U.S Fish and Wildlife Services


The Trichechus manatus is considered to be endangered by the U.S Department of Fish and Wildlife services. Because the T. manatus has virtually no natural predators we can deduce that their endangered status is due to human interaction and/or destruction of their natural habitat.

In 2006, 151 manatees were reported to have been killed of the southwestern coast of Florida due to the effects from of the Red Tides (Flewelling et al., 2005).  Red Tides (shown below) are algae blooms caused by a high concentration or micro-organisms called dinoflagellates. The presence of one dinoflagellate, named Karenia brevis, produces a neurotoxin called brevetoxin (Lin et al., 1981). Red Tides are most common in coastal regions and are estimated to kill hundreds of manatees each year (Flewellin et al., 2005).
Photo taken by Miriam Godfrey. Science Education Resource cener of Carlton College
The most prevalent effect on T. manatus mortality comes from us humans. Nearly 50% of documented T. manatus deaths are attributed to human related incidents (Nowacek et al., 2004). The habitat of T. manatus is in the coastal regions of bodies of water which also happen to be the most popular areas for boats. Collisions with boats are estimated to account for 30% of adult manatees fatalities (Sorice et al., 2003). Nearly all manatees that are observed in the wild have scarring from incidents with boats. An example of scarring that occurs is shown in the picture of the manatee below. A study performed by the Florida Research Institution explains that while manatees recognize the danger of incoming vessels, they are often not fast enough to get to deeper water quickly enough to prevent damage (Sorice et al., 2003).
Photo provided by: USGS Sirenia Project.
 T. manatus have a diet nearly entirely comprised of sea vegetation, (Mignucii-Giannoni et al., 2006). This vegetation grows in the shallow coastal regions of water because it requires adequate sunlight to survive. It is estimated that only 80% of this sea vegetation present in 1900 was still present in 1980 (Sorice et al., 2003).  In addition to the loss of sea grass, the quality of the sea grass present has drastically decreased. The run-off of nitrogenous wastes and the water pollution by boats has caused the level of nutrients in the sea vegetation to be severely lowered (Mignucii-Giannoni et al., 2006). Florida has recently begun taking measures to control nitrogen loading into watershed, and this has helped increase the levels of water vegetation, and increase the quality. (Sorice et al., 2003). It will become increasingly important for the governments of coastal areas with year round warm water to take similar conservation efforts. Without these regulations in winter habitats, migrating manatees will have to swim further and concentrate into smaller areas just to forage in sub-par environments (Mignucii-Giannoni et al., 2006).

If we as humans don't stop taking our bodies of water for granted, and continue this current trend of careless pollution, we might lose a multitude of water dwelling creatures like the T. manatus. If you would like to learn more about the steps that Florida has been taking to keep their water follow this link to the Florida Department of Environmental Protection. If you would like to learn more about the endangered status of Trichechus manatus follow this link to the U.S Department of Fish and Wildlife Services.

Return to home page