Fish sounds of photic and mesophotic coral reefs: variation with depth and type of island

Mesophotic Coral Ecosystems remain largely unexplored. The aim of this study was to determine how the acoustic fish biodiversity varied depending on the depth and the type of island in six Polynesian islands. The link between benthic cover and fish sound diversity was established. In most islands, acoustic fish alpha-diversity decreased between 20 and 60 m but not between 60 and 120 m. Fish sound types community composition was more driven by depth, likely due to benthic coral cover differences, than by the type of island. These results show fish sounds exhibit a bathymetric stratification and can reflect different habitat features. It opens perspectives in the monitoring of mesophotic coral ecosystems using passive acoustics.

Automated summary

The aim of this study was to investigate the acoustic fish biodiversity in mesophotic coral ecosystems. It was found that the alpha-diversity of acoustic fish decreased between depths of 20 and 60 m, but remained stable between depths of 60 and 120 m. The composition of fish sound types was mainly influenced by depth rather than the type of island. These findings suggest that fish sounds can be used to monitor the mesophotic coral ecosystems.