Mapping of benthic biophony at ecologically relevant scales

Benthic communities emit a variety of sounds associated with movement and feeding activities. Snaps are wide-band signals, their waveforms allow to detect and estimate time-of-arrival difference between sensors reliably. Because of the snap’s bandwidths, a 2 m-compact hydrophone array is adequate to locate emissions. Merging the localization results of successive emissions allows to map the benthic biophony using 2 metrics as a function of position: (1) the number of snaps per minute and square meter and (2) their mean Source Level dB re 1μPa@1m. Algorithms to easily detect and locate benthic snaps using two hydrophones are detailed, accuracy and resolution are assessed. With data from artificial reefs, we were able to locate and image the shape of each artificial reef in a 100 m radius around a fixed array with a resolution of 5 meters. For the 3 m-nearest artificial reef, the image shows intra-reef details with a resolution of 20 cm. To map a larger area, the array is carried by a drifting buoy. With da...