Abstract
Anthropogenic noise sources range from intermittent to continuous, with
seismic and navy sonar technology moving towards near-continuous
transmissions. Continuous active sonar (CAS) may be used at a lower
amplitude than traditional pulsed active sonar (PAS), but potentially
with greater cumulative sound energy. We conducted at-sea experiments to
contrast the effects of navy PAS versus CAS on sperm whale behaviour
using animal-attached sound- and movement-recording tags (n=16
individuals) in Norway. Changes in foraging effort and proxies for
foraging success and cost during sonar and control exposures were
assessed while accounting for baseline variation [individual effects,
time of day, bathymetry and blackfish (pilot/killer whale) presence] in
generalized additive mixed models (GAMMs). We found no reduction in time
spent foraging during exposures to medium-level PAS (MPAS) transmitted
at the same peak amplitude as CAS. In contrast, we found similar
reductions in foraging during CAS (d.f.=1, F=8.0, P=0.005) and higher amplitude PAS (d.f.=1, F=20.8, P<0.001)
when received at similar energy levels integrated over signal duration.
These results provide clear support for sound energy over amplitude as
the response driver. We discuss the importance of exposure context and
the need to measure cumulative sound energy to account for intermittent
versus more continuous sources in noise impact assessments.
Original language | English |
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Article number | jeb219741 |
Number of pages | 10 |
Journal | Journal of Experimental Biology |
Volume | 223 |
Issue number | 7 |
DOIs | |
Publication status | Published - 8 Apr 2020 |
Keywords
- Anthropogenic noise
- Continuous active sonar
- DTAG
- Intermittent sound
- Time budget
- Time-series model
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Dive into the research topics of 'When the noise goes on: received sound energy predicts sperm whale responses to both intermittent and continuous navy sonar'. Together they form a unique fingerprint.Datasets
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Sperm whale response to continous vs. pulsed sonar (dataset)
Isojunno, S. (Creator), University of St Andrews, 17 Feb 2020
DOI: 10.17630/73a5ddb2-78b0-4e99-a56b-6fc6c48e8a7b
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