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The endangered Greater Caribbean manatee (Trichechus manatus manatus), one of the largest aquatic herbivores in the Caribbean, plays a crucial role in nutrient recycling within the ecosystem, and the study of its feeding ecology is important for its conservation. Despite several studies determining the items consumed by manatees, there remains limited understanding of their nutritional significance for the species in the Western Caribbean. This study, aimed to analyze the bromatological composition of the food components in the manatee’s diet in the Mexican Caribbean across three distinct environments. We manually collected aquatic and semi-aquatic primary producers potentially part of the manatee diet in marine, brackish and riverine areas of the southern region of Quintana Roo, Mexico. Then, we analyzed them for moisture, crude protein, crude fiber, ash, ether extract, digestible nutrients, and digestible energy. We present the initial data on nutrient values in the manatee diet in the Caribbean, establishing a foundation for exploring the factors that influence spatial, temporal, and species-specific variations in nutrient content at a regional level. Our bromatological analysis demonstrated that the most nutritionally important plants for manatees, based mainly on protein content and freshwater contribution, include the seagrasses Halodule wrightii, Syringodium filiforme, Thalassia testudinum, the water lily Pontederia crassipes, and Vallisneria sp. Effective habitat management for manatees is crucial for their survival, ensuring that feeding resources are maintained in both enough quantity and high quality. Given its nutritional significance for manatees, we recommend that seagrasses in the region should be prioritized as conservation targets. [ABSTRACT FROM AUTHOR]

Greater Caribbean manatees Trichechus manatus manatus face complex conservation challenges throughout their distribution range, many of which are associated with human factors; and in consequence, the subspecies is considered Endangered (EN) by the International Union for Conservation of Nature (IUCN). Human‐related threats as hunting for meat consumption, collisions with boats, entanglement in fishing nets, pollution and loss of habitat put the Greater Caribbean manatee at risk in Colombia. Studies aiming to describe traditional knowledge and local perceptions provide information that can be useful to design local manatee conservation programmes. We analyse the fishers' perceptions regarding manatees in Ayapel, Córdoba. One hundred semi‐structured interviews were conducted, focusing on personal data, fishing practices, perceptions and knowledge about the manatees. According to the interviews, bycatch is the greatest threat to manatees (56%), followed by pollution (16%), whereas boat collisions (12%), hunting (11%) and drought (5%) are lower ranking threats. Our results demonstrated that participants have a good understanding of manatee biology and ecology. However, a human–manatee conflict was evidenced, as 39% of fishers consider that manatees negatively impact fishing by competition for the fishing resources and/or by damaging fishing gear. We recommend strengthening awareness about the importance of manatee to guarantee an optimal management of this subspecies and its habitat. Fishers should be directly involved in the formulation of management and conservation plans for the subspecies, as their knowledge becomes critical to understanding and mitigating the risks to manatee populations. This work has a clear application to understand the human factor in manatee recovery not only in our study area but also in other locations where manatees share habitat with people, particularly in marginalized human communities. [ABSTRACT FROM AUTHOR]

The Gulf toadfish (Opsanus beta) is a soniferous and abundant species native to Gulf of Mexico estuarine environments—now considered a likely invasive species in coastal Brazil. Males produce distinctive boatwhistle calls during their reproduction behaviors, offering an acoustic cue for ecological functions such as mate selection, prey detection, and predator avoidance. Their calls can also be readily detected with passive acoustics to monitor Gulf toadfish distributions and serve as acoustic indicators for their preferred nesting habitats. In this study, we describe the spatial, annual, seasonal, monthly, daily, daytime, and diel variation of Gulf toadfish call occurrence in Cedar Key, Florida (USA), with multiple sampling efforts at seagrass and dock sampling locations in the years 2019–2022. From April through June during our dock sampling, calls were detected across almost all our sampled dates and often every hour of the day, with daily and diel fluctuations in call occurrence. In our seagrass meadow sampling, call occurrence showed some positive correlation with manatee grass (Syringodium filiforme) and salinity. Moreover, snapshot recordings as short as 5 min were sufficient to detect calls in 37 of our 45 sampling events compared to only five where trawls captured Gulf toadfish. Our findings demonstrate the efficacy of listening to Gulf toadfish calls for monitoring applications and can support future efforts seeking to understand the availability of a prevalent acoustic cue in estuarine soundscapes. [ABSTRACT FROM AUTHOR]

Introduction: This work presents an unsupervised learning-based methodology to identify and count unique manatees using underwater vocalization recordings. Methods: The proposed approach uses Scattering Wavelet Transform (SWT) to represent individual manatee vocalizations. A Manifold Learning approach, known as PacMAP, is employed for dimensionality reduction. A density-based algorithm, known as Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN), is used to count and identify clusters of individual manatee vocalizations. The proposed methodology is compared with a previous method developed by our group, based on classical clustering methods (K-Means and Hierarchical clustering) using Short-Time Fourier Transform (STFT)-based spectrograms for representing vocalizations. The performance of both approaches is contrasted by using a novel vocalization data set consisting of 23 temporally captured Greater Caribbean manatees from San San River, Bocas del Toro, in western Panama as input. Results: The proposed methodology reaches a mean percentage of error of the number of individuals (i.e., number of clusters) estimation of 14.05% and success of correctly grouping a manatee in a cluster of 83.75%. Discussion: Thus having a better performances than our previous analysis methodology, for the same data set. The value of this work lies in providing a way to estimate the manatee population while only relying on underwater bioacoustics. [ABSTRACT FROM AUTHOR]

The biobanks from dermal biopsies represent an interesting strategy for biodiversity conservation. Nevertheless, the morphological and cellular patterns of the dermis can be influenced by the age and sex of the individual. Therefore, evaluating these factors is interesting for forming biobanks of Antillean manatees. These animals, representatives of marine fauna, have had their population reduced, and biobanks are essential for their conservation. Then, we evaluated the effects of age (3.5 years vs. 3.6–16 years vs. 23.6 years) and sex (males vs. females) on morphological and cellular parameters using histological and in vitro culture techniques. Regardless of age, no differences were observed for dermal thickness, collagen fibres, tissue proliferative activity and viable cell recovery. Nonetheless, fibroblast reduction was observed in groups aged 23.6 years compared to other animals (p < 0.05). Additionally, cells from animals aged 3.6–16 years showed more significant mitochondrial damage than the other groups (p < 0.05). Regardless of sex, no differences were observed for dermal thickness, collagen fibres, tissue proliferative activity and viable cell recovery; however, females had fewer fibroblasts than males (p < 0.05). Cells from females showed lower mitochondrial damage when compared to cells from males. In summary, although age and sex do not influence dermal thickness and cell recovery, variations in the number of fibroblasts and mitochondrial characteristics were observed among the groups. These differences may be significant for understanding the dermis aspects to be correlated to biobank systems. [ABSTRACT FROM AUTHOR]

The Amazonian manatee (Trichechus inunguis) is an aquatic mammal threatened with extinction. However, few studies have investigated the pathogens in this species, which may affect both animal and human health. This study aimed to evaluate the frequency, distribution, and patterns of antimicrobial susceptibility of Staphylococcus spp. and Escherichia coli colonizing the nasal and rectal cavities of Amazonian manatees kept in captivity at the National Institute for Amazonian Research (INPA) in the state of Amazonas, Brazil. Rectal and nasal swabs from 44 manatees of different ages were used in this study. The genus Staphylococcus was isolated from the nasal swabs of 32 (72.7%) animals, with two individuals harboring more than one species of Staphylococcus. S. sciuri was the most commonly isolated species. Resistance to penicillin was observed in 13 (40.6%) isolates, more frequent than the other antimicrobials tested (P = 0.01). E. coli was isolated from the rectal swabs of all animals, with phylogroup B1 being the most frequent among the strains obtained (P = 0.0008). Four isolates (6.8%) were positive for virulence factors, three of which were classified as enterotoxigenic E. coli (ETEC) and one as enteropathogenic E. coli (EPEC). To our knowledge, this is the first study to evaluate Staphylococcus spp. and E. coli in Amazonian manatee samples. This study revealed nasal colonization by Staphylococcus spp., mainly S. sciuri, and diarrheagenic E. coli isolates, including antimicrobial-resistant strains. [ABSTRACT FROM AUTHOR]

The population sizes of manatees in many regions remain largely unknown, primarily due to the challenging nature of conducting visual counts in turbid and inaccessible aquatic environments. Passive acoustic monitoring has shown promise for monitoring manatees in the wild. In this study, we present an innovative approach that leverages a convolutional neural network (CNN) for the detection, isolation and classification of manatee vocalizations from longterm audio recordings. To improve the effectiveness of manatee call detection and classification, the CNN works in two phases. First, a long-term audio recording is divided into smaller windows of 0.5 seconds and a binary decision is made as to whether or not it contains a manatee call. Subsequently, these vocalizations are classified into distinct vocal classes (4 categories), allowing for the separation and analysis of signature calls (squeaks). Signature calls are further subjected to clustering techniques to distinguish the recorded individuals and estimate the population size. The CNN was trained and validated using audio recordings from three different zoological facilities with varying numbers of manatees. Three different clustering methods (community detection with two different classifiers and HDBSCAN) were tested for their suitability. The results demonstrate the ability of the CNN to accurately detect manatee vocalizations and effectively classify the different call categories. In addition, our study demonstrates the feasibility of reliable population size estimation using HDBSCAN as clustering method. The integration of CNN and clustering methods offers a promising way to assess manatee populations in visually challenging and inaccessible regions using autonomous acoustic recording devices. In addition, the ability to differentiate between call categories will allow for ongoing monitoring of important information such as stress, arousal, and calf presence, which will aid in the conservation and management of manatees in critical habitats. [ABSTRACT FROM AUTHOR]

Antillean manatees (Trichechus manatus manatus) are endangered coastal, marine, and riverine megaherbivores with high environmental plasticity, constrained by tidal and seasonal water level cycles that affect access to food and fresh water. Accurate quantification of the species' habitat requirements, typically achieved through home range (HR) estimation, is required to implement area‐based conservation initiatives. In this study, we used GPS tracking data from 38 wild and captive‐rehabilitated released manatees to estimate HR using autocorrelated kernel density estimators (AKDE) and average time speed. We investigated whether body size, habitat type, sex and behavioural group influence home range size due to energy requirements, resources availability, a scramble‐competitive polygyny mating system, and adaptation to the wild. Eighteen manatees exhibited range‐resident behaviour, with a mean 95% home range of 72.96 km2 (± 218.52) and a median of 10.69 km2. The mean daily speed was estimated to be 13.47 km/day (± 4.16). Home range and body size were positively correlated, consistent with HR allometry theory. Long‐term tracked individuals showed a trend of increasing HR over time. Only four released animals (17.4%) were range‐resident, suggesting that they may need additional time to establish a home range. Individuals using only the marine environment had larger home ranges compared to mixed (marine and estuarine) and estuarine environments, probably due to freshwater availability. Our study contributes to the understanding of the factors driving manatee movement and provides more accurate estimates of area requirements, which can inform the establishment and zoning of marine protected areas. [ABSTRACT FROM AUTHOR]

Exploratory behaviors describe the actions performed by an animal to obtain information on an object, environment, or individual by using its different senses. Exploration is described in some marine mammals, but not yet in manatees. Our study investigated behavioral and acoustic responses of two groups of Antillean manatees (N = 12 and N = 4) housed in zoological parks toward various stimuli involving three sensory modalities: visual, tactile, and auditory. Simultaneous audio and video recordings were collected during three periods of time (i.e., before, during, and after the presentation of all stimuli). Behaviors related to interest, social behaviors, the number and type of calls produced, and their frequency and duration were recorded and analyzed. Manatees reacted more to submerged stimuli than to out-of-water and sound stimuli, with an increase in approach, social contacts, and number of vocalizations. The proportion of squeaks and squeals call types also varied according to stimuli, and call entropy and F0 range varied according to periods. Our results suggest that manatees display sensory preferences when exploring stimuli, with more interest in manipulable stimuli, supporting the importance of their somatic perception. We highlight the need for particular enrichment programs (i.e., involving submerged objects) in zoological facilities. By displaying social contacts and by producing vocalizations, manatees communicate information such as their motivational state. The increase in call rate, harsh calls, and entropy values could be valid indicators of heightened arousal. We encourage further studies to associate acoustic recordings with ethological data collection to increase the understanding of manatees' behaviors andperception. [ABSTRACT FROM AUTHOR]

Wildlife tourism often focuses on marine mammals, and the growing frequency of human interactions raises concerns about the sustainability of these activities and their impact on aquatic species. Tourists have the opportunity to view the Florida manatee (Trichechus manatus latirostris) in various locations; however, the level of tourist activity in some areas and their effects on manatees are unknown. Preliminary studies are essential to assess whether these areas warrant additional regulatory and mitigation strategies based on tourism impact.Here, we investigated tourism activity on a site often visited by small aggregations of Florida manatees. From 2022 to 2023, interviews, citizen science, and trail cameras were used to assess watercraft activity, tourist knowledge, and the educational practices offered by watercraft rental businesses at Portosueno Park, Florida, USA.Both trail cameras and citizen science revealed that boats were the most common visitors to the park, averaging 23 watercraft visits per week. Interviews indicated that the majority of the public did not observe the posted signs addressing manatee harassment and were unaware of the prohibition against chasing manatees, the most frequently observed form of harassment at the park.The methods used complemented each other to elucidate tourism activity and has the potential to inform outreach efforts and mitigation strategies. [ABSTRACT FROM AUTHOR]

To survive cold winters, Florida manatees (Trichechus manatus latirostris) depend on artificial (i.e., power plants) and natural warm water sources such as springs and passive thermal basins. Passive thermal basins can provide critical habitat for manatees for short or extended periods of time. The Henry D. King Powerplant in Fort Pierce, Florida discharged warm water into Moore's Creek until it went offline in 1995. However, it is unknown to what degree manatees continue to occupy this area and how environmental factors influence their occurrence in the creek. To explore this, we examined the habitat use of Florida manatees in Moore's Creek after the shutdown from November 1997 to March 2020 from daily counts of manatees. In addition, we correlated local environmental data (ambient air, temperature, salinity) to assess if Moore's Creek had properties indicative of a passive thermal basin. Results indicated there was not an increase or decrease in habitat use over twenty years in the Creek. The consistent use of Moore's Creek over the study period suggests that this habitat possesses thermal and freshwater resources to support manatee occurrence long-term. These findings provide robust support for the importance of this habitat and passive thermal basins for Florida manatees. [ABSTRACT FROM AUTHOR]

Simple Summary: The conservation of endangered wild species such as the Amazon manatee (Trichechus inunguis) requires important attention, as the species plays a crucial role in the maintenance and stability of the Amazon ecosystem. Among several areas of scientific research that help in the conservation of species, cryopreservation is a technique that guarantees storing cells at extremely low temperatures for long-term preservation. In this work, we established the first Amazonian manatee cell line (TINsf) from a skin biopsy. We observe its shape and growth rate over time. Furthermore, we also evaluated how Amazonian manatee cells reacted to andiroba seed oil (ASO) and found that low concentrations of ASO do not affect the growth of TINsf cells, but high concentrations cause a reduction in cell proliferation and cell death. Here, we promisingly show that, in addition to establishing Amazonian manatee cell lines, it was possible to guarantee their applicability for future research. The vulnerable status of the Amazon manatee, Trichechus inunguis, indicates the need to seek measures to guarantee its conservation. In this context, the cultivation of cells in vitro is a strategy that should at least guarantee the preservation of their genetic material. Thus, we established for the first time a primary culture of Amazonian manatee fibroblasts (TINsf) from a skin biopsy of a young male. Karyotypic analysis of the 3rd, 7th, and 12th passages confirmed the taxonomic identity of the species T. inunguis (2n = 56/NF = 92) and indicated that this culture presents genomic stability. Gene and protein expression of vimentin at the 13th passage show the predominant presence of fibroblasts in TINsf. To test the cell line's responsiveness to materials and demonstrate a possible application of this culture, it was exposed to andiroba seed oil (ASO), and its viability and proliferative capacity were evaluated. ASO demonstrated toxic effects at the highest concentrations and longest exposure times tested, reproducing results observed in human cultures, indicating the applicability of TINsf in toxicological and biotechnological studies. After cryopreservation, the TINsf line maintained its proliferative potential, indicating the establishment of a new culture available for future studies. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel and enhanced approach for crowd counting within the domain of manatee monitoring, aiming to significantly improve efficiency and accuracy. The proposed model achieves state-of-the-art results in the challenging task of manatee counting, simplifying the work of scientists and experts in the field. Our model not only facilitates the identification and enumeration of manatees in images and videos but also excels in scenarios that pose considerable challenges for human observers. To enhance accurate counting of the manatee aggregation, we introduce a framework with three key innovations to tackle the challenge: a new approach to generate density maps during the training process, an augmented technique to balance the dataset, and a cross-domain solution to enhance overall performance. The proposed two-dimensional Gaussian kernel offers a refined method for creating density maps, providing a more robust foundation for the training phase. Additionally, we built a balanced and augmented dataset, ensuring that the model is exposed to diverse and representative instances, thus improving its generalization capabilities. Furthermore, we incorporate a cross-domain phase pretraining the model utilizing an image dataset of wild animals to initialize the weights and further improve performance. Experiments and comparisons, with respect to previously established CSRNET model presented in Wang et al. (2023), demonstrate noteworthy improvements. Remarkably, our model achieves a Mean Absolute Error (MAE) of nearly half compared to the rival approach, showcasing the substantial advancements achieved through our refined methodology. This progress boosts the reliability of manatee counting in conservation efforts and ecological research.

The dynamics and drivers of inter-species interactions in the wild are poorly understood, particularly those involving social animal species. Inter-species interactions between cetaceans and sirenians have rarely been documented and investigated. Here, we report 10 cases of interaction initiated by adult bottlenose dolphins (Tursiops truncatus) towards Antillean manatee (Trichechus manatus manatus). Interactions were documented through behavioral observations in the wild (n = 7) and from the examination of orphaned calves (i.e., tooth rake marks on their body; n = 4) that entered a rehabilitation facility, one individual both observed interacting with dolphins and found stranded with bite marks. Bottlenose dolphins were observed interacting with orphan manatee calves and with mother-calf pairs, exhibiting agonistic behavior (n = 2), affiliative or neutral behaviors (n = 1), but the behavioral contexts of these interactions remain unclear in most cases (n = 7). Information on stranded individuals was collected from four calves (of 13 examined calves) recovered in poor condition with bottlenose dolphin tooth rakes and bite wounds on their bodies, one of which died. Injury from bite wounds varied in extent and severity, ranging from superficial scratches leaving rake marks to deep lacerations. Our findings suggest the regular occurrence of agonistic behaviors initiated by adult bottlenose dolphins and directed toward manatee calves. However, the drivers of these interactions remain unknown and need to be further investigated. [ABSTRACT FROM AUTHOR]

In Venezuela, Antillean manatees (Trichechus manatus manatus) have declined mainly due to habitat loss and degradation, but other threats to the species persist. The objective of this work was to investigate the manatee distribution and conservation issues in Maracaibo Lake, Venezuela. Aiming to collect evidence on manatee presence, we conducted 404.14 hours of boat-based surveys and observations from the shore during 2003, 2004, 2009, and 2010. Environmental parameters were collected in areas where manatees were observed including pH, temperature, dissolved oxygen, salinity, transparency, and depth. Also, we recorded plants or algae that could serve as potential food for manatees. We developed 96 informal and opportunistic talks with local fishermen, to gather information about manatee occurrence, boat traffic, and people’s perception of the species. Finally, we reviewed published and unpublished documents containing information on manatees in Maracaibo Lake. The resulting database contains information on 39 sightings and 13 reports of dead manatees. The known causes of death were poaching, vandalism, boat collision, and entanglement in fishing nets. The Maracaibo Lake offers many suitable habitats for manatees, but also faces a wide array of conservation problems that represent critical threats to this endangered subspecies. Long-term monitoring of this population and potential sources of mortality is highly needed. [ABSTRACT FROM AUTHOR]

Sirenians are a well-known example of morphological adaptation to a shallow-water grazing diet characterized by a modified feeding apparatus and orofacial morphology. Such adaptations were accompanied by an anterior tooth reduction associated with the development of keratinized pads, the evolution of which remains elusive. Among sirenians, the recently extinct Steller's sea cow represents a special case for being completely toothless. Here, we used μ-CT scans of sirenian crania to understand how motor-sensor systems associated with tooth innervation responded to innovations such as keratinized pads and continuous dental replacement. In addition, we surveyed nine genes associated with dental reduction for signatures of loss of function. Our results reveal how patterns of innervation changed with modifications of the dental formula, especially continuous replacement in manatees. Both our morphological and genomic data show that dental development was not completely lost in the edentulous Steller's sea cows. By tracing the phylogenetic history of tooth innervation, we illustrate the role of development in promoting the innervation of keratinized pads, similar to the secondary use of dental canals for innervating neomorphic keratinized structures in other tetrapod groups. [ABSTRACT FROM AUTHOR]

Many marine mammals exhibit diel trends in vocal production, which can provide information on habitat use and behavioral activity. In Belize, Antillean manatees (Trichechus manatus manatus) commonly inhabit small depressions in the substrate or deep-water coves known as "resting holes". Determining if manatees exhibit diel temporal trends in their call production rate and call types between microhabitats can provide insights into their diurnal and nocturnal activity patterns. Here, we investigate the diel vocalization patterns of wild Antillean manatees in two adjacent resting holes off of St. George's Caye, Belize. Recordings of manatees were made using a bottom-mounted hydrophone located near a reef barrier reef for nine days in July of 2017 and ten days in January of 2018. To explore if and how manatee acoustic activity differs between sites, we compared the number of calls per hour, the number of manatee positive hours, the number of tonal and atonal sounds, and the number of boats detected across sites. A total of 370 hours of acoustic recordings were analyzed resulting in the detection of 3,262 calls. There were no significant differences in the number of manatee calls produced per hour between sites. The average number of calls produced by manatees decreased over the course of several days. The proportion of tonal calls decreased with hours after sunset and increased in boat presence. These results suggest manatees in this region may exhibit different diel activity patterns which appear to be influenced by the characteristics of the environment. These findings can support ongoing conservation and management efforts to safeguard species in Belize. [ABSTRACT FROM AUTHOR]

Manatees are aquatic mammals with voracious appetites. They rely on sea grass as the main food source, and often spend up to eight hours a day grazing. They move slow and frequently stay in groups (i.e. aggregations) in shallow water to search for food, making them vulnerable to environment change and other risks. Accurate counting manatee aggregations within a region is not only biologically meaningful in observing their habit, but also crucial for designing safety rules for boaters, divers, etc., as well as scheduling nursing, intervention, and other plans. In this paper, we propose a deep learning based crowd counting approach to automatically count number of manatees within a region, by using low quality images as input. Because manatees have unique shape and they often stay in shallow water in groups, water surface reflection, occlusion, camouflage etc. making it difficult to accurately count manatee numbers. To address the challenges, we propose to use Anisotropic Gaussian Kernel (AGK), with tunable rotation and variances, to ensure that density functions can maximally capture shapes of individual manatees in different aggregations. After that, we apply AGK kernel to different types of deep neural networks primarily designed for crowd counting, including VGG, SANet, Congested Scene Recognition network (CSRNet), MARUNet etc. to learn manatee densities and calculate number of manatees in the scene. By using generic low quality images extracted from surveillance videos, our experiment results and comparison show that AGK kernel based manatee counting achieves minimum Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). The proposed method works particularly well for counting manatee aggregations in environments with complex background. [ABSTRACT FROM AUTHOR]

Introduction: Small populations are at risk of losing genetic variability much faster than large populations; this subsequently decreases their ability to adapt when facing environmental changes. A small population of the endangered Antillean manatee (Trichechus manatus manatus) has been identified in Guatemala. Objective: This study explored the genetic diversity of the Antillean manatee in Guatemala by analysing mitochondrial DNA control region haplotypes in the two most important habitats for the species, Bahía La Graciosa, a coastal bay and Bocas del Polochic, a coastal wetland, both located in the Izabal State. Methods: Genetic samples were collected using non or minimally invasive sampling techniques: scraping of epidermal tissue, collection of floating feces, and collection of tissue from carcasses. DNA extractions, DNA amplification using polymerase chain reaction (PCR), and sequencing of the control D-loop region were used to process and analyse the samples. Results: Seven mitochondrial DNA sequences were obtained from 36 samples collected (minimum of four and maximum of seven individuals). Four haplotypes were identified, A01, A03, A04, and J01. No other Central American country has reported this number of haplotypes in a manatee population, and it is the first time that haplotype A01 has been reported for the region. The Guatemalan manatee population comprises at least two genetic lineages, the Florida/Greater Antilles lineage (haplotypes A01, A03, and A04) and the Mesoamerican lineage (J01). Conclusion: Further studies, with the use of nuclear markers, are necessary to understand the population dynamics between Bahia La Graciosa and Bocas del Polochic to identify the number of management units present in the country; also, the degree of relatedness with the Belizean population needs to be established to better coordinate conservation efforts. [ABSTRACT FROM AUTHOR]

Introduction: The Antillean manatee (Trichechus manatus manatus) is an endangered species found throughout the Caribbean, and the coastal waters of Central and northeastern South America. Their low numbers are the result of a variety of human-related pressures. A small population of manatees has been identified in Guatemala; however, their spatial and temporal dynamics remain unclear. Objective: To examine long-term trends in the spatiotemporal distribution and abundance of manatees in Guatemala. This included identification of priority areas for manatees including the presence of calves, assessing whether distribution areas are inside protected areas, and studying the relationship between manatee sightings and human activities. Methods: Nine years of standardized aerial surveys were conducted along the Atlantic coast (1992, 2005-2008, 2010-2011, 2014, 2022). Quantitative approaches to detect priority areas, specifically the Kernel density estimation and the Getis-Ord Gi* statistic, were used in the spatiotemporal analysis. A Spearman rank correlation analysis tested for significant correlations between human activities, coastline topographies, and manatee numbers along coastline segments. Manatee abundance across years, survey sections, and protected areas were also examined. Results: A total of 293 sightings and 518 manatees were observed including 476 adults (92 %) and 42 calves (8 %). Manatees were most frequently observed as solitary individuals (60 %). Most manatee (61 %) and calf (68 %) sightings occurred inside protected areas where several priority areas were identified. The two priority areas were Refugio de Vida Silvestre Bocas del Polochic (Bocas del Polochic) and Refugio de Vida Silvestre Punta de Manabique, which were identified as important manatee habitats in 1992. Bocas del Polochic had the highest manatee abundance of all protected areas (p < 0.05). However, a shift in manatee distribution was recorded in 2014, although the cause is unclear. No annual significant differences in manatee abundance were found over time (p = 1.0), but significant differences in abundance were detected between survey sections and protected areas (p < 0.05). Manatee numbers had positive significant correlations with ecological and human parameters. The highest correlation was between manatees and rivers (p < 0.01), and the weakest correlation was between manatees, motorboats, and fishing nets (p < 0.01). Conclusions: The results indicate that the local manatee population remained relatively stable for over 20 years, although changes in overall distribution were noted. It is unclear if the changes are temporary or permanent. As a sentinel species, manatee distribution shifts can be used as early warnings about the health of the environment and can depict current or potential impacts on individual- and population-level animal health. [ABSTRACT FROM AUTHOR]

Introduction: The two subspecies of the West Indian manatee (Trichechus manatus), Florida manatees (T. m. latirostris) and Antillean manatees (T. m. manatus), face different environmental challenges. While Florida manatees have to cope with winter water temperatures below their lower critical temperature of ~ 20 °C and air temperatures below freezing, Antillean manatees live in year-round warm Caribbean waters. Sirenians lack effective thermal insulation and have limited capability of controlling peripheral heat loss. Although severe cold related health issues and mortality are primarily known in Florida manatees, it can be assumed that Antillean manatees and other extant sirenians share the cold-sensitivity, but hardly ever experience it. Contrarily, during summer, Antillean manatees may face the opposite form of thermal stress by being exposed to water temperatures close to their body temperature. However, the upper critical temperature of manatees is not known. Objective: To improve understanding of the impact of high ambient temperatures on manatee physiology. Methods: We measured skin temperature in six Antillean manatees in two different habitats in Belize, and compared the results to skin temperatures measured in two captive Florida manatees. Results: We found a similar temperature distribution pattern over the body surface in both subspecies, but significantly higher temperatures and larger temperature ranges among measuring points in Antillean manatees as compared to Florida manatees. In one Antillean manatee, skin temperature was consistently lower than ambient water temperature by up to 2.5 °C. This implies potential heat uptake from the environment, in contrast to the heat loss experienced by Florida manatees at low water temperatures, apparent in skin temperatures above ambient water temperature. Conclusions: Our findings suggest that heat stress may be a more likely risk for manatees in warm tropical waters. Despite the small sample size, our results present important findings towards understanding thermal tolerance and impact of high ambient temperatures on manatee physiology. [ABSTRACT FROM AUTHOR]

Introduction: Marine mammal strandings can be used to determine the impacts of anthropogenic activity on the species survival, population health, and levels of environmental pollution in ecosystems. In addition, these data can help design conservation and management strategies as well as identify priority areas for the species. The West Indian manatee (Trichechus manatus) is listed as endangered throughout its range. In Guatemala, it is distributed along the Caribbean coast. Anthropogenic activities appear to be having a direct pressure on the species, affecting the status of the population. Objective: The general purpose of this study was to analyze the 30 years of documented manatee stranding reports available for Guatemala. Two specific objectives were defined to: 1) conduct a spatial analysis of manatee strandings to identify the areas of high stranding concentration, and 2) determine whether there were sex differences in the number of strandings. Methods: Characteristics and areas of concentration of manatee strandings were described along the Caribbean coast between 1992 to 2022. Sites with the highest probable density of strandings were identified using a Kernel density analysis. We compared the number of stranding events that occurred in each protected area that included manatees in their management plans and each municipality of Izabal. We determined whether there were sex differences in the number of stranded manatees. We use the potential biological removal to estimate the maximum number of manatees that can be removed from the population due to anthropogenic causes without negatively impacting species survival. Results: Forty-three manatee stranding events were recorded throughout the species' range in Guatemala (48 total individuals). The sites with the highest predicted density of strandings were Santo Tomás de Castilla bay, followed by Lake Izabal (including the limits of the Refugio de Vida Silvestre Bocas del Polochic) and Parque Nacional Río Dulce. The majority of the cases were registered in protected areas (60 %). Estimates of potential biological removal were equivalent to less than one manatee per year, which was exceeded by the annual average of stranded manatees recorded (three manatees). Conclusions: Anthropogenic activities cause mortality of manatees in this region, despite the implementation of protected areas. Poaching was identified as the main cause of manatee mortality in Guatemala. The implementation of management strategies focused on minimizing threats to the species, based on the application of environmental legislation and environmental awareness, is essential. The creation and implementation of a protocol for the stranding of marine mammals on the Caribbean coast of Guatemala is necessary, in order to obtain standardized records of these events and conduct rescue efforts and releases when possible. [ABSTRACT FROM AUTHOR]

Simple Summary: Fewer than 200 manatees are hosted permanently by zoological parks worldwide. Their living conditions differ considerably from zoo to zoo. Recent research on ecology, acoustics, cognition and behaviour has changed the perception humans have on manatees with implications for their welfare. Using the five-model approach, this study examines our current knowledge on manatees' behaviour and cognition, and suggests ways to improve their welfare in zoological parks. The order Sirenia comprises several species of manatees and one species of dugong. These popular marine mammals are relatively recent acquisitions to zoological parks throughout the world. As far as we know, there are less than 200 manatees, mostly American, a few African, and ever less Amazonian, currently in zoological parks. American manatees are predominantly found in zoos in Europe, North America, and in some Asian countries, while African ones are present exclusively in Asian zoos. The living conditions of captive manatees differ considerably from zoo to zoo (i.e., numbers, sex ratio, outdoor vs. indoor habitats, complex vs. simple habitats). Most research on manatee behaviour has been relatively recent, and studies on cognition, sociality, and ecology have a significant impact on our perception of manatee needs and management, with wider implications for their welfare. In the wild, manatees demonstrated various cognitive capacities; spatial memory and learning abilities play an important role in their daily life in a complex and dynamic environment. Furthermore, there is evidence that these mammals are more social animals than expected. Individuals show various personality traits on the boldness–shyness continuum and their sociality varies. All those parameters are important in terms of animal welfare. Several behavioural studies showed that standardized enrichment programs benefit and ensure the welfare of captive zoo animals. However, obtaining accurate information on the presence of manatees in zoos, living conditions, management, and consequently welfare remains challenging. This study examines the current knowledge on manatee behaviour and cognition and then discusses different approaches to improving the welfare of this charismatic marine mammal in zoological parks. [ABSTRACT FROM AUTHOR]

Hematology and blood chemistry tests constitute an easy-to-apply veterinary tool that evaluates an organism's systemic functioning and disease process by comparing the level of specific analytes against species norms. Such analyses help monitor marine mammals' health and nutritional status. Although reference values have been published for a few manatee populations, there are none for Antillean manatees (Trichechus manatus manatus) in Colombia. We aim to establish the reference values for hematology and serum chemistries for these manatees and determine if there are variations between individuals of different age groups and sex. Thus, we obtained whole blood and serum samples from 45 rehabilitated manatees from Colombia between 1992 and 2021. Complete Blood Count and Comprehensive Metabolic Panel values were calculated, and differences between age groups and sex were determined. Results were compared with published reference intervals of other Antillean manatee populations, Florida manatees (Trichechus manatus latirostris), and Amazonian manatees (Trichechus inunguis) from Brazil. We determined the reference intervals of hematology and serum chemistry for manatees in Colombia for different age and sex categories. No relevant clinical variations were found in hematological parameters due to sex. Marked differences were found between age groups, mainly among young animals with an expected faster metabolism. There were significant variations between hematological and blood chemistry values when the Colombian manatees were compared to manatees from Puerto Rico and Amazonian manatees from Brazil. Such variations are likely influenced by evolutionary history and environmental factors associated with differences in habitat salinity and diet. We recommend that future studies correlate these blood tests with specific panels. We further recommend conducting wild manatee health assessments as this information will yield essential data for species management schemes needed due to the multiple anthropogenic and environmental threats that manatees face today which put the Colombian manatee's health and ultimate survival at risk. [ABSTRACT FROM AUTHOR]

Acoustic signalling plays a crucial role in mother–calf communication. Here, we describe the acoustic signalling of three free-living Antillean manatee mother and calf pairs and one trio. The mother–calf pairs/trio produced six call types. The call rate varied between the pairs. The pair that experienced human interaction during the recording period had the highest call rate. Additionally, the Squeak vocalisations produced by each mother–calf pair differed structurally. Our results indicate that age and human interaction may affect call rate and suggest the potential production of signature vocalisations by manatee mothers and calves. Our findings add to the current knowledge of manatee acoustic communication. [ABSTRACT FROM AUTHOR]

While all sirenian species are considered sentinel animals for the ecological health of their habitat, they are currently facing extinction risk. The Antillean manatee (Trichechus manatus manatus) is classified as an endangered species in Brazil.Its distribution and behaviour are mainly influenced by the presence of aquatic vegetation, freshwater and anthropogenic activities, as well as by variations in tides, temperature and salinity.The study investigated the behaviour of manatees in the Barra do Rio Mamanguape Environmental Protection Area in north‐eastern Brazil, and the relationship between these behaviours and the biotic and abiotic characteristics of this estuarine environment.The behavioural data were collected between November 2016 and May 2017, during 35 days of monitoring. The records of surface behaviour were obtained using animal focal sampling. Anthropogenic activities were recorded qualitatively and quantitatively during the surveys.Warmer water (30–31°C), reduced turbidity (1–2 m) and sandy sediments had a significant influence on the behaviour of the manatees.The manatees presented neutral behaviour more often than expected in response to anthropogenic activities, which indicates that the animals were undisturbed by these activities.This is the first systematic study of the influence of biotic and abiotic factors on the behaviour and ecology of Antillean manatees in a protected area of a tropical region, providing important new insights into the behavioural ecology of an endangered species.The Barra do Rio Mamanguape Environmental Protection Area seems to fulfil the goal of adequate management and conservation of manatees in a tropical region. Specifically, it shows that appropriate management, law enforcement and inspection measures are essential for maintaining endangered populations. [ABSTRACT FROM AUTHOR]