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Antillean manatees (Trichechus manatus manatus) are endangered throughout the southwestern Gulf of Mexico, the Caribbean coast of Central and South America, the Greater Antilles, and the northeastern coast of South America to Brazil. Establishing blood reference intervals is essential as a tool in classifying health status, diagnosing, establishing treatment regimens, and monitoring the progress of a disease in rescued manatees. We collected blood samples from 44 free-ranging and 26 rescued manatees from Puerto Rico between 1992 and 2020 for hematology and blood chemistry analysis. We obtained values for white blood cell count and red blood cell count, hemoglobin, hematocrit, platelet, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, and red cell distribution width. A manual leukocyte differential allowed for the evaluation of different cell types. In addition, we performed a comprehensive metabolic panel on serum samples. These analytes were grouped based on six physiologic processes: liver-associated enzymes and pigments; muscle-associated enzymes; kidney-associated compounds and products; sugars, lipids, and pancreatic-associated enzymes; proteins; and electrolytes. For every parameter, summary statistics of values were calculated on all the samples. Reference ranges were determined as ±1 standard deviation around the mean. An unpaired two-sample T-test was done comparing males versus females and adults versus calves for any significant differences (p ≤ 0.05). We establish the reference intervals of hematology and blood chemistry for the population of Antillean manatees in Puerto Rico and compare them with those established for manatees from Belize, Brazil, Florida, Guyana, and Mexico. [ABSTRACT FROM AUTHOR]

Cognition refers to the mechanisms for acquiring, processing, storing, and acting on information, all of which are critical to understanding the behavior of animals. These mechanisms are poorly known in manatees, especially how they are expressed in the wild. To expand our understanding of manatee cognition, we gathered information from behavioral experimentation in the laboratory, neuroanatomical research, controlled field studies, integrated laboratory and field measurement, and natural history observations (published reports, written surveys, and interviews with knowledgeable observers). Laboratory research, both neuroanatomical and behavioral, provided the most empirical data, primarily on sensory/perceptual capacities. Inferences from these data and narratives from surveys and interviews illuminated possibilities for higher order cognition. Evidence from field measurements was sparse, although substantial amounts of information have been collected from tracking data and to a lesser extent vessel impact studies, which can be used to infer cognitive attributes. Manatees are tactile-auditory specialists with complementary visual and chemosensory abilities. They demonstrate learning characteristics typical of vertebrates. Movement tracking data plus direct observations suggest that they have good spatial cognition, indicated by their ability to traverse complicated water networks and memory for foraging and warm water sites. They engage in a wide range of play-like, object manipulation, and mimetic behaviors, which suggests cognitive capacities beyond basic associative learning. Understanding manatee cognition beyond the laboratory will be necessary for conservation of manatees as they face challenges such as habitat degradation and threats from water-borne vessel traffic. There is a clear need for more direct research in natural settings. [ABSTRACT FROM AUTHOR]

In this paper, we present a review of the current knowledge related to the cognitive abilities of the manatee, with a focus on the Antillean manatee in situ and ex situ. Following a biocentric approach, we consider the animals' ecology, perception and sociality and we introduce future perspectives on their cognition. Scientific literature on the cognitive abilities of Antillean manatees' is limited and mainly linked to medical training and veterinary manipulations. To perceive and to interact with their social and natural environment (e.g. social interactions, foraging and traveling), manatees use visual, acoustic and tactile modalities that may be involved in a large range of cognitive abilities. Research on stimuli perception in manatees is scarce; however, these animals demonstrate abilities to learn and appear to show long-term memory. For example, to mate and/or to forage manatees travel at medium and large geographical scales; without doubt their movements entail the use of a set of stimuli and learning processes. Furthermore, their social skills (e.g. social organization, tactile and acoustic communications) are also poorly understood although their social interactions appear to be more complex than previously thought. Finally, as for many animals, temperament/personality may play a key role during their interactions with conspecifics and the environment. These aspects on manatee behavior and cognition are important for management and conservation purposes and help us understand the evolution of these marine mammals. [ABSTRACT FROM AUTHOR]

West Indian manatees (Trichechus manatus) are separated into two allopatric subspecies: the Florida manatee (T. m. latirostris) and the Antillean manatee (T. m. manatus). In the winter of 2020–2021, an adult manatee was sighted off the coast of Cancun, Quintana Roo, Mexico, in areas where Antillean manatees are not typically seen. The individual had distinct watercraft scars on its body, which were matched using photo-identification to a known male Florida manatee (PE424) that had been repeatedly photographed in Florida since 1998. This is the first record of a Florida manatee visiting the Mexican Caribbean. Previous reports of individuals from this subspecies in Cuba, combined with genetic evidence, suggest some level of connectivity among geographically separated manatee populations. We present the first evidence of a long-distance movement by a manatee from Florida to the Yucatan Peninsula (Quintana Roo, Mexican Caribbean). This case, previous reports of Florida manatees in Cuba, and genetic evidence, suggest a certain degree of genetic mixture among the two subspecies. [ABSTRACT FROM AUTHOR]

Melanocortin 5 receptor (MC5R), which is expressed in the terminally differentiated sebaceous gland, is a G protein-coupled receptor (GPCR). MC5R exists mostly in mammals but is completely lost in whales; only the relic of MC5R can be detected in manatees, and phenotypically, they have lost sebaceous glands. Interestingly, whales and manatees are both aquatic mammals but have no immediate common ancestors. The loss of MC5R and sebaceous glands in whales and manatees is likely to be a result of convergent evolution. Here, we find that MC5R in whales and manatees are lost by two different mechanisms. Homologous recombination of MC5R in manatees and the insertion of reverse transcriptase in whales lead to the gene loss, respectively. On one hand, in manatees, there are two "TTATC" sequences flanking MC5R, and homologous recombination of the segments between the two "TTATC" sequences resulted in the partial loss of the sequence of MC5R. On the other hand, in whales, reverse transcriptase inserts between MC2R and RNMT on the chromosome led to the loss of MC5R. Based on these two different mechanisms for gene loss in whales and manatees, we finally concluded that MC5R loss might be the result of convergent evolution to the marine environment, and we explored the impact on biological function that is significant to environmental adaptation. [ABSTRACT FROM AUTHOR]

Data on the demography and distribution of wildlife populations are important for informing conservation and management decisions; however, determination of life history traits and population trends often are elusive. All four extant species in the order Sirenia are deemed vulnerable to extinction; therefore, determining the demography and distribution for populations worldwide is crucial. Aerial surveys, radio-tagging and tracking, genetic sampling and analyses, health assessments, carcass examination, and photographic documentation are all techniques used to study sirenian populations. A 40 +-year computer-aided catalog of images and demography data collected on Florida manatees enables searches of individuals by descriptions of feature (scar) types and has enabled estimates of annual survival and reproductive rates, documented extra-limital movements, and advanced modeling designs. Photography is discussed as a method for the documentation of unique and acquired features specifically on Florida manatees. By means of these features, individual Florida manatees have been re-identified as far from their established range as Cape Cod, Massachusetts, Houston, Texas, and in Cuba, The Bahamas, and Mexico. The length of gestation (11–13 months) and calf dependency (1–3 years), and potential longevity in the wild (> 50 years), have been verified. To meet the challenge of an increasing number of images collected with the advent of digital photography, there has been an increasing interest and potential for new techniques to assist with individual identification. Several researchers are utilizing drones and artificial intelligence to find, photograph, and streamline the individual identification of sirenians as well as other marine mammal species. New techniques have potential to simplify the photographic identification of Florida manatees. Photographic documentation could be a model for demographic and distribution research of sirenian populations outside of Florida and as a tool to monitor the viability of sirenian populations, particularly as threats emerge due to anthropogenic pressures and global climate change. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic studies that have included sirenians from the genera Trichechus, Dugong, and Hydrodamalis have resolved their interrelationships but have yielded divergence age estimates that are problematically discordant. The ages of these lineage splits have profound implications for how to interpret the sirenian fossil record--including clade membership, biogeographic patterns, and correlations with Earth history events. In an effort to address these issues, here we present a total evidence phylogenetic analysis of Sirenia that includes living and fossil species and applies Bayesian tip-dating methods to estimate their interrelationships and divergence times. In addition to extant sirenians, our dataset includes 56 fossil species from 106 dated localities and numerous afrotherian outgroup taxa. Genetic, morphological, temporal, and biogeographic data are assessed simultaneously to bring all available evidence to bear on sirenian phylogeny. The resulting time-tree is then used for Bayesian geocoordinates reconstruction analysis, which models ancestral geographic areas at splits throughout the phylogeny, thereby allowing us to infer the direction and timing of dispersals. Our results suggest that Pan-Sirenia arose in North Africa during the latest Paleocene and that the Eocene evolution of stem sirenians was primarily situated in the Tethyan realm. In the late Eocene, some lineages moved into more northern European latitudes, an area that became the source region for a key trans-Atlantic dispersal towards the Caribbean and northern-adjacent west Atlantic. This event led to the phylogenetic and biogeographic founding of crown Sirenia with the Dugongidae-Trichechidae split occurring at the Eocene-Oligocene boundary (~33.9 Ma), temporally coincident with the onset of dropping global sea levels and temperatures. This region became the nexus of sirenian diversification and supported taxonomically-rich dugongid communities until the earliest Pliocene. The Dugonginae-Hydrodamalinae split occurred near Florida during the early Miocene (~21.2 Ma) and was followed by a west-bound dispersal that gave rise to the Pacific hydrodamalines. The late middle Miocene (~12.2 Ma) split of Dugong from all other dugongines also occurred near Florida and our analyses suggest that the Indo-Pacific distribution of modern dugongs is the result of a trans-Pacific dispersal. From at least the early Miocene, trichechid evolution was based entirely in South America, presumably within the Pebas Wetlands System. We infer that the eventual establishment of Amazon drainage into the South Atlantic allowed the dispersal of Trichechus out of South America no earlier than the mid-Pliocene. Our analyses provide a new temporal and biogeographic framework for understanding major events in sirenian evolution and their possible relationships to oceanographic and climatic changes. These hypotheses can be further tested with the recovery and integration of new fossil evidence. [ABSTRACT FROM AUTHOR]

The article discusses research on signature calls in West Indian manatee or Trichechus manatus manatus. The study describes the vocalization of West Indian manatees related to sex and behavior, location and distance to hydrophones, and body position orientating towards or away from the hydrophones. The research analyzed signal-to-noise ratio of vocalizations and classified vocalizations using discriminant function analysis according to duration, tonality, mean F0 and amplitude ration.

Great efforts have been made to preserve manatees. Recently, a hybrid zone was described between Trichechus inunguis (TIN) and the Trichechus manatus manatus (TMM) in the Amazon estuary. Cytogenetic data on these sirenians are limited, despite being fundamental to understanding the hybridization/introgression dynamics and genomic organization in Trichechus. We analyzed the karyotype of TMM, TIN, and two hybrid specimens ("Poque" and "Vitor") by classical and molecular cytogenetics. G-band analysis revealed that TMM (2n = 48) and TIN (2n = 56) diverge by at least six Robertsonian translocations and a pericentric inversion. Hybrids had 2n = 50, however, with Autosomal Fundamental Number (FNA) = 88 in "Poque" and FNA = 74 in "Vitor", and chromosomal distinct pairs in heterozygous; additionally, "Vitor" exhibited heteromorphisms and chromosomes whose pairs could not be determined. The U2 snDNA and Histone H3 multi genes are distributed in small clusters along TIN and TMM chromosomes and have transposable Keno and Helitron elements (TEs) in their sequences. The different karyotypes observed among manatee hybrids may indicate that they represent different generations formed by crossing between fertile hybrids and TIN. On the other hand, it is also possible that all hybrids recorded represent F1 and the observed karyotype differences must result from mechanisms of elimination. [ABSTRACT FROM AUTHOR]

Florida manatees (Trichechus manatus) produce five broadly defined call types (squeaks, squeals, high squeaks, chirps, squeak‐squeals) but their use in social and nonsocial settings is unclear. The goal of this study was to investigate whether call categories and structure of manatee vocalizations varied with behavior. Multiple hydrophones were used to record vocalizations in four different environments and broad behavioral states. Vocalizations recorded from resting, cavorting, stressed, or feeding wild animals were subjected to mixed linear effects models to test whether vocalizations produced varied with behavior and calf presence. Measures of duration, entropy, and frequency modulation were extracted from vocalizations to investigate if structural parameters differ among behaviors. Although all five call categories were recorded, results suggest manatees vocalize using primarily three call types and vary the structure of the call based on behavior. High squeaks were correlated with calf presence. High entropy squeals were proportionally higher during cavorting suggesting they may be related to a heightened state of arousal. Squeaks were the dominant call type produced and were longer in duration and higher in frequency modulation when animals were stressed. This research provides a foundation for comparative studies on vocal behavior for the Florida manatee as well as studies on related species. [ABSTRACT FROM AUTHOR]

Rovotics is a fourteen-person company with years of collective experience designing, manufacturing, and operating robotic solutions to ecological problems in aquatic settings. Manatee is Rovotics' newest and most advanced Remotely Operated Vehicle (ROV) and is designed to operate in a multitude of underwater environments. The ROV is fully equipped with tools to maintain offshore wind farms, inspect aquaculture pens, monitor the health of the ocean, and ensure a healthy environment for sea life. [ABSTRACT FROM AUTHOR]

Threats to aquatic mammals may occur in isolation or in combination, leading to cumulative effects on populations and their ecosystems. Thus, conservation actions must consider the complexity of factors involved in patterns of habitat use, including feeding ecology, such as ontogenetic, spatial and temporal dietary shifts.The Amazonian manatee (Trichechus inunguis) occurs in a variety of environments, such as várzeas and igapós (flooded areas) and estuaries. Different environments can lead to variation in the diet of manatees according to the availability and abundance of plant species.Stable isotope analysis (δ13C and δ15N) of manatee teeth was performed to assess spatio‐temporal, ontogenetic and sex‐related patterns in resource use. Mixing models were applied to identify the most consumed plant groups.In várzeas, there were significant interactions between sex and ontogenetic class and ontogenetic class and time series for δ13C values. For manatees sampled from 1994 to 2004, males and adults showed the highest δ15N values, and aquatic C3, followed by C4 plants, were the groups that most contributed to the species' diet.Comparisons among the environments showed the highest δ13C values for manatees from várzeas and the lowest values for manatees from igapós. Várzeas had the highest abundance of C4 plants (high δ13C values), whereas they are scarce in igapós, leading manatees to consume mainly C3 species.The isotopic values of manatees mirrored those of the most available food sources in each environment, supporting the generalist and opportunist behaviour described for the species. Therefore, threats to the diversity, distribution and abundance of aquatic macrophytes, such as contamination, cattle raising and changes in the hydrological cycle (as a consequence of dams and climate change), will affect the diet of the manatee and should be taken into account when designing conservation strategies for the species. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic studies that have included sirenians from the genera Trichechus, Dugong, and Hydrodamalis have resolved their interrelationships but have yielded divergence age estimates that are problematically discordant. The ages of these lineage splits have profound implications for how to interpret the sirenian fossil record—including clade membership, biogeographic patterns, and correlations with Earth history events. In an effort to address these issues, here we present a total evidence phylogenetic analysis of Sirenia that includes living and fossil species and applies Bayesian tip-dating methods to estimate their interrelationships and divergence times. In addition to extant sirenians, our dataset includes 56 fossil species from 106 dated localities and numerous afrotherian outgroup taxa. Genetic, morphological, temporal, and biogeographic data are assessed simultaneously to bring all available evidence to bear on sirenian phylogeny. The resulting time-tree is then used for Bayesian geocoordinates reconstruction analysis, which models ancestral geographic areas at splits throughout the phylogeny, thereby allowing us to infer the direction and timing of dispersals. Our results suggest that Pan-Sirenia arose in North Africa during the latest Paleocene and that the Eocene evolution of stem sirenians was primarily situated in the Tethyan realm. In the late Eocene, some lineages moved into more northern European latitudes, an area that became the source region for a key trans-Atlantic dispersal towards the Caribbean and northern-adjacent west Atlantic. This event led to the phylogenetic and biogeographic founding of crown Sirenia with the Dugongidae-Trichechidae split occurring at the Eocene-Oligocene boundary (~33.9 Ma), temporally coincident with the onset of dropping global sea levels and temperatures. This region became the nexus of sirenian diversification and supported taxonomically-rich dugongid communities until the earliest Pliocene. The Dugonginae-Hydrodamalinae split occurred near Florida during the early Miocene (~21.2 Ma) and was followed by a west-bound dispersal that gave rise to the Pacific hydrodamalines. The late middle Miocene (~12.2 Ma) split of Dugong from all other dugongines also occurred near Florida and our analyses suggest that the Indo-Pacific distribution of modern dugongs is the result of a trans-Pacific dispersal. From at least the early Miocene, trichechid evolution was based entirely in South America, presumably within the Pebas Wetlands System. We infer that the eventual establishment of Amazon drainage into the South Atlantic allowed the dispersal of Trichechus out of South America no earlier than the mid-Pliocene. Our analyses provide a new temporal and biogeographic framework for understanding major events in sirenian evolution and their possible relationships to oceanographic and climatic changes. These hypotheses can be further tested with the recovery and integration of new fossil evidence.

Florida manatees (Trichechus manatus latirostris) are protected as a threatened species, and data are lacking regarding their reproductive physiology. This study aimed to (1) quantify plasma steroid hormones in Florida manatees from two field sites, Crystal River and Indian River Lagoon, at different gestational stages and to (2) identify individual lipids associated with pregnancy status. Ultra-high performance liquid chromatography-tandem mass spectrometric analysis was used to measure plasma steroid hormones and lipids. Pregnant female manatees were morphometrically distinct from male and non-pregnant female manatees, characterized by larger body weight and maximal girth. Progesterone concentrations in manatees were also elevated during early gestation versus late gestation. Cholesterol, an important metabolic lipid, and precursor for reproductive steroids, was not different between groups. Mass spectrometry quantified 949 lipids. Plasma concentrations of glycerophospholipids, glycerolipids, sphingolipids, acylcarnitines, and cholesteryl esters were associated with pregnancy status in the Florida manatee. Most of the lipid species associated with pregnancy were triacylglycerides, phosphatidylethanolamines, and ether-linked phosphatidylethanolamines, which may serve as energy sources for fetal development. This research contributes to improving knowledge of manatee reproductive physiology by providing data on plasma steroid hormones relative to reproductive status and by identifying plasma lipids that may be important for pregnancy. Elucidation of lipid species directly associated with pregnancy has the potential to serve as a diagnostic approach to identify pregnant individuals in fresh and archived samples. These biochemical and morphometric indicators of reproductive status advance the understanding of manatee physiology. Experimental design layout. [Display omitted] • Progesterone, weight, and maximum girth were increased in pregnant female manatees. • A total of 949 lipids, representing 39 different lipid subclasses, were detected. • Triacylglycerides (TAG) and phosphatidylethanolamines (PE) were major subclasses associated to pregnancy status. • TAGs were decreased and PEs were increased in pregnant manatees. [ABSTRACT FROM AUTHOR]

A manatee's primary modality to detect a vessel on a possible collision course is hearing as underwater visibility is limited in many manatee habitats and their visual acuity is poor. We estimate a Florida manatee's ability to detect the sound of an approaching boat and vocalizations in four different soundscapes in Sarasota Bay, FL. Background noise samples were collected every 5 minutes for a two-week period during winter and summer at each location (2019 or 2020). Sound levels in third octave bands (0.5, 1, 2, 4, and 8 kHz) were measured and compared to manatee auditory hearing thresholds and to sound levels of an approaching boat traveling at a slow, medium, or fast speed. Background sound levels in a wider band (1–20 kHz) were calculated to model vocal communication space at each location. We found that a manatee's estimated ability to detect an approaching boat differs greatly among locations, with time of day, and by season, and that fast boats are predicted to be detected later than slow boats. Latency of boat noise detection is estimated to sharply increase when considering unusually loud background noise levels. We suggest that such uncommonly loud conditions (e.g. 95th percentile sound level), not just typical conditions (median sound level), are important to consider for understanding the problem of manatee-boat collisions. Additionally, background noise impacts estimated vocal communication space and may limit the ability of vocal-mediated mother-calf cohesion. Altogether, a manatee's ability to detect acoustic signals of interest is expected to vary greatly spatially and temporally. [ABSTRACT FROM AUTHOR]

Objective: To present a novel case of perinatal bilateral exophthalmos and corneal ulcers in a neonate Antillean manatee and describe the medical treatment that led to the resolution of the observed clinical signs and vision restoration. Animal studied: A manatee stranded alone in Puerto Rico on July 5, 2020. Results: The manatee was found in critical condition with pronounced exophthalmos, lagophthalmos, and corneal opacification of both eyes (OU). Vision impairment was evident due to the lack of ocular menace reflex and bumping into the tank's walls. Biomicroscopy revealed conjunctival hyperemia and chemosis, limited third eyelid movement, but had viscous tears present OU. Dense, full‐thickness, white to cream‐colored cellular infiltrates affected 70% of the cornea with peripheral active vascularization OU. Rubeosis iridis was also present OU. Treatment consisted of supportive medical management, including nutritional support and topical treatment for ulcerative keratitis. Resolution of the corneal ulcers and functional vision were achieved after 6 weeks of therapy. Currently, bilateral, mild, intermittent exophthalmos is observed with no adverse clinical signs, and the calf is in good health. Conclusions: The extent of bilateral corneal disease on a neonatal calf may be a result of an intrauterine infection or possible trauma at or right after birth. While the latter may have led to exophthalmia and consequent corneal disease, the exact cause could not be determined. Supportive therapy and medical management of infectious keratitis were successful and led to vision recovery. This is the first report of ocular pathology in a neonatal manatee. [ABSTRACT FROM AUTHOR]

Two species of manatees are found in Northern Brazil—the Antillean manatee (Trichechus manatus), which is found along the coast from Florida to Northeastern Brazil, and the Amazonian manatee (Trichechus inunguis), endemic to the Amazon drainage basin. These species show a sympatric distribution in the region of the Marajó Archipelago, an estuarine area surrounding the Amazon River mouth. There is evidence of the occurrence of interspecific hybrids in this area, based on mitochondrial DNA analyses, although the use of nuclear markers has not corroborated this proposal. Considering that these species show very distinct karyotypes, despite being closely related (2n = 48 in T. manatus and 2n = 56 in T. inunguis), hybrids would present distinct chromosome numbers. Based on this, we conducted cytogenetic analyses using classic and molecular techniques in three calves found stranded in the Marajó Island and Amapá coast. The results showed that one of them, morphologically classified as T. inunguis, presented the correspondent karyotype, with 2n = 56. However, the other two, which were phenotypically similar to T. manatus, showed 2n = 49. Despite the same diploid number, their G-banding patterns revealed some differences. The results of the distribution of some microsatellite sequences have also confirmed the heterozygosity of some chromosomal pairs in these two individuals. These results are the first indubitable confirmation of the occurrence of natural hybrids between T. manatus and T. inunguis, and also brings about some issues concerning the viability of hybrids, considering that these two individuals do not correspond to an F1 hybrid, but instead, both presented a possible F2 karyotype. [ABSTRACT FROM AUTHOR]

Multielement concentrations (P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Rb, and Rh) and total mercury (T-Hg) were analyzed in different organs and tissues of Amazonian manatee (Trichechus inunguis). Samples of 27 T. inunguis specimens, maintained in the collection of the Amazonian Center for the Research and Preservation of Aquatic Mammals, were used, situated in an area highly impacted by gold mining in the northern region of the Brazilian Amazon. Samples of aquatic plants used as food by the animals were also analyzed. The elements S, Cl, K, Cr, and Mn accumulated mainly in the musculature, while Fe and Cu were more concentrated in the liver. Trace elements, such as rubidium (Rb) and rhodium (Rh), not previously reported in the organs of animals of the family Trichechidae, were also identified. The averages for T-Hg in the skin, muscle, encephalon, liver, kidney, and lung samples were, respectively, 0.1540 ± 0.1332, 0.0593 ± 0.1044, 0.0517 ± 0.0467, 0.0486 ± 0.0543, 0.0237 ± 0.0336, and 0.0013 ± 0.0032 µg.g−1. The values obtained for the vibrissae samples were below the limit of quantification, which allows for the conclusion that this tissue cannot be used as a contamination marker. It was observed that even when kept in a conservation breeding site, these animals were exposed to non-essential trace elements. Differences in the accumulation of elements were observed between the different organs and tissues analyzed. The presence of contaminants in animals that live in a preservation center, even at low levels, deserves attention. [ABSTRACT FROM AUTHOR]

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%).

Ecosystem services are the benefits derived from the ecosystems we occupy. These services are related to biodiversity and this interaction ensures the functioning of the processes necessary for their own maintenance. This study aimed to describe and analyze social and professional variables and identify the knowledge of ecological and ecosystem services of professionals who work with the marine manatee in Brazil. National legislation lacks data about ecosystem services associated with manatees, so the familiarity of professionals with the subject becomes essential for their identification. Data were collected using forms completed autonomously by professionals who participated in the elaboration of the National Action Plan for the Conservation of Sirenia. The questionnaires were sent by email to 21 professionals from April to October 2020. Among these professionals, 15 completed and returned the form. Most respondents work at private institutions and have more than ten years' experience. No differences were observed regarding the presence of ecosystem services, that is, the respondents believe that all categories were relevant in their geographic area. We found a positive and significant correlation between pressures and threats in manatees, demonstrating that the current impacts affecting the species and its ecosystem services will remain in the future. Most respondents stated that there is a relationship between the culture of the community and the manatee. The cultural manifestations associated with the animal proved to be exclusive to some areas of occurrence, thus providing an identity for these regions. This attraction can generate income for local communities and reduce threats to the animal. Recognizing ecosystem services can help in the management of protected areas and in conducting priority actions for the conservation of the manatee. [ABSTRACT FROM AUTHOR]

Vocal production learning is the ability to modify a vocal output in response to auditory experience. It is essential for human speech production and language acquisition. Vocal learning evolved independently several times in vertebrates, indicating evolutionary pressure in favor of this trait. This enables cross-species comparative analysis to be used to test evolutionary hypotheses. Humans share this ability with a versatile but limited group of species: songbirds, parrots and hummingbirds, bats, cetaceans, seals, and elephants. Although case studies demonstrate that African savanna and Asian elephants are capable of heterospecific imitation, including imitation of human words, our understanding of both the underlying mechanisms and the adaptive relevance within the elephant's natural communication system is limited. Even though comparing phylogenetically distant species is intriguing, it is also worthwhile to investigate whether and to what extent learned vocal behavior is apparent in species phylogenetically close to an established vocal learner. For elephants, this entails determining whether their living relatives share their special ability for (complex) vocal learning. In this review, we address vocal learning in Elephantidea and Sirenia, sister groups within the Paenungulata. So far, no research has been done on vocal learning in Sirenians. Because of their aquatic lifestyle, vocalization structure, and evolutionary relationship to elephants, we believe Sirenians are a particularly interesting group to study. This review covers the most important acoustic aspects related to vocal learning in elephants, manatees, and dugongs, as well as knowledge gaps that must be filled for one to fully comprehend why vocal learning evolved (or did not) in these distinctive but phylogenetically related taxa. [ABSTRACT FROM AUTHOR]

Introduction: Marine mammals are affected by diverse threats that must be identified for mitigation efforts. Objective: To visually quantify threats to marine mammals in Colombia, and to identify mitigation actions. Methods: We georeferenced threats based on the literature, covering 35 species in the period 1991-2020, and superimposed them on species range maps. Results: 22 species had at least one threat. Bycatch and interactions with fishing gear affected 16 species, followed by direct capture (8 species), vessel traffic/transit (6 species) and alteration of ocean physics (6 species). The most affected species, in terms of the greatest diversity of threats, are: humpback whale (Megaptera novaeangliae), Caribbean West Indian manatee (Trichechus manatus), marine tucuxi (Sotalia guianensis) and bottlenose dolphin (Tursiops truncatus). Nearly all of Colombia’s marine territory presents some degree of risk for marine mammals. High-risk areas are Buenaventura, Guapi, Cupica Gulf and Tumaco in the Pacific; and Urabá Gulf, Darién Gulf, Morrosquillo Gulf, off Barranquilla, Ciénaga Grande de Santa Marta and Coquivacoa Gulf in the Caribbean. Conclusion: Marine mammals in Colombia are currently at risk due to several threats, especially related to fishing, hunting/capture and shipping activities, mainly in coastal areas. Urgent evaluation and management actions are needed in the ten high-risk areas identified in this study. [ABSTRACT FROM AUTHOR]

Few twinning events have been recorded in the West Indian manatee (Trichechus manatus, Sirenia: Trichechidae) and no previous published study has provided confirmation of this phenomenon based in molecular tools. Here we investigate a possible case of twinning in an endangered Brazilian population of T. manatus using molecular tools. We analyzed two male neonates found stranded in Ceará State, on the northeastern coast of Brazil. The DNA of both individuals was isolated, and 10 microsatellite loci were amplified and genotyped. Following the identification of the alleles, the probabilities of identity by descent (Δ7 and Δ8) and relatedness (rxy) were calculated using estimators that evaluate inbreeding. The two individuals shared most of the alleles, with differences in the genotypes being identified in only two loci. All the estimators identified a level of relatedness compatible with that found between siblings (selfed or outbred), indicating they were dizygotic twins. This is the first confirmed case of fraternal twins in free-ranging West Indian manatees in South America. The recognition of this type of twinning provides elements to improve actions for the rehabilitation of stranded animals and their subsequent release to the environment. [ABSTRACT FROM AUTHOR]

The Antillean manatee (Trichechus manatus) and the Amazonian manatee (Trichechus inunguis) are distributed in rivers in the Caribbean and Amazonian region of Colombia respectively. For 30 years, genetic information has been obtained from these populations in order to inform conservation programs for these endangered species and decide on the location to release them back to the wild. However, in previous studies, samples from rivers in some areas of the country were not included, given the difficulties to access these regions due to either logistic or safety issues. In this study, we analyzed mitochondrial DNA (mtDNA) control region (CR) sequences of from samples of T. manatus (n = 37) and T. inunguis (n = 4) (410 and 361 bp, respectively), obtained in new and previously unexplored rivers and bays in the country, including Santa Marta, Urabá Gulf, Ayapel Marsh (San Jorge River Basin), Meta River and Magdalena Medio and the low Magdalena River (Cesar Province and Canal del Dique) as well as additional samples from Puerto Nariño in the Colombian Amazon. Our results included the discovery of two newly described mtDNA CR haplotypes for T. manatus. In addition, we confirmed significant population differentiation at the mitochondrial level between the Magdalena and Sinú rivers and differentiation among areas of the same river, including the middle and low Magdalena River. This differentiation may be related to anthropic changes in the river since construction of the Canal del Dique in the XVI century. We also tested environmental DNA sampling and analyses techniques to evaluate its potential use for manatee detection and monitoring in bodies of water in Colombia, in order to evaluate new areas for future manatee conservation initiatives. We emphasize the need to continue using genetic information to provide evidence on the potential best locations to undertake animal release to prevent outbreeding depression. [ABSTRACT FROM AUTHOR]

The present study aimed to investigate the diet of African manatees in Cameroon to better inform conservation decisions within protected areas. A large knowledge gap on diet and seasonal changes in forage availability limits the ability to develop informed local management plans for the African manatee in much of its range. This research took place in the Sanaga River Watershed, which includes two protected areas in the Littoral Region of Cameroon: the Douala-Edea National Park and the Lake Ossa Wildlife Reserve. We analyzed 113 manatee fecal samples and surveyed shoreline emergent and submerged vegetation within the Sanaga River Watershed. We used microhistological analyses to determine the relative contribution of each plant species to African manatee diets and compared across locations and across seasons (wet vs. dry season). We found that the shoreline vegetation is diverse with over 160 plant species, unevenly distributed across space and season, and dominated by emergent vegetation mostly represented by the antelope grass (Echinochloa pyramidalis). We recorded a total of 36 plant species from fecal samples with a spatial and temporal distribution mostly reflecting that of the corresponding shoreline vegetation. African manatees appear to be primarily opportunistically feeding on available vegetation across the seasons and habitat. This work documents the current, but changing, state of plant availability in the Sanaga River Watershed and reports the African manatee diet in Cameroon for the first time. This information can play a critical role in successfully managing the species and these protected areas. If we wish to protect the African manatee and the aquatic ecosystems within the Sanaga River Watershed, we must understand how forage availability changes over time, especially as its waters become nutrient enriched, eutrophic, and exposed to invasive species of plants in a changing world. [ABSTRACT FROM AUTHOR]

The present study aims at investigating the past and current trophic status of Lake Ossa and evaluating its potential impact on African manatee health. Lake Ossa is known as a refuge for the threatened African manatees in Cameroon. Little information exists on the water quality and health of the ecosystem as reflected by its chemical and biological characteristics. Aquatic biotic and abiotic parameters including water clarity, nitrogen, phosphorous, and chlorophyll concentrations were measured monthly during four months at each of 18 water sampling stations evenly distributed across the lake. These parameters were then compared with historical values obtained from the literature to examine the dynamic trophic state of Lake Ossa. Results indicate that Lake Ossa's trophic state parameters doubled in only three decades (from 1985 to 2016), moving from a mesotrophic to a eutrophic state. The decreasing nutrient gradient moving from the mouth of the lake (in the south) to the north indicates that the flow of the adjacent Sanaga River is the primary source of nutrient input. Further analysis suggests that the poor transparency of the lake is not associated with chlorophyll concentrations but rather with the suspended sediments brought‐in by the Sanaga River. Consequently, our model demonstrated that despite nutrient enrichment, less than 5% of the lake bottom surface sustained submerged aquatic vegetation. Thus, shoreline emergent vegetation is the primary food available for the local manatee population. During the dry season, water recedes drastically and disconnects from the dominant shoreline emergent vegetation, decreasing accessibility for manatees. The current study revealed major environmental concerns (eutrophication and sedimentation) that may negatively impact habitat quality for manatees. The information from the results will be key for the development of the management plan of the lake and its manatee population. Efficient land use and water management across the entire watershed may be necessary to mitigate such issues. [ABSTRACT FROM AUTHOR]

Even among the understudied sirenians, African manatees (Trichechus senegalensis) are a poorly understood, elusive, and vulnerable species that is difficult to detect. We used passive acoustic monitoring in the first effort to acoustically detect African manatees and provide the first characterization of their vocalizations. Within two 3-day periods at Lake Ossa, Cameroon, at least 3367 individual African manatee vocalizations were detected such that most vocalizations were detected in the middle of the night and at dusk. Call characteristics such as fundamental frequency, duration, harmonics, subharmonics, and emphasized band were characterized for 289 high-quality tonal vocalizations with a minimum signal-to-noise ratio of 4.5 dB. African manatee vocalizations have a fundamental frequency of 4.65 ± 0.700 kHz (mean ± SD), duration of 0.181 ± 0.069 s, 97% contained harmonics, 21% contained subharmonics, and 27% had an emphasized band other than the fundamental frequency. Altogether, the structure of African manatee vocalizations is similar to other manatee species. We suggest utilizing passive acoustic monitoring to fill in the gaps in understanding the distribution and biology of African manatees. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluoroalkyl substances (PFAS) are environmental contaminants linked to adverse health effects in humans and wildlife. Marine mammals, particularly manatees, have shown potential as sentinels for evaluating the presence and effects of anthropogenic chemicals. However, traditional blood collection techniques with marine mammals can be challenging, highlighting the need for improved strategies. In the present study, four different methods for the extraction of PFAS from dried blood spots were evaluated. Environ Toxicol Chem 2021;40:2726–2732. © 2021 SETAC [ABSTRACT FROM AUTHOR]

The Mexican Caribbean and Belize are home to one of the largest populations of Caribbean manatees (Trichechus manatus manatus). However, the transboundary Hondo River estuary is less examined compared to the surrounding protected areas. This paper provides a quantitative description of the spatial and temporal variability in abiotic factors and manatee distribution throughout the Hondo River estuary, with monthly field measurements during 2018–2019. Simultaneously, visual observations and side‐scan sonar detection were implemented, with 84 manatee sightings reported (calves 11.9%, noncalves 88.1%). Heatmap and frequency analyses showed that most manatee sightings occurred at the riverine estuary limit, the confluences between the river and the bay into which it flows. The surface water temperature and salinity ranged 28°C ≤ T ≤ 32°C and 0.5 PSU ≤ S ≤ 4.5 PSU for ~72% of the manatees identified, potentially describing locally preferred conditions for manatees. During the regional mid‐summer drought, higher temperature (31.5°C), salinity (18 PSU), and estuary extent (17.6 km) were recorded, including the maximum peak of manatee sightings (~31%). The roles of these abiotic factors are discussed as tentative environmental comfort conditions for manatees that could reduce their energy and maintenance costs. The identification of preferred conditions could broaden perspectives on how manatees interact with their habitats. [ABSTRACT FROM AUTHOR]

Flow from high-magnitude springs fed by the Floridan aquifer system contributes hundreds of liters of water per second to rivers, creating unique lotic systems. Despite their importance as freshwater sources and their contributions to the state's major rivers, little is known about the composition and spatiotemporal variability of prokaryotic and viral communities of these spring systems or their influence on downstream river sites. At four time points throughout a year, we determined the abundance and diversity of prokaryotic and viral communities at three sites within the first-magnitude Manatee Springs system (the spring head where water emerges from the aquifer, a mixed region where the spring run ends, and a downstream site in the Suwannee River). The abundance of prokaryotes and virus-like particles increased 100-fold from the spring head to the river and few members from the head communities persisted in the river at low abundance, suggesting the springs play a minor role in seeding downstream communities. Prokaryotic and viral communities within Manatee Springs clustered by site, with seasonal variability likely driven by flow. As water flowed through the system, microbial community composition was affected by changes in physiochemical parameters and community coalescence. Evidence of species sorting and mass effects could be seen in the assemblages. Greater temporal fluctuations were observed in prokaryotic and viral community composition with increasing distance from the spring outflow, reflecting the relative stability of the groundwater environment, and comparisons to springs from prior work reaffirmed that distinct first-magnitude springs support unique communities. [ABSTRACT FROM AUTHOR]

Among the bacterial infections that impair the health status of marine mammals, those caused by Brucella spp. are the most reported worldwide. Brucella infections in marine mammals can result in acute or chronic disease and are associated with variable clinical outcomes, depending on the organ involved during the infectious process, infection route, host immunity, and strain pathogenicity. Asymptomatic infections may also occur. The current study expands the investigation of Brucella infection in northeast Brazil by analyzing 19 dead, stranded cetaceans and 52 Antillean manatees Trichechus manatus manatus. The manatees included 8 dead, captive manatees and 44 live specimens, of which 10 were analyzed only after reintroduction into the wild as part of a rehabilitation program, 9 were analyzed both while in captivity or semi‐captivity and after reintroduction, 20 were sampled only in captivity or semi‐captivity, and 5 were free‐living manatees. Serological tests were used to screen for antibodies against smooth Brucella spp. Whole blood, swabs, and tissue samples were screened for Brucella spp. DNA by PCR. Samples with positive PCR results were cultured for Brucella spp. isolation. All manatees yielded negative results in serological and molecular tests. Brucella spp. DNA was detected in the kidney of one adult Guiana dolphin Sotalia guianensis exhibiting necrosis in the liver. No growth of Brucella spp. was observed via microbiological culturing. This study is the first report of Brucella spp. DNA detection in cetaceans in the state of Pernambuco, and it highlights the importance of conducting systematic monitoring for the presence of Brucella infection in marine mammals along the Brazilian coast, especially in the northeast region, where several cases have been reported. [ABSTRACT FROM AUTHOR]

Trichechus manatus and Trichechus inunguis are the two Sirenia species that occur in the Americas. Despite their increasing extinction risk, many aspects of their biology remain understudied, including the repetitive DNA fraction of their genomes. Here we used the sequenced genome of T. manatus and TAREAN to identify satellite DNAs (satDNAs) in this species. We report the first description of TMAsat, a satDNA comprising ~0.87% of the genome, with ~684bp monomers and centromeric localization. In T. inunguis , TMAsat showed similar monomer length, chromosome localization and conserved CENP-B box-like motifs as in T. manatus. We also detected this satDNA in the Dugong dugon and in the now extinct Hydrodamalis gigas genomes. The neighbor-joining tree shows that TMAsat sequences from T. manatus , T. inunguis , D. dugon , and H. gigas lack species-specific clusters, which disagrees with the predictions of concerted evolution. We detected a divergent TMAsat-like homologous sequence in elephants and hyraxes, but not in other mammals, suggesting this sequence was already present in the common ancestor of Paenungulata, and later became a satDNA in the Sirenians. This is the first description of a centromeric satDNA in manatees and will facilitate the inclusion of Sirenia in future studies of centromeres and satDNA biology. [ABSTRACT FROM AUTHOR]

The article discusses the unusual mass manatee mortalities recorded in Florida in 2021. Topics covered include the history and current status of legal protections for Florida's manatees, the current state of manatee mortality rate under the Marine Mammal Protection Act, and the regulations in place to help restore and protect water quality. Also discussed are the arguments, both scientific and governmental, on the causes of the recent mass manatee mortalities.

Cold stress syndrome (CSS) in the Florida manatee (Trichechus manatus latirostris) results in perturbations to many physiological pathways, often leading to further illness or death. In this study, we applied a non-targeted lipidomics approach with ultra-high performance liquid chromatography and high-resolution tandem mass spectrometry to characterize changes related to CSS in the lipidomic profiles of manatee plasma. Lipidomic analyses were conducted on healthy manatee (control) and cold-exposed manatee plasma samples with varying concentrations of Serum Amyloid A (SAA), an acute-phase protein that is associated with inflammatory disease. Control manatees (n = 10) were compared to all manatees exposed to cold temperatures (n = 17), and a subset of those manatees with SAA values > 120 μg/mL (n = 9). Increased SAA values were associated with higher levels of various acylcarnitine lipids, while several triacylglycerols and oxidized triacylglycerols were significantly lower in manatees with cold exposure. These identified lipids are critical molecules involved in the maintenance of energy homeostasis and could potentially be examined in conjunction with current physical parameters to characterize cold stress. The ability to detect such differences highlights the addition of lipidomics as a valuable tool in understanding cold stress and potentially other illnesses in manatees. Further investigation into the function of the altered lipids could greatly increase our understanding of lipid metabolism in physiologically stressed manatees as well as other marine mammals and inform future management recovery strategies. [ABSTRACT FROM AUTHOR]

A large-scale oil spill along the northeastern Brazilian coast in 2019–2020 severely impacted primary manatee habitats in Brazil. This study aimed to assess metal and metalloid contamination in a dead manatee calf found following this oil spill. Several elements were detected, including chromium, iron, nickel, lead, and vanadium, which are crude oil components, and thallium, a component of dispersants used to degrade and dissipate crude oil. The presence of these contaminants in the manatee calf is indicative of maternal exposure, metabolism, and newborn transference via placenta and lactation. This is the first report of mother-calf metal transfer in manatees, highlighting the species' vulnerability and potential long-term population dynamics effects, and the first report for several metals and metalloids in these animals, laying the foundation for future research efforts. These findings highlight the urgent need for continued environmental monitoring, ecotoxicological assessments, and conservation initiatives. • The 2019 oil spill severely impacted manatee habitats along the Brazilian coast. • Several metals and metalloids were detected in an infant manatee after the oil spill. • Maternal exposure, metabolism, and newborn placental transference are probable. • This is the first study to report mother-calf metal transfer in manatees. • The findings raise concerns about potential long-term population effects. [ABSTRACT FROM AUTHOR]

Abstract Background Antillean manatees (Trichechus manatus manatus) are large herbivorous aquatic mammals living in limited areas of South, Central and North America. As with other aquatic mammals, Antillean manatees can be infected by a variety of protozoan and metazoan parasites, some of them with zoonotic potential, which affect not only their welfare but also population health status. Therefore, we conducted the first epidemiological survey in Colombian free-ranging Antillean manatees to estimate their actual gastrointestinal parasite status. Results In total, 69 faecal samples were collected from free-ranging individual manatees during ecology field studies in the rivers Carare and San Juan and in two associated wetlands in the Andean region of Colombia. Parasite diversity encompassed six different endoparasite species. The highest prevalence was found for protozoan infections with Eimeria nodulosa (47.8%) and Eimeria manatus-like species (type A, B; 43.4%), followed by Entamoeba sp. (14.49%) and Giardia sp. (1.4%) infections. In addition, infections with the trematode Chiorchis fabaceus were detected at a high prevalence (33.3%). Molecular characterization of sirenian Eimeria species led to the distinction of three species, E. nodulosa and two E. manatus-like species (type A, B). Phylogenetic analyses indicated a host-specific adaptation of sirenian Eimeria species as previously reported for Eimeria species from other mammalian hosts. Conclusions This study provides the first record of Antillean manatee infection with Giardia and Entamoeba species in Colombia, representing two important anthropozoonotic parasite genera. This survey should serve as a baseline investigation for future monitoring on parasitic zoonoses in this mammal and encourage for investigations on their impact on both public health and wild manatee welfare.