Identifying suitable areas for common bottlenose dolphin in anthropized waters

Understanding the processes that determine the occurrence of species, especially for those exposed to human activities, is key to appropriate management. The common bottlenose dolphins, Tursiops truncatus, is well studied worldwide, but very little attention has been given to transient groups of this species and how such groups are exposed to human activities. Here, we modeled and mapped how the environment and human activities drives bottlenose dolphin habitat suitability, and residence patterns in an anthropized area of the Southwestern Atlantic Ocean. To predict habitat suitability, we ran 300 distribution models, including six algorithms, and generated an ensemble model. In parallel, we used photo-identification techniques to investigate dolphins' residence patterns. Our results demonstrated that primary productivity, seabed slope and port activities explained dolphins' habitat suitability. The most suitable areas included coastal waters, nearby port complexes and shipping routes. We also identified a low degree of residence in Cabo Frio and Rio de Janeiro city waters, but calves were constantly sighted there, indicating an important area for caring and nursing. The high overlap between the dolphins' most suitable areas and human activities, such as ports, vessel traffic and fisheries spots, plus the presence of calves in these areas, highlights the need for safeguard measurements to protect these animals from anthropogenic threats. Our results can be used to support management decisions, such as fisheries regulations and the creation of new marine protected areas to conserve critical habitats for this species.

Automated summary

Understanding the processes that determine species occurrence is crucial for effective management, especially for species exposed to human activities. This study examined how environmental factors and human activities impact the habitat suitability and residence patterns of bottlenose dolphins in the Southwestern Atlantic Ocean. The results revealed that primary productivity, seabed slope, and port activities significantly influenced dolphins' habitat suitability.