Acoustic monitoring of a seismic survey using lagrangian profilers

An acoustic monitoring program was implemented in Barreirinhas Basin aiming to estimate changes in the soundscape of the region due to a seismic survey in the area. The offshore region was monitored by 5 lagrangian profilers equipped with passive acoustic systems. This type of profiler performs 5 acoustic windows of 1 minute each at selected depths while being passively transported by the ocean currents. Deployment strategies were designed to maximize the profiler presence in the region of interest and to sample the water column evenly to 1000 m. Analysis of the sound pressure levels indicates an increase of 25 dB for low frequencies (below 100 Hz) within 30 km from the seismic source and 14 dB for distances greater than 100 km, in agreement with the existing literature. Spatial analysis shows a fair agreement between data collected and average ship traffic maps in the area. However, further studies including more traffic data should be conducted in order to correlate the data to the actual traffic during the period.