Data from: Variation in harbour porpoise activity in response to seismic survey noise

Animals exposed to anthropogenic disturbance make trade-offs between perceived risk and the cost of leaving disturbed areas. Impact assessments tend to focus on overt behavioural responses leading to displacement, but trade-offs may also impact individual energy budgets through reduced foraging performance. Previous studies found no evidence for broad-scale displacement of harbour porpoises exposed to impulse noise from a 10 day two-dimensional seismic survey. Here, we used an array of passive acoustic loggers coupled with calibrated noise measurements to test whether the seismic survey influenced the activity patterns of porpoises remaining in the area. We showed that the probability of recording a buzz declined by 15% in the ensonified area and was positively related to distance from the source vessel. We also estimated received levels at the hydrophones and characterized the noise response curve. Our results demonstrate how environmental impact assessments can be developed to assess more subtle effects of noise disturbance on activity patterns and foraging efficiency.

暴露于人为干扰的动物，会在感知到的风险与离开受干扰区域的代价之间做出权衡取舍。环境影响评估往往侧重于会导致栖息地偏移的显性行为响应，然而这类权衡取舍也可能通过降低觅食效率，进而影响个体的能量收支平衡。既往研究未发现暴露于为期10天的二维地震勘探产生的脉冲噪声中的港湾鼠海豚（harbour porpoise）存在大范围栖息地偏移的证据。本研究采用被动声学记录仪阵列结合校准后的噪声测量手段，探究此次地震勘探是否会对留在研究区域内的鼠海豚的活动模式产生影响。我们发现，在受噪声照射的区域内，记录到觅食蜂鸣的概率下降了15%，且该概率与声源船的距离呈正相关。我们还估算了水听器（hydrophone）处的接收声级，并对噪声响应曲线进行了特征刻画。本研究结果表明，环境影响评估可被优化完善，以评估噪声干扰对动物活动模式与觅食效率产生的更为细微的影响。