Fish chorus and vessel noise in a marine protected coastal reef vary with lunar phase

This study implemented Passive Acoustic Monitoring (PAM) to evaluate temporal acoustic patterns in a protected coastal reef area in Tamandare beach (100 km south of Recife city, Pernambuco State, Brazil). We used an autonomous underwater recorder that allowed continuous recordings from December to March. The sounds detected in the marine protected area indicated the presence of six chorus types, two of them occurring only in winter. We detected choruses occurring in different times of the day and presenting a daily pattern, with differences in the initial time of detection (p < 0.05). Overlapping signals from four choruses occurred mainly after sunset (17:30 p.m.), while two choruses occurred after midnight. Choruses usually lasted for 1 h 30 m. One of the choruses produced a wide frequency band (300 to 4000 Hz) that masked the frequency of the other choruses. Lunar phase changes influenced all choruses, with major differences during the first-quarter moon. Vessel noise occurred primarily in the early morning and at night. Vessels had low dominant frequencies, with higher peaks below 155 Hz and different peaks that can reach 7000 Hz. The vessels produced noises with energy of 90 dB re 1 mu Pa-2 Hz(-1), distributed in a wide frequency band. These noises were enough to mask all the choruses, although characterized by short peaks (< 10 min of detection). Fish chorus and vessel noise were detected using passive acoustic monitoring that indicated the need to implement short- and long-term monitoring and management plans.

Automated summary

This study implemented Passive Acoustic Monitoring (PAM) to evaluate temporal acoustic patterns in a protected coastal reef area in Tamandare beach, Brazil. The study detected fish choruses and vessel noise using PAM, and identified six chorus types, two of which only occurred in winter. Choruses occurred at different times of the day and exhibited a daily pattern. Vessel noise was primarily detected in the early morning and at night.