Extreme passive acoustic telemetry detection variability on a mesophotic coral reef, United States Virgin Islands

Understanding passive acoustic telemetry equipment limitations is critical for correctly interpreting movements of aquatic animals. Range test studies have been performed to determine what environmental factors may interfere with acoustic equipment efficiency. Many of these studies have been performed on shallow coral reef environments for a few days to weeks. This study examined environmental factors that influence detection variability on a mesophotic coral reef south of St. Thomas, United States Virgin Islands (−64.96°, 18.19°). Data from a stationary transmitter were examined against numerous environmental variables from June to September 2011. A generalized linear model was used to examine the daily detection proportion response to eight different environmental variables. Factors which had strong negative effects on detections received included when the current direction was flowing from receiver to transmitter, current speeds above 0.2 ms −1 , a strong temperature gradient between transmitter and receiver, and increased water temperature. Detections varied throughout the different time periods of the day with sunset and sunrise having significantly lower detections than day, and sunset having significantly lower detections than night. The results highlight the importance of conducting a long-term range test and will aid design of future passive acoustic telemetry studies on mesophotic coral reefs.