Sobreposição entre a área de vida do boto-cinza (Sotalia guianensis) e os estressores antrópicos na baía de Sepetiba, Rio de Janeiro, Brasil.

Abstract

In the current Anthropocene context, the growing pressure of multiple anthropogenic stressors is increasingly impacting coastal and marine ecosystems. The Guiana dolphin (Sotalia guianensis), a key species and indicator of environmental health, is particularly affected by these pressures in Sepetiba bay, on the southern coast of Rio de Janeiro state, Brazil. The study aimed to determine the Guiana dolphin's home range and its relationship with anthropogenic stressors in the bay. Home range is an important ecological parameter because it represents the daily activities of individuals and was calculated using the Minimum Convex Polygon (MCP) method, and overlapping with areas of human activity was estimated using GIS. Seventy-seven field trips were conducted between 2006 and 2007, totaling 261.37 hours of sampling effort. During this period, 59 individuals were photo-identified, of which 48 were recaptured over more than three days of sampling effort. Of these, 9 had information on the geographic positions of each recapture. The results revealed that home ranges ranged from 19.14 km² to 73.97 km², with an average of 42.60 ± 16.24 km², and overlap of 7.85% to 20.60% with anthropogenic stressors, especially navigation channels and anchoring areas. This indicates that dolphins use strategic feeding areas, even in high-traffic areas, exposing themselves to risks such as collisions, noise pollution, and chemical contamination. It was concluded that, although the Amazon River Dolphin Environmental Protection Area (APA) has potential for conservation, its effectiveness is limited by the intensification of human activities. The implementation of mitigating measures, such as speed reduction zones and a review of the management plan, is recommended to balance economic development and species conservation.