The coral reef around Europa island is one of the world’s rare reefs that remain in a near pristine condition. Its conservation is both a priority and a logistic challenge due to its remoteness. The frequency of visual surveys (a snapshot every 3 to 5 years) is insufficient to support its effective management. Indeed, accelerating effects of climate change and temporal dynamics of reef populations require frequent monitoring. Moreover, visual surveys are expensive and provide only partial information.

In April 2018, we installed an autonomous acoustic monitoring station on Europa’s reef at 12 m depth. A hydrophone continuously records the soundscape. Data are transmitted to a terrestrial station, providing a near real-time information about the state of the ecosystem. To understand how variations in soundscape relate to ecosystem state, ecoacoustic indices were determined by coupling acoustic and visual surveys (videos for fishes, 3D modelling for habitat) on 9 sites around the island.