Cyclones Affect Vocalization and the Marine Soundscape Within a Blue Hole

Tropical cyclones are a major disturbance on nearshore marine and reef communities, which are highly valuable for their biodiversity and for commercial and recreational purposes. The increasing study of soundscape ecology and the usefulness of sound in the marine environment has led to growing awareness of factors altering the marine soundscape and how changes in the soundscape impact fish behavior, usually negatively. Studies have noted the input of sound from cyclones alter the marine soundscape, though these studies are mainly limited to offshore and deep-water environments. Sound has rarely been used to quantify cyclone effects on coral reefs. Here we use a long time-series of acoustic recordings to examine and quantify the effects of four tropical cyclones (hurricanes Matthew, Irma, Jose, and Maria), on the coral reef soundscape and fish vocalizations at Dean’s Blue Hole (DBH), The Bahamas. We used both root mean square and spectral analyses from the audio recorded on a 12.9s per 5 minute duty cycle, sampled at 20 kHz. We found that the hurricanes increased the sound pressure and spectrum levels on the DBH soundscape on the order of 2-6 days and across all frequencies examined (0-10 kHz). During this period, the hurricanes that were close enough to directly input high winds also showed an elevated effect on frequency range of 200 – 2000 Hz, associated with fish hearing and sound production. Vocalization behavior, identified and counted from the same recordings, significantly decreased in response to the soundscape changes in the study site across three of the four cyclones examined. This is the first record of decreased fish vocalization behavior as a direct response of the passage of close and relatively distant cyclones, as well as the first quantitative assessment of the effect of these cyclones on coral reef soundscapes. The study shows that tropical cyclones continue to impact reef soundscapes after their ephemeral passage and may further exacerbate other associated stressors on reef communities