unlike the existing wildlife refuge, this one doesn't set aside additional land or water. Instead it creates special manatee viewing prohibitions to protect the manatees.

Diane Oestreich, who owns Bird's Underwater Dive Center in Crystal River with her husband, Bill Oestreich, says the enlarged no-entry sanctuaries and the new rules of the Kings Bay Manatee Refuge work well. "Those of us who live here and work here know the rules and obey them. The rules are not draconian; they're just enough to let the rangers referee the activities effectively."

Ivan Vicente, a visitor services specialist at the Chassahowitzka National Wildlife Refuge Complex that includes the Crystal River refuge, acknowledges that the increased enforcement last winter was a good thing. Two full-time officers patrol the refuge, along with five more who rotate around the state's manatee "hot spots." Additional state enforcement officers are also deputized to work in the refuge. Disturbing sleeping manatees was the violation most frequently cited, with a penalty of several hundred dollars, depending on circumstances. Last year's emergency rule refuge expired on March 15, 2011, though, and USFWS will be taking public comments this spring and summer on the provisions of a permanent refuge. Mandatory visitor training, time limits on site, mooring buoys and viewing stands are among the measures being considered.

But many people, including K.C. Nayfield, a veterinary surgeon and former chairman of the City of Crystal River Waterfronts Advisory Board, maintain that the real threat to manatees is not human interaction, but habitat destruction. "Restoring water flow to the springs and returning Kings Bay to its native condition should be our focus," he says. "The Three Sisters acquisition was a huge step forward for the manatees, but we're still diminishing water flow by allowing development on spring recharge areas and planting high-maintenance landscaping. The twin-reactor nuclear power plant to be built in adjacent Levy County is going to take even more water from the aquifer."

What can you do? Contact USFWS and tell them what you think is important about the Kings Bay Manatee Refuge. Or adopt a manatee with the Save the Manatee Club. Your donation goes to research, education and lobby efforts. Better still, come to Florida next winter and see the manatees. You'll almost certainly become what Bonde calls "a swimming advocate for manatees."
For More Information
Crystal River NWR
Kings Bay Manatee Refuge (for comments)
Save the Manatee Club
University of Florida Aquatic Animal Health

© Alert Diver — Spring 2011