Proximity to freshwater and seagrass availability mediate the impacts of climate change on the distribution of the West Indian manatee

How climate change alters persistence and distribution of endangered species is an urgent question in current ecological research. However, many species distribution models do not consider consumers in the context of their resources. The distribution and survival of the West Indian manatee (Trichechus manatus), listed as a Vulnerable species on the IUCN Red List, critically depend on seagrass resources and freshwater sources for drinking. We parameterized Maxent models with Bio-ORACLE environmental layers, freshwater proximity data, and modelled seagrass distance layers, to determine manatee and seagrass distributions under future climate change scenarios. We used two plausible IPCC Representative Concentration Pathways (RCP45 and RCP26, respectively) for the year 2050. The model fits had high accuracies and predicted a marked decline in seagrass coverage (RCP26: -1.9%, RCP45: -6%), coinciding with declines in manatee ranges (RCP26: -9%, RCP45: -11.8%). We also found that over 94% of the projected manatee distribution for all scenarios fell within the seagrass distribution. The analysis showed a decline in seagrass coverage to significantly impact manatee distributions, since the distance to seagrass ecological layer contributed significantly to manatee distributions, along with distance to freshwater sources. Our findings suggest that manatees will lose substantial range due to future climate change, but the extent and direction of this change will be mediated by the degree of warming and its impact on the resources manatees depend on

Quantifying minimum survey effort to reliably detect Amazonian manatees using an unoccupied aerial vehicle (UAV) at an ex situ soft-release site

Detection of many threatened aquatic mammals, such as manatees (Trichechus spp.), using traditional visual observation methods is associated with high uncertainty due to their low surfacing times, cryptic behaviors, and the environmental heterogeneity of their habitats. Rapid advancements in technology provide an opportunity to address these challenges. In this study, we aimed to quantify survey effort of unoccupied aerial vehicles (UAVs) for detecting the Vulnerable Amazonian manatee (T. inunguis). Using a closed population of manatees that is being rehabilitated within a lake at the Rainforest Awareness, Rescue, and Education Center in Iquitos, Peru, we calculated the number of repeat surveys needed to detect at least one individual with 95% (n = 3.10) and 99% (n = 4.76) confidence. We used both generalized linear mixed-effect models and Bayesian single-species and single-season detection models to determine the effects of the environment (water depth, water transparency, cloud cover, wind speed), time of day, and behavior (breathing, foraging, milling) on the time-to-detection and detection probability, respectively. Both models indicated a significant interaction between water depth and water transparency, causing an increase in the time-to-detection (β = 0.032; 95% CI = 0.028, 0.037) and a decrease in the probability of detecting manatees (α = -0.65; 95% CI = -1.3, -0.007), which was calculated to be 0.62 (95% CI = 0.23, 0.94). Due to the similarities between the lake and in situ habitats, the results of this study could be used to design in situ UAV survey protocols for Amazonian manatees or other difficult-to-detect freshwater aquatic mammals and to monitor ex situ animals pre-and post-release, which should ultimately contribute to a better understanding of their spatial ecology and facilitate data-driven conservation efforts

Conservation challenges and emerging threats to the West Indian manatee (Trichechus manatus) in Florida and Puerto Rico

Sirenians are experiencing unprecedented anthropogenic threats around the globe due to habitat destruction, interaction with fisheries, collisions with watercrafts, and climate change. Although the West Indian manatee (Trichechus manatus) has been protected by law for the past five decades, significant threats persist in the United States. In 2017, the US Fish and Wildlife Service (USFWS) downlisted the West Indian manatee from Endangered to Threatened under the Endangered Species Act of 1973 (ESA). Here, we provide an overview of the current conservation status of manatees in US waters, particularly in Florida and Puerto Rico. In recent years, there has been a marked increase in manatee mortalities in the US. The sources of these mortalities are relatively well known, particularly collisions with watercrafts. However, other sources have recently emerged and constitute threats of increasing concern, particularly resource depletion due to seagrass loss and emerging diseases. Recommendations for future research are proposed to improve our understanding of the magnitude of the threats affecting manatees in the US, and support management decisions and conservation actions

Franciscana, Pontoporia blainvillei, stranding records from systematic beach surveys, opportunistic and incidental capture reports at theRío Negro Estuary, Patagonia, Argentina (2003 – 2023)

Detailed here are records of 34 franciscanas (Pontoporia blainvillei) that stranded, including nine rescued alive and returned to sea, from the Río Negro Estuary, Patagonia, Argentina, between 2003 and 2023. The years with the highest stranding records were 2014 and 2020 (n = 6/ each). Autumn and winter/spring were the seasons with the lowest and highest number of strandings, respectively. These strandings comprised 15 females, six males, and 13 unknowns. Total body length of females ranged from 64 to 155 cm and for males ranged from 70 to 138 cm. Five of the strandings involved calves and occurred within the birthing periods previously reported for the species at the Río Negro Estuary. A complete necropsy was performed on three animals. One showed multifocal pneumonic lesions from which Klebsiella pneumoniae was isolated and identified microbiologically. In a second specimen, Pseudomonas sp. and coagulase-negative Staphylococcus sp. were identified, and in a third individual tuberculosis caused by a member of the Mycobacterium tuberculosis complex was identified. Despite these results, it was not possible to be certain that they were the causes of death of these three individuals. Three franciscanas had beak deformities. A total of 79 otoliths representing 41 specimens of white croaker (Micropogonias furnieri) were found in one stomach content analyzed. Eleven franciscanas showed signs of having been bycaught (four with net marks, four entangled in gillnets or reported by the fishermen who bycaught them (n=3)). This is the first report of franciscana entanglements in sport fishing gear at the Río Negro Estuary. This paper provides information highlighted as important by the International Whaling Commission Conservation Management Plan for franciscana, and contributes to knowledge of the species in the Franciscana Management Area IVe. Keywords: bycatch, calves, disease, fishing rods, gillnets, odontocete

Gross anatomy and histology of the heart and great vessels of a leopard seal (Hydrurga leptonyx)

Keywords: pinniped physiology, cardiovascular system, diving adaptations, histolog

Site fidelity and population parameters of short-finned pilot whales (Globicephala macrorhynchus ) in the Eastern Caribbean through photographic identification

The short-finned pilot whale (Globicephala macrorhynchus) is distributed throughout the Caribbean and within the Agoa Sanctuary, where it is protected. This top predator is overlooked in the Caribbean, and no data is available on the variability of the degree of fidelity to the islands, or even on the demographic parameters and social structure of this species, which is essential for its conservation and the understanding of its behavior. This study focuses on the islands of Guadeloupe and Martinique and is based on 24,374 photos collected between 2014 and 2022. This data was analyzed using the CMR method via photo-identification, then open population modeling under the POPAN formulation and via SOCPROG for the study of social links. This revealed two interconnected populations. Within each of these populations, there are three patterns of residence: core residents, residents, and visitors. A total of 193 core residents and residents were estimated in Guadeloupe, and 565 core residents, residents, and visitors in Martinique. Survival rates for both populations were high. Abundance was constant in Guadeloupe for core residents and residents, but a decline has been observed for the three patterns of residencies in Martinique - special attention must be given to this population. International collaboration throughout the Lesser Antilles is essential in order to estimate the number of populations and understand the behavior of the short-finned pilot whale in the Caribbean Sea. Keywords: catch-mark-release, pattern of residence, photo-identification, short-finned pilot whale, site fidelity, social link

Artificial intelligence improves the identification of fur seals recorded at Southern Brazilian coast

The genus Arctocephalus represents the group of fur seals that mainly inhabit the Southern Hemisphere. In general, Arctocephalus species are extremely similar in appearance, often making it very difficult to impossible to distinguish them only by characteristics of their external morphology. In this context, it is important to find new tools to differentiate them, especially in locations outside of their traditional distribution area, such as Brazilian waters, in order to take appropriate actions for their management. This study proposes the use of an artificial intelligence method, based on machine learning and convolutional neural networks, to classify and identify three species of southern fur seals by analysing 121 facial images from living specimens of Arctocephalus australis, A. gazella, and A. tropicalis found on the Brazilian coast. The image database Keywords: citizen science convolutional neural networks, machine learning, pinnipeds