13. Anthropogenic Noise and Guiana Dolphins (Sotalia guianensis) in Brazil: Ecological and Conservation Concerns

The Sotalia guianensis dolphin occurs in the western Atlantic Ocean, from the south of Brazil to Central America. It is a coastal species, much susceptible to human impacts, as anthropogenic noises, which in general causes potential impacts in marine mammals’ populations, because the emission and reception of sound signals plays a complex and vital role in this populations’ ecology through many different ways. This study reviews the acoustic repertoire and potential anthropic impacts on populations of Guiana dolphin (S. guianensis) through its occurrence, and described and compared the anthropogenic noises with the acoustic repertoire of three Brazilian populations: Cananéia estuary – São Paulo State, Caravelas estuary – Bahia State and Pipa beach – Rio Grande do Norte State. Data was collected similarly in these three sites during boats surveys using hydrophones and audio recorders. Results showed overlapping of the S. guianensis repertoire and noises produced from boats, dredge activities and wood-barges, leading to harm on individuals and populations. This review has gathered important information supporting marine activity management, and can be used to evaluate acoustic impacts over cetaceans population.