Baseline assessment of tourism-related sound pollution effects on the marine soundscapes of the largest coastal Marine Protected Area in Brazil

Sound pollution affects reef organisms, interfering with various key behaviours such as territoriality and reproduction. Soundscape ecology can reveal the effects of sounds produced by anthropophony on reef ecosystems and guide mitigation strategies. This study provides a baseline assessment and comparison of marine soundscapes in reef environments of Northeastern Brazil, focusing on the influence of sound pollution across different types and seasons of tourism in marine protected areas. Recordings were conducted at distinct sites, covering different exposures, types and seasons of tourism. Sound pollution influenced soundscapes, with higher levels of sound pollution sources being associated with a lower occurrence of biophonic sounds. PSD analysis revealed three main energy peaks across the frequency range studied (0.05 to 10 kHz), but a flattened profile was identified in sites with a higher incidence of sound pollution, resulting in a loss of the sound peak detected at lower frequencies. Sound pollution also affected ACI values, both spatially and temporally. Exposure was the most influential factor, followed by tourism season and tourism type. These results reinforce the role of sound pollution as a significant factor in reef environments, underscoring the urgent need for increased attention, further research, and the development of effective mitigation strategies.