Migrating to warmer waters

Just as entrepreneurs realized a need for hotels in Florida, so did Tampa Electric Co. when people started lining up at their fences 15 years ago.

But onlookers didn’t want a room with a view; they merely wanted a chance to see the manatees more closely.

The manatees are concentrated around the Florida peninsula between November and March due to warmer water temperatures. They have been migrating to TECO’s Big Bend Station power plant for 50 years, although it wasn’t until 1986 that the warm water discharge canal became an official manatee sanctuary.

“In the beginning, TECO employees would unlock the gate during the week and also on the weekends so people could see the manatees better,” said Stan Maloy, manager for Compliance and Stewardship Programs at TECO. “But now we have a viewing platform and an educational building.”

The water adjacent to the power plant appears to be an unlikely place for manatees to gather. However, the warm water the power plant generates serves as a thermal blanket for the cold-susceptible mammals.

Manatees grow to be 10-12 feet long and average 1,500-1,800 pounds. Despite their large size, the manatee has low body fat, which prevents it from adapting to cold temperatures. Therefore, manatees migrate to warm water sources, be they artificial, such as Big Bend’s warm water discharge canal, or natural, such as Blue Springs in Orange City.

“We have blocked off the bay to boaters and are providing a safe haven for manatees,” Maloy said.

However, protecting the manatees is a daunting endeavor. Not only do manatees have a low fertility rate, but they also have to contend with humans.

“Almost one-half of all manatee deaths are human-related circumstances, mainly watercraft collisions,” said Nancy Sadusky, communications director for Save the Manatee Club.

Although manatees are capable of short, 20-mph bursts, they are no match for engine-powered boats, Sadusky said.

Another significant factor affecting the manatees is the destruction of their natural habitat, said Sadusky.

“More and more people are buying land along the coast, rivers and waterways,” she said.

Sadusky said dock structures built along the water destroy seagrass, the manatees’ main food source, by shading areas that are not used to shading. Another reason for the loss of seagrass stems from herbicides and pesticides some homeowners use. These chemicals often reach the life-sustaining vegetation and inevitably kill it.

Not only do homeowners contribute to the destruction of seagrass, Sadusky said, but they also bring with them more boats, increasing the likelihood of more manatee deaths.

“People who are putting up homes more often than not have boats,” Sadusky said.

Nevertheless, boaters can prevent manatee deaths by avoiding shallow waters where manatees generally feed on seagrasses, following designated speed limits and wearing polarized sunglasses to reflect glare in order to see the manatees, Sadusky said.

Sadusky also suggested not feeding or touching the manatees, so as not to interfere with their natural behavior. Manatees will become less apprehensive about approaching boats, which could prove fatal.

“The best way to view manatees is to view them from a distance,” Sadusky said.

Manatees did not always inhabit the waters near power plants. In fact, it wasn’t until the power plants were built 50 years ago that the manatees migrated farther south, said Bruce Ackerman, a marine mammal biologist at the Florida Marine Research Institute in St. Petersburg.

About 1,000 years ago they would have spent the winter at Crystal River and farther south, Ackerman said.

Although the effects on the manatees’ migratory patterns are unnatural, the power plants have done more good than harm for the manatees, Ackerman said.

If the power plants were to be shut down, Ackerman said, then the lack of warm water would pose a serious threat to the manatees. But even if a power plant were to shut down, an alternative warm water source would be implemented in its place, Ackerman said.

“I imagine we (TECO) would be required to have a plan in place because the manatees have become dependent on the warm water,” Maloy said.

Because manatees usually migrate to the same place each year, they would probably return to their usual site even if there wasn’t warm water. In extreme cold, a manatee could run out of energy and die within one to two days.