The return of the giant otter (Pteronura brasiliensis) to Tauramena (Casanare, Colombia): relative abundance, distribution, and conservation considerations

The giant otter (Pteronura brasiliensis) is endemic to South America, and in Colombia it is distributed in the Amazon and Orinoquia regions. It inhabits rivers, streams, and lagoons, but prefers the latter two in response to resource availability depending on the season. Giant otters are endangered in Colombia, and aspects of their natural history are still unknown in much of their geographic range. Our research aim is to generate information focused on relative abundance, habitat use, and distribution of the giant otter in an area of Colombia where it was thought to be extirpated. The distribution was evaluated with spatial distribution modeling (SDM) and habitat use using the Wallace 2.0.4 package for the department of Casanare in northeastern Colombia. To assess the population status and abundance in the municipality of Tauramena, 30 transects were surveyed in the Tua River and the Piñalito and El Huesero streams in 2021 and 2022. In general, the distribution models highlighted the importance of precipitation, temperature, and forests for the occurrence of this species. In Tauramena, five family groups were detected, which were composed of an average of 4.83 ± SD 3.16 individuals per group and a relative abundance of 1.03 ind./km. These are positive results for giant otters, as they indicate signs of population recovery of a species previously thought to have been extirpated from this region because of hunting and illegal pelt trade. Even though Tauramena is an area with high levels of anthropic disturbances, giant otters are showing signs of adaptability and plasticity, which provide important conservation opportunities. It is expected that this work will become the first step for the generation of additional information on diet, behavior, and population structure that can inform management plans for the giant otter in Colombia

Pseudomonas aeruginosa sepsis in a neonate Franciscana dolphin (Pontoporia blainvillei): clinical approach and laboratory findings

A neonate (4,2 kg and 71 cm total body length) female Franciscana dolphin, Pontoporia blainvillei, was found stranded alive on a beach in Santa Catarina, Southern Brazil, with respiratory signs (dyspnea, crackles during thoracic auscultation and changes in buoyancy) suggestive of pneumonia. Hand-rearing and rehabilitation efforts were unsuccessful, and the neonate died three days after it was rescued. Postmortem investigation was conducted using diagnostic imaging techniques, such as endoscopy and computed tomography. A complete necropsy and histopathology were performed, revealing bronchopneumonia as well as neutrophilic and discrete otitis media. A pure Pseudomonas aeruginosa culture was obtained from the blowhole, bronchoalveolar lavage, and blood using the API NE System. Our results indicate the cause of death to be related to bacterial sepsis. Further understanding of the main causes of death of Franciscana dolphin calves is warranted for conserving this threatened and understudied species. Keywords: bacterial septicemia, cetacean, otitis, pneumonia, Pseudomonas aeruginosa, rehabilitation, stranding even

Macroscopic and histologic characteristics of sexual maturation in the Burmeister’s porpoise Phocoena spinipinnis from Peru

The morphology and maturation process of gonads of 70 Burmeister’s porpoises Phocoena spinipinnis, with body lengths ranging 135 - 183 cm (n = 34 females) and 64.5 - 182 cm (n = 36 males) are described. Samples were collected in six ports of central and northern Peru from 1987 to 1999. In the field, sexual maturity was determined through macroscopic examination of gonads. Ovarian corpora indicated mature females (resting, lactating, pregnant). Semen in epididymides was considered evidence for mature males. The ovaries of Burmeister’s porpoises are ovoid or bean-shaped and flattened, with corpora modifying surface appearance. In the laboratory, ovaries were examined macro- and microscopically, measured, weighed and sliced. The number of corpora ovarica (lutea, albicantia, atretica) and their morphology were documented. The follicles, oocytes, and nuclei were measured. Follicular development was predominantly left-sided, but occurred in both ovaries in 16.3% of females, mainly in those with numerous corpora. Macroscopically, several corpora atretica with luteinization had characteristics similar to those of corpora albicantia, making microscopic determination essential. Inconclusive evidence of recent ovulation was reported for January. Two of three immature females showed good follicular development in March and April. The testes of Burmeister’s porpoise are elongated and cylindrical. Of 36 males examined macroscopically, seven were immature, five pubescent and 24 mature. The histological analysis allowed to confidently determine sexual maturity status. Field evaluation of maturity based on the presence of sperm in the epididymides is a useful but in 8.3% of cases not an exact method. No histological evidence of male reproductive seasonality was found. Spermatogenesis was perceptible year-round and tubule diameters showed stochastic monthly variations. The body length at 50% sexual maturity was estimated at 157 cm and 152.7 cm, for males and females, respectively. There was no evidence of reproductive senescence. This study is the first evaluation of the sexual maturation process in the Burmeister’s porpoise, using both macroscopic observations and elaborate gonads histology. It provides important new information on the natural history of the species, including parameters (e.g., mean body length at maturation, reproductive seasonality) highly relevant to its conservation

Influence of sex and home range on released Antillean manatees’ behavior in Brazil

The Antillean manatee is a threatened aquatic mammal subspecies which inhabits the northern and northeastern Brazilian coasts and estuarine areas. In this study we analyzed behavior data from rehabilitated and released manatees, to evaluate if sex and home range affect behavior richness and activity budget. Behavioral data from 29 manatees (15 females and 14 males) of northeastern Brazil was analyzed from 2006 to 2018. The animals were monitored by trained staff, who followed the animals using satellite and VHF telemetry systems. Six behavior states and 17 behavior events were recorded. The data was analyzed using GLM, ANOVA, and regression statistical tests. Behavior richness varied from three to 14 and activity budget indicated that individuals spent more time engaged in behaviors such as moving slowly and feeding in the bottom of the water body, but neither behavior richness nor activity budget were affected by sex. Behavior richness related to home range varied from five to 14 behaviors. Behavior richness and the activity budget for two social behaviors events - touch and interaction with wild manatees - were positively influenced by home range size, highlighting the importance of the use of space on behavior expression in manatees

Occurrence of cetacean strandings on the coast of São Paulo, Brazil: a spatio-temporal assessment from 2017 to 2021

This study is part of the Projeto de Monitoramento de Praia– Bacia de Santos - (PMP-BS, Santos Basin Beach Monitoring Project) and is based on data from stranded cetaceans collected during beach monitoring in the state of São Paulo, between 2017 and 2021. Our aim was to assess the temporal and spatial patterns of strandings, including the main recorded species, stranding locations, and their distribution throughout the year. The analysis covered 258 beaches along the coast of São Paulo, which was divided into three mesoregions: South Coast (LSP), Central Coast (LCP), and North Coast (LNP). We calculated the number of regularly monitored beach kilometers and the number of cetacean records for each of these mesoregions. These records were termed ‘Strandings per Unit of Sampling Effort’ (EPUE). The total regular daily monitoring covered 430,596.36 kilometers along the beaches, with a record of 2,055 stranded individuals belonging to 18 cetacean species. On average, there were 411 ± 38 stranded individuals per year, ranging from 387 in 2019 to 470 in 2021. The species most frequently encountered were Franciscana dolphin (Pontoporia blainvillei), Guiana dolphin (Sotalia guianensis), humpback whale (Megaptera novaeangliae), and Atlantic spotted dolphin (Stenella frontalis). The Franciscana and Guiana dolphins accounted for 86% of records. Forty-three percent of strandings (877) was located in LSP , 33% (670) in LCP, and 25% (508) in LNP. These results were expected and supported by previous studies, as LSP encompasses important priority conservation areas with a diversity of ecosystems and the presence of endemic and endangered species. Keywords: beach monitoring, cetaceans, conservation, mesoregions, São Paulo coast, stranding

Antillean manatee (Trichechus manatus manatus) occurrence and grazing spots in three protected areas of Costa Rica

The Antillean manatee is a poorly studied marine mammal in Costa Rica. Its distribution covers the entire Caribbean coast, but sighting reports are scarce. This research was conducted in three protected areas (PA) where the species is primarily observed. The objectives were to determine the density patterns of sightings and grazing spots; to explore the relationship between grazing spots and sightings with geographic and temporal variables, for PA separately; to study the frequency of sightings and grazing spots according to season, month, and period of the day, for PA together; and to determine the pertinence of using a marine ecology application MarEco to register manatee sightings by the public. Data on manatee sightings and grazing spots gathered with the MarEco app, under a citizen science mechanism, were complemented with data obtained by the Tortuguero Conservation Area Administration (TCAA) through other means. The number of sighting records registered through MarEco during nine months was alike to the number of records reported to the TCAA over six years in two of the PA studied. The areas with the highest density of grazing spots and sightings matched with studies conducted 10 to 20 years ago. In two of the PA, sightings were most often associated with the rainy season, while fresh grazing spots were specially counted from 6:00 h to 8:59 h. The results suggest that manatees exhibit high site fidelity in the three PA, that their increased presence during the rainy season is likely due to increased availability of food, and that they perform feeding activity predominantly at night

First record of humpback whales in the Caribbean coast of Costa Rica

Keywords: population dynamics, breeding areas, migration patterns, sightings, threats

Stranding reports of the Antillean manatee in the middle Magdalena Basin, Colombia 2011 to 2023

The aim of this study was to conduct an analysis of reported events concerning Antillean manatee (Trichechus manatus manatus) strandings in the middle Magdalena Basin region of Colombia from January 2011 to December 2023. To achieve this, a literature search was conducted in newspapers, news broadcasts, as well as gray and published reports, complemented by interviews and workshops with various governmental and non-governmental organizations. This search resulted in reliable information regarding past experiences involving stranded manatees over the years. Cases attended to by the environmental authority and its partners were also considered. Forty-four stranding events were recorded, with 34 deaths and 10 live manatees. Of the cases discovered, 79.5% of the reported cases were addressed. This effort highlighted the current lack of an official database that would provide firsthand knowledge of Antillean manatee stranding events in Colombia, thereby hindering timely and appropriate territorial management during response to the challenges faced by this species in the region. Furthermore, it underscores the need to implement a standardized response pathway for manatee cases, following appropriate protocols, and promoting the coordination of stakeholders within the regional stranding network in the middle Magdalena Basin. This approach, in addition to supporting the capacity building of communities, institutions, and organizations for improving response knowledge, conservation, and manatee recovery, is of paramount importance for the long-term sustainability of manatee populations in the region

Tooth wear and dental pathology in Amazon River dolphins (Inia geoffrensis) and tucuxis (Sotalia fluviatilis)

The investigation of tooth wear and pathology in freshwater dolphins can increase our understanding of their life history, including interactions with the environment and impacts of disease and morbidity. This paper evaluated the occurrence, prevalence and discussed the putative etiology of dental wear and pathology in freshwater dolphins - tucuxi (Sotalia fluviatilis) and the Amazon River dolphin (Inia geoffrensis) - from the central Amazon basin. Teeth of 29 Amazon River dolphins and 14 tucuxis were visually inspected to identify wear facets and the presence of pathology. Dental wear was observed in 55% (n = 16) of the Amazon River dolphin and 79% (n = 11) of the tucuxi specimens. For both species, superficial wear restricted to the tooth crown was more frequent. Calculus deposits were observed in both species, occurring in 14% of tucuxi (n = 2) and 41% of Amazon River dolphin (n = 12) specimens. Caries-like lesions were observed in a third of Amazon River dolphin specimens (n = 10), affecting 10% of the teeth (n = 197). Gross caries was the most commonly caries type observed. Only one tucuxi had caries-like lesions, affecting 1.6% of the teeth (n = 13). While conditions such as tooth wear arise from normal physiological processes, severe wear and pathology such as caries and calculus can contribute to further disease development and morbidity, impacting the health of the animals. Further studies using materials from museum collections in other regions from the Amazon Basin will help elucidate the occurrence, etiology, and health impact of tooth wear and dental pathology in freshwater cetaceans, contributing to our growing understanding of their life history. Keywords: abrasion, calculus, caries, dental wear, pigmentation, river dolphin