Manatee Research Articles

Golgi Analysis of Neuron Morphology in the Presumptive Somatosensory Cortex and Visual Cortex of the Florida Manatee (Trichechus manatus latirostris)

The current study investigates neuron morphology in presumptive primary somatosensory (S1) and primary visual (V1) cortices of the Florida manatee (Trichechus manatus latirostris) as revealed by Golgi impregnation. Sirenians, including manatees, have an aquatic lifestyle, a large body size, and a relatively large lissencephalic brain. The present study examines neuron morphology in 3 cortical areas: in S1, dorsolateral cortex area 1 (DL1) and cluster cortex area 2 (CL2) and in V1, dorsolateral cortex area 4 (DL4). Neurons exhibited a variety of morphological types, with pyramidal neurons being the most common. The large variety of neuron types present in the manatee cortex was comparable to that seen in other eutherian mammals, except for rodents and primates, where pyramid-shaped neurons predominate. A comparison between pyramidal neurons in S1 and V1 indicated relatively greater dendritic branching in S1. Across all 3 areas, the dendritic arborization pattern of pyramidal neurons was also similar to that observed previously in the afrotherian rock hyrax, cetartiodactyls, opossums, and echidnas but did not resemble the widely bifurcated dendrites seen in the large-brained African elephant. Despite adaptations for an aquatic environment, manatees did not share specific neuron types such as tritufted and star-like neurons that have been found in cetaceans. Manatees exhibit an evolutionarily primitive pattern of cortical neuron morphology shared with most other mammals and do not appear to have neuronal specializations for an aquatic niche.

Influence of Manatees' Diving on Their Risk of Collision with Watercraft.

Watercraft pose a threat to endangered Florida manatees (Trichechus manatus latirostris). Mortality from watercraft collisions has adversely impacted the manatee population’s growth rate, therefore reducing this threat is an important management goal. To assess factors that contribute to the risk of watercraft strikes to manatees, we studied the diving behavior of nine manatees carrying GPS tags and time–depth recorders in Tampa Bay, Florida, during winters 2002–2006. We applied a Bayesian formulation of generalized linear mixed models to depth data to model the probability (Pt) that manatees would be no deeper than 1.25 m from the water’s surface as a function of behavioral and habitat covariates. Manatees above this threshold were considered to be within striking depth of a watercraft. Seventy-eight percent of depth records (individual range 62–86%) were within striking depth (mean = 1.09 m, max = 16.20 m), illustrating how vulnerable manatees are to strikes. In some circumstances manatees made consecutive dives to the bottom while traveling, even in areas >14 m, possibly to conserve energy. This is the first documentation of potential cost-efficient diving behavior in manatees. Manatees were at higher risk of being within striking depth in shallow water (<0.91 m), over seagrass, at night, and while stationary or moving slowly; they were less likely to be within striking depth when ≤50 m from a charted waterway. In shallow water the probability of a manatee being within striking depth was 0.96 (CI = 0.93–0.98) and decreased as water depth increased. The probability was greater over seagrass (Pt = 0.96, CI = 0.93–0.98) than over other substrates (Pt = 0.73, CI = 0.58–0.84). Quantitative approaches to assessing risk can improve the effectiveness of manatee conservation measures by helping identify areas for protection.

Occurrence of the Endangered Antillean manatee Trichechus manatus manatus in a marine protected area, Isla de la Juventud, Cuba

AbstractThe Antillean manatee Trichechus manatus manatus is categorized as Endangered on the IUCN Red List but little is known about the status of the species in Cuba. Marine protected areas can contribute to manatee conservation in Cuba but the effectiveness of these areas may be jeopardized by a lack of information regarding appropriate design and management. We developed an index of manatee occurrence in the Fauna Refuge Ciénaga de Lanier, Isla de la Juventud, to assess patterns of manatee use in the reserve. We completed 26 field trips during November 2007–October 2013, with a total of 147 survey days. Manatee presence was detected on 47% of survey days and in 96% of field trips; 133 individuals were recorded in 93 sightings. The index of manatee occurrence varied between trips, suggesting a discontinuous use of the area. The mean group size was 1.4 individuals (range 1–5), and calves were observed in 13% of sightings. Observations of manatee behaviour, occurrence and habitat characteristics indicate the importance of the study area as a resting place, refuge and source of fresh water. We recommend that manatee protection be strengthened to avoid human-related mortality and to ensure that the habitats that provide critical resources are given special consideration in future management plans.

Seasonal response of ghrelin, growth hormone, and insulin-like growth factor I in the free-ranging Florida manatee (Trichechus manatus latirostris)

Seasonal changes in light, temperature, and food availability stimulate a physiological response in an animal. Seasonal adaptations are well studied in Arctic, Sub-Arctic, and hibernating mammals; however, limited studies have been conducted in sub-tropical species. The Florida manatee (Trichechus manatus latirostris), a sub-tropical marine mammal, forages less during colder temperatures and may rely on adipose stores for maintenance energy requirements. Metabolic hormones, growth hormone (GH), insulin-like growth factor (IGF)-I, and ghrelin influence growth rate, accretion of lean and adipose tissue. They have been shown to regulate seasonal changes in body composition. The objective of this research was to investigate manatee metabolic hormones in two seasons to determine if manatees exhibit seasonality and if these hormones are associated with seasonal changes in body composition. In addition, age related differences in these metabolic hormones were assessed in multiple age classes. Concentrations of GH, IGF-I, and ghrelin were quantified in adult manatee serum using heterologous radioimmunoassays. Samples were compared between short (winter) and long (summer) photoperiods (n=22 male, 20 female) and by age class (adult, juvenile, and calf) in long photoperiods (n=37). Short photoperiods tended to have reduced GH (p=0.08), greater IGF-I (p=0.01), and greater blubber depth (p=0.03) compared with long photoperiods. No differences were observed in ghrelin (p=0.66). Surprisingly, no age related differences were observed in IGF-I or ghrelin concentrations (p>0.05). However, serum concentrations of GH tended (p=0.07) to be greater in calves and juveniles compared with adults. Increased IGF-I, greater blubber thickness, and reduced GH during short photoperiod suggest a prioritization for adipose deposition. Whereas, increased GH, reduced blubber thickness, and decreased IGF-I in long photoperiod suggest prioritization of lean tissue accretion. Hormone profiles in conjunction with difference in body composition between photoperiods indicate seasonal adjustments in manatee nutrient partitioning priorities.

Antifungal Resistance and Virulence Among Candida spp. from Captive Amazonian manatees and West Indian Manatees: Potential Impacts on Animal and Environmental Health.

This work aimed at evaluating the antifungal susceptibility and production of virulence factors by Candida spp. isolated from sirenians in Brazil. The isolates (n=105) were recovered from the natural cavities of Amazonian and West Indian manatees and were tested for the susceptibility to amphotericin B, itraconazole, and fluconazole and for the production of phospholipases, proteases, and biofilm. The minimum inhibitory concentrations (MICs) for amphotericin B ranged from 0.03 to 1µg/mL, and no resistant isolates were detected. Itraconazole and fluconazole MICs ranged from 0.03 to 16µg/mL and from 0.125 to 64µg/mL, respectively, and 35.2% (37/105) of the isolates were resistant to at least one of these azole drugs. Concerning the production of virulence factors, phospholipase activity was observed in 67.6% (71/105) of the isolates, while protease activity and biofilm production were detected in 50.5% (53/105) and 32.4% (34/105) of the isolates, respectively. Since the natural cavities of manatees are colonized by resistant and virulent strains of Candida spp., these animals can act as sources of resistance and virulence genes for the environment, conspecifics and other animal species, demonstrating the potential environmental impacts associated with their release back into their natural habitat.

Rescue and handling of Antillean manatees Trichechus manatus manatus in Venezuela 1992–2014

Given the importance of the rescue and rehabilitation of confiscated manatees from illegal traffic or accidental fishery entanglements, the handling and transport of two Antillean manatees Trichechus manatus manatus in the ‘Llanos’ of Apure state in Venezuela is described. In 1992, two ♀ calves were confiscated in the region of Arichuna in the Apure River and transported to a lagoon at the Fondo Nacional de Investigaciones Agropecuarias, Biruaca, for rehabilitation. Data about age, size, weight and haematological values were recorded. In 1994, one of the manatees was transferred to the Parque Zoologico y Botanico Bararida, Barquisimeto, in order to form a breeding pair and start a captive‐breeding programme. Successful reproduction was achieved in 2007, 2011 and 2013. In 1995, the second ♀ Antillean manatee was released into a natural environment in Santa Luisa Cattle Ranch, Apure state. The confiscation, rescue, rehabilitation and transport (by land and air) of these two ♀ Antillean manatees were carried out satisfactorily.

Behavioral Lateralization in the Florida Manatee (Trichechus manatus latirostris)

We examined side preferences in the Florida manatee (Trichechus manatus latirostris) through observations of limb use (right and left flipper) in 123 wild and 16 captive individuals. We also analyzed archival data on wild manatees to develop an index of boat-caused body scars to determine lateralization of evasive action. Wild and captive manatees displayed flipper lateralization at the individual, but not the population level for several behaviors including substrate touches, sculling, and feeding. In contrast, manatees were lateralized at the population level for boat-scar biases with more manatees showing a left scar bias (45%) versus right (34%) or dorsal (21%).

Increasing the size of portion options affects intake but not portion selection at a meal

In an environment with large portion sizes, allowing consumers more control over their portion selection could moderate the effects on energy intake. We tested whether having subjects choose a portion from several options influenced the amount selected or consumed when all portion sizes were systematically increased. In a crossover design, 24 women and 26 men ate lunch in the lab once a week for 3 weeks. At each meal, subjects chose a portion of macaroni and cheese from a set of 3 portion options and consumed it ad libitum. Across 3 conditions, portion sizes in the set were increased; the order of the conditions was counterbalanced across subjects. For women the portion sets by weight (g) were 300/375/450, 375/450/525, and 450/525/600; for men the portions were 33% larger. The results showed that increasing the size of available portions did not significantly affect the relative size selected; across all portion sets, subjects chose the smallest available portion at 59% of meals, the medium at 27%, and the largest at 15%. The size of portions offered did, however, influence meal intake (P < 0.0001). Mean intake (±SEM) was 16% greater when the largest set was offered (661 ± 34 kcal) than when the medium and smallest sets were offered (both 568 ± 18 kcal). These results suggest that portions are selected in relation to the other available options, and confirm the robust effect of portion size on intake. Although presenting a choice of portions can allow selection of smaller amounts, the sizes offered are a critical determinant of energy intake. Thus, the availability of choices could help to moderate intake if the portions offered are within an appropriate range for energy needs.

Molecular characterization of novel mucosotropic papillomaviruses from a Florida manatee (Trichechus manatus latirostris).

We isolated two new manatee papillomavirus (PV) types, TmPV3 and TmPV4, from a Florida manatee (Trichechus manatus latirostris). Two PV types were previously isolated from this species. TmPV1 is widely dispersed amongst manatees and a close-to-root PV; not much is known about TmPV2. The genomes of TmPV3 and TmPV4 were 7622 and 7771 bp in size, respectively. Both PVs had a genomic organization characteristic of all PVs, with one non-coding region and seven ORFs, including the E7 ORF that is absent in other cetacean PVs. Although these PVs were isolated from separate genital lesions of the same manatee, an enlarged E2/E4 ORF was found only in the TmPV4 genome. The full genome and L1 sequence similarities between TmPV3 and TmPV4 were 63.2 and 70.3 %, respectively. These genomes shared only 49.1 and 50.2 % similarity with TmPV1. The pairwise alignment of L1 nucleotide sequences indicated that the two new PVs nested in a monophyletic group of the genus Rhopapillomavirus, together with the cutaneotropic TmPV1 and TmPV2.

Neuron Types in the Presumptive Primary Somatosensory Cortex of the Florida Manatee (Trichechus manatus latirostris)

Within afrotherians, sirenians are unusual due to their aquatic lifestyle, large body size and relatively large lissencephalic brain. However, little is known about the neuron type distributions of the cerebral cortex in sirenians within the context of other afrotherians and aquatic mammals. The present study investigated two cortical regions, dorsolateral cortex area 1 (DL1) and cluster cortex area 2 (CL2), in the presumptive primary somatosensory cortex (S1) in Florida manatees (Trichechus manatus latirostris) to characterize cyto- and chemoarchitecture. The mean neuron density for both cortical regions was 35,617 neurons/mm³ and fell within the 95% prediction intervals relative to brain mass based on a reference group of afrotherians and xenarthrans. Densities of inhibitory interneuron subtypes labeled against calcium-binding proteins and neuropeptide Y were relatively low compared to afrotherians and xenarthrans and also formed a small percentage of the overall population of inhibitory interneurons as revealed by GAD67 immunoreactivity. Nonphosphorylated neurofilament protein-immunoreactive (NPNFP-ir) neurons comprised a mean of 60% of neurons in layer V across DL1 and CL2. DL1 contained a higher percentage of NPNFP-ir neurons than CL2, although CL2 had a higher variety of morphological types. The mean percentage of NPNFP-ir neurons in the two regions of the presumptive S1 were low compared to other afrotherians and xenarthrans but were within the 95% prediction intervals relative to brain mass, and their morphologies were comparable to those found in other afrotherians and xenarthrans. Although this specific pattern of neuron types and densities sets the manatee apart from other afrotherians and xenarthrans, the manatee isocortex does not appear to be explicitly adapted for an aquatic habitat. Many of the features that are shared between manatees and cetaceans are also shared with a diverse array of terrestrial mammals and likely represent highly conserved neural features. A comparative study across manatees and dugongs is necessary to determine whether these traits are specific to one or more of the manatee species, or can be generalized to all sirenians.

A quantitative framework for investigating risk of deadly collisions between marine wildlife and boats

Summary Speed regulations of watercraft in protected areas are designed to reduce lethal collisions with wildlife but can have economic consequences. We present a quantitative framework for investigating the risk of deadly collisions between boats and wildlife. We apply encounter rate theory to demonstrate how marine mammal–boat encounter rate can be used to predict the expected number of deaths associated with management scenarios. We illustrate our approach with management scenarios for two endangered species: the Florida manatee Trichechus manatus latirostris and the North Atlantic right whale Eubalaena glacialis. We used a Monte Carlo simulation approach to demonstrate the uncertainty that is associated with our estimate of relative mortality. We show that encounter rate increased with vessel speed but that the expected number of encounters varies depending on the boating activities considered. For instance, in a scenario involving manatees and boating activities such as water skiing, the expected number of encounters in a given area (in a fixed time interval) increased with vessel speed. In another scenario in which a vessel made a transit of fixed length, the expected number of encounters decreases slightly with boat speed. In both cases, the expected number of encounters increased with distanced travelled by the boat. For whales, we found a slight reduction (˜0·1%) in the number of encounters under a scenario where speed is unregulated; this reduction, however, is negligible, and overall expected relative mortality was ˜30% lower under the scenario with speed regulation. The probability of avoidance by the animal or vessel was set to 0 because of lack of data, but we explored the importance of this parameter on the model predictions. In fact, expected relative mortality under speed regulations decreases even further when the probability of avoidance is a decreasing function of vessel speed. By applying encounter rate theory to the case of boat collisions with marine mammals, we gained new insights about encounter processes between wildlife and watercraft. Our work emphasizes the importance of considering uncertainty when estimating wildlife mortality. Finally, our findings are relevant to other systems and ecological processes involving the encounter between moving agents.

Establishment of reference values for various coagulation tests in healthy Florida manatees (Trichechus manatus latirostris) and evaluation of coagulation in debilitated manatees during rehabilitation.

To establish reference ranges for coagulation parameters in healthy Florida manatees (Trichechus manatus latirostris) and compare results with those for debilitated manatees undergoing treatment at a rehabilitation facility. Prospective study. 29 healthy manatees and 45 debilitated manatees with various diseases. Manatees considered healthy on the basis of results of physical examination, CBC, and serum biochemical analysis underwent coagulation testing including measurement of prothrombin time, partial thromboplastin time, D-dimer concentration, platelet count, and fibrinogen concentration to establish reference ranges. For comparison, a group of manatees undergoing rehabilitation was also tested, and the results were compared. Thromboelastography was also performed on some animals. Values for D-dimer concentration were significantly higher in debilitated versus healthy animals. There was no significant difference for prothrombin time, partial thromboplastin time, platelet count, or fibrinogen concentration between groups. Thromboelastography was performed on 8 healthy animals. Reference ranges were established for various tests of coagulation that may assist clinicians during the initial evaluation and rehabilitation of Florida manatees. Future research to evaluate the effect of specific disease processes on the coagulation cascade is recommended.

Metals in Bone Tissue of Antillean Manatees from the Gulf of Mexico and Chetumal Bay, Mexico.

Concentrations of seven metals (As, Cd, Cr, Cu, Pb, Ni, and Zn) were analyzed in 33 bone tissue samples of Antillean manatees (Trichechus manatus manatus) found dead in lagoons and rivers of Tabasco and Campeche in the Gulf of Mexico and Chetumal Bay in the Caribbean region. The concentrations of Cr, Cu, Pb, and Zn were significantly different between regions, with greater levels found in the Gulf of Mexico group than in the Mexican Caribbean group (p<0.05). Pb concentrations differed significantly between adults and calves. No differences were observed between sexes. Metal concentrations detected in the manatee bones were higher than most of those reported for bones in other marine mammals around the world. Future studies are necessary to establish whether the metal concentrations represent a risk to the health of the species.

Manatíes y delfines en sitios arqueológicos precolombinos de Cuba

Se revisa el registro de los mamíferos acuáticos hallados en sitios arqueológicos precolombinos de Cuba, el cual incluye mayormente el manatí (Trichechus manatus) y en muy escasa frecuencia al delfín nariz de botella (Turciops truncatus) y otro cetáceo. Se reitera que la foca monje del Caribe (Neomonachus tropicalis) no está presente en sitios arqueológicos cubanos.

Debris ingestion by the Antillean Manatee (Trichechus manatus manatus)

The Antillean manatee inhabits coastal regions of North and Northeastern Brazil and currently is considered an endangered species in the country. Aiming to gather information for the development of public policies focusing on the conservation of manatees, the National Center for Research and Conservation of Aquatic Mammals of the Chico Mendes Institute for Biodiversity has been rescuing, rehabilitating and releasing these mammals since the 1980s. Over the last 36years, 40 manatees were released by the CMA/ICMBio and four of them were rescued again due to debris ingestion. Two of these manatees died and the other two were taken back into captivity for a new rehabilitation process. The four mammals had confirmed diagnosis of plastic debris ingestion. These findings demonstrate that the environment where the manatees live after being released had a significant amount of garbage which may hinder the success of the species conservation in Brazil.

Spatial and temporal distribution of manatees (trichechus manatus) reintroduced in the northeastern coast of Brazil

Many West Indian manatees (Trichechus manatus) that strand along the northeast Brazilian coast are calves, which are often rescued and carried to the Peixe-Boi Project rehabilitation facilities in Itamaracá, Pernambuco State where they are prepared to reintroduction. During the ten years period of October 1994 to December 2004, thirteen captive manatees were radio tagged, released and tracked in three main northeast coastal areas as part of the Brazilian Manatee Reintroduction Program. All individuals were monitored locally with VHF transmitters, during brief periods, four were also tracked remotely with satellite-monitored radio tags. Five manatees (39.5%) had long-term tracks over 14 months or 420 days (Total= 10166 days; Maximum=2663 days; Mean=2031 days; SD=1572 days) that met criteria for inclusion in analyses of spatial and seasonal movement patterns. Manatees were tracked from Praia do Forte, Bahia (12.538ºS/38.474ºW) to Macau, Rio Grande do Norte (5.084ºS/36.682ºW), covering around 1200 km and six states along the northeast coast. Three manatees occupied large home ranges, with each containing a few sites of high fidelity where they spent considerable time, while two used restrict home range having only one site with high fidelity. Others two manatees not showed movements along coast and occupied a restrict area like their fidelity site. Two manatees with short tracking histories showed visible weight loss soon after release and were re-captured after having moved long distances, including offshore movements into deep waters. The high rate of survival for released manatees, their adaptation to areas within the former range of wild manatees, and birth of a calf to a released captive manatee are indicators of the success of the Brazilian Manatee Reintroduction Program.

Assessment of the first decade (1994-2004) of west indian manatee´ reintroduction (trichechus manatus) program in the northeastern coast of Brazil

Thirteen captive manatees were released and tagged in three different northeastern coastal areas as part of the Brazilian Manatee Reintroduction Program from October 1994 to December 2004. All individuals were monitored locally with VHF transmitters and four were also tracked with satellite tags for different lengths of time. Manatees were tracked from Praia do Forte, Bahia state (12.538ºS/38.474ºW) to Macau, Rio Grande do Norte state (5.084ºS/36.682ºW) along 1200 coastal km of the northeast six states. To evaluate the re-adaptation process was the main objectives of this work, which will hopefully help researchers to make decisions in the future. Two release areas (RA) were beaches with shallow waters, seagrass beds, reefs and close to small rivers; and one was located inside a large estuary with few seagrass beds. Captivity time was not considered in this evaluation but can be an important factor on the success of the manatee reintroduction program. Five manatees occupied home ranges and each contained sites of high fidelity where they spent considerable time. Two manatees were re-captured shortly after release, having moved long distances, including offshore movements into deep waters. Six manatees had few tracked time. Although manatees had few age when released they have found natural conditions for them survival including reproductive behavior. The fidelity sites choose to release manatees in terms of environmental was very similar. A discontinuous occurrence area (RA2) has been used by some released manatees where a first released manatee female had her calf. We strongly recommend: Continuous of this Manatee Reintroduction Program, to protect this three released areas, develop studies in fidelity sites and one new release area in Ceara coast.

Post‐release monitoring of Antillean manatees: an assessment of the Brazilian rehabilitation and release programme

AbstractMammalian reintroduction programmes frequently aim to reconnect isolated sub‐populations and restore population viability. However, these long‐term objectives are rarely evaluated due to the inadequacy of post‐release monitoring. Here, we report the results of a unique long‐term telemetry‐based monitoring programme for rehabilitated Antillean manatees Trichechus manatus manatus reintroduced into selected sites in north‐east Brazil with the aim of reconnecting isolated relict populations. Twenty‐one satellite‐tagged rehabilitated manatees, 13 males and 8 females, were released into the wild from two sites between November 2008 and June 2013. Individual accumulation curves were plotted and home ranges were calculated through the fixed kernel method using 95% of the utilization distribution. The number and size of the centres of activity (COAs) were calculated using 50% of the utilization distribution. Manatees displayed a dichotomous pattern of movement, with individuals either characterized by sedentary habits or by much more extensive movements. Moreover, home‐range size was not significantly influenced by gender, age at release or release site. COAs were strongly associated with sheltered conditions within reefs and estuaries, and also by the presence of freshwater and feeding sites. Our data confirm that manatee reintroductions in Brazil have the potential to reconnect distant sub‐populations. However, pre‐release identification of potential long‐distance migrants is currently unfeasible, and further analysis would be required to confirm genetic mixing of distant sub‐populations.

The relationship between acoustic habitat, hearing and tonal vocalizations in the Antillean manatee (Trichechus manatus manatus, Linnaeus, 1758).

ABSTRACTThe Antillean manatee (Trichechus manatus manatus) is an endangered marine mammal that inhabits the Caribbean Sea and riverine systems in Central America. Their acoustic behavior is relevant for individual identification, mating and parental care. Manatees produce tonal sounds with highest energy in the second harmonic (usually 5 kHz), and their audiogram indicates sensitivity from 0.3 kHz to 90 kHz with lowest thresholds in the 16 to 18 kHz range. We recorded manatees in the San San River, a highly polluted riverine system in Panama, using a stereo array. Frequency transmission experiments were conducted in four subhabitats, categorized using riverine vegetation. Incidental interactions of manatees and small motorboats were examined. Acoustic transmission was linearly related to tonal vocalization characters: correlations were stronger in freshwater than in transition and marine environments. Two bands, 0.6 to 2 kHz and 3 to 8 kHz, attenuate similarly in all subhabitats, and these bands encompass F0 (tone) and peak frequency respectively of manatee tonal calls. Based on our data we conclude that frequency transmission depends mainly on river depth and bottom characteristics, also motorboat sounds mask signals from 3.5 kHz to 8 kHz, which overlaps the peak frequency of tonal calls. In spite of differences between acoustic transmission in subhabitats of the San San River, manatees utilize bands that transmit efficiently in all subhabitats.

First successful capture and satellite tracking of a West Indian manatee (Trichechus manatus) in Panama: feasibility of capture and telemetry techniques

It is currently unknown how important the Central American countries south of Belize are as a link between manatee populations in the north (Belize and Mexico) and populations in South America. Therefore, apart from knowing where manatees are found, it is important to understand how manatees are using these habitats and if they are moving between countries or distinct population centers. Here we report the results of a multi-national and multiinstitutional collaboration resulting in the first successful capture and satellite tracking of a West Indian manatee in southern Central America