SoundTrap (ST-300, Ocean Instruments NZ) acoustic recorders were deployed to continuously record at 48 kHz sampling frequency from 25-27 July, 2017. Recorders were positioned approximately 0.5 m above the seafloor.
Sites:
Tektite Reef (18.30962N, 64.72218W)
Cocoloba Reef (18.31528N, 64.76065W)
OffReef (18.31789N, 64.75059W) - A sand site with no reef structure within 100m
Soundscape and habitat characterization:
Acoustic recordings were analyzed to compare the experimental soundscapes, first by examining acoustic spectra (sound power as a function of frequency). Mean power spectral densities were estimated (Hamming window, non-overlapping 0.5-sec windows) within 1-minute samples across the total experiment length (62 hours). Root-mean-square (rms) sound pressure levels (SPL; dB re 1Pa) were calculated for each site in the 1-minute samples, within two frequency bands of interest. The lower analysis band (50-1000 Hz) contains the majority of fish-produced acoustic signals, as well as noise generated by wind and waves, while the higher analysis band (1000-20000 Hz) primarily represents the acoustic energy derived from invertebrate sounds (e.g., snapping shrimp). Because reef soundscapes exhibit diel variability, spectrograms were produced to further detect acoustic differences between sites.
Benthic cover and fish diversity and abundance at the sites were characterized during July 2017 using visual surveys as previously described (Kaplan et al. 2015). Benthic surveys included six 10m long, 1m wide transects, with benthic cover recorded every 10cm. For fish, three 30m-long, 2m-wide video transects were performed, with fish enumerated and identified. Fish abundances were calculated as the total number per transect, and fish species richness was the total number of species identified at each site.