6 research outputs found

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

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    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

    Reports of strandings and sightings of bottlenose dolphins (Tursiops truncatus) in northeastern Brazil and Brazilian oceanic islands

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    This study revises and updates information on bottlenose dolphin Tursiops truncatusstrandings and sightings in northeastern Brazil. A total of 72 strandings were recorded from 1992 to 2010, and 51 sightings were recorded from 1988 to 2010 along the states from Ceará to Bahia, including Fernando de Noronha and São Pedro and São Paulo archipelagos, Rocas Atoll and Abrolhos Bank. Most strandings were recorded in the states of Pernambuco, Bahia and Rio Grande do Norte. The number of reports was higher during summer, but no statistically significant difference was found between summer and other seasons. The majority of the stranded animals were adults (70.6%). Stranded calves were not observed. Total body length ranged from 138 to 321cm: 138 to 310cm for males; and 168 to 288cm for females. The average adult body length was 281cm (SD = 0.22). For stranding events where sex was determined (n = 29), a highly statistically significant difference was found between the number of males (n = 21) and females (n = 8). A total of six animals (8.3%) showed evidence of fisheries interactions such as net marks or removal of meat, blubber and eyes. Twenty-two sightings were recorded in the northeastern region, mostly in small islands and Rocas Atoll. This finding shows that the bottlenose dolphin is mainly an oceanic species in the region. More efforts are needed to improve our understanding of the populations and conservation status of bottlenose dolphins in this region
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