Managing the Manatee

Those who live and work on the Indian River Lagoon are well acquainted with the comings and goings of our Florida manatees, but many visitors are not aware that we harbor the aquatic equivalent of the world’s largest dairy cows grazing on the lagoon’s seagrass. Those who are put manatee sightings high on their list of things to do. 

Florida manatees are one of two subspecies of West Indian manatees. They range from Florida, north to Rhode Island in the summer and across the Gulf of Mexico to Texas. The second subspecies, the Antillean manatees, are found in the Caribbean Sea and northern South America. Although found in different regions, they successfully crossbreed, making them the same species. 

Varying from 70 pounds at birth to upwards of 3,000 pounds, you would think they would be hard to miss, but a nutrient-rich semi-enclosed estuary such as ours supports a phytoplankton community that keeps the water less than clear most of the time. Ironically, our views of these beasts are obscured by organisms that are a million times smaller than they are. However, because they are mammals that need to breathe air, we do catch glimpses of them as they come to the surface — or at least their nostrils do. In other parts of Florida where they are drawn to the relatively warm and clear waters of our natural springs in the winter, they are easier to see.

Officially Florida’s state marine mammal, the Florida manatee is unlike its distant relatives the great whales in that manatees have dense bones and heavy fat-free skin. It is thought that these act like ship ballast, providing a reliable center of gravity. This stable center is counterbalanced by two important physiological systems: large lungs and a muscular, longitudinal diaphragm. This dynamic duo effectively couples the ability to compress air in their lungs with precise regulation of intestinal gases to control buoyancy and body positioning, including the pitch and roll necessary for maneuvering in shallow water to feed.