Comparison of ichthyological acoustic communities based on ichthyological communities: A case study from protected and non-protected marine areas of Moorea Island (French Polynesia)

Sounds have been described in many fish taxa, and the fish acoustic community can be routinely used in Passive Acoustic Monitoring (PAM) in temperate ecosystems. However, in coral reefs, the vast number of soniferous fish makes it challenging to use the whole community for PAM. While PAM is recognized as an innovative, non-intrusive method for monitoring Marine Protected Areas (MPAs)—which play a crucial role in mitigating the impacts of habitat modification on ichthyofauna—it remains unclear whether fish sounds accurately reflect changes in fish abundance and species richness within MPAs. This research aims to enhance the comparison of ichthyological acoustic communities by analyzing fish communities inside and outside MPAs along the coasts of Moorea Island (French Polynesia). The goal is to identify sounds that could serve as potential environmental indicators. This study highlighted that within MPAs, coral cover, species richness, sound types abundance, and sound types richness were all higher. We also found that ichthyological composition varied depending on the observed coasts. The results align with studies on temperate reefs, which have shown that sound type richness is higher in protected areas. While some sound types were not suitable indicators for environmental monitoring—either because they were recorded only at a single site or on a single day, or conversely, because they were produced at all sites by generalist species—others appeared to be more useful as indicators. Extending the listening periods and further clarifying the precise link between these sounds and ecological conditions would aid future research in identifying reliable acoustic indicators for PAM-based studies in coral reefs.