Spatial patterns in reef-generated noise relate to habitats and communities: evidence from a Panamanian case study

Abstract

Noise generated by a reef community provides a valuable orientation cue for reef fish; both for larvae as they recruit to reefs, and for adults and juveniles during nocturnal movements. However, the nature of the information conveyed in reef noise is as yet unknown. In this study, the characteristics of daytime acoustic recordings from patch and fringing reefs in the Las Perlas Archipelago, Pacific Panama were compared. Recordings of ambient noise made during the day showed coral reef communities produced acoustic profiles that varied spatially across the Archipelago. At eleven reef sites in the north of the Archipelago, data were also collected on fish and benthic communities using standard visual survey techniques. These data, along with existing survey data from 40 reef sites, were compared with short-term (2 minute) acoustic profiles to explore associations between point sampled acoustic and census data. Using a correlation matrix, the best predictors of acoustic characteristics were identified from a range of factors, including fish density and biomass, coral and fish diversity, coral and algal cover, reef depth and sea state. Multiple regression GLMs highlighted the importance of fish density and diversity on noise below 1 kHz, and coral and benthic diversity on noise above 1 kHz. A positive correlation was also found between coral cover and daytime noise intensity across the entire Archipelago, suggesting potential in the future development of passive acoustics as a method for rapid ecological assessment or for long-term monitoring of reefs. These findings demonstrate the richness of information available to reef fishes, and make the case for further studies that explore the relationships between habitat and community characteristics with temporal and spatial variation in reef noise.