Trichechus manatus Linnaeus 1758

The West Indian manatee (Trichechus manatus) — sometimes called the sea cow—is found along the coast of Florida and in the Caribbean. Most adult manatees are about 10 feet long and weigh 800 to 1,200 pounds, although some larger than 12 feet and weighing as much as 3,500 pounds have been recorded. These “gentle giants” have tough, wrinkled brown-to-gray skin that is continuously being sloughed off. Hair is distributed sparsely over the body. With stiff whiskers around its mouth, the manatee’s face looks like a walrus without tusks. Christopher Columbus was the first European to report seeing a manatee in the New World. To Columbus, and other sailors who had been at sea for a long time, manatees were reminiscent of mermaids—the mythical half-fish, half-woman creatures of the ocean. Manatees are not fish, however, but marine mammals. The manatee maneuvers through the water moving its paddle-like tail up and down and steering with its flippers. It is very agile for such a large animal, sometimes somersaulting and doing barrel rolls in the water. The manatee often rests suspended just below the water’s surface with only the snout above water. It feeds underwater, but must surface periodically to breathe. Although the manatee can remain underwater for as long as 12 minutes, the average time is 4-1/2 minutes. Manatees are herbivores, a term that means they eat only plants. They consume 4 to 9 percent of their body weight each day—that’s 32 pounds of plants for an 800-pound animal! To do this, manatees spend 5 to 8 hours a day eating—typically non-native water hyacinths and hydrilla, along with native aquatic plants such as Vallisneria or eelgrass. Manatees move between fresh- water, brackish, and saltwater environments. They prefer large, slow-moving rivers, river mouths, and shallow coastal areas such as coves and bays. The animals may travel great distances as they migrate between winter and summer grounds. During the winter, manatees congregate around warm springs and around power plants that discharge warm water. During summer months, they have occasionally been seen as far north as Virginia and Maryland. Manatees reach breeding maturity between 3 and 10 years of age. The gestation period is approximately 13 months. Calves may be born at any time during the year. Usually a single calf is born, but twins do occur. An adult manatee will usually give birth to a calf every 2 to 5 years. The low reproductive rate makes the species less capable of rebounding from threats to its survival. Newborn calves weigh 60 to 70 pounds and are 4 to 4-1/2 feet long. They nurse underwater for about three minutes at a time from a nipple located behind their mother’s forelimb. Born with teeth, calves begin eating plants within a few weeks but remain with their mother for up to 2 years. Manatees may live for several decades. Manatees communicate with each other by emitting underwater sounds that are audible to humans. The vocalizations, which sound like squeaks and squeals, are especially important for maintaining contact between mother and calf. One field report described a mother and her calf, separated by a flood gate, calling to each other for three hours without interruption until they were reunited. Manatees face many threats to their survival throughout their range. Historically, they were hunted for their flesh, bones, and hide. Manatee fat was used for lamp oil, bones were used for medicinal purposes, and hides were used for leather. Hunting is thought to be largely responsible for the initial decline of the species; however, hunting is no longer allowed in countries where manatees are protected. Today, the greatest threats to manatee survival are collisions with boats and, in Florida, loss of warm water habitat.

This species is found in the Belizean coast mangroves ecoregion (part of the larger Mesoamerican Gulf-Caribbean mangroves ecoregion), extending along the Caribbean Coast from Guatemala, and encompassing the mangrove habitat along the shores of the Bahía de Annatique; this ecoregion continues along the Belizean coast up to the border with Mexico. The Belizean coast mangroves ecoregion includes the mainland coastal fringe, but is separate from the distinct ecoregion known as the Belizean reef mangroves which are separated from the mainland. This ecoregion includes the Monterrico Reserve in Guatemala, the estuarine reaches of the Monkey River and the Placencia Peninsula. The ecoregion includes the Burdon Canal Nature Reserve in Belize City, which reach contains mangrove forests and provides habitat for a gamut of avian species and threatened crocodiles.

Pygmy or scrub mangrove forests are found in certain reaches of the Belizean mangroves. In these associations individual plants seldom surpass a height of 150 centimetres, except in circumstances where the mangroves grow on depressions filled with mangrove peat. Many of the shrub-trees are over forty years old. In these pygmy mangrove areas, nutrients appear to be limiting factors, although high salinity and high calcareous substrates may be instrumental. Chief disturbance factors are due to hurricanes and lightning strikes, both capable of causing substantial mangrove treefall. In many cases a pronounced gap is formed by lightning strikes, but such forest gaps actually engender higher sapling regrowth, due to elevated sunlight levels and slightly diminished salinity in the gaps.

Chief mangrove tree species found in this ecoregion are White Mangrove (Laguncularia racemosa), Red Mangrove (Rhizophora mangle), Black Mangrove (Avicennia germinans); the Button Mangrove (Conocarpus erectus) is a related tree associate. Red mangrove tends to occupy the more seaward niches, while Black mangrove tends to occupy the more upland niches. Other plant associates occurring in this ecoregion are Dragonsblood Tree (Pterocarpus officinalis), Guiana-chestnut (Pachira aquatica) and Golden Leatherfern (Acrostichum aureum).

In addition to hydrological stabilisation leading to overall permanence of the shallow sea bottom, the Belizean coastal zone mangrove roots and seagrass blades provides abundant nutrients and shelter for a gamut of juvenile marine organisms. A notable marine mammal found in the shallow seas offshore is the threatened West Indian Manatee (Trichecus manatus), who subsists on the rich Turtle Grass (Thalassia hemprichii) stands found on the shallow sea floor.

Wood borers are generally more damaging to the mangroves than leaf herbivores. The most damaging leaf herbivores to the mangrove foliage are Lepidoptera larvae. Other prominent herbivores present in the ecoregion include the gasteropod Littorina angulifera and the Mangrove Tree Crab, Aratus pisonii.

Many avian species from further north winter in the Belizean coast mangroves, which boast availability of freshwater inflow during the dry season. Example bird species within or visiting this ecoregion include the Yucatan Parrot (Amazona xantholora), , Yucatan Jay (Cyanocorax yucatanicus), Black Catbird (Dumetella glabrirostris) and the Great Kiskadee (Pitangus sulfuratus)

Upland fauna of the ecoregion include paca (Agouti paca), coatimundi (Nasua narica),Baird’s Tapir (Tapirus bairdii), with Black Howler Monkey (Alouatta caraya) occurring in the riverine mangroves in the Sarstoon-Temash National Park. The Mantled Howler Monkey (Alouatta palliata) can be observed along the mangrove fringes of the Monkey River mouth and other portions of this mangrove ecoregion.

Other aquatic reptiian species within the ecoregion include Morelet's Crocodile (Crocodylus moreletti), Green Turtle (Chelonia mydas), Hawksbill Sea Turtle (Eretmochelys imbricata), Loggerhead Sea Turtle (Caretta caretta), and Kemp’s Ridley (Lepidochelys kempi).

Conservation, education, and advocacy organization for manatees