Malignant lymphoma in a West Indian manatee (Trichechus manatus)

We identified a malignant lymphoma infiltrating the lung, liver, kidney, mesenteric lymph nodes, and eye as the cause of death in a male West Indian manatee (Trichechus manatus). Diagnosis was based on gross, histopathologic, and immunohistochemical studies. Tissue samples from ten organs were included in a tissue microarray and sections from this array were subjected to immunohistochemical staining. The cytoplasm of the neoplastic lymphocytes identified in six organs was positive for CD3, a marker for T-cell differentiation. The neoplastic cells were negative for CD79alpha, a marker for B-cell differentiation. The cause of this neoplasm was not determined. This is the first report of malignant lymphoma in the mammal order Sirenia.     

Omphalitis and peritonitis in a young West Indian manatee (Trichechus manatus)

Mortality data for the West Indian manatee (Trichechus manatus) indicates that from 1979 to 1984 16% of the recorded deaths involved young juveniles. Necropsy of a young manatee from the west coast of Florida revealed an active infection of the umbilical area (omphalitis) extending down the umbilical artery and veins. A generalized peritonitis was present. Bacterial cultures revealed Streptococcus faecium, Plesiomonas shigelloides, Pseudomonas putrefaciens and Escherichia coli.     

Auditory evoked potentials in the West Indian manatee (Sirenia:Trichechus manatus)

Summary Potentials evoked by clicks and tone pips were recorded by fine wires inserted extracranially in four West Indian manatees (Trichechus manatus) in air. Sounds were delivered via padded ear phones.Averaging a few thousand trials at 20/s reveals early peaks at N5.4 (vertex negativity to a frontal reference, at 5.4 ms), P7.6, N8.8, P9.5 — probably equivalent to waves IV and VII of the typical mammalian auditory brainstem response (ABR). Averaging 100 trials at <4/s suffices to reveal a complex sequence of later peaks including N25, P80, N150 and P190; consistent smaller peaks are visible when several hundred trials are averaged.Using tone pips with a rise and fall time of 2–5 ms the carrier frequency becomes important. Evoked potential wave forms are not the same at different frequencies, bringing out the fact that frequency is not a scalar that can be compensated for by intensity. Therefore the method was not used to obtain audiograms; however the largest EPs occur in the range of 1–1.5 kHz. EPs are found up to 35 kHz; almost no evoked potential is discernible at 40 kHz but the undistorted intensity available was limited. This is in reasonable agreement with the theoretical expectation for the upper limit of behavioral hearing from Heffner and Masterton based on head size and aquatic medium.Among several ear phone placements, that over the external auditory meatus was the most effective, but only slightly so. The external canal is presumably fluid or tissue filled and sound enters over a large area.Comparing data for two species on the most effective range of frequencies and the power spectra of their vocalizations,T. manatus is lower thanT. inunguis in both respects.The results show the utility and limitations of the method of recording extracranial evoked potentials to sounds, especially for large and valuable animals under makeshift conditions.Abbreviations ABR auditory brainstem response - AEP averaged evoked potentials - EMG electromyogram - F frontal sinuses - V vertex     

Erythropoiesis and granulopoiesis in the West Indian manatee, Trichechus manatus (Mammalia: Sirenia)

The West Indian manatee, Trichechus manatus, has amedullary, pachyostotic long bones. Since marrow cavities of the long bones typically are the locations of hemopoiesis in adult mammals, the manatee has evolved an alternative primary site of hemopoiesis. Histological examinations of spleens, livers, kidneys, and vertebral bodies indicate that the last-named location is the main site of erythropoiesis and granulopoiesis in T. manatus. This conclusion is based on the presence in the vertebrae of bone-marrow-containing diagnostic cell types including erythroblasts, megakaryocytes, and myelocytes, which are the precursor cells of erythrocytes, platelets, and granular leukocytes, respectively. No developing lymphocytes were found, so that the location of lymphopoiesis remains unknown.     

The digestive strategy and efficiency of the West Indian manatee, Trichechus manatus

During the winters of 1982/83 and 1983/84, samples of digesta were collected from nine sites along the gastrointestinal tracts of seven West Indian manatees, Trichechus manatus. The voluminous large intestine of the manatee is responsible for considerable water reabsorption, as well as being the major site of organic matter, nitrogen and crude fat digestion. Cellulose digestion occurs primarily in the cecum and anterior portion of the colon in a pattern similar to terrestrial nonruminant herbivores like the horse. Overall digestibility coefficients for organic matter (71%), nitrogen (61%) and crude fat (77%) are comparable to those of terrestrial herbivores. Manatees have one of the highest digestibility coefficients for cellulose (80%) of any known mammalian herbivore. This high efficiency of cellulose digestion is due primarily to an extremely slow rate of passage. In addition, it appears that seagrasses may be more digestible than terrestrial forages, possibly due to their relatively low lignin content.     

Anatomy of the cecum of the West Indian manatee,Trichechus manatus (Mammalia,Sirenia)

Summary The anatomy of the cecum of the West Indian manatee (Trichechus manatus) is described at the macroscopic and microscopic levels. The cecum possesses a voluminous corpus ceci with two lateral outpocketings; two diverticulae (cecal horns) extend from the corpus at the vicinity of the ileocecal junction. An ampulla ceci is found distal to the corpus ceci, the two compartments communicating via a wide-opened orifice. The most striking microscopic finding is the mucosal covering of a keratinized stratified squamous epithelium overlying the crypts of Lieberkühn.An attempt is made to interpret the morphological observations in terms of the functional digestive process in the manatee, giving alternative suggestions concerning the significance of the cecum and colon in the nutritional status of the manatee.Abbreviations A Ampulla ceci - CC Corpus ceci - CH Cecal horns - I Ileum - C Colon The present investigation was supported by a grant from the Deutsche Forschungsgemeinschaft (La 325/7-1)The author is greatly indebted to the members of the Fish and Wildlife Service, Sirenia Project, Gainesville Station, Gainesville Florida: special thanks are extended to Dr. Thomas O'Shea for organizing this undertaking, to Cathy A. Beck and Robert K. Bonde for their generous hospitality, for allowing the author to participate in the salvaging project, which they carried out with great efficiency, and for help in collecting the material. Without this aid, this study could not have been completed     

A PCR assay for gender assignment in dugong (Dugong dugon) and West Indian manatee (Trichechus manatus)

Gender assignment for some aquatic mammals in the field is difficult. Molecular sexing from tissue biopsies is possible as males are heterogametic. Here we describe a multiplex PCR assay that amplifies the male specific SRY gene and differentiates ZFX and ZFY gametologues in two sirenian species, dugong (Dugong dugon) and West Indian manatee (Trichechus manatus). The assay was validated with animals of known gender and proved accurate and robust to experimental failure.     

Phylogeography of the West Indian manatee (Trichechus manatus): how many populations and how many taxa?

To resolve the population genetic structure and phylogeography of the West Indian manatee ( Trichechus manatus ), mitochondrial (mt) DNA control region sequences were compared among eight locations across the western Atlantic region. Fifteen haplotypes were identified among 86 individuals from Florida, Puerto Rico, the Dominican Republic, Mexico, Colombia, Venezuela, Guyana and Brazil. Despite the manatee's ability to move thousands of kilometres along continental margins, strong population separations between most locations were demonstrated with significant haplotype frequency shifts. These findings are consistent with tagging studies which indicate that stretches of open water and unsuitable coastal habitats constitute substantial barriers to gene flow and colonization. Low levels of genetic diversity within Florida and Brazilian samples might be explained by recent colonization into high latitudes or bottleneck effects. Three distinctive mtDNA lineages were observed in an intraspecific phylogeny of T. manatus , corresponding approximately to: (i) Florida and the West Indies; (ii) the Gulf of Mexico to the Caribbean rivers of South America; and (iii) the northeast Atlantic coast of South America. These lineages, which are not concordant with previous subspecies designations, are separated by sequence divergence estimates of d = 0.04–0.07, approximately the same level of divergence observed between T. manatus and the Amazonian manatee ( T. inunguis , n = 16). Three individuals from Guyana, identified as T. manatus , had mtDNA haplotypes which are affiliated with the endemic Amazon form T. inunguis . The three primary T. manatus lineages and the T. inunguis lineage may represent relatively deep phylogeographic partitions which have been bridged recently due to changes in habitat availability (after the Wisconsin glacial period, 10 000 BP ), natural colonization, and human-mediated transplantation.     

Volatile fatty acid concentrations in the digestive tract of the West Indian manatee, Trichechus manatus

1. Digesta samples were collected from five West Indian manatees, Trichechus manatus, for volatile fatty acid (VFA) analysis. 2. Mean total VFA concentrations were low in the stomach and duodenum (18.6 and 12.3 mM/l, respectively). Mean VFA concentrations were considerably higher in the cecum and colon (220.6 and 307.3 mM/l, respectively). 3. The relative proportions of the individual VFA's shifted from predominantly acetic acid in the foregut to a mixture of acetic, butyric and propionic acids in the hindgut. 4. The VFA concentrations in the manatee are similar to those in the dugong, Dugong dugon, and the green sea turtle, Chelonia mydas. 5. The mean total VFA concentrations indicate that the cecum and colon of the manatee are sites of microbial cellulose fermentation. The contribution of VFAs to the manatees' total energy requirements could not be calculated, but it is probably considerable.     

Gross and microscopic anatomy of the kidney of the West Indian manatee, Trichechus manatus (Mammalia: Sirenia)

Examination of the gross and microscopic anatomy of the kidney of the West Indian manatee, Trichechus manatus, revealed that: (1) the medulla is about 6 times thicker than the cortex; (2) juxtamedullary glomeruli have a mean diameter 1.3 times greater than that of cortical glomeruli; (3) juxtamedullary glomeruli have 1.7 times as much volume as cortical glomeruli; (4) there are about twice as many cortical glomeruli as juxtamedullary glomeruli per square millimeter of cortical tissue, and (5) the vasa recta are closely juxtaposed to the thin loops of Henle in the outer medulla. Many of these results suggest an enhanced urine-concentrating ability in this species.     

Circadian and ultradian activity rhythms in manatee (Trichechus manatus manatus) in captivity

In this study, we show temporal organization of activity patterns in larger temporal series recording. The objective of this study was to determine the temporal pattern of the rest-activity rhythm in manatee (Trichechus manatus manatus) in captivity. Activity recordings were programmed from August 2010 to September 2011 with actimetry devices, and behavior recordings were conducted in dry and rainy seasons. We showed that the marine manatee presents a complex temporal organization, in which the rest-activity rhythm comprises several frequencies with a predominant circadian component and multiple ultradian components. Our results indicate that the animals were more active during the day with respect to the night. The temporal organization of this cycle entails multiple frequencies that include ultradian rhythms, which may be expressions generated by physiological needs, such as food availability and thermoregulatory requirements. These patterns should be taken into consideration for future studies of biological rhythms in manatee.     

Digesta passage rates in the Florida manatee (Trichechus manatus latirostris)

The Florida manatee, Trichechus manatus latirostris (Sirenia: Trichechidae), is an herbivorous marine mammal found within coastal areas throughout the state of Florida, which feeds on both fresh and salt water sea grasses. Manatees, like other Sirenians, are a tropical species with little tolerance for water temperatures below 20°C, rely on a relatively poor nutritional food source, and have a low metabolic rate. Although manatees are hindgut fermenting herbivores, they are very efficient at extracting nutrients from the plants on which they feed. Slow passage rates of digesta have been suggested to be a factor in this increased efficiency. Two studies monitored the digesta passage times and mixing of particulate digesta within the manatee digestive tract using MicroGrits colored corncob grit as a fecal marker. Fecal samples were collected subsequently from four manatees in Study 1 and 3 manatees in Study 2, grit pieces removed, counted, and measured. The digesta passage times ranged from 6 and 10 days in Study 1, and 4.3 and 8.3 days in Study 2, supporting data presented in previous studies. When two different colored markers were administered on sequential days, minimal to no mixing was seen in recovered feces, suggesting that the digesta from a given day traveled through the tract as a bolus. Less than 1% of the marker fed was recovered and we hypothesize that perpendicular folds of the large intestine may be the major contributing factor, with pieces being retained and eventually digested. Zoo Biol 26:503–515, 2007. © 2007 Wiley‐Liss, Inc.     

Detection of hydrodynamic stimuli by the Florida manatee (Trichechus manatus latirostris)

Florida manatees inhabit the coastal and inland waters of the peninsular state. They have little difficulty navigating the turbid waterways, which often contain obstacles that they must circumnavigate. Anatomical and behavioral research suggests that the vibrissae and associated follicle–sinus complexes that manatees possess over their entire body form a sensory array system for detecting hydrodynamic stimuli analogous to the lateral line system of fish. This is consistent with data highlighting that manatees are tactile specialists, evidenced by their specialized facial morphology and use of their vibrissae during feeding and active investigation/manipulation of objects. Two Florida manatees were tested in a go/no-go procedure using a staircase method to assess their ability to detect low-frequency water movement. Hydrodynamic vibrations were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz, which are below the apparent functional hearing limit of the manatee. The manatees detected particle displacement of less than 1?μm for frequencies of 15–150 Hz and of less than a nanometer at 150 Hz. Restricting the facial vibrissae with various size mesh openings indicated that the specialized sensory hairs played an important role in the manatee’s exquisite tactile sensitivity.     

Polymorphic microsatellite DNA markers for the Florida manatee (Trichechus manatus latirostris)

Florida manatees (Trichechus manatus latirostris) are marine mammals that inhabit the coastal waters and rivers of the southeastern USA, primarily Florida. Previous studies have shown that Florida manatees have low mitochondrial DNA variability, suggesting that nuclear DNA loci are necessary for discriminatory analyses. Here we report 10 polymorphic microsatellite loci with an average of 4.2 alleles per locus, and average heterozygosity of 50.1%. These loci have been developed for use in population studies, parentage assignment, and individual identification.     

Nephrolithiasis and pyelonephritis in two West Indian manatees (Trichechus manatus spp.)

Two West Indian manatees (Trichechus manatus spp.) were reported with severe emaciation. One animal was a Florida manatee from the Everglades; the other was an Antillean manatee from Cuba. On necropsy, both animals had nephrolithiasis, pyelonephritis, and moderate to severe renomegaly. Histopathology revealed multifocal to diffuse pyelonephritis, interstitial nephritis, and nephrocalcinosis. The stones were analyzed and consisted primarily of calcium carbonate. Serum chemistry values for the Florida animal revealed no renal abnormalities. The mechanism of calculus formation remains unclear in manatees. In horses, another hindgut fermenter, the most common urolith is also calcium carbonate. Urinalyses performed on manatees are very similar to those of horses (i.e., alkaline urine, low specific gravity, and calcium carbonate crystals). Formation of uroliths in manatees may have a pathogenesis similar to equine urolithiasis.     

Bile salts of the West Indian manatee, Trichechus manatus latirostris: novel bile alcohol sulfates and absence of bile acids

The bile salts present in gallbladder bile of the West Indian manatee, Trichechus manatus latirostris, an herbivorous marine mammal of the tropical and subtropical margins of the Atlantic Ocean, were found to consist of a mixture of bile alcohol sulfates. Bile acids, previously believed to be present in all mammals, were not detected. Using chromatography, mass spectrometry, and 1H- and 13C-nuclear magnetic resonance spectroscopy, the major bile alcohol was identified as 5 beta-cholestane-3 alpha,6 beta,7 alpha-25,26-pentol; that is, it had the nuclear structure of alpha-muricholic acid and the side chain structure of bufol. This compound has not been described previously and the trivial name "alpha-trichechol" is proposed. The second most abundant compound was 5 beta-cholestane-3 alpha,7 alpha,25,26-tetrol. Other bile alcohols were tentatively identified as 5 beta-cholestane-3 alpha,6 beta,7 beta,25,26-pentol (named beta-trichechol), 3 alpha,6 alpha,7 beta, 25-26-pentol (named omega-trichechol) and 5 beta-cholestane-3 alpha,6 beta,7 alpha,26-tetrol. The 1H and 13C NMR spectra of the four 6,7 epimers of 3,6,7 trihydroxy bile acids are described and discussed. All bile alcohols were present as ester sulfates, the sulfate group being tentatively assigned to the 26-hydroxy group. 12-Hydroxy compounds were not detected. The manatee is the first mammal found to lack bile acids, presumably because it lacks the enzymes required for oxidation of the 26-hydroxy group to a carboxylic acid. Trichechols, like other bile salts, are water-soluble end products of cholesterol metabolism; whether they also function as biological surfactants in promoting biliary cholesterol secretion or lipid digestion is unknown.     

The influence of age and sex on the vocal repertoire of the Antillean manatee (Trichechus manatus manatus) and their responses to call playback

Limited information is available regarding the acoustic communication of Antillean manatees, however, studies have shown that other manatee taxa produce vocalizations as a method of individual recognition and communication. Here, the acoustic signals of 15 Antillean manatees in captivity were recorded, aiming to (1) describe their acoustic repertoire, (2) investigate the influence of sex and age on vocalization, and (3) examine manatee responses to call playback. Six acoustic signals ranging in mean fundamental frequencies from 0.64 kHz to 5.23 kHz were identified: squeaks and screeches were common to adult males, adult females, and juveniles; trills were common to adult males and females; whines were specific to males; creaks were specific to females; and rubbing was specific to juveniles. The structure of squeak vocalizations was significantly different between age and sex classes and screech structure was significantly different between age classes. Squeaks and screeches produced by juveniles had higher frequencies of maximum energy when compared to those produced by adult males and females. A significant increase in the vocalization rate following vocalization playbacks was found for all three age/sex groups. Our results introduce the potential of using acoustic signals in identifying and noninvasively monitoring manatees in the wild in Brazil.     

The heart of the dugong (Dugong dugon) and the west indian manatee (Trichechus manatus) (Sirenia)

Thirty-eight dugong (Dugong dugon) hearts and 28 Florida manatee (Trichechus manatus) hearts were obtained from stranding programs in Australia and the United States. In addition to a double ventricular apex, a feature that has astonished scientists since the eighteenth century, the hearts of both animals have a double subvalvular conus and a dorsal left atrium. The heart lies in a vertical plane at right angles to that of the completely dorsal, symmetrical lungs. The dugong heart has a deeper interventricular cleft and a more conical left ventricle. The latter features may be part of a general morphological trend toward specialization for a more energetic aquatic existence. The presence of a bulbous ascending aorta in the manatee but not in the dugong is without explanation.