Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK
Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife KY16 8LB, UK.
J Exp Biol. 2020 Apr 8;223(Pt 7):jeb219741. doi: 10.1242/jeb.219741.
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 (=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, =8.0, =0.005) and higher amplitude PAS (d.f.=1, =20.8, <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.
人为噪声源的范围从间歇性到连续性，地震和海军声纳技术正朝着近连续传输的方向发展。连续主动声纳（CAS）的振幅可能低于传统的脉冲主动声纳（PAS），但潜在的累积声能量更大。我们在挪威进行了海上实验，使用动物附着的声和运动记录标签（=16 个个体）对比海军 PAS 和 CAS 对抹香鲸行为的影响。在广义加性混合模型（GAMM）中，我们考虑了基线变化（个体效应、一天中的时间、水深和黑鳍（领航/虎鲸）存在），评估了在声纳和对照暴露期间觅食努力的变化以及觅食成功和成本的替代指标。我们没有发现中能级 PAS（MPAS）暴露期间觅食时间减少，MPAS 的峰值振幅与 CAS 相同。相比之下，当以相似的能量水平接收时，我们发现 CAS（d.f.=1，=8.0，=0.005）和更高振幅 PAS（d.f.=1，=20.8，<0.001）期间的觅食减少相似。这些结果为声能作为响应驱动因素提供了明确的支持。我们讨论了暴露背景的重要性，并需要测量累积声能，以在噪声影响评估中考虑间歇性和更连续的声源。
