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Longterm Acoustic Monitoring of Fish Courtship Sounds to Detect Changes in Reproductive Timelines Associated with Climate Change

Eric Montie, University of South Carolina Beaufort

17 November 2017

Phenology or the timing of seasonal activities of animals and plants is perhaps the simplest process to track changes in species ecology in response to climate change. Shifts in migration and reproduction can lead to trophic mismatches, which can affect fitness and populations. In marine ecosystems, recognizing natural rhythms of behavior and shifts associated with climate variability can be challenging to separate. Soundscape ecology may offer an exciting and novel approach; it is a rather new scientific field that uses sound to characterize ecosystems. Since 2013, we have been monitoring the soundscape of the May River, SC using an array of long-term acoustic recorders. Our research has revealed that estuarine soundscapes are acoustically rich and can track the acoustic behavior of snapping shrimp, fish courtship sounds and spawning seasons, and foraging and social behavior of bottlenose dolphins. To date, we have made the most progress with understanding the timing and rhythms of fish courtship sounds. We detected the acoustic presence of six fish species: Atlantic croaker, black drum, silver perch, oyster toadfish, spotted seatrout, and red drum. We estimated the start and end dates of the spawning season and calculated the total hours of chorusing. A negative temperature anomaly correlated with decreased fish calling intensity, while a positive anomaly increased sound production. For oyster toadfish and spotted seatrout, the lunar phase significantly influenced calling. These data are serving as a foundation for future studies that are investigating how climate variability may affect seasonal shifts in fish spawning timelines.