Characterization of the fish acoustic communities in a Mozambican tropical coral reef

Coral reefs are biodiversity hotspots in urgent need of protection in most areas of the tropical belt due to increasing local anthropogenic pressures and climate change. Sounds produced by fishes are an important component of soundscapes in these ecosystems, making passive acoustic monitoring (PAM) an effective tool to map the presence of target species or to estimate changes in biodiversity. The present study aims to identify sound-producing fishes in Mozambican coral reefs based on the literature and to catalogue fish sound types recorded in situ. Based on the literature, we found 183 potentially soniferous species and 29 soniferous species with characterized sound production. Using acoustic recordings from coral reefs near Mozambique Island in March-April 2017 and 2018, a total of 47 putative fish sound types were recognized, from which the 37 most common were further characterized for several temporal and spectral features. A dichotomous classification of the major fish sound categories was prepared. Additional video recordings allowed identification of 4 sound-producing species: Chromis weberi, Dascyllus trimaculatus, Amphiprion akallopisos and A. latifasciatus. This study provides the first fish sound library for Western Indian Ocean coral reefs. Here, we also discuss how these simple methodologies can provide baseline knowledge to acoustically monitor marine habitats like coral reefs. Such knowledge may pave the way to use sounds to assess changes in single-fish species or reef fish biodiversity.