The biological soundscape of temperate reefs: characterizing natural and artificial reefs in the Dutch Wadden Sea

Abstract Monitoring coastal marine habitats presents many challenges. Often, using multiple approaches to capture different aspects of ecosystems can strengthen the information gained regarding habitat status. The use of passive acoustics to document, describe, and monitor coastal habitats through soundscapes presents one such complementary technique. Habitats have distinct acoustic patterns, or soundscapes, as a result of their specific features and biological communities. Passive acoustic monitoring (PAM) presents a lower impact, innovative method to provide metrics for long-term monitoring of habitats. Marine soundscapes have not yet been described for the Wadden Sea; an ecosystem where reef habitats have experienced major changes over time due to various human-mediated impacts. This study provides a first catalogue of biotic acoustic signatures recorded at shellfish reef and neighbouring sand habitat in this ecosystem. Furthermore, recordings from natural reefs were compared to recordings from recently deployed artificial reefs, showing similar patterns of greater biotic acoustic diversity at the natural and artificial reefs compared to nearby sandflat. These results demonstrate that fine-scale differences in habitat soundscapes exist across reef habitats within a small geographic scale. This study provides the foundations for further quantitative research using PAM to monitor the Wadden Sea soundscape dynamics and understanding the role of sound in changing coastal ecosystem.