SoundGarden: Applying healthy soundscapes to support coral reef restoration

Abstract

Coral reefs are a hub of ocean biodiversity supporting a range of socioeconomic and ecosystem services. Yet reefs and these important services are imperiled due to climate change and related stressors. Healthy coral reefs can be characterized by distinctive soundscapes, and there is increasing realization that acoustic cues are vital ecosystem components. Here we present a series of experiments examining if replaying healthy soundscapes can increase the settlement of coral larvae, a fundamental ecological process. Work was conducted in the U.S. Virgin Islands, leveraging a decade of soundscape studies on those reefs, and used a novel solar-powered acoustic playback system calibrated in sound pressure and particle motion. We studied larvae from three coral species, brooding Porites astreoides and Favia fragum, and broadcast-spawning Diploria labyrinthiformis. Larvae on degraded reefs enriched with healthy reef sounds settled at significantly higher rates compared to control sites that were not acoustically enriched. Acoustic enrichment settlement rates were influenced by received level, ecosystem properties and species biology reflecting the need for holistically evaluating the reef restoration process. Overall, this work outlines a new, potentially scalable means of supporting healthy reef habitat, and enhancing coral settlement on imperiled reefs undergoing restoration.