Brazilian Coast Research Articles

The good, the bad and the boa: An unexpected new species of a true boa revealed by morphological and molecular evidence.

Snakes of the genus Boa are outstanding elements of the New World biota with a broad sociological influence on pop culture. Historically, several taxa have been recognized in the past 300 years, being mostly described in the early days of binomial nomenclature. As a rule, these taxa were recognized based on a suite of phenotypic characters mainly those from the external morphology. However, there is a huge disagreement with respect to the current taxonomy and available molecular phylogenies. In order to reconcile both lines of evidence, we investigate the phylogenetic reconstruction (using mitochondrial and nuclear genes) of the genus in parallel to the detailed study of some phenotypic systems from a geographically representative sample of the cis-Andean mainland Boa constrictor. We used cyt-b only (744bp) from 73 samples, and cyt-b, ND4, NTF3, and ODC partial sequences (in a total of 2305 bp) from 35 samples, comprising nine currently recognized taxa (species or subspecies), to infer phylogenetic relationships of boas. Topologies recovered along all the analyses and genetic distances obtained allied to a unique combination of morphological traits (colouration, pholidosis, meristic, morphometric, and male genitalia features) allowed us to recognize B. constrictor lato sensu, B. nebulosa, B. occidentalis, B. orophias and a distinct lineage from the eastern coast of Brazil, which we describe here as a new species, diagnosing it from the previously recognized taxa. Finally, we discuss the minimally necessary changes in the taxonomy of Boa constrictor complex; the value of some usually disregarded phenotypic character system; and we highlight the urgency of continuing environmental policy to preserve one of the most impacted Brazilian hotspots, the Atlantic Forest, which represents an ecoregion full of endemism.

Saturated Iso-Type Fatty Acids from the Marine Bacterium Mesoflavibacter zeaxanthinifaciens with Anti-Trypanosomal Potential.

Chagas disease is a Neglected Tropical Disease with limited and ineffective therapy. In a search for new anti-trypanosomal compounds, we investigated the potential of the metabolites from the bacteria living in the corals and sediments of the southeastern Brazilian coast. Three corals, Tubastraea coccinea, Mussismilia hispida, Madracis decactis, and sediments yielded 11 bacterial strains that were fully identified by MALDI-ToF/MS or gene sequencing, resulting in six genera-Vibrio, Shewanella, Mesoflavibacter, Halomonas, Bacillus, and Alteromonas. To conduct this study, EtOAc extracts were prepared and tested against Trypanosoma cruzi. The crude extracts showed IC50 values ranging from 15 to 51 μg/mL against the trypomastigotes. The bacterium Mesoflavibacter zeaxanthinifaciens was selected for fractionation, resulting in an active fraction (FII) with IC50 values of 17.7 μg/mL and 23.8 μg/mL against the trypomastigotes and amastigotes, respectively, with neither mammalian cytotoxicity nor hemolytic activity. Using an NMR and ESI-HRMS analysis, the FII revealed the presence of unsaturated iso-type fatty acids. Its lethal action was investigated, leading to a protein spectral profile of the parasite altered after treatment. The FII also induced a rapid permeabilization of the plasma membrane of the parasite, leading to cell death. These findings demonstrate that these unsaturated iso-type fatty acids are possible new hits against T. cruzi.

Human health risks assessment of the fluctuations in mercury levels in seafood from different key regions of Rio de Janeiro, Brazil.

Mercury (Hg) contamination on the Brazilian southeast coast has been highlighted, especially in relation to species of commercial importance. This study aimed to quantify the Hg concentration in species of mussels, fish, and crabs obtained from fishing colonies on the beaches of the west and south of the city of Rio de Janeiro, investigate the possible effect of seasonality, sex, and location sampling, and finally, the risk to consumer health in four different age groups. The difference between cooked and raw commercially available mussel samples was also verified. The main results highlight that the fish presented higher levels of Hg and that the mussel samples sold cooked presented lower levels of Hg when compared to the raw ones. For Micropogonias furnieri, Sardinella brasiliensis, and Callinectes spp., the season variable influenced Hg concentrations, while only for Merluccius merluccius was a difference between the sexes identified, with males having the highest values. Although Hg concentrations in animals were below the permitted limit, consumption of all species exceeded the monthly intake limit for this metal. For the hazard quotient (HQ) calculation, most species presented HQ > 1, especially when ingested by the child population. These results are fundamental for designing consumption strategies for these animals, in order to prioritize the acquisition of some species over others, depending on the location and/or season, for each age group, with the aim of maintaining seafood consumption with minimal risk to the population's health.

Global Chlorophyll Concentration Distribution and Effects on Bottom Reflectance of Coral Reefs

Despite the limited coverage of coral reefs in the world’s oceans, they play a crucial role in global marine biodiversity and providing essential ecosystem services. This study explores the influence of chlorophyll-a (Chl-a) concentration in the water column on the estimation of bottom reflectance (rb) in coral reefs monitored by the Allen Coral Atlas coral reef monitoring system, using satellite imagery from a Sentinel-2 MSI sensor. We conducted a comprehensive analysis, considering Chl-a global distribution and variability, and its combined effect with water column depth over rb calculation. Our results demonstrated that the impact of Chl-a on rb estimation becomes significant when the water column depth exceeds 3 m. While suggesting the optionality of using regional Chl-a values, our study highlights potential overestimations of Chl-a in optically complex environments, such as along the Brazilian coast. This research contributes to refining coral reef monitoring systems and underscores the importance of accurate Chl-a assessments for robust environmental evaluations.

Population aspects of Crassostrea sp. in a protected mangrove estuary: perspectives for artisanal fishing management

ABSTRACT The mangrove oyster (Crassostrea) is one of the most common bivalves found on the Brazilian coast, widely used in artisanal fisheries. Oysters are dioecious with external reproduction, typically found in estuarine environments. The present study aimed to identify the population aspects of Crassostrea in different fishing locations in northeastern Brazil. The study area was the Acaú-Goiana Extractive Reserve, a protected area focused on the development of artisanal fisheries. Oysters were collected during low tide at three sampling points, where their removal from mangrove roots was carried out, during May, July, September, November 2021, and January and March 2022. In the laboratory, biometric measurements were conducted, and for the months of May and November 2021 histological preparations to study the reproductive cells. Biometric measurements were significantly higher in the dry season at all sampling points. The sex ratio was M = 0.38, F = 0.62, for May, and M = 0.30, F = 0.69, for November. The biometric and reproductive data obtained can support the development of management strategies, including a rotation plan between collection sites and the establishment of a minimum size for fishing. Here we recommend a minimum size of 20 mm shell length (SL) or larger for fishing.

Current knowledge of Holothuriida (Holothuroidea: Echinodermata) from Brazil

Sea cucumbers are the second most diverse class among echinoderms. They are characterized by an elongated body and dermal ossicles in the body wall. Among the included groups in that class, the order Holothuriida encompasses many species of commercial interest. Faced with the threats of biodiversity loss resulting from the climate crisis and the advancement of cities, this study provides an overview of recent research involving the Holothuriida of the Brazilian Coast. Searches were carried out in the main periodical databases, using appropriate keywords, targeting publications on the subject in the period between 2000 and 2023. In total, 69 publications were found, most of them corresponding to scientific articles in international journals. Most of the studies come from the Northeast region in Brazil (56.52%). Regarding lines of research, those involving taxonomy and molecular analysis were the most prevalent. Over these 20 years, seven species constituted new occurrences. Of note are the studies focused on Holothuria (Halodeima) grisea, which makes up 39.13% of papers. Despite progress, little is known about morphological variations, genetic distance between populations, population densities, and on reproductive biology of species. Brazil has a vast, heterogeneous coastal area, with unique characteristics to which the species are adapted. The findings reinforce the importance to expand studies aiming on knowing the biodiversity, reproductive biology, and population densities of species. Such data are essential for the creation of public policies aimed at the conservation of species of Holothuriida and their habitats.

Hematology and Serum Biochemistry of Coastal Seabirds Rehabilitated on the Southeastern and Southern Coast of Brazil.

Complete blood counts (n=566) and serum biochemistry (n=426) were assessed in seven coastal seabirds species that underwent rehabilitation along the southeastern and southern coast of Brazil from Saquarema, Rio de Janeiro State (22°56'16.44″S, 42°18'24.16″W) to Laguna, Santa Catarina State (28°29'43″S, 48°45'39.2″W), from August 2016 to August 2020. Blood samples were collected from four species of Charadriiformes, including Kelp Gull (Larus dominicanus, n=136), South American Tern (Sterna hirundinacea, n=25), Cabot's Tern (Thalasseus acuflavidus, n=17), and Common Tern (Sterna hirundo, n=14) as well as three species of Suliformes, the Brown Booby (Sula leucogaster, n=212), Magnificent Frigatebird (Fregata magnificens, n=104), and Neotropic Cormorant (Nannopterum brasilianum, n=58). The individuals were sampled as part of the protocol required before their release into the wild when considered healthy. This work aimed to establish the normal hematologic and biochemical reference values of those seabird species and, when possible, to analyze variations among age class and sex and to compare those with the available data in the literature. In addition, we provide the first baseline data for the South American Tern, Cabot's Tern, and Neotropic Cormorant. Baseline hematologic data are crucial for assessing health status of individuals and to support management and conservation actions, including release of seabirds into the wild.

Food preference for native and invasive prey in the naive lancehead pitviper

AbstractThe presence of invasive species in the environment can be highly detrimental. The success of these species depends on their interaction with native ones. The prey–predator relationship between invasive and native species can result in biodiversity loss or the introduction of new food items for local predators. Due to its tropical and extensive nature, Brazil is vulnerable to the colonization of invasive species. Snakes are a group of animals that can act as both predators and prey for invasive species. The pitviper Bothrops jararaca is an abundant and widely distributed native species on the Brazilian coast. Based on this, we conducted a study on the feeding preferences of naive B. jararaca juveniles regarding invasive and native prey. We found that this species exhibits a greater preference for native anurans compared to Rana catesbeiana, an invasive amphibian associated with significant environmental impacts. Additionally, the gecko Hemidactylus mabouia, a prey that triggered intense predatory responses from the pitviper, reveals that this species, even with a short period of coexistence with B. jararaca, has established an intense prey–predator relationship. The negative correlation between prey size and feeding interest, guided solely by olfactory cues, adds a layer of complexity to understanding the feeding choices of B. jararaca, providing valuable insights for conservation and environmental management strategies.Abstract in Portuguese is available with online material.

Mixed-marker data indicate the population biology, history, and the stock structure of crevalle jack Caranx hippos (Linnaeus, 1766) in the tropical Atlantic: A regional and latitudinal conservation genetics approach

The crevalle jack Caranx hippos (Carangidae: Caranginae) is a commercially important carangid, especially along the Brazilian Northeastern coast. However, little is known about its population structure and genetic diversity, which is crucial information for species conservation. Using mitochondrial [barcode region COI and control region] and nuclear (first intron S7) data, we investigated the genetic structure and demographic history of C. hippos along the Brazilian Northeastern coast, and included the COI public database to provide a latitudinal approach. Both mitochondrial markers revealed two coexistent lineages along the Brazilian Northeastern coast, while the nuclear DNA did not recover any signals of structure. This mitonuclear discordance can be explained by both male dispersal and demographic history, which seem to be closely related to the Pleistocene period. Over the glacial cycles, the lineages may have used different refuges, regaining contact during the interglacial cycles. This hypothesis of previous allopatry is reinforced by the profound genetic distance found. The latitudinal approach reveals a deep differentiation between the Carolina and both Brazilian and Caribbean Provinces, with high and significant FST pairwise values, such that the tropical-temperate climate transition may be acting as a gene flow barrier between them. Thus, we suggest two preliminary stocks for C. hippos in the Atlantic: (1) Carolina and (2) Brazilian and Caribbean Provinces.

Fatal interactions of albatrosses with weather radiosondes/balloons on the Southern and Southeastern coasts of Brazil

Weather radiosondes play a crucial role in gathering atmospheric data for weather modeling and forecasting. However, their impact on marine wildlife, particularly seabirds, has raised concerns regarding the potential threats posed by these instruments. This study aims to assess the adverse effects of weather balloons on albatrosses, with a focus on the Southwest Atlantic region. The research reveals seven cases of entanglement of radiosonde equipment, leading to severe injuries and mortality along the Southern and Southeastern coasts of Brazil. Recommendations for mitigating the environmental impact of weather balloons include the adoption of biodegradable materials in their design and the implementation of improved retrieval protocols. Furthermore, the study stresses the importance of continued monitoring and research to address the interaction of weather radiosondes with marine animals. This approach is vital for ensuring the sustainable collection of scientific data while minimizing harm to marine life and ecosystems.

New volcanological, 40Ar/39Ar dating and paleomagnetic record from Trindade Island and stratigraphic implications

Unrevealing the stratigraphy of volcanic systems is fundamental to understanding their eruptive history and requires a multiproxy approach for the accurate correlation and interpretation of deposits. We present new volcanological, 40Ar/39Ar ages and paleomagnetic data from the volcanic rocks of Trindade Island, located at ∼1.260 km from the Brazilian coast in the South Atlantic Ocean. The reconstruction of the volcanic history of Trindade Island is important because it is the youngest volcanic terrain in Brazil and part of a submarine chain that represents the most recent plume-induced alkaline manifestation beneath the South American plate. Our results suggest Trindade Island underwent two main phases of volcanism. The first phase (3.9–1.5 Ma) formed the Trindade Complex and Desejado Formation, with eruptive styles ranging from phreatomagmatic/Surtseyan to Vulcanian and of dominant phonolitic composition. The second phase (1.0–0.06 Ma) formed the nephelinitic monogenetic centers Morro Vermelho, Valado and Paredão Volcano Formations through dominant Hawaiian and Strombolian styles. The new ages imply a revised stratigraphy for the youngest units of Trindade Island, with partial overlap between them. The revised chronology integrated to the paleomagnetic directional data evidence that Trindade Complex formed during Gauss normal chron (D = 355.4°; I = −49.6°), Valado and Paredão Volcano during Brunhes normal chron (D = 14°; I = −42.3° and D = 9.2°; I = −35.2°, respectively), while Morro Vermelho records the late Matuyama-early Brunhes chron (D = 36.5°; I = −19.8°), with site-level mean paleodirections of normal and transitional polarity within the reverse Matuyama interval.

Optimization of alginate extraction conditions from the brown seaweed Dictyota mertensii using a central composite design

This work extracts alginate from Dictyota mertensii, a brown macroalga found on the north coast of northeastern Brazil. A Central Composite Design (CCD) using Response Surface Methodology (RSM) was used to optimize the process of extracting the alginate present in the brown alga Dictyota mertensii, considering the factors of time, temperature, and concentration Na2CO3. Extraction yield (η), sulfate content, intrinsic viscosity ([η]), viscosimetric molar mass (Mv), color parameters (a*, b* e L*), M/G ratio and inhibitory concentration IC50 are model response variables. The Dictyota mertensii algae has its chemical composition expressed. Response surfaces are plotted from the variables studied, a quadratic model was predicted, the influence of factors is analyzed, and response variables are subjected to analysis of variance (ANOVA) and F-test at 95 % confidence. The predicted conditions are experimentally validated. The antioxidant potential was evaluated at seven concentrations (0.2–5.0 mg/mL) based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging. The maximum extraction yield was 29.28±0.02 %, and sulfate content ranged from 3.50±0,00 % to 12.33±0.29 %. The maximum values of [η] and Mv were 5.84±0.06 dL/g and 278.00±2.66 kDa, respectively. The alginate showed a dark brown color and M/G ratio < 1, indicating that the extracted alginate provides rigid and compact gels, which allows its application in films, encapsulations, and protecting probiotics. The maximum antioxidant capacity and the IC50 were 54.93±0.27 % and 0.51±0.07 mg/mL, respectively, indicating the material obtained as a moderate natural antioxidant.

Back on top: Resuspended by dredging and other environmental disturbances, organochlorine compounds may affect the health of a dolphin population in a tropical estuary, Sepetiba Bay

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins’ (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 μg/g of ΣPCB; 0.08–130 μg/g of ΣDDT; <0.002–4.56 μg/g of mirex; <0.002–1.84 μg/g of ΣHCH and <0.001–0.16 μg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline.

Emerging and legacy contaminants on the Brazilian southern coast (Santa Catarina): A multi-biomarker approach in oysters Crassostrea gasar (Adanson, 1757)

Coastal environments, such as those in the Santa Catarina State (SC, Brazil), are considered the primary receptors of anthropogenic pollutants. In this study, our objective was to evaluate the levels of emerging contaminants (ECs) and persistent organic pollutants (POPs) in indigenous Crassostrea gasar oysters from different regions of SC coast in the summer season (March 2022). Field collections were conducted in the São Francisco do Sul, Itajaí, Florianópolis and Laguna coastal zones. We analyzed the bioaccumulation levels of 75 compounds, including antibiotics (AB), endocrine disruptors (ED), non-steroidal anti-inflammatory drugs (NSAIDs), polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and pesticides. Furthermore, we assessed biomarker responses related to biotransformation, antioxidant defense, heat shock protection and oxidative damage in oysters' gills. Prevalence of ECs was observed in the central and southern regions, while the highest concentrations of POPs were detected in the central-northern regions of SC. Oysters exhibited an induction in biotransformation systems (cyp2au1 and cyp356a1, sult and GST activity) and antioxidant enzymes activities (SOD, CAT and GPx). Higher susceptibility to lipid peroxidation was observed in the animals from Florianópolis compared to other regions. Correlation analyses indicated possible associations between contaminants and environmental variables in the biomarker responses, serving as a warning related to climate change. Our results highlight the influence of anthropogenic activities on SC, serving as baseline of ECs and POPs levels in the coastal areas of Santa Catarina, indicating more critical zones for extensive monitoring, aiming to conserve coastal regions.

Artificial neural networks ensemble methodology to predict significant wave height

The forecast of wave variables are important for several applications that depend on a better description of the ocean state. Due to the chaotic behaviour of the differential equations which model this problem, a well know strategy to overcome the difficulties is basically to run several simulations, by for instance, varying the initial condition, and averaging the result of each of these, creating an ensemble. Moreover, in the last few years, considering the amount of available data and the computational power increase, machine learning algorithms have been applied as surrogate to traditional numerical models, yielding comparative or better results. In this work, we present a methodology to create an ensemble of different artificial neural networks architectures, namely, MLP, RNN, LSTM, CNN and a hybrid CNN–LSTM, which aims to predict significant wave height on six different locations in the Brazilian coast. The networks are trained using NOAA’s numerical reforecast data and target the residual between observational data and the numerical model output. A new strategy to create the training and target datasets is demonstrated. Results show that our framework is capable of producing high efficient forecast, with an average accuracy of 80%, that can achieve up to 88% in the best case scenario, which means 5% reduction in error metrics if compared to NOAA’s numerical model, and a increasingly reduction of computational cost.

NURSERY AREA FOR THE THREATENED GUIANA DOLPHIN, SOTALIA GUIANENSIS, ON THE NORTHEAST COAST OF BRAZIL

Cetacean calves are considered fragile and vulnerable, especially in the first year of life. To guarantee safety and increase the likelihood of survival, females with calves use habitats with unique characteristics, called nursery areas. In the present study, we investigated whether the Guiana dolphin Sotalia guianensis, considered a threatened species in Brazil, uses the Tibau do Sul Coastal Wildlife Reserve (REFAUTS) as a nursery area. We identified the Guiana dolphins through photographs and recorded the composition of the groups during the 41-day sampling period, between 2013 and 2019. We identified 17 adults/juveniles in the company of calves, five of which were recorded in three or more years of the study. The average size of the Guiana dolphin groups (mean±SE) was 2.4±0.08 individuals, ranging from 2 to 5 individuals (n = 98). Groups with calves were recorded in every year of the study and on 53.7% of the sampling days. A total of 35.8% of the Guiana dolphin groups had calves. These results suggest that REFAUTS is an important nursery area for Guiana dolphins on the Northeast coast of Brazil.

Biological patterns of reproduction of the Brazilian sardine Sardinella brasiliensis in the purse seine fishery of Southwest Atlantic Ocean: A long-term assessment

Recent estimates of the size at first maturity (L50) of Sardinella brasiliensis showed contradictory results with a decreasing in the fish stock biomass encompassed by increasing values of L50. The methodological approach used hereby allowed to separate sardines classified in the virginal maturity stage from those categorized in the recovery stage, and ready for one next spawning event. This study evaluated the hypothesis of the existence of separated stocks experiencing distinct environmental conditions and fishing pressures which may have altered L50 estimates using a robust dataset based on biological samples collected along the entire species distribution area in the southeast-south Brazilian coast [Rio de Janeiro (RJ), São Paulo (SP), Paraná (PR), Santa Catarina (SC) and Rio Grande do Sul (RS)] between 2000 and 2018. A reclassification of the gonadal maturity stages provided a more realistic estimate of L50. Combining biological, reproductive, fishing data and the mean temperature of the catch (MTC), the leave-one-out classification correctly re-assigned individuals with an overall accuracy of 85% [100% (RJ), 45% (SP), 99% (PR), 99% (SC) and 82% (RS)]. The connectivity between the local populations of S. brasiliensis off RJ (23°S) and the southern populations is limited, contrasting to spatial structured semi-discrete population-units found between SP and RS (24°S-30°S). The northern extreme population-unit (RJ, 22°S-23°S) showed an expressive reduction of L50, and a negative correlation was detected between the increasing MTC values and the abundance of early maturing individuals and recruits of the species. Stock specific L50 estimates seemed to act as indicators of long term environmental fluctuations.

Traits vary differently across a lowland forest–sand dune gradient in two common trees of the Amazon restinga coast

Intraspecific trait variation is a key feature that enables species to occur in heterogeneous landscapes. We studied Clusia grandiflora and Anacardium occidentale traits over a forest–dune gradient on the Brazilian Amazon coast (restinga). C. grandiflora showed a drought-avoidance strategy, storing water in its leaves, whereas A. occidentale showed conservative resource use in leaves, evidenced by its high dry-matter content and acquisitive resource in wood, showing lower wood density. Only A. occidentale changed its trait values through the forest–dune gradient, showing more conservative leaves in dunes and shrublands, despite a lower wood density than in forest. Leaf and wood traits are likely to be decoupled among Amazon coastal trees and their responses to environmental gradients are species-specific.

Biodiversity patterns of macrofauna associated with Halodule wrightii (Ascherson) in meadows of north-eastern Brazil

Context Seagrass meadows are highly productive habitats with a vast species diversity that perform multiple ecosystem services. The fauna associated with these environments is responsible for many of the ecosystem services. Therefore, the fauna composition and functional characteristics should be considered in studies addressing seagrass meadows. Aims This study aimed to evaluate the differences in the taxonomic and functional compositions of the macrofauna associated with Halodule wrightii (Ascherson) meadows subject to different settings of habitat characteristics in the shallow coastal regions of the north-eastern coast of Brazil. Methods We used the Hill diversity series to estimate taxonomic diversity, whereas functional diversity was estimated through biological-trait analyses. Key results Distinct patterns of taxonomic and functional diversities were observed among meadows. However, the composition of functional traits diverged more. Lower taxonomic and functional diversity were observed in the Suape meadows, with values mainly related to the low organic matter content. Catuama meadows presented opposite results, associated with higher organic matter and plant density. Conclusions The meadow heterogeneity can influence the associated macrofauna and its functional characteristics. Implications These results are highly relevant for predicting the consequences of changes in seagrass meadows and how this affects the functioning of these ecosystems.

Morphological analysis of the digestive tract of Antillean manatee (Trichechus manatus manatus, Linnaeus, 1758) in northeast Brazil

Morphological studies of the digestive tract are relevant to know the biology and understand the eating habits to conserve species. Our objective was to analyze macroscopically and microscopically the digestive tract of Antillean manatee (Trichechus manatus manatus). Samples were collected from 20 animals found dead stranded on the coast of northeastern Brazil or that died during the rehabilitation process in captivity between July 1995 and March 2017. The macroscopic analysis of the gastrointestinal tract was carried out from the in loco monitoring of the two necropsies. For microscopic evaluation, tissue fragments were collected during necropsy, fixed with 10% buffered formaldehyde and subjected to routine histological processing, with 5 μm thick slices, and subsequently submitted to the Hematoxylin-Eosin staining method, the Verhoeff method, and the periodic acid-Schiff method. Macroscopically, neonates and adults have the same digestive tract structures, namely esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, and rectum. The microscopic analysis demonstrated that the digestive tract is formed by four histological layers (mucosa, submucosa, muscularis, and serosa or adventitia). In the esophagus, esophageal glands are absent and there are elastic fibers in the submucosal layer and between the external muscle and adventitial layers. The stomach has a structure called the cardiac gland, which microscopically presents ontogenetic differences regarding the depth of the lining epithelium and the orderly distribution of cells along the gastric gland. In the duodenal ampulla and in the diverticula, duodenal glands were identified in the submucosa. The luminal portion of the mucous layer of the cecal ampulla, colon, and rectum is lined by keratinized stratified squamous epithelium. The digestive tract of the species Antillean manatee is similar to what has been reported for the order Sirenia.