Assessment of cetacean exposure to underwater noise in the southwestern Atlantic ocean

Cetacean exposure to underwater noise in the Southwestern Atlantic Ocean is largely unknown. With the goal to characterize sound pressure and sound exposure levels in different environments, we have employed data from one month of passive acoustic monitoring in a coastal and an oceanic location to register sound pressure level variations and to calculate sound exposure levels to which cetacean species are subjected. Noise profiles varied between locations; Rio de Janeiro coastal area had higher levels than the Vitória-Trindade Seamount Chain area. At both sites, low-frequency hearing cetaceans were the group under higher exposure during day and night. For high-frequency and very high-frequency groups, the day period presented higher levels. Results highlight the conditions of these unexplored soundscapes and the necessity for taking underwater noise into consideration for space-time regulation of marine areas in cetacean conservation efforts.