Manatees Take to Reefs in Belize

From Earthwatch Institute
Wednesday, May 12, 2004

Earthwatch teams find that the Belize Barrier Reef is significant manatee habitat, and may be important to seasonal movements

West Indian manatees are familiar denizens of rivers, mangrove islands, and coastal lagoons, from Florida to South America, where they are vulnerable to injury from boat traffic. But Earthwatch-supported research in Belize has identified that fringing and barrier reefs should also be considered primary manatee habitat, significant to their conservation in this Central American nation.

In a recent paper in Aquatic Mammals, Caryn Self-Sullivan (Texas A&M University) and colleagues reported that manatees, particularly males, were commonly found in breaks along the Belize Barrier Reef, the second largest barrier reef in the world. Their use of the reef was concentrated in the summer months, suggesting seasonal movements that may be related to mating behavior.

"Fringing and barrier reefs should be included as a primary component of manatee habitat," said Self-Sullivan, principal investigator of the Earthwatch-supported Manatees of Belize project along with coauthor Katherine LaCommare (University of Massachusetts, Boston). "They may serve as important travel routes both in Belize and between fragmented populations of manatees throughout the Meso-American barrier reef system."

Reefs have not typically been considered manatee habitat, possibly due to the prevalence of research from Florida where reefs are not present in manatee study areas. In contrast to manatees in Florida, those in Belize are in the less-studied Antillean subspecies (Trichechus manatus manatus), listed by the IUCN as vulnerable. The Antillean manatee is apparently in decline, with severely fragmented populations, making any information about their habitat use crucial.

Although physical changes related to mating season have been documented in manatees in Florida, population movements there are chiefly directed by changes in water temperature. Self-Sullivan's research suggests that seasonal movements related to manatee mating behavior or other stimuli may be more discernable in tropical waters, where ambient water temperature seldom falls below the lower limit for manatees.

"Detecting all manatee habitat components is essential to conservation management of the species," said Self-Sullivan, who reports all of their findings to the Belize National Working Group and others charged with manatee recovery in Belize. "The more we know about manatee behavior, travel corridors, and distribution, the easier it is for decision-makers in Belize to implement rules and regulations to expand manatee protection."

Earthwatch volunteers on Manatees in Belize in 2001 were responsible for collecting some of the data for this paper, namely all the samples at the Gallows' Reef sites at the south end of the barrier reef. They will continue to assist Self-Sullivan and LaCommare as they study the behavior and habitat needs of manatees in Belize in order to improve the marine mammals' conservation.

"Thanks to hundreds of hours of observations by Earthwatch volunteers, we now have an emerging picture of how manatees use our study area, an area increasingly impacted by tourism and recreational boaters," said Self-Sullivan.

Earthwatch Institute is an international nonprofit organization that supports scientific field research by offering members of the public unique opportunities to work alongside leading field scientists and researchers. The Institute's mission is to engage people worldwide in scientific field research and education to promote the understanding and action necessary for a sustainable environment.

For more information, see "Seasonal occurrence of male Antillean manatees (Trichechus manatus manatus) on the Belize Barrier Reef." Caryn Self-Sullivan, et al. Aquatic Mammals 2003, 29.3: 342-354.

To help learn more about Belize's manatees, go to