Deciphering complex coral reef soundscapes with spatial audio and 360° video

Abstract

Coral reef soundscapes hold an untapped wealth of biodiversity information. While they are easy to record and filled with snapping shrimp and fish sounds, they are difficult to decipher because we know little about which sounds are made by which species. With identified fish sounds, acoustic monitoring can directly inform biodiversity metrics, detect indicator or invasive species, identify behavioural events and estimate abundance at temporal and spatial scales that are impossible with methods like eDNA or visual surveys. The missing link, knowing which sounds come from which species, is exceedingly difficult to establish with fish, especially on a species-rich coral reef. Using a novel method to visualize in situ underwater sound, we have developed a technique that combines visualizations of spatial audio with concentric 360° video recordings, a combination not previously accomplished underwater. We have identified and assigned the most extensive collection of natural sounds of fishes. Further, we demonstrate that these species identifications can be used to decipher a passive acoustic monitor recording. We have collected our identified recordings into a growing open-access resource to catalyse passive acoustic monitoring research, enabling a species-specific resolution of coral reef soundscape dynamics and providing critical validated information for developing machine-learning models to analyse an ever-expanding collection of long-term recordings.