What does long-term monitoring of the ocean soundscape tell us?

International audienceMooring arrays of few hydrophones is an effective way for monitoring the ocean soundscape and its sources: undersea earthquakes and volcanic eruptions, marine mammals, iceberg cracks, sea-state, ship noise, etc. This is due to the exceptional acoustic properties of the ocean and to the presence of a sound channel, which acts as a waveguide carrying acoustic waves over thousands of kilometers. Active plate boundaries, such as mid-ocean spreading centers, generate a large number of earthquakes and thus acoustic waves, which are evidence of ongoing magmatic or tectonic processes. Large baleen whales produce many loud and distinctive calls and songs, which provides clues as to when and where species are residing and migrating, as well as their vocal behavior. Other sounds of interest are cryogenic sounds produced by icebergs or man-made noises (ship traffic, seismic exploration), which can have an impact on ecosystems. All these sounds share the same low-frequency range (0-120Hz) and require continuous time-series as long as possible to be representative of the observed phenomenon: seismic activity of the ocean floor, evolution of whale populations, or noise pollution in the open ocean