Acoustic recordings from narrow-band telemetry arrays allow long-term monitoring of the marine ecological state

The use of Passive Acoustic Monitoring (PAM) to monitor marine diversity and ecological health is gaining popularity. However, long-term marine ecoacoustics monitoring remains limited, primarily due to technical challenges associated with data storage limitations and energy sources underwater. Acoustic telemetry is a widely used tracking technique in which receivers record signals from acoustic tags, typically over long periods of time. While this method is widely used to record animal location and behavior, the receiver's recorded environment sound levels are mostly overlooked. In this study, we introduce a new PAM method, which we call Telemetry-based PAM, that provides continuous long-term monitoring of the state of marine systems using currently untapped sound levels from acoustic telemetry. We demonstrate strong correlations between sound levels and biophonic sound sources, specifically invertebrate sounds, on a coral reef. We further demonstrate that the spatial and temporal decline and recovery patterns of sound from the receivers on the reef following a major storm closely aligned with parallel information from visual surveys. As acoustic receiver arrays are already widespread globally, Telemetry-based PAM can provide an easy and affordable monitoring tool for marine environments. Importantly, as recordings are continuous, deployed for long durations, and based on multiple receivers, we can use these recordings to detect small-scale variations in sound levels over space and time, offering an unparalleled fine-grained view of reef dynamics.