West Indian manatee

The West Indian manatee (Trichechus manatus), also known as the North American manatee, is a large, aquatic mammal native to warm coastal areas of the Caribbean, from the eastern US to northern Brazil. Living alone or in herds, it feeds on underwater plants and uses its whiskers to navigate. It is divided into two endangered subspecies, the Florida manatee (T. m. latirostris) in the US and the Antillean manatee (T. m. manatus) in the Caribbean,^[8][9] both of which face pressure from habitat loss, pollution, and other human activity. The West Indian manatee is the largest living member of the sirenians (order Sirenia), a group of large aquatic mammals that includes the dugong, other manatees, and the extinct Steller's sea cow.

West Indian manatee^[1] Temporal range: Pleistocene-Recent^[2]^[3]
Adult with calf
Conservation status
Vulnerable (IUCN 3.1)^[4] (Overall species)
Endangered (IUCN 3.1)(Each subspecies: T. m. latirostris^[5] and T. m. manatus^[6])
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Sirenia
Family:	Trichechidae
Genus:	Trichechus
Species:	T. manatus
Binomial name
Trichechus manatus Linnaeus, 1758^[7]
West Indian manatee range

Manatees are herbivores, have developed vocal communication abilities, and are covered in highly sensitive whiskers (called vibrissae) that are used for feeding and navigation.^[10] In breeding season, several males form mating herds around an individual female; on average, one calf is born to a female manatee every two to three years.^[11]

In the 1970s, the West Indian manatee was listed as endangered in the United States under the Endangered Species Act, when there were only several hundred left.^[12] The decades since have witnessed significant efforts to protect this species from natural and human threats, particularly collisions with watercraft.^[13] In 2017, the US changed the classification to threatened, citing a substantial increase in the total population.^[12][14]

Description

The average West Indian manatee is about 2.7–3.5 m (8.9–11.5 ft) long and weighs 200–600 kg (440–1,320 lb), with females generally larger than males.^[15] The largest individual on record weighed 1,655 kg (3,649 lb) and measured 4.6 m (15 ft) long.^[16][17] Manatees are estimated to live 50 years or more in the wild,^[11] and one captive Florida manatee, Snooty, lived for 69 years (1948–2017).^[18]

 

Skull of a West Indian manatee on display at The Museum of Osteology, Oklahoma City, Oklahoma

Since manatees are mammals, they breathe air, have warm blood, and produce milk. Like the other sirenians, the West Indian manatee has adapted fully to aquatic life, having no hind limbs. Instead of hind limbs, the manatee has a spatula-like paddle for propulsion in the water. Manatees have evolved streamlined bodies which lack external ear flaps, thus decreasing resistance in the aquatic environment. Pelage cover is sparsely distributed across the body, which may play a role in reducing the build-up of algae on their thick skin. Manatee skin is gray but can vary in coloration due to algae and other biota, like barnacles, that opportunistically live on manatees. Scar tissue on manatees is white and persists for decades, allowing for easy identification. The Florida manatee has three to four nails on each flipper.^[19]

The West Indian manatee has a prehensile snout, like their relative the elephant, for grabbing vegetation and bringing it into their mouths. Manatees have six to eight molariform teeth in each jaw quadrant. These molariform teeth are generated at the back of the mouth and slowly migrate towards the front of the mouth, at a rate of 1–2 mm per month, where they then fall out. This tooth ‘conveyor belt’ provides unlimited tooth production which is beneficial for the manatee which feeds on vegetation four to eight hours per day and consumes 5-10% of its body weight per day. Manatees have 3–5 cm hairs that cover their whole body and provide somatosensory information. Manatee bones are dense and solid which allows them to act as ballast and promote negative buoyancy. This helps counteract the positive buoyancy which comes from their high fat content. These two buoyancy counterparts, along with air in the lungs, helps manatees achieve neutral buoyancy in the water. This makes breathing, foraging, and swimming easier for the manatee. Manatees are unique, compared to other mammals, in that they have a longitudinally oriented diaphragm that is split in half to form two hemidiaphragms. Each hemidiaphragm is capable of independent muscular contractions.^[19]

Distribution and habitat

The West Indian manatee inhabits mostly shallow coastal areas, including rivers and estuaries. Manatees can withstand large changes in salinity and are found in both freshwater and saltwater.^[11] Manatees' extremely low metabolic rate and lack of a thick layer of insulating body fat limits them to locations with warm waters, including tropical regions.

The Florida subspecies is primarily found along the Florida coast, but has been spotted as far north as Dennis, Massachusetts, as well as along the Gulf Coast of Texas.^[20] Concerning their forays inland, a manatee was once spotted in the Wolf River (near where it enters the Mississippi) in Memphis, Tennessee, in 2006: a distance of over 700 river miles from the Gulf of Mexico.^[21] The Antillean subspecies has a sparse distribution throughout the Caribbean, ranging as far north as Mexico and as far south as Brazil.^[22][23]

An analysis of mitochondrial DNA patterns indicates there are actually three primary geographic groups of the West Indian manatee: (i) Florida and the Greater Antilles; (ii) Mexico, Central America and northern South America; and (iii) northeastern South America.^[24][23]

The seasonal distribution of the West Indian manatee varies with water temperatures. Temperatures below approximately 20 °C (68 °F) increase the risk of cold-induced stress or mortality for manatees.^[11][25] Consequently, Florida manatees seek out warm-water refuges during the winter, concentrated primarily along the Florida peninsula.^[26] Many of these refuges are artificial, created by the runoff from nearby power plants.^[4] In contrast, the Antillean manatee is less susceptible to cold-induced stress due to the warmer waters across its range.

 

Manatee from Crystal River, Florida

Florida manatees inhabit the most northern limit of sirenian habitats. There are four recognized subpopulations of the Florida manatee, termed the Northwest, Southwest, Atlantic Coast and St. John's River populations.^[27] Large concentrations of Florida manatees are located in the Crystal River^[28] and Blue Springs regions in central and north Florida. The Antillean manatee is sparsely distributed throughout the Caribbean and the northwestern Atlantic Ocean, from Mexico, east to the Greater Antilles, and south to Brazil. Populations can also be found in The Bahamas, French Guiana, Suriname, Guyana, Trinidad, Venezuela, Colombia, Panama, Costa Rica, Curaçao, Nicaragua, Honduras, Guatemala, Belize, Cuba, the Dominican Republic, Jamaica and Puerto Rico. It is possibly extirpated from the Turks and Caicos Islands, and definitively so from all the Lesser Antilles except Trinidad and Curaçao. Its presence in Haiti is uncertain.^[14] A reintroduction was planned to take place in Guadeloupe, but was terminated early due to political issues.^[29]

Behavior and diet

 

Basking at Haulover Canal, Merritt Island National Wildlife Refuge, Florida

Behavior

Because manatees evolved in habitats without natural predators, they lack predator avoidance behavior. The large size and low metabolic rates of manatees lends to their capacity for long and deep dives, as well as their relative lack of speed. Manatees are frequently solitary creatures, but they do aggregate at warm-water habitats during the winter and during the formation of breeding herds.^[11] In spite of their docile demeanor, due to their large size the West Indian manatee has nearly no natural predators in its native environment. American alligators and American crocodiles have been suspected to on occasion take a manatee.^[30][31] A dying manatee was discovered in Puerto Rico, wounded by a large shark bite thought to be inflicted by either a tiger shark or bull shark.^[32] It is projected that large sharks may threaten manatees occasionally but rarely enter the manatee's brackish habitats, whereas marine mammals in more direct coastal oceanic waters are well known to be highly vulnerable to sharks and orcas.^[33]

Communication

Manatees have been shown to form large mating herds when males come across estrous females, indicating that males may be able to sense estrogen or other chemical indicators.^[34][35] Manatees can communicate information to each other through their vocalization patterns.^[36] Sex and age-related differences are apparent in the vocalization structure of common squeaks and screeches in adult males, adult females, and juveniles.^[37][38][39] This may be an indication of vocal individuality among manatees.^[38] An increase in manatee vocalization after a vocal playback stimulus shows that they may be able to recognize another manatee's individual voice.^[38] This behavior in manatees is found mostly between mother and calf interactions.^[40] However, vocalization can still be commonly found in a variety of social interactions within groups of manatees, which is similar to other aquatic mammals.^{[40][citation needed]} When communicating in noisy environments, manatees that are in groups experience the same Lombard effect as humans do; where they will involuntary increase their vocal effort when communicating in loud environments.^[41] Based on acoustic and anatomical evidence, mammalian vocal folds are assumed to be the mechanism for sound production in manatees.^[42] Manatees also eat other manatees' feces; it is assumed that they do this to gather information about reproductive status or dominance, indicating the important role chemoreception plays in the social and reproductive behavior of manatees.^[34]

Diet

Manatees are obligate herbivores that feed on over 60 species of aquatic plants in both fresh and salt water. Seagrass is a staple of the manatee diet, particularly in coastal areas.^[43][44][45] In addition, when the tide is high enough, they will also feed on grasses, roots and leaves (including those of mangroves), as well as algae.^[46][47][48] Manatees typically graze for five or more hours per day, consuming anywhere from 4% to 10% of their body weight in wet vegetation per day, though the exact amount depends on their body size and activity level.^[49] Because manatees feed on abrasive plants, their molars are often worn down and are replaced many times throughout their lives, thus earning the nickname "marching molars." The molar teeth are similar in shape, but of varying sizes. Manatees do not have incisors; these have been replaced by horny gingival plates.^[50] Some individuals may also inadvertently eat invertebrates (such as small aquatic insects and crustaceans) and will eat fish both in captivity and in the wild.^[47][48]

Manatees are nonruminants with an enlarged hindgut. Unlike other hindgut fermenters, such as the horse, manatees efficiently extract nutrients, particularly cellulose, from the aquatic plants in their diet. Manatees have a large gastrointestinal tract with contents measuring about 23% of its total body mass. In addition, the passage rate of food is very long (about seven days).^[51] This slow process increases the digestibility of their diet. It is suggested that chronic fermentation may also provide additional heat and is correlated with their low metabolic rate.^[46]

Vibrissae

 

Sculpture of manatee showing vibrissae

 

All the hairs of the manatee may be vibrissae

Manatees have sensitive tactile hairs that cover their bodies and faces called whiskers or vibrissae. Each individual hair is a vibrissal apparatus called a follicle-sinus complex. Vibrissae are blood filled sinuses bound by a dense connective tissue capsule with sensitive nerve endings that provides haptic feedback to the manatee.^[10]

Usually vibrissae are found on the facial regions of terrestrial and non-sirenian aquatic animals and are called whiskers. Manatees, however, have vibrissae all over their bodies. The vibrissae located in their facial region are roughly 30 times denser than the vibrissae on the rest of their body. Their mouth consists of very mobile prehensile lips which are used for grasping food and objects. The vibrissae on these lips are turned outward during grasping and are used in locating vegetation. Their oral disks also contain vibrissae which have been classified as bristle-like hairs that are used in nongrasping investigation of objects and food.^[52][53]

Manatee vibrissae are so sensitive that they are able to perform active touch discrimination of textures. Manatees also use their vibrissae to navigate the turbid waterways of their environment. Research has indicated that they are able to use these vibrissae to detect hydrodynamic stimuli in the same way that fish use their lateral line system.^[10]

Reproduction

Male manatees reach sexual maturity at 3–4 years of age, while females reach sexual maturity at 3–5 years of age.^[54][11] Manatees appear capable of breeding throughout their entire adult life, although most females first breed successfully at ages 7–9. Breeding occurs in ephemeral mating herds, where several males aggregate around an estrous female and compete for access to her.^[52] These mating herds can last up to 2 to 4 weeks. The estrous cycles of female manatees typically are approximately one month long. Females in captivity have been observed to skip cycles.^[55] Larger males, presumably older, have been observed to dominate mating herds and are likely responsible for most successful copulation events.^[56] However, between males and females there is a little sexual dimorphism where females are typically slightly larger than males.^[57]

The reproductive anatomy of males consists of internal testes within the abdominal cavity, which are located posterior to the kidneys. In the Florida manatee, males experience seasonal changes in their spermatogenesis. They are active during the warm breeding season; during this time all stages of spermatogenesis can be seen. However, during the cold non-breeding season, they are inactive, and spermatogenesis is inhibited.^[58] Recently there has been a study that shows support that males use chemosensation for the anal glands to locate females in estrous.^[59]

The reproductive anatomy of females is most like that of elephants. Female manatees resemble elephants in their zonary placenta, bicornuate uterus, and corpora albicantia. The female manatees’ ovary gross morphology consists of an oval disk shape with a flat surface of the cortex. And since they are polyovular the ovulation scar is often challenging to identify.^[55]

The gestation period in manatees lasts for 12–14 months, after which they give birth to one calf at a time, or rarely twins.^[56] When twins are born, they are fraternal twins and are dizygotic.^[60] When a calf is born, it usually weighs 60–70 lb (27–32 kg) and is 4.0–4.5 ft (1.2–1.4 m) long. Manatees do not form permanent pair bonds and the male contributes no parental care to the calf, which remains with the mother for up to two years prior to weaning. Female manatees have two axillary mammary glands located under their flippers. The lactation period for mothers and their calves last typically for 1 to 2 years. Prior to weaning, there is an increase in the hormone progesterone in the mother.^[61] During this two-year period with their mother, calves learn how to locate warm water sources for winter and about migration routes for the summer seasons.^[62] A single female can reproduce once every 2–3 years, which is referred to as the calving interval.^[11] Wild manatees have been documented producing offspring into their late 30s, and a female captive manatee has given birth in her 40s.^[4]

Captive breeding programs are not being conducted for the Florida manatee due to conservation concerns that are being addressed in their natural environments. Until these concerns are rectified, a captive breeding program will not be beneficial for this species.^[63]

Threats and conservation

 

Manatees in a conservation project in Brazilian northeastern coast

The West Indian manatee has been included on the U.S. Endangered Species List since the 1970s. In October 2007, the International Union for Conservation of Nature (IUCN) assessed the West Indian manatee as vulnerable, and both the Florida and Antillean subspecies as endangered.^[4] The full species and both subspecies qualified for their respective classifications due to a combination of a low number of mature individuals, and a significant projected decline in total population numbers over the next two generations (about 20 years per generation in manatees). Similarly, NatureServe considers both the Florida subspecies and the species as a whole as "Imperiled".^[64][65]

The Florida and Antillean subspecies face different threats, though some overlap. The largest causes of Florida manatee deaths can be attributed to collisions with watercraft, the loss of warm-water habitat, high perinatal mortality, entanglements and ingestion of debris, pollution, habitat loss, and harmful algae blooms (HABs), such as red tide.^[66][67][68] Antillean manatees face severe habitat fragmentation,^[69] as well as continued pressure from illegal hunting.^[70] In some countries, like Belize, collisions with watercraft are on the rise as tourism grows.^[71][72]

The 2017 decision to reclassify the West Indian manatee from endangered to threatened under the Endangered Species Act cited increases in the populations of both subspecies.^[14] The decision was not without controversy, however: according to Save the Manatee Club, the U.S. Fish and Wildlife Service failed to adequately consider data from 2010 to 2016, during which time manatees suffered from unprecedented mortality events linked to habitat pollution, dependence on artificial warm water sources, and record deaths from watercraft strikes.^[73] The official notice of the reclassification made clear that, even with the downlisting, all federal protections for the West Indian manatee under the Endangered Species Act would remain in place.^[12] The West Indian manatee is also protected by the Florida Manatee Sanctuary Act of 1978^[74] and the U.S. Marine Mammal Protection Act of 1972.

T. m. latirostris (Florida manatee)

A 1997 population viability analysis of the Florida manatee projected a 44% chance of extinction within the next 1,000 years without improvements in habitat conditions and new protective regulations.^[75] Since then, prospects for the subspecies have improved. In 2016, the U.S. Geological Survey collaborated with the Florida Fish and Wildlife Service to re-evaluate the status of the Florida manatee under the Core Biological Model, which is used to estimate population viability. This assessment analyzed total population on the east and west coasts of Florida and estimated that the likelihood of either population falling under 500 adults within 100 years was about 0.42%.^[76] The projected improvement of population numbers and stability is contingent on continued intervention and monitoring efforts.

 

Manatee Crossing Sign from South Florida Museum

Collision with watercraft

Over 20% of manatee mortalities per year are a result of watercraft collisions.^[77] Between 1985 and 2017 53% of adult manatee mortalities were the result of boat strikes.^[68] 96% of adult Florida manatee carcasses have scars from a boat collision with some individuals showing signs of 10 or more boat strikes.^[78] Manatees can hear boats, but they oftentimes do not have enough time to get out of the way of a fast approaching boat. A boat going at a slower speed gives the manatee more time to react and move out of the way.^[79][80] Manatees respond to approaching vessels by orienting towards deeper waters and increasing their speed,^[81][82] but they are nevertheless frequently struck as they don't have the ability to swim very fast and in shallow habitat they oftentimes don't have anywhere to go to get out of the way. Over half of all watercraft deaths are caused by the impact trauma from the hull of a fast-speeding boat, whereas the remaining percentage is caused by the boat propeller.^[83] Aerial surveys of Florida manatee and boat distribution have been conducted to map the areas in which collisions are most likely to occur, accounting for environmental and seasonal factors.^[84] Watercraft can frequently avoid hitting manatees simply by reducing speed, allowing time for the manatee to escape out of range.^[85] Despite improvements in modeling and changes to local regulations, manatee mortalities from watercraft collisions continue to rise with an all-time high of 137 recorded deaths in 2019.^[86]

Loss of warm-water habitat

Projected long-term loss of warm-water habitats presents a significant risk to manatees, who are unable to tolerate temperatures lower than 20 °C (68 °F) for prolonged periods of time.^[87][19] Florida manatees frequently congregate around natural warm-water springs, as well as the warm discharge given off by power plants throughout the winter months. However, as older plants are replaced with more energy-efficient structures, manatees could become at risk of cold-induced death due to reduced availability of warm-water refuges.^{[88][89][90][91]} Manatees exhibit high site fidelity and can recall previous refuge sites to which they frequently return in successive winters. Some conservationists fear that manatees may become overly reliant on warm-water locations generated by power plants that may shut down soon.^[92][93] Natural warm-water springs face problems from over-pumping of groundwater for human consumption, reduced spring flow, and nutrient pollution. In addition, some springs that were historically accessible to manatees are blocked off by dams or other structures.^[90][94][95] In areas where manatees lack access to power plants or natural warm springs, they instead seek out natural deep water zones that passively remain above tolerable temperatures.^[96]

Harmful algae blooms

Harmful algae blooms are an additional threat to manatees.^[97][98] Red tide is a common name for algal blooms, deriving its distinctive color from pigmentation molecules in the algae. The blooms produce brevetoxins which are potentially fatal to marine life. Most manatee deaths from red tide occur when manatees inhale the toxins, or ingest the toxins when consuming seagrass, their primary food source.^[99] During a 1996 epizootic more than 150 manatees died from red tide exposure.^[100] Although manatees can survive exposure to red tide if rescued and rehabilitated in time, researchers fear that there might be long-term effects from sublethal red tide exposure, which can affect the manatee's immune system through reduced lymphocyte proliferation response.^[101] In addition to red tide, blue/green and brown algae blooms triggered by excessive nutrient pollution from fertilizer, runoff, and leaking septic tanks can cloud the water. This results in seagrasses dying off since seagrasses and aquatic plants need light to photosynthesize. Manatees in turn may not be able to find sufficient food sources, which can lead to starvation.^{[102][103][104][105][106][107]} Manatees have experienced several Unusual Mortality Events (UMEs) over the years, which are usually related to either cold-stress syndrome, or brevetoxicosis from red tide. A current UME is ongoing along the Atlantic coast of Florida and is most likely related to a shortage in food sources.^[108][109]

Entanglement, entrapment and ingestion of debris

Manatees can easily get entangled in monofilament fishing line, crab traps, and other debris, which can lead to the loss of flippers and severe body wraps. In addition, they may also ingest a variety of debris, such as plastics, cloth, fishing gear, and other items.^{[110][111][112]} Manatees can also get crushed by flood control structures and locks and may get entrapped behind weirs or other structures, especially after heavy rainfall. Some manatees have gotten trapped in culverts and pipes and needed intervention.^[113]

 

West Indian manatee skeletons on display at the North Carolina Museum of Natural Sciences in Raleigh, North Carolina

T. m. manatus (Antillean manatee)

There is relatively little data on the Antillean manatee compared to its Florida counterpart. Phylogenetic studies on the Antillean manatee have revealed low genetic diversity among its populations, likely due to limitations on dispersal.^[114][115] Captive breeding, as well as the rehabilitation of manatee calves discovered without their mothers nearby, can supplement local conservation strategies, but populations are nevertheless at risk of inbreeding depression and local extinction.^[116][117]

Whereas the population trends of the Florida manatee are relatively well monitored, population data for the Antillean manatee is sparse due to its patchy distribution, as well as the relative turbidity and low levels of light in its habitat which can mitigate the effectiveness of aerial or sonar-based surveys, often resulting in inaccurate or erroneous measurements.^[118][119] A 2016 study on the Antillean manatee population of Brazil found a potential range for current population size between 485 and 2,221 individuals.^[120] The U.S. Fish and Wildlife Service estimated in 2017 that as many as 6,782 individuals might exist in the Antillean subspecies, but these results rely in large part on personal anecdotes and may overestimate the true population number.^[14] A 2012 study of the Antillean population documented significant human-related causes of mortality, and projected that if the share of human-caused manatee deaths per year rose to 5% or more, the population would face a severe decline and eventual extinction.^[69]

References

1. Shoshani, J. (2005). "Order Sirenia". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 93. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. "Trichechus manatus Linnaeus 1758 (manatee)". PBDB.
3. "Collared peccary (Mammalia, Artiodactyla, Tayassuidae, Pecari) from the late Pleistocene of Florida". 2009-01-01. {{cite journal}}: Cite journal requires |journal= (help)
4. Deutsch, C.J.; Self-Sullivan, C.; Mignucci-Giannoni, A. (2008). "Trichechus manatus". IUCN Red List of Threatened Species. 2008: e.T22103A9356917. doi:10.2305/IUCN.UK.2008.RLTS.T22103A9356917.en. Retrieved 12 November 2021.
5. Deutsch, C.J.; Self-Sullivan, C. & Mignucci-Giannoni, A. (2008-06-30). "Trichechus manatus latirostris". IUCN Red List of Threatened Species. 2008: e.T22106A9359881. doi:10.2305/IUCN.UK.2008.RLTS.T22106A9359881.en.|date= / |doi= mismatch
6. Deutsch, C.J.; Self-Sullivan, C. & Mignucci-Giannoni, A. (2008-06-30). "Trichechus manatus manatus". IUCN Red List of Threatened Species. 2008: e.T22105A9359161. doi:10.2305/IUCN.UK.2008.RLTS.T22105A9359161.en.|date= / |doi= mismatch
7. Linnæus, Carl (1758). Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I (in Latin) (10th ed.). Holmiæ: Laurentius Salvius. p. 34. from the original on 8 November 2012. Retrieved 22 November 2012.
8. Domning, Daryl P.; Hayek, Lee-Ann C. (1986). "Interspecific and intraspecific morphological variation in manatees (Sirenia: Trichechus)". Marine Mammal Science. 2 (2): 87–144. doi:10.1111/j.1748-7692.1986.tb00034.x.
9. Hatt, Robert T. (1934). "The American Museum Congo Expedition manatee and other recent manatees". Bulletin of the American Museum of Natural History. 66: 533–566.
10. Gaspard, JC; Bauer, GB; Reep, RL; Dziuk, K; Read, L; Mann, DA (2013). "Detection of Hydrodynamic Stimuli by the Florida Manatee (Trichechus manatus latirostris)". Journal of Comparative Physiology. 199 (6): 441–50. doi:10.1007/s00359-013-0822-x. PMID 23660811. S2CID 9152922.
11. "South Florida Multi-Species Recovery Plan". 18 May 1999.
12. Daley, Jason (April 3, 2017), "Manatees Move From Endangered to Threatened: But conservationists say the species still faces significant threats", Smithsonian, retrieved April 4, 2017
13. Martin, Julien; Sabatier, Quentin; Gowan, Timothy A.; Giraud, Christophe; Gurarie, Eliezer; Calleson, Charles Scott; Ortega-Ortiz, Joel G.; Deutsch, Charles J.; Rycyk, Athena; Koslovsky, Stacie M. (2016). "A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats". Methods in Ecology and Evolution. 7 (1): 42–50. doi:10.1111/2041-210X.12447. ISSN 2041-210X.
14. "Manatee Reclassified from Endangered to Threatened as Habitat Improves and Population Expands". fws.gov (Press release). Fish & Wildlife Service, US Department of the Interior. March 30, 2017. from the original on April 7, 2017. Retrieved April 4, 2017.
15. Trichechus manatus 2011-09-04 at the Wayback Machine, Animal Diversity Web
16. Wood, G.L. (1983). The Guinness Book of Animal Facts and Feats. 3rd revised edition. Sterling Pub Co Inc., ISBN 978-0851122359
17. Manatees 2012-01-18 at the Wayback Machine, Busch Gardens
18. "Snooty, world's oldest known manatee, dies one day after celebrating birthday". Fox News. 2017-07-23. from the original on 2017-07-23. Retrieved 2017-07-23.
19. Reep, R. L. & Bonde, R. K. (2006). The Florida manatee: Biology and conservation. Gainesville: The University Press of Florida.
20. Manatees 2012-05-08 at the Wayback Machine, Buzzards Bay National Estuary Program
21. "Manatee found dead in Tenn. lake". Associated Press. 11 December 2006. from the original on 24 September 2016. Retrieved 24 June 2017.
22. Morales-Vela, Benjamı́n; Olivera-Gómez, David; Reynolds III, John E.; Rathbun, Galen B. (2000-08-01). "Distribution and habitat use by manatees (Trichechus manatus manatus) in Belize and Chetumal Bay, Mexico". Biological Conservation. 95 (1): 67–75. doi:10.1016/S0006-3207(00)00009-4. ISSN 0006-3207.
23. Vianna, Juliana A.; Bonde, Robert K.; Caballero, Susana; Giraldo, Juan Pablo; Lima, Régis P.; Clark, Annmarie; Marmontel, Míriam; Morales-Vela, Benjamín; Souza, Maria José De; Parr, Leslee; Rodríguez-Lopez, Marta A. (2006). "Phylogeography, phylogeny and hybridization in trichechid sirenians: implications for manatee conservation". Molecular Ecology. 15 (2): 433–447. doi:10.1111/j.1365-294X.2005.02771.x. ISSN 1365-294X. PMID 16448411. S2CID 6130316.
24. Garcia-Rodriguez, A. I.; Bowen, B. W.; Domning, D; Mignucci-Giannoni, A; Marmontel, M; Montoya-Ospina, A; Morales-Vela, B; Rudin, M; Bonde, R. K.; McGuire, P. M. (1998). "Phylogeography of the West Indian manatee (Trichechus manatus): How many populations and how many taxa?". Molecular Ecology. 7 (9): 1137–1149. doi:10.1046/j.1365-294x.1998.00430.x. PMID 9734072. S2CID 36860021.
25. Haubold, E.; et al. (April 2006). Final Biological Status Review of the Florida Manatee (Trichechus manatus latirostris)] (PDF) (Report). Assessment 2005–2006. Florida Manatee Biological Review Panel. p. 133. Retrieved April 5, 2017.
26. Deutsch, Charles J.; Reid, James P.; Bonde, Robert K.; Easton, Dean E.; Kochman, Howard I.; O'Shea, Thomas J. (2003). "Seasonal Movements, Migratory Behavior, and Site Fidelity of West Indian Manatees along the Atlantic Coast of the United States". Wildlife Monographs (151): 1–77. ISSN 0084-0173. JSTOR 3830830.
27. Laist, David W.; Taylor, Cynthia; Iii, John E. Reynolds (2013-03-20). "Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold". PLOS ONE. 8 (3): e58978. Bibcode:2013PLoSO...858978L. doi:10.1371/journal.pone.0058978. ISSN 1932-6203. PMC 3604035. PMID 23527063.
28. "About the Manatees | Crystal River, Florida | Bird's Underwater". Birds Underwater. from the original on 2017-10-07. Retrieved 2017-10-06.
29. "First demonstration of reintroduction of West Indian Manatee in the Grand Cul-de-Sac Marin Bay, Guadeloupe". European Commission. Retrieved 20 June 2023.
30. Bonde, R. K., Mignucci-Giannoni, A. A., Bossart, G. D., Hines, E., Reynolds, J., & Aragones, L. (2012). Sirenian pathology and mortality assessment. Sirenian Conservation: Issues and strategies in developing countries, 148-156.
31. Charnock-Wilson, J. (1968). The manatee in British Honduras. Oryx, 9(4), 293-294.
32. Falcón-Matos, L., Mignucci-Giannoni, A. A., Toyos-González, G. M., Bossart, G. D., Meisner, R. A., & Varela, R. A. (2003). Evidence of a shark attack on a West Indian manatee (Trichechus manatus) in Puerto Rico. Mastozoología Neotropical, 10(1), 161-166.
33. Weller, D. W. (2009). Predation on marine mammals. In Encyclopedia of marine mammals (pp. 923-932). Academic Press.
34. Bauer, G. B.; Colbert, J. C. Gaspard III (2010). "Learning About Manatees: A Collaborative Program between New College of Florida and Mote Marine Laboratory to Conduct Laboratory Research for Manatee Conservation". International Journal of Comparative Psychology. 23 (4): 811–825. doi:10.46867/IJCP.2010.23.04.01. from the original on 2018-05-14.
35. Reynolds, J. E. III; Odell, D. K. (1991). Manatees and Dugongs. New York: Facts on File, Inc.
36. Sousa-Lima, Renata S.; Paglia, Adriano P.; Fonseca, Gustavo A. B. (2002). "Signature information and individual recognition in the isolation calls of Amazonian manatees, Trichechus inunguis (Mammalia: Sirenia)". Animal Behaviour. 63 (2): 301–310. doi:10.1006/anbe.2001.1873. S2CID 53177219.
37. Sousa-Lima, Renata S.; Paglia, Adriano P.; Fonseca, Gustavo A. B. (2008). "Gender, Age, and Identity in the Isolation Calls of Antillean Manatees (Trichechus manatus manatus)". Aquatic Mammals. 34 (1): 109–122. doi:10.1578/AM.34.1.2008.109.
38. Umeed, Rebecca; Attademo, Loffler N.; Bezerra, Bruna (2018). "The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their response to call playback". Marine Mammal Science. 34 (3): 577–594. doi:10.1111/mms.12467.
39. O'Shea, Thomas J.; Lynn B. Poché, Jr. (2006). "Aspects of Underwater Sound Communication in Florida Manatees (Trichechus manatus latirostris)". Journal of Mammalogy. 87 (6): 1061–1071. doi:10.1644/06-MAMM-A-066R1.1. ISSN 0022-2372. JSTOR 4126883. S2CID 42302073.
40. Reynolds, John E. II (1981). "Aspects of the social behavior and herd structure of a semi-isolated colony of West Indian manatees, Trichechus manatus". Mammalia. 45 (4): 431–451. doi:10.1515/mamm.1981.45.4.431. S2CID 201700122.
41. Mikisis-Olds, Jennifer L.; Tyack, Peter L. (2008). "Manatee (Trichechus manatus) vocalization usage in relation to environmental noise levels". The Journal of the Acoustical Society of America. Acoustical Society of America (ASA). 125 (3): 1806–1815. doi:10.1121/1.3068455. hdl:1912/2740. PMID 19275337.
42. Landrau-giovannetti, Nelmarie; Mignucci-giannoni, Antonio A.; Reidenberg, Joy S. (2014). "Acoustical and Anatomical Determination of Sound Production and Transmission in West Indian (Trichechus manatus) and Amazonian (T. inunguis) Manatees". The Anatomical Record. 297 (10): 1896–1907. doi:10.1002/ar.22993. PMID 25044536. S2CID 9973317.
43. Lefebvre, Lynn W.; Reid, James P.; Kenworthy, W. Judson; Powell, James A. (1999). "Characterizing Manatee habitat use and seagrass grazing in Florida and Puerto Rico: implications for conservation and management". Pacific Conservation Biology. 5 (4): 289–298. doi:10.1071/pc000289. ISSN 2204-4604.
44. Reich, Kimberly J.; Worthy, Graham A. J. (2006). "An isotopic assessment of the feeding habits of free-ranging manatees". Marine Ecology Progress Series. 322: 303–309. Bibcode:2006MEPS..322..303R. doi:10.3354/meps322303. ISSN 0171-8630. JSTOR 24870879.
45. MacFadden, Bruce J.; Higgins, Pennilyn; Clementz, Mark T.; Jones, Douglas S. (2004). "Diets, Habitat Preferences, and Niche Differentiation of Cenozoic Sirenians from Florida: Evidence from Stable Isotopes". Paleobiology. 30 (2): 297–324. doi:10.1666/0094-8373(2004)030<0297:DHPAND>2.0.CO;2. ISSN 0094-8373. JSTOR 4096848. S2CID 17889395.
46. Best, Robin C. (1981-03-01). "Foods and feeding habits of wild and captive Sirenia". Mammal Review. 11 (1): 3–29. doi:10.1111/j.1365-2907.1981.tb00243.x. ISSN 1365-2907.
47. https://sta.uwi.edu/fst/lifesciences/sites/default/files/lifesciences/documents/ogatt/Trichechus_manatus%20-%20West%20Indian%20Manatee.pdf
48. "Trichechus manatus (West Indian manatee)". Animal Diversity Web.
49. Allen, Aarin (2015). "Using the West Indian Manatee (Trichechus manatus) as a Mechanism for Invasive Aquatic Plant Management in Florida". Journal of Aquatic Plant Management. 53: 95–104. from the original on 2017-09-02.
50. Dierauf, Leslie A.; Gulland, Frances M. D. (2001). CRC handbook of marine mammal medicine (2nd ed.). Boca Raton, FL: CRC Press. ISBN 9780849308390. OCLC 45888920.
51. Reynolds, John E.; Rommel, Sentiel A. (1996-07-01). "Structure and function of the gastrointestinal tract of the Florida manatee, Trichechus manatus latirostris". The Anatomical Record. 245 (3): 539–558. doi:10.1002/(sici)1097-0185(199607)245:3<539::aid-ar11>3.0.co;2-q. ISSN 1097-0185. PMID 8800413.
52. Hartman, Daniel Stanwood (1979). Ecology and behavior of the Manatee (Trichechus manatus) in Florida. Special publication (American Society of Mammalogists), no. 5. Pittsburgh, Pa.: American Society of Mammalogists. pp. 1–153. doi:10.5962/bhl.title.39474.
53. Marshall, CD; Huth, GD; Edmonds, VM; Halin, DL; Reep, RL (1998). "Prehensile use of perioral bristles during feeding and associated behaviors of the Florida manatee (Trichechus manatus latirostris)". Marine Mammal Science. 14 (2): 274–289. doi:10.1111/j.1748-7692.1998.tb00716.x.
54. Rommel, Sentiel A. (2001). "Functional morphology of venous structures associated with the male and female reproductive systems in Florida manatees (Trichechus manatus latirostris)". The Anatomical Record. 264 (4): 339–47. doi:10.1002/ar.10022. PMID 11745089. S2CID 21211567.
55. Sheldon, Julie D.; Ferrante, Jason A.; Bills, Meghan L.; Larkin, Iskande V. (2011). The Reproductive Cycle of a Female Florida Manatee (Trichechus manatus latirostris): Comparisons of Behavior and Fecal Progesterone Levels. Vin.com (Thesis).
56. "Reproduction in free-ranging Florida manatees". National Biological Service Information and Technology Report 1.
57. "All About Manatees - Reproduction | SeaWorld Parks & Entertainment".
58. Miller, DL; Dougherty, MM; Decker, SJ; Bossart, GD (December 20, 2011). "Ultrastructure of the Spermatozoa from a Florida Manatee (Trichechus manatus latirostris)". Anatomia, Histologia, Embryologia: Journal of Veterinary Medicine Series C. 30 (4): 253–256. doi:10.1046/j.1439-0264.2001.00330.x. PMID 11534332. S2CID 27986063.
59. Bills, Meghan L.; Samuelson, Don A.; Larkin, Iskande V. (April 2013). "Anal glands of the Florida manatee, Trichechus manatus latirostris: A potential source of chemosensory signal expression". Marine Mammal Science. 29 (2): 280–292. doi:10.1111/j.1748-7692.2012.00564.x.
60. Moreira, Sávia; de Meirelles, Ana Carolina O.; Carvalho, Vitor Luz; do Rêgo, Péricles Sena; Araripe, Juliana (2022). "Molecular confirmation of twinning in the West Indian Manatee (Trichechus manatus)". Biota Neotrop. 22 (1). doi:10.1590/1676-0611-bn-2021-1241. S2CID 247418288.
61. "Lactation and Milk Composition".
62. "Reproduction". 7 June 2023.
63. "All About Manatees - Reproduction".
64. "Trichechus manatus latirostris". explorer.natureserve.org. Retrieved 27 October 2022.
65. "Trichechus manatus". explorer.natureserve.org. Retrieved 27 October 2022.
66. Halvorsen, K. M.; Keith, E. O. (2008). "Immunosuppression cascade in the Florida manatee (Trichechus manatus latirostris)". Aquatic Mammals. 34 (4): 412–419. doi:10.1578/AM.34.4.2008.412. S2CID 40327317.
67. Runge, Michael C.; Sanders-Reed, Carol A.; Langtimm, Catherine A.; Hostetler, Jeffrey A.; Martin, Julien; Deutsch, Charles J.; Ward-Geiger, Leslie I.; Mahon, Gary L. (2017). "Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016". Scientific Investigations Report. doi:10.3133/sir20175030.
68. "Manatee Mortality Statistics". Florida Fish And Wildlife Conservation Commission. Retrieved 2021-08-22.
69. Castelblanco-Martínez, Dn; Nourisson, C; Quintana-Rizzo, E; Padilla-Saldivar, J; Schmitter-Soto, Jj (2012-08-16). "Potential effects of human pressure and habitat fragmentation on population viability of the Antillean manatee Trichechus manatus manatus: a predictive model". Endangered Species Research. 18 (2): 129–145. doi:10.3354/esr00439. ISSN 1863-5407.
70. Olivera-Gómez, L. D; Mellink, E (2005-01-01). "Distribution of the Antillean manatee (Trichechus manatus manatus) as a function of habitat characteristics, in Bahı́a de Chetumal, Mexico". Biological Conservation. 121 (1): 127–133. doi:10.1016/j.biocon.2004.02.023. ISSN 0006-3207.
71. Self-Sullivan, C (2007). "Non-lethal boat scars on manatees in Belize as a tool for evaluation for a Marine Protected Area. 59th Gulf and Caribbean Fisheries Institute". {{cite journal}}: Cite journal requires |journal= (help)^{[failed verification]}
72. Galvez, JA; Clarke, CJ; Rosado, SK (2013). "Ameliorating Threats to Manatees in the Heart of Belize" (PDF). Retrieved July 10, 2021.
73. "Opposition to Manatee Downlisting".
74. "68C-22 : THE FLORIDA MANATEE SANCTUARY ACT - Florida Administrative Rules, Law, Code, Register - FAC, FAR, eRulemaking".
75. Marmontel, Miriam; Humphrey, Stephen R.; O'Shea, Thomas J. (1997). "Population Viability Analysis of the Florida Manatee (Trichechus manatus latirostris), 1976-1991". Conservation Biology. 11 (2): 467–481. doi:10.1046/j.1523-1739.1997.96019.x. ISSN 0888-8892. JSTOR 2387620. S2CID 39477590.
76. Runge, Michael C.; Sanders-Reed, Carol A.; Langtimm, Catherine A.; Hostetler, Jeffrey A.; Martin, Julien; Deutsch, Charles J.; Ward-Geiger, Leslie I.; Mahon, Gary L. (2017). "Status and threats analysis for the Florida manatee (Trichechus manatus latirostris), 2016". Scientific Investigations Report. doi:10.3133/sir20175030.
77. U.S. Fish and Wildlife Service. Florida Manatee Recovery Plan Third Revision. Prep by Florida Manatee Recover Team US Fish Wildl Serv Atlanta, Georg. Published online 2001:144.
78. Bassett, BL; Hostetler, JA; Leone, E.; Shea, CP; Barbeau, BD; Lonati, GL; Panike, AL; Honaker, A.; Ward-Geiger, LI (2020). "Quantifying sublethal Florida manatee-watercraft interactions by examining scars on manatee carcasses". Endangered Species Research. 43: 395–408. doi:10.3354/esr01075. S2CID 226545194.
79. Laist, David (2006). "Preliminary Evidence That Boat Speed Restrictions Reduce Deaths of Florida Manatees" (PDF). Marine Mammal Science. 22 (2): 472–479. doi:10.1111/j.1748-7692.2006.00027.x. (PDF) from the original on 2016-12-21.
80. Gerstein E. Manatees, Bioacoustics and Boats: Hearing tests, environmental measurements and acoustic phenomena may together explain why boats and animals collide. American Scientist, 90(2), 154-163. 2002. http://www.jstor.org/stable/27857630
81. Nowacek, Stephanie M; Wells, Randall S; Owen, Edward C. G; Speakman, Todd R; Flamm, Richard O; Nowacek, Douglas P (2004-10-01). "Florida manatees, Trichechus manatus latirostris, respond to approaching vessels". Biological Conservation. 119 (4): 517–523. doi:10.1016/j.biocon.2003.11.020. ISSN 0006-3207.
82. Edwards, Holly H.; Martin, Julien; Deutsch, Charles J.; Muller, Robert G.; Koslovsky, Stacie M.; Smith, Alexander J.; Barlas, Margaret E. (2016). "Influence of Manatees' Diving on Their Risk of Collision with Watercraft". PLOS ONE. 11 (4): e0151450. Bibcode:2016PLoSO..1151450E. doi:10.1371/journal.pone.0151450. PMC 4822772. PMID 27049326.
83. Wright SD, Ackerman BB, Bonde RK, Beck CA, Banowetz DJ. Analysis of Watercraft-related Mortality of Manatees in Florida 1979-1991. In: O’Shea TJO, Ackerman BB, Percival HF, eds. Population Biology of the Florida Manatee. National Biological Service Information and Technology Report 1.; Washington, D.C; 1995: 259-268.
84. Bauduin, Sarah; Martin, Julien; Edwards, Holly H.; Gimenez, Olivier; Koslovsky, Stacie M.; Fagan, Daniel E. (2013-03-01). "An index of risk of e mammals and watercraft: Example of the Florida manatee". Biological Conservation. 159: 127–136. doi:10.1016/j.biocon.2012.10.031. ISSN 0006-3207.
85. Rycyk, Athena M.; Deutsch, Charles J.; Barlas, Margaret E.; Hardy, Stacie K.; Frisch, Katherine; Leone, Erin H.; Nowacek, Douglas P. (2018). "Manatee behavioral response to boats". Marine Mammal Science. 34 (4): 924–962. doi:10.1111/mms.12491. ISSN 1748-7692.
86. Florida Fish and Wildlife Conservation Commission. Manatee Mortality Statistics. Yearly Summary 2019. Accessed July 10, 2021. https://myfwc.com/media/25782/2019yearsummary.pdf
87. Haubold, E.; et al. (April 2006). Final Biological Status Review of the Florida Manatee (Trichechus manatus latirostris)] (PDF) (Report). Assessment 2005–2006. Florida Manatee Biological Review Panel. p. 133. Retrieved April 5, 2017.
88. Laist, David W.; Reynolds, John E. (2005). "Influence of Power Plants and Other Warm-Water Refuges on Florida Manatees". Marine Mammal Science. 21 (4): 739–764. doi:10.1111/j.1748-7692.2005.tb01263.x. ISSN 1748-7692.
89. Laist, David W.; Taylor, Cynthia; Reynolds, John E. (2013). "Winter Habitat Preferences for Florida Manatees and Vulnerability to Cold". PLOS ONE. 8 (3): e58978. Bibcode:2013PLoSO...858978L. doi:10.1371/journal.pone.0058978. PMC 3604035. PMID 23527063.
90. Laist, David W.; Reynolds, John E. (2005). "Florida Manatees, Warm-Water Refuges, and an Uncertain Future". Coastal Management. 33 (3): 279–295. Bibcode:2005CoasM..33..279L. doi:10.1080/08920750590952018. S2CID 62841264.
91. Spellman AC. Physiological constraints on warm-water habitat site selection and utilization by the Florida Manatee (Trichechus manatus latirostris) in East Central Florida. Published online 2014.
92. . 2011-03-15. Archived from the original on 2011-03-15. Retrieved 2019-12-09.
93. Alvarez-Alemán, Anmari; Beck, Cathy A.; Powell, James A. (2010-06-01). "First Report of a Florida Manatee (Trichechus manatus latirostris) in Cuba". Aquatic Mammals. 36 (2): 148–153. doi:10.1578/AM.36.2.2010.148.
94. Marine Mammal Commission. Manatees and Warm-Water refuges. Accessed June 14, 2021. https://www.mmc.gov/priority-topics/species-of-concern/florida-manatee/manatees-and-warm-water-refuges/
95. Sucsy, P., Hupalo, R., Freeman B. Minimum Flow Determination for Blue Spring, Volusia County: The Relationship between Ground Water Discharge and Winter Refuge for Manatees.; 1998.
96. Stith, Bradley M.; Reid, James P.; Langtimm, Catherine A.; Swain, Eric D.; Doyle, Terry J.; Slone, Daniel H.; Decker, Jeremy D.; Soderqvist, Lars E. (2011). "Temperature Inverted Haloclines Provide Winter Warm-Water Refugia for Manatees in Southwest Florida". Estuaries and Coasts. 34 (1): 106–119. doi:10.1007/s12237-010-9286-1. ISSN 1559-2723. JSTOR 41059029.
97. Florida Fish and Wildlife Conservation Commission. Red Tide Mortality. Accessed July 10, 2021. https://myfwc.com/research/manatee/rescue-mortality-response/statistics/mortality/red-tide/
98. Hall Scharf B., Ubeda A. How Red Tides Impact Manatees. UF IFAS. Accessed July 10, 2021. https://edis.ifas.ufl.edu/publication/SG188
99. Landsberg, J. H.; Flewelling, L. J.; Naar, J. (2009-03-01). "Karenia brevis red tides, brevetoxins in the food web, and impacts on natural resources: Decadal advancements". Harmful Algae. Understanding the causes and impacts of the Florida Red Tide and improving management and response. 8 (4): 598–607. doi:10.1016/j.hal.2008.11.010. ISSN 1568-9883.
100. Bossart, Gregory D.; Baden, Daniel G.; Ewing, Ruth Y.; Roberts, Brenda; Wright, Scott D. (1998). "Brevetoxicosis in Manatees (Trichechus manatus latirostris) from the 1996 Epizootic: Gross, Histologic, and Immunohistochemical Features". Toxicologic Pathology. 26 (2): 276–282. doi:10.1177/019262339802600214. PMID 9547868. S2CID 25123898.
101. Walsh, Catherine J.; Butawan, Matthew; Yordy, Jennifer; Ball, Ray; Flewelling, Leanne; De Wit, Martine; Bonde, Robert K. (2015). "Sublethal red tide toxin exposure in free-ranging manatees (Trichechus manatus) affects the immune system through reduced lymphocyte proliferation responses, inflammation, and oxidative stress". Aquatic Toxicology. 161: 73–84. doi:10.1016/j.aquatox.2015.01.019. PMID 25678466.
102. Deutsch, CJ, deWit, M, Barlas, ME, Greer, W, Howell, AR, Garrett, A, Ward-Geiger L. Unprecedented Mortality of Florida Manatees along the Atlantic Coast. Sirennews. 2021;(73):24-26.
103. Short, Frederick T.; Wyllie-Echeverria, Sandy (1996). "Natural and human-induced disturbance of seagrasses". Environmental Conservation. 23 (1): 17–27. Bibcode:1996EnvCo..23...17S. doi:10.1017/s0376892900038212. S2CID 86134425.
104. Smith KN. Manatee Habitat and Human-Related Threats to Seagrass in Florida: A Review.; 1993.
105. Marine Resource Council. Indian River Lagoon Report Card. Accessed June 14, 2021. https://savetheirl.org/irl-health-update/irl-report-card/
106. Phlips, Edward J.; Badylak, Susan; Lasi, Margaret A.; Chamberlain, Robert; Green, Whitney C.; Hall, Lauren M.; Hart, Jane A.; Lockwood, Jean C.; Miller, Janice D.; Morris, Lori J.; Steward, Joel S. (2015). "From Red Tides to Green and Brown Tides: Bloom Dynamics in a Restricted Subtropical Lagoon Under Shifting Climatic Conditions". Estuaries and Coasts. 38 (3): 886–904. doi:10.1007/s12237-014-9874-6. S2CID 83480080.
107. Reid J P, Slone D. Winter Manatee Foraging Behavior and the Decline of Seagrass Beds in the Northern Indian River Lagoon. Accessed June 14, 2021. https://www.usgs.gov/centers/wetland-and-aquatic-research-center-warc/science/winter-manatee-foraging-behavior-and?qt-science_center_objects=0#qt-science_center_objects
108. NOAA. Active and Closed Unusual Mortality Events. Accessed June 17, 2021. https://www.fisheries.noaa.gov/national/marine-life-distress/active-and-closed-unusual-mortality-events
109. Florida Fish and Wildlife Conservation Commission. Manatee Mortality Event Along The East Coast: 2020-2021. Accessed July 10, 2021. https://myfwc.com/research/manatee/rescue-mortality-response/ume/
110. Laist D., Coe JM, O’Hara KJ. Marine debris pollution. In: Conservation and Management of Marine Mammals.(JR Twiss, Jr., and RR Reeves, eds). 1999.
111. Oceana. Choked, Strangled, Drowned. The Plastics Crisis Unfolding in our Oceans. 2020. Accessed July 10, 2021. https://usa.oceana.org/sites/default/files/report_spreadsdoi_choked_strangled_drowned_final.pdf
112. Reinert, TR; Spellman, AC; Bassett, BL (2017). "Entanglement in and ingestion of fishing gear and other marine debris by Florida manatees, 1993 to 2012". Endangered Species Research. 32: 415–427. doi:10.3354/esr00816.
113. Gallop JD. Rescuers free 19 manatees from Satellite Beach drain. Florida Today. February 23, 2015. Accessed July 10, 2021. https://www.floridatoday.com/story/news/local/2015/02/23/crews-satellite-beach-trying-free-stuck-manatees/23908945/
114. Hunter, M. E.; Auil-Gomez, N. E.; Tucker, K. P.; Bonde, R. K.; Powell, J.; McGuire, P. M. (2010). "Low genetic variation and evidence of limited dispersal in the regionally important Belize manatee". Animal Conservation. 13 (6): 592–602. doi:10.1111/j.1469-1795.2010.00383.x. ISSN 1469-1795. S2CID 83003801.
115. Nourisson, Coralie; Morales-Vela, Benjamín; Padilla-Saldívar, Janneth; Tucker, Kimberly Pause; Clark, AnnMarie; Olivera-Gómez, Leon David; Bonde, Robert; McGuire, Peter (2011-06-17). "Evidence of two genetic clusters of manatees with low genetic diversity in Mexico and implications for their conservation". Genetica. 139 (7): 833–42. doi:10.1007/s10709-011-9583-z. ISSN 1573-6857. PMID 21681472. S2CID 24655603.
116. Luna, Fábia O.; Bonde, Robert K.; Attademo, Fernanda L. N.; Saunders, Jonathan W.; Meigs-Friend, Gaia; Passavante, José Zanon O.; Hunter, Margaret E. (2012-07-01). "Phylogeographic implications for release of critically endangered manatee calves rescued in Northeast Brazil". Aquatic Conservation: Marine and Freshwater Ecosystems. 22 (5): 665–672. doi:10.1002/aqc.2260. ISSN 1099-0755.
117. Serrano, Arturo; Daniel-Rentería, Iliana del Carmen; Hernández-Cabrera, Tania; Sánchez-Rojas, Gerardo; Cuervo-López, Liliana; Basáñez-Muñoz, Agustín (2017-03-15). "Is the West Indian Manatee (Trichechus manatus) at the Brink of Extinction in the State of Veracruz, Mexico?". Aquatic Mammals. 43 (2): 201–207. doi:10.1578/AM.43.2.2017.201.
118. Puc-Carrasco, Gissel; Morales-Vela, Benjamín; Olivera-Gomez, León David; González-Solís, David (2017-12-22). "First field-based estimate of Antillean manatee abundance in the San Pedro River system suggests large errors in current estimates for Mexico". Ciencias Marinas. 43 (4): 285–299–285–299. doi:10.7773/cm.v43i4.2704. ISSN 2395-9053.
119. Collazo, Jaime A.; Krachey, Matthew J.; Pollock, Kenneth H.; Pérez-Aguilo, Francisco J.; Zegarra, Jan P.; Mignucci-Giannoni, Antonio A. (September 2019). "Population estimates of Antillean manatees in Puerto Rico: an analytical framework for aerial surveys using multi-pass removal sampling". Journal of Mammalogy. 100 (4): 1340–1349. doi:10.1093/jmammal/gyz076. ISSN 0022-2372.
120. Alves, Maria Danise; Kinas, Paul Gerhard; Marmontel, Miriam; Borges, João Carlos Gomes; Costa, Alexandra Fernandes; Schiel, Nicola; Araújo, Maria Elisabeth (June 2016). "First abundance estimate of the Antillean manatee (Trichechus manatus manatus) in Brazil by aerial survey". Journal of the Marine Biological Association of the United Kingdom. 96 (4): 955–966. Bibcode:2016JMBUK..96..955A. doi:10.1017/S0025315415000855. ISSN 0025-3154. S2CID 85596019.

External links

 

Wikimedia Commons has media related to Trichechus manatus.

• ARKive –
• Animal Diversity Website: Trichechus manatus
• "Manatee" . New International Encyclopedia. 1905.
• View the triMan1 genome assembly in the UCSC Genome Browser.
• Photos of West Indian manatee on Sealife Collection
• Manatees Lived in Texas During the Last Ice Age, on: SciTechAlert, October 4, 2020, Source: University of Texas at Austin.
• Bell, Christopher; Godwin, William; Jenkins, Kelsey; Lewis, Patrick (2020). "First fossil manatees in Texas: Trichechus manatus bakerorum in the Pleistocene fauna from beach deposits along the Texas Coast of the Gulf of Mexico". Palaeontologia Electronica. doi:10.26879/1006. S2CID 224934462.