Acoustic behaviors in Hawaiian coral reef fish communities

Abstract

Coral reef fish communities often include hundreds of sympatric species which are of great interest to reef conservation and fisheries managers. Longterm acoustic monitoring of fish sounds can be used to infer periodic reproductive activity and changes in population abundance. However, limited records of sound production by coral reef species have precluded the application of acoustic monitoring at the population or community levels. We used rebreather and digital acoustic/video techniques to produce a sound library for fishes on coral reefs of west Hawai'i Island, HI, USA. We documented 85 sounds produced by 45 (47%) of the 96 resident species that were associated with agonistic interactions and resource defense, reproduction, nest defense, feeding, and vigilance behaviors. Most nonfeeding sounds consisted of single or trains of pulse events <100 ms long that were distributed across a spectrum of <100 to 1000 Hz with the majority of peak frequencies between 100 and 300 Hz. Agonistic sounds created during competitive interactions over food, space, or nest brood resources were identified for damselfishes, surgeonfishes, butterflyfishes, and triggerfishes, among others. Reproductive sounds associated with courtship, spawning, or nest defense were produced by damselfishes, goatfishes, butterflyfishes, parrotfishes, and surgeonfishes, as well as wrasses and Moorish idols. The distinct adventitious feeding sounds recorded for some parrotfishes and triggerfishes occurred in a higher frequency band (2-6 kHz) and may be useful indicators of feeding activity and rates of reef bioerosion. This is the first study to characterize the species-specific behavior soundscape that can be applied to acoustic monitoring of a coral reef fish community.