Analysis of coral reef sound recordings in the Phoenix and Line Islands

Automated acoustic recording stations are being considered to allow managers to monitor remote coral reefs. Sounds of interest include those of biological, environmental, and anthropogenic origin. Preliminary data about remote acoustic monitoring of reefs were obtained in February–March of 2001 and 2002 during National Oceanic and Atmospheric Administration (NOAA) cruises to the Phoenix and Line Islands in the western Pacific Ocean. In 2001, sonobuoys manufactured by East Carolina University (ECU) were deployed to make a 90-s acoustic recording every hour for a 24-h period at each location. In 2002, continuous 24-h acoustic recordings were made using an experimental Remote Underwater Digital Acoustic Recording (RUDAR) system. The ECU sonobuoys recorded diurnal and locational variations in the sounds of snapping shrimp as well as variations in ambient noise. At most locations, the snapping shrimp sound level increased near sunset and decreased near sunrise. The experimental RUDAR system recorded limited data due to some technical problems arising from field use. Analysis of the recordings as well as recommendations for future studies will be presented.