85
deep) compared to those in deeper waters (Fig. 11 ). This difference in total noise
with depth was most notable at frequencies of 10–500 Hz, which overlaps with the
low frequency spectra of representative tail slap, body shake, and body pulse sounds
produced by C. multicinctus , as well as with several low frequency sounds produced
by other species (e.g., C. ornatissimus and F. fl avissimus ) that live on the same reef
(see Fig. 5 ). Calculated sound pressure levels in the frequency band of the tail slap
sound decrease with depth whereas ambient noise in the higher frequency band of
the body pulse sound did not (Fig. 12a ). Subsequent estimation of the signal to noise
ratio (SNR) of each sound band at different territory sites showed an increase in
SNR with increased territory depth for the tail slap sound, but not for the body
Fig. 11 Hearing thresholds, four representative vocalization intensities and the ambient background noise environment for acoustic social communication by Chaetodon multicinctus , in coral
reef territories at Puako Reef, Hawai’i. Fish AEP thresholds to tone stimuli from 100 to 2000 Hz
were determined in the lab and show a low pass sensitivity below 600 Hz ( black solid dots ). Curves
for the power spectrum of four representative sounds (tail slap, body shake, body pulse, and tail
click) were determined by fast Fourier transforms of sound waveforms. The low frequency band of
best hearing sensitivity is nearest to the band of the body pulse sound used commonly in close
social interactions ( light green dashed curve ). The infrasound tail slap ( solid blue line curve ) and
body shake ( dark green dashed curve ) pulses are produced during agonistic interactions and have
peak frequencies <100 Hz, but sensitivity to these low frequency stimuli remain to be experimentally determined. The high frequency tail click sound ( dark red dashed curve ) is likely beyond their
hearing capabilities. The range of average ambient background octave noise band ( red shaded
area ) is shown for 11 territories at depths from 2.5 to 12.8 m and illustrate the general higher
background noise levels that occur within territories in shallow habitats ≤6 m deep. The background noise levels in the band <20 Hz remain to be characterized for most coral reef environments. From Tricas and Boyle ( 2015b )
Acoustic Communication in Butterfl yfi shes…
deep) compared to those in deeper waters (Fig. 11 ). This difference in total noise
with depth was most notable at frequencies of 10–500 Hz, which overlaps with the
low frequency spectra of representative tail slap, body shake, and body pulse sounds
produced by C. multicinctus , as well as with several low frequency sounds produced
by other species (e.g., C. ornatissimus and F. fl avissimus ) that live on the same reef
(see Fig. 5 ). Calculated sound pressure levels in the frequency band of the tail slap
sound decrease with depth whereas ambient noise in the higher frequency band of
the body pulse sound did not (Fig. 12a ). Subsequent estimation of the signal to noise
ratio (SNR) of each sound band at different territory sites showed an increase in
SNR with increased territory depth for the tail slap sound, but not for the body
Fig. 11 Hearing thresholds, four representative vocalization intensities and the ambient background noise environment for acoustic social communication by Chaetodon multicinctus , in coral
reef territories at Puako Reef, Hawai’i. Fish AEP thresholds to tone stimuli from 100 to 2000 Hz
were determined in the lab and show a low pass sensitivity below 600 Hz ( black solid dots ). Curves
for the power spectrum of four representative sounds (tail slap, body shake, body pulse, and tail
click) were determined by fast Fourier transforms of sound waveforms. The low frequency band of
best hearing sensitivity is nearest to the band of the body pulse sound used commonly in close
social interactions ( light green dashed curve ). The infrasound tail slap ( solid blue line curve ) and
body shake ( dark green dashed curve ) pulses are produced during agonistic interactions and have
peak frequencies <100 Hz, but sensitivity to these low frequency stimuli remain to be experimentally determined. The high frequency tail click sound ( dark red dashed curve ) is likely beyond their
hearing capabilities. The range of average ambient background octave noise band ( red shaded
area ) is shown for 11 territories at depths from 2.5 to 12.8 m and illustrate the general higher
background noise levels that occur within territories in shallow habitats ≤6 m deep. The background noise levels in the band <20 Hz remain to be characterized for most coral reef environments. From Tricas and Boyle ( 2015b )
Acoustic Communication in Butterfl yfi shes…