What does a manatee need to survive?

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Florida manatees were among the first animals listed as endangered soon after the Endangered Species Act came into effect in 1973. When that happened, there were only about 1,000 of them left. Forty years later after the implementation of a series of manatee-protection measures, including habitat protection and boat speed limits, their numbers have rebounded and there are over 6,600 of them now. And manatee experts believe, if the conservation efforts are maintained, their population will more than double in the next 50 years and then endure for over 100 years if the threats are managed.

Adaptations to survival in marine environment

Manatees are very large, measuring 8-10 feet and weighing 440-1,300 pounds. Their sheer size helps protect them from predators. They also have broad, strong tails to propel themselves through water and enable them achieve bursts of speed, hitting up to 15 mph. To survive in water, they have developed unique breathing behaviors. When resting underwater, the animals can remain submerged for up to 20 minutes before coming to the water surface to breathe. But when swimming, they take in more oxygen and breathe every 30 seconds or so.

Manatees eat 4-9 percent of their body weight in vegetation every day, grazing for 6-8 hours daily. They predominantly feed on sea grasses and other water vegetation, using their hind-gut fermentation to efficiently digest plant cellulose. But when vegetation is sparse, they sometimes feed on fish and invertebrates. Soon after giving birth, mothers drag their babies to the water surface for a breath, preparing the calf to be able to swim and breathe on its own. The calves survive on milk, but they are able to consume vegetation three weeks after birth. Manatees also are able to communicate with each other through whistles, chirps and squeaks, usually making sounds when sexually aroused, frightened or relating with each other.

So what does a manatee need to survive?

A manatee needs warm water to thrive and survive. Although very large, a manatee has a lower metabolic rate and little body fat compared to other aquatic mammals so it can’t stand water temperatures below 20 C (68 F) for longer periods of time. It doesn’t produce enough metabolic heat to replace the heat lost in the environment. In fact, during winter months when it’s unusually cold in Florida, there is a significant increase in manatee mortality.

Due to their susceptibility to cold, Florida manatees are usually migratory animals. While they are generally found in shallow, slow-moving estuaries, bays, rivers and coastal waters of the southeastern United States, they travel freely around coastal waters and rivers during the summer months. In the winter, often from November through March, they primarily gather in Florida refuge areas where water temperatures don’t usually fall below 21 C (70 F). It’s not yet known how manatees know when cold weather is approaching, but they seem to know and tend to seek warm-water areas in time.

Need for warm-water passageways and refuge areas

Since manatees usually move back and forth between their winter and summer habitats and between their resting, feeding and calving areas, passageways or travel corridors are necessary for their survival. In fact, manatees have preferred habitats and refuge areas they return to every year so they need passageways to reach these destinations in time.

The sea giants often gather in natural springs like those in Homosassa River, Crystal River or Blue Spring, with the springs serving as a perfect refuge with their relatively constant temperature — averaging around 22 C (72 F) throughout the year. These springs are where manatees move when surrounding waterways get colder. The animals also gather in warm water effluents of different power plants, such as Florida Power and Light Company’s plant in Riviera Beach or Ft. Myers and Tampa Electric Company’s plant in Apollo Beach. The power plant effluents protect manatees from the cold water and have even extended their range of migration.

Unfortunately, these warm water areas are at risk of disappearing as some aging power plants are going offline while spring flows continue to be affected by the growing human population and increased water needs in Florida. The sustained loss of warm-water habitats could be catastrophic to manatee population as more of them die during cold winters.

While the threats on manatee populations will continue to exist, continuous management of these threats will help improve their survival. The most important goal is maintaining warm natural springs and devising new warm-water alternatives to diminishing effluents of aging power plants. For more information on manatees and swim with manatee tours, visit the “Captain Mike’s Swimming With The Manatees” site.

Swimming with the Manatees boasts the best water adventure in Crystal River, Florida with lots of things to do for you and your family. For more information, contact us online, or call us at (352) 571-1888.

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