Trichechus Inunguis Research Articles

Karyotypical Confirmation of Natural Hybridization between Two Manatee Species, Trichechus manatus and Trichechus inunguis

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.

Study of inorganic elements in different organs and tissues of Amazonian manatee (Trichechus inunguis) from Brazil

Study of inorganic elements in different organs and tissues of Amazonian manatee (Trichechus inunguis) from Brazil

Survey for Leptospira and Brucella in Amazonian manatees, Amazon river dolphins, and a tucuxi in the Brazilian Amazon.

Leptospirosis and brucellosis are zoonotic diseases with global distributions that represent severe hazards to humans and animals. We investigated exposure to Leptospira spp. and Brucella spp. in samples from Amazonian manatees Trichechus inunguis, Amazon river dolphins Inia geoffrensis, and a tucuxi Sotalia fluviatilis. The animals were free-ranging or undergoing in situ rehabilitation in the mid-Solimões River region, Brazilian Amazon. Serum samples from 19 Amazonian manatees were tested by microscopic agglutination test, Rose Bengal test, and 2-mercaptoethanol Brucella agglutination test. Antibodies against Leptospira spp. were detected in 63% of the manatees tested and serovar Patoc was considered the infecting serovar in all positive samples. Titers were generally low, indicating chronic exposure, but higher titers indicative of an active infection were detected in 3 animals. Anti-Brucella spp. antibodies were not detected. Tissue and/or body fluid samples from 12 Amazon river dolphins, a tucuxi, and 2 Amazonian manatees were investigated by multiplex PCR and bacteriology for Leptospira spp. and Brucella spp. All samples were negative. However, Enterococcus faecalis was isolated from uterine fluid, lymph node, and lung of 3 Amazon river dolphins. Bacillus spp. were isolated from milk and synovial fluid from 2 Amazon river dolphins and from a milk sample from 1 Amazonian manatee. Knowledge of the pathogens present in Amazonian manatees, Amazon river dolphins, and tucuxis is of great relevance to species conservation and environmental health. Although no clinical signs were noted, further research is needed to elucidate the clinical relevance of infection by Leptospira sp. serovar Patoc in Amazonian aquatic mammals.

Mitochondrial Genetic Diversity, Population Structure and Detection of Antillean and Amazonian Manatees in Colombia: New Areas and New Techniques.

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.

The first confirmed pregnancy of a released Amazonian manatee

The first confirmed pregnancy of a released Amazonian manatee

Using osteological measurements to estimate body length in Amazonian manatees

ABSTRACT Body length is an important parameter in morphological, ecological and behavioral studies of a species and contributes to the understanding of the body condition of individuals. This parameter is essential for conservation and management strategies by informing studies evaluating growth rates, physical maturity and classification of individuals into age groups, promoting better accuracy for the biological parameters of the species. The aim of this study was to identify predictors of body length for Amazonian manatees (Trichechus inunguis) using metric characters of osteological materials. Eleven linear measurements of skull, jaw, scapulae and humeri were collected from 41 Amazonian manatee skeletons of different age classes (calf, juvenile and adult). Data were analyzed by simple linear regression. The condylobasal length was the best predictor of body length for the species (R = 0.943), however, all bones evaluated showed at least one measurement with the capacity to predict body size (R2 > 0.9). Results of this study are useful for inferring body length of Amazonian manatees using bones deposited in museums and biological collections, expanding the informative potential of these materials.

Estimating occupancy and detection probability of the Amazonian manatee (Trichechus inunguis), in Central Amazon, Brazil

Understanding the distribution and abundance of threatened species is crucial to elaborate effective management plans for wild populations; however, elusive species prove difficult to detect. To support conservation strategies for the Vulnerable Amazonian manatee (Trichechus inunguis), the only freshwater sirenian, we analyzed presence/absence data with hierarchical models based on imperfect detection to assess T. inunguis occupancy in a Sustainable Development Reserve, Brazilian Central Amazon. In parallel, we compared the effectiveness of direct and indirect sampling methods to provide occupancy (ψ) and detection (p) estimates. Combining both sampling methods’ presence datasets provided higher accuracy estimates. The Amazonian manatee’s detection probability had never been estimated before: surprisingly, it was high (p = 0.50, SD = 0.05) and positively related with macrophyte coverage. Results suggest that the studied communities resident impact is not affecting the manatee occupancy, with greatest probabilities closer to human settlements. The final occupancy estimate obtained (ψ = 0.85, SD = 0.12) can be a baseline to Amazonian manatee long-term monitoring studies, and provide support for decision makers and local communities to establish effective protection zones for the species. Our approach highlights the potential of hierarchical models to understand the distribution not only of T. inunguis in different habitats, but also of other threatened Amazonian aquatic mammals.

Conservation of Amazonian aquatic mammals

Abstract Aquatic mammals worldwide are highly threatened in freshwater ecosystems where they are affected by direct human activities (e.g. hunting) as well as indirect human alteration of freshwater ecosystems (e.g. dams, mining activity). Although aquatic mammals of the Amazon Basin are experiencing many growing threats, little is known about the escalating impacts on them, current limitations in protection mechanisms, and possible strategies to ensure their conservation. This study synthesizes the available information on Amazonian aquatic mammals, including the ecological characteristics of these species, key threats, population status and conservation prospects. Amazonian aquatic mammals comprise seven species – Inia geoffrensis, Inia boliviensis, Inia araguaiaensis, Sotalia fluviatilis, Trichechus inunguis, Pteronura brasiliensis and Lontra longicaudis – which are characterized by low reproductive rates and keystone ecosystem roles. These species are endangered mainly by biological resource use, natural ecosystem modifications, energy production and mining, and climate change. Although information is sparse, there is evidence that these threats are inducing population declines of Inia spp., and hindering the recovery of populations of P. brasiliensis. Protection mechanisms for these species mostly include national and international laws and agreements, legislation governing environmental licensing and protected areas. Each of these protection mechanisms, however, has limited capacity to protect Amazonian aquatic mammals, largely because they are poorly enforced, lack transnational coordination or require population trend data that do not exist. Reversing the current state of affairs for Amazonian aquatic mammals requires an integrated research and policy approach that, at a minimum, substantially increases the present capacity to monitor their population responses to human impacts, establishes effective enforcement of existing legislation and prevents further impacts from hydropower development. To implement such an approach, information on the ecology of these species is necessary to create public and scientific awareness.

ESFUERZOS DE CONSERVACIÓN DEL MANATÍ AMAZÓNICO TRICHECHUS INUNGUIS (NATTERER, 1833) EN EL PERÚ: UNA REVISIÓN ACTUALIZADA

Los manatíes cumplen un rol muy importante en los ecosistemas acuáticos en el Perú y el mundo. Son considerados especies clave por ser reguladores de la vegetación flotante y además excelentes fertilizadores. El manatí amazónico (Trichechus inunguis Natterer, 1833) es el ejemplar más pequeño dentro del orden Sirenia y es exclusivo de la cuenca Amazónica. Hoy en día es considerado una especie vulnerable, con una población que tiende al descenso. La presente revisión busca resumir la información disponible y actualizada sobre los esfuerzos de conservación del manatí amazónico en el Perú. Para ello, se revisaron un total de 70 documentos, tanto en inglés como en español, que tuvieran un enfoque de investigación basado en la conservación del manatí amazónico dentro de la Cuenca Amazónica. En Perú, desde el año 2001, se han tomado diversas iniciativas que buscan promover su conservación. Actualmente, Perú cuenta con investigaciones realizadas con respecto al manatí amazónico en el aspecto descriptivo y también con interés particular en su protección. Sin embargo, la información disponible es aún escasa y limitada en comparación con la de otros países en donde este animal se distribuye. La dificultad que hay para censar a la especie, principalmente por su característico comportamiento evasivo y las condiciones de su ambiente, como la turbidez del agua, y el color oscuro de esta lo que impide su visibilidad, restringen el desarrollo de más investigaciones. Estas investigaciones, con enfoque hacia la difusión de la información y conservación del manatí amazónico en todo su rango de distribución, han sido consolidadas de manera entendible en este artículo para facilitar el alcance de la información de las distintas estrategias y herramientas de conservación que se han ido incorporando a lo largo del tiempo en favor de la protección del manatí amazónico. Actualmente en Perú la conservación de especies amenazadas como el manatí amazónico, está en su etapa inicial, debido a que la caza indiscriminada de esta especie a pesar de las regulaciones existentes todavía continúa. Es por esto que los esfuerzos de conservación de la especie tanto científicos como de manejo deben ir de la mano para una adecuada regulación del estado de la población.

The evolutionary history of manatees told by their mitogenomes

The manatee family encompasses three extant congeneric species: Trichechus senegalensis (African manatee), T. inunguis (Amazonian manatee), and T. manatus (West Indian manatee). The fossil record for manatees is scant, and few phylogenetic studies have focused on their evolutionary history. We use full mitogenomes of all extant manatee species to infer the divergence dates and biogeographical histories of these species and the effect of natural selection on their mitogenomes. The complete mitochondrial genomes of T. inunguis (16,851 bp), T. senegalensis (16,882 bp), and T. manatus (16,882 bp), comprise 13 protein-coding genes, 2 ribosomal RNA genes (rRNA - 12S and 16S), and 22 transfer RNA genes (tRNA), and (D-loop/CR). Our analyses show that the first split within Trichechus occurred during the Late Miocene (posterior mean 6.56 Ma and 95% HPD 3.81–10.66 Ma), followed by a diversification event in the Plio-Pleistocene (posterior mean 1.34 Ma, 95% HPD 0.1–4.23) in the clade composed by T. inunguis and T. manatus; T. senegalensis is the sister group of this clade with higher support values (pp > 0.90). The branch-site test identified positive selection on T. inunguis in the 181st position of the ND4 amino acid gene (LRT = 6.06, p = 0.0069, BEB posterior probability = 0.96). The ND4 gene encodes one subunit of the NADH dehydrogenase complex, part of the oxidative phosphorylation machinery. In conclusion, our results provide novel insight into the evolutionary history of the Trichechidae during the Late Miocene, which was influenced by geological events, such as Amazon Basin formation.

Genetic Connectivity of the West Indian Manatee in the Southern Range and Limited Evidence of Hybridization With Amazonian Manatees

The Antillean subspecies of the West Indian manatee is classified as endangered by the International Union for the Conservation of Nature (IUCN) Red List. In Brazil, the manatee population is listed as endangered with an estimated population size of 500–1,000. Historic hunting, recent habitat degradation, and fisheries bycatch have decreased the population size. The Amazonian manatee is listed as vulnerable by the IUCN with unknown population sizes within Brazil. The Antillean manatee occurs in sympatry with the Amazonian manatee in Brazil and hybridization has been previously indicated. To provide information on the genetic structure, diversity, and degree of hybridization in the sympatric zone near the Amazon River mouth, the mitochondrial DNA control region and 13 nuclear microsatellite markers were assessed on the two species. Samples were analyzed from the Antillean subspecies across its distribution in Brazil (n= 78) and from the Amazonian species (n= 17) at the Amazon River mouth and inland mainstem river. To assess the previously defined evolutionary significant units of Antillean manatees in the area, an additional 11 samples from Venezuela and Guyana were included. The Antillean manatee was found to be a single population in Brazil and had lower than average number of alleles (3.00), expected heterozygosity (0.34), and haplotype diversity (0.15) when compared to many other manatee populations. The low values may be influenced by the small population size and extended pressures from anthropogenic threats. Gene flow was identified with Venezuela/Guyana in admixed Antillean Brazil samples, although the two populations were found to be moderately divergent. The nuclear loci in Venezuela/Guyana Antillean manatee samples indicated high differentiation from the samples collected in the Amazon River (FST= 0.35 andRST= 0.18,p= 0.0001). No indication of nuclear hybridization was found except for a single sample, “Poque” that had been identified previously. The distribution of Antillean manatees in Brazil is extensive and the areas with unique habitat and threats would benefit from independent management and conservation actions. Gene flow, resulting in genetic diversity and long-term population stability, could be improved in the southern range through habitat restoration, and the establishments of travel corridors and protected areas, which are particularly important for successful parturition and neonatal calf survival.

Salmonellosis in a young Amazonian manatee (Trichechus inunguis)

ABSTRACT: The objective of this study was to describe a case of salmonellosis in an Amazonian manatee (Trichechus inunguis). The animal was rescued from a tributary of the Capim River, in the municipality of Goianésia do Pará, Pará, Brazil, kept in a pool, and died approximately five months after being rescued. The main changes observed at necropsy were that the cecum and colon had serosal hyperemia, wall edema, thickened mucosa with ulcerated areas and covered by a thin layer of fibrin, and a yellowish liquid content. Histologically, there was moderate multifocal fibrinonecrotic typhlocolitis associated with intense bacterial colonization. Salmonella enterica subsp. enterica (rough) was isolated in cecum and colon fragments. This is the first report of salmonellosis in an Amazonian manatee.

TLR4 and TLR8 variability in Amazonian and West Indian manatee species from Brazil.

Amazonian (Trichechus inunguis) and West Indian (Trichechus manatus) manatees are aquatic mammals vulnerable to extinction found in the Amazon basin and the coastal western Atlantic. Toll-like receptors (TLR) play a key role in recognizing pathogen-associated molecular patterns using leucine-rich repeats (LRRs). We described the diversity of TLR4 and TLR8 genes in these two species of manatee. Amazonian manatee showed seven SNPs in TLR4 and the eight in TLR8, while West Indian manatee shared four and six of those SNPs, respectively. In our analysis, TLR4 showed one non-conservative amino acid replacement substitution in LRR7 and LRR8, on the other hand, TLR8 was less variable and showed only conserved amino acid substitutions. Selection analysis showed that only one TLR4 site was subjected to positive selection and none in TLR8. TLR4 in manatees did not show any evidence of convergent evolution compared to species of the cetacean lineage. Differences in TLR4 and TLR8 polymorphism may be related to distinct selection by pathogens, population reduction of West Indian manatees, or an expected consequence of population expansion in Amazonian manatees. Future studies combining pathogen association and TLR polymorphism may clarify possible roles of these genes and be used for conservation purposes of manatee species.

Conservation issues using discordant taxonomic and evolutionary units: a case study of the American manatee (

The delimitation of evolutionarily significant units (ESUs) frequently results in controversy, but prioritising populations with evolutionary independence is essential for effective in situ conservation management. The American manatee (Trichechus manatus) is distributed along subtropical and tropical coastal waters from Florida (USA) to Alagoas (Brazil), and two subspecies are traditionally recognised, namely, T. m. latirostris, restricted to the Florida peninsula, and T. m. manatus, found in the remaining areas. However, this subspecific classification is not supported by genetic and morphologic evidence, which, rather, recognises two deeply differentiated populations or ESUs called Atlantic (Brazil) and Caribbean (from Venezuela to Florida). In this viewpoint paper, we compare both intraspecific divisions of T. manatus and the conservation implications. First, we used all available mtDNA evidence to test the genealogical clustering of the two American manatee ESUs by using a tree-based coalescent method. Second, we have used different models under a coalescent framework to estimate the historic gene flow among manatee populations. The analysis of the spatial distribution of mtDNA clusters confirmed the existence of the two suggested ESUs, rather than the two claimed subspecies. Furthermore, the best model to explain historic migration indicates that Brazilian manatees belong to an isolated population, whereas Florida and Caribbean populations are connected by more recent gene flow. These results have confirmed that T. manatus of the Caribbean, Gulf of Mexico and Florida belong to the same deme or Caribbean ESU, and the relatively isolated population inhabiting the Atlantic coast of Brazil belongs to the Atlantic ESU. Furthermore, both ESUs are separated by an interspecific hybrid zone (with the Amazonian manatee) located around the mouth of the Amazon River towards the Guianas coastline. The subdivision of two ESUs is also highly supported by karyotypic, morphological and ecological data, and is in clear disagreement with the traditional subspecies designations and the IUCN priorities, which manages Brazilian manatees as part of the Antillean manatee subspecies (T. m. manatus). Rather, Brazilian manatees should be considered as a full priority for conservation and require further taxonomic research; because of their deep history of isolation, they present high genetic and morphologic differentiation from all other American manatees.

Distribution of South American manatees, Trichechus manatus Linnaeus, 1758 and T. inunguis (Natterer, 1883) (Sirenia: Trichechidae)

South America is unique as it is home of two species of manatees: the West Indian manatee, Trichechus manatus, and the Amazonian manatee, T. inunguis. These species are easily identified by the belly skin coloration, the first is entirely gray whereas T. inunguis has a white mark pattern in the belly, and presence of nails in T. manatus, absent in T. inunguis. The morphology and the range of Trichechus species have been clearly established. However, we show that the belly skin coloration and the presence of nails on the pectoral flipper may be polymorphic. These findings prompted us to check all available information about the manatee. In view of lack of accurate data on manatee locations, we produced a gazetteer and a map of Trichechus spp. in South America using records obtained by regular monitoring of aquatic mammal strandings conducted by the Grupo de Estudos de Mamíferos Aquáticos da Amazônia of the Museu Paraense Emílio Goeldi, all available peer-reviewed data, reports, thesis, and newspaper files with photos showing diagnostic characters. These findings showed the need of improving the identification of these species before implementing conservation strategies. Finally, we present a complete report on the extant distribution of these species in South America.

Conservation of Amazonian manatee (Sirenia: Trichechidae): the case of Extractive Reserve Verde para Sempre, Brazil

The Amazonian manatee (Trichechus inunguis) is the largest aquatic freshwater mammal in South America found in the main rivers of the Amazon Basin. The main objective of this work was to describe the ecological knowledge and use of the Amazonian manatee in the Extractive Reserve Verde para Sempre (RESEX), located in Porto de Moz, Para, Brazilian Amazon. This study was conducted through semi-structured interviews, free interviews, participant observation and image capture. Thirty-one residents were interviewed in 21 RESEX communities. The interviewees were previously identified by local informants and selected according to their level of knowledge of the species. We collected information on the morphology, behavioral characteristics and feeding habits of manatees, as well as on the uses of the species. According to interviewees, poaching and consumption of manatees is rare, and entanglement of calves in fishing nets is accidental. The headwaters of rivers and streams, that make up the water network of this extractive reserve, are little affected by human activity, and constitute potential areas of refuge for the species. The study shows that the maintenance of the extractive reserve gives good results in the protection of the Amazonian manatee. Even though, these animals are accidentally caught, and sometimes poached. Thus, it corroborates with the statement that sustainable development reserves are efficient strategies for biodiversity conservation. Thus, it is suggested the application of environmental education programs and awareness measures, aimed at the general public.

Occupancy and population density estimates of the Amazonian manatee in eastern Ecuador

The Amazonian manatee Trichechus inunguis has been categorized as Vulnerable by the IUCN. There have been few studies on the species in its natural habitats due to its elusive nature and the low visibility of its aquatic habitats. Understanding the conservation status of Amazonian manatees, as well as any changes in their population trends and direct threats, is the basis for their management and conservation. Our study was carried out in 2 localities of the Ecuadorian Amazon (Tambococha-Jatuncocha and the Lagarto River), in the provinces of Sucumbíos and Orellana. We surveyed Amazonian manatees along rivers and in lagoons, using fish finder side-scan sonar to increase detectability rates. We estimated encounter rates, population density and occupancy. With a sampling effort of 573 km, we obtained an average encounter rate of 0.90 records 10 km-1 and estimated a population density of 1.09 and 0.94 ind. km-2 in Tambococha-Jatuncocha and the Lagarto River, respectively. In addition, occupancy rates varied between 0.51 and 0.57, and presence and distribution of the species were associated with distance to humans. The Amazonian manatee population estimates presented here represent a baseline for future research, and additional surveys will be needed to understand population fluctuations over time. An evaluation of population viability in Tambococha-Jatuncocha and the Lagarto River would also be required to determine whether these populations will be able to persist over the long term under different deterministic and stochastic scenarios.

Infectious and Non-Infectious Diseases in Manatees in Brazil

Background: Antillean manatee (Trichechus manatus) and Amazonian manatee (Trichechus inunguis) are the two species of manatees that occur in Brazil, and both are endangered. Studies on manatee disease in Brazil were previously based mainly on Florida manatees. In recent years, these studies have increased in Brazil. Thus, the objective was to carry out a survey of the publications of infectious and non-infectious diseases in the two species of manatees that occur in the country, to assist in the identification of threats to the species and in the health assessment of manatees in the country.Review: Regarding infectious and contagious diseases, parasites have affected both species of manatees in Brazil, such as Pulmonicola cochleotrema in wild T. manatus, Toxoplasma gondii in both species, and Cryptosporidium spp. also in both species, this being an important agent of zoonotic character. Giardia sp., another zoonotic parasite, has also been reported in both species of manatees in Brazil. Mycotic lesions caused by B. hawaiiensis have been described in calves of T. manatus in captivity. Meanwhile, Candida sp., Trichosporon sp., Rhodotorula sp., and Cryptococcus sp. have been identified in T. inunguis. Studies on viruses in manatees are still not widespread compared to other species; however, it has been verified that rotavirus is present in T. manatus in captivity. In studies carried out to identify bacteria in T. manatus, the following bacteria were isolated: Arizona sp., Bacillus sp., Corynebacterium equi, Corynebacterium pseudodiphteriticum, Corinebacterium sp., Edwasiella tarda, Enterobacter aerogenes, Enterobacter agglomerans, Enterobacter sakasakii, Escherichia coli, Leptospira spp., Proteus sp., Proteus vulgaris, Providencia rettgeri, Pseudomonas aeruginosa, Salmonella spp., Serratia marcescens, Staphylococcus sp., Staphylococcus aureus, Staphylococcus coagulase-negativa, Stenotrophomonas maltophilia, Streptococcus sp., and Streptococcus viridans. Regarding noninfectious diseases, food-related diseases stand out, where gastrointestinal complications in manatees and obesity in animals in captivity are among the highest occurrences. Intestinal tympanism was reported in a T. inunguis calf, causing death of the animal. Pollution and contamination have also been a concern for the health of these animals. In studies carried out with T. manatus in Paraíba state, accumulation of heavy metals in the animals was verified, possibly originating from sugarcane farms in the region. The ingestion of garbage has also been one of the greatest threats to the health of manatees, where it was registered as a possible cause of death of T. inunguis in Amazonas state. Regarding congenital diseases, although rare in manatees, two calves of T. manatus in Ceará state have been described as having congenital malformations in the heart and brain, without a well-defined etiology. Trauma has been affecting both species; in Brazil, 17.3% of manatees reintroduced by 2018 showed evidence of collisions with vessels. Hunting for T. inunguis still occurs frequently, which has been greatly reduced for T. manatus.Conclusion: Pathogens and other factors that affect manatees have a potential impact on both species. Some of the identified agents have a zoonotic potential and, therefore, are also public health issues. This survey demonstrates that the need for incentives for studies on health assessment and pathogens in these species, both in the wild and in captivity, should be encouraged.

Manatee genomics supports a special conservation area along the Guianas coastline under the influence of the Amazon River plume

The West Indian manatee (Trichechus manatus) occurs along the Atlantic coastline and the adjacent freshwater systems of South, Central and North America, from Alagoas (Brazil) to Florida (USA) and the Greater Antilles. The Amazonian manatee (Trichechus inunguis) is the only sirenian adapted exclusively to freshwater and is endemic to the Amazon River basin. Previous studies have reported hybrids between T. inunguis and T. manatus close to the Amazon River mouth, likely composing an extensive hybrid zone under the influence of the Amazon River plume along the Guianas coast in South America. We have generated ddRAD SNP data, and sequences of nuclear and mtDNA loci to characterize the manatees’ genomic composition along the French Guiana coastline. Using analyses and simulations to examine the process of hybridization, we found this population to be formed by introgressed or later generation interspecific hybrids. We also describe the first pure T. inunguis found outside the Amazon River basin. Our results indicate that T. inunguis can survive in the Amazon River plume and have colonized independent water streams of the Guianas coastline where they likely hybridize with T. manatus. This hypothesis offers a plausible explanation for the known extension of the hybrid zone between the two species along the Guianas coastline. It also reinforces the importance of the Amazon plume, which flows westwards to the Guianas coastline and favors the dispersion of the freshwater species. The Amazon plume functions as a large estuary-like system that provides an ecological continuum from the Amazon River mouth to the disconnected waterflows of the Guianas, which deserves status as a special conservation area.

A new species of Trichechus Linnaeus, 1758 (Sirenia, Trichechidae), from the upper Pleistocene of southwestern Amazonia, and the evolution of Amazonian manatees

ABSTRACTThe genus Trichechus (Mammalia, Sirenia, Trichechidae) harbors a modest diversity, comprising only three living species of manatees, and no species currently recognized as fossil. Herein, we report a new extinct species of manatee from the late Pleistocene of the Brazilian Amazonia, Trichechus hesperamazonicus, sp. nov. It comes from the alluvial deposits of the Rio Madeira Formation along the Madeira River, state of Rondônia, western Brazil, and is represented by a partial palate with both molar series and two partial right dentaries. The new taxon shows a mosaic of characteristics resembling those of other manatee species, as well as some unique characters. It differs from all other Trichechus species by possessing a wide space between the posterior lower tooth row and ascending ramus of dentary, and by having the anterior border of the ascending ramus covering the posterior end of the tooth row in lateral view. The results of morphometric analyses (principal component analysis and discriminant analysis) further support the distinctiveness of the new species. A phylogenetic analysis recovers the new species in a polytomy with T. inunguis and the clade formed by T. senegalensis and T. manatus. The levels from which the remains were recovered produced a radiocarbon date of 44,710 ± 880 years before present; together with molecular clock estimates, this date suggests that until recently at least two species of manatees coexisted in the fluvial systems of western Amazonia.