Padrões de adequabilidade de habitat e impactos para o peixe-boi marinho, Trichechus manatus, na costa brasileira

Abstract

The Antillean manatee, Trichechus manatus, is classified as Endangered in Brazil, with an estimated population of 500 individuals and threatened mostly by habitat loss and fragmentation. This study aimed to investigate the suitability of the habitat available for the species along the Brazilian coast, as well as the degree of cumulative impact. For this, an ensemble model was created from 120 habitat suitability models built using the BIOCLIM, Domain, Mahalanobis, GLM, Maxent, and SVM algorithms, based on important environmental variables for manatee distribution. The suitability results obtained were used to build T. manatus potential distribution map and compared to the degree of cumulative impact observed on the coast of Brazil. Areas of low suitability for the species were found in the mouth of the Amazon River, and in parts of the coast of Maranhão, Rio Grande do Norte, and Bahia states. The areas of high suitability are more consolidated between the east coast of Ceará and the coast of Alagoas states, with patches of high suitability also on the coast of Piauí and Maranhão states. The southern limit of potential distribution observed was the Todos-os-Santos Bay, in the state of Bahia. Cumulative impact analyzes indicate that most of the suitable areas are under low impact. It was also observed that the areas of high suitability and high cumulative impact are concentrated in the Northeastern Brazilian coast, especially close to the state capitals. Continuous patches of high cumulative impact were also observed from the Parnaíba River Delta to the Piauí-Ceará state border, and along the entire coast of Pernambuco state. The results found in this study can help in the development of conservation strategies for the species along the entire coast of Brazil, supporting decision-making and the allocation of resources more efficiently.