Data from: Sound exposure in harbour seals during the installation of an offshore wind farm: predictions of auditory damage

1. With ambitious renewable energy targets, pile driving associated with offshore wind farm construction will become widespread in the marine environment. Many proposed wind farms overlap with the distribution of seals, and sound from pile driving has the potential to cause auditory damage. 2. We report on a behavioural study during the construction of a wind farm using data from GPS/GSM tags on 24 harbour seals Phoca vitulina L. Pile driving data and acoustic propagation models, together with seal movement and dive data, allowed the prediction of auditory damage in each seal. 3. Growth and recovery functions for auditory damage were combined to predict temporary auditory threshold shifts in each seal. Further, M-weighted cumulative sound exposure levels [cSELs(Mpw)] were calculated and compared to permanent auditory threshold shift exposure criteria for pinnipeds in water exposed to pulsed sounds. 4. The closest distance of each seal to pile driving varied from 4·7 to 40·5 km, and predicted maximum cSELs(Mpw) ranged from 170·7 to 195·3 dB re 1μPa2-s for individual seals. Comparison to exposure criteria suggests that half of the seals exceeded estimated permanent auditory damage thresholds. 5. Prediction of auditory damage in marine mammals is a rapidly evolving field and has a number of key uncertainties associated with it. These include how sound propagates in shallow water environments and the effects of pulsed sounds on seal hearing; as such, our predictions should be viewed in this context. 6. Policy implications. We predicted that half of the tagged seals received sound levels from pile driving that exceeded auditory damage thresholds for pinnipeds. These results have implications for offshore industry and will be important for policymakers developing guidance for pile driving. Developing engineering solutions to reduce sound levels at source or methods to deter animals from damage risk zones, or changing temporal patterns of piling could potentially reduce auditory damage risk. Future work should focus on validating these predictions by collecting auditory threshold information pre- and post-exposure to pile driving. Ultimately, information on population-level impacts of exposure to pile driving is required to ensure that offshore industry is developed in an environmentally sustainable manner.

1. 伴随可再生能源领域雄心勃勃的发展目标，海上风电场建设配套的打桩作业将在海洋环境中愈发普及。诸多拟建风电场与海豹的栖息分布区域存在重叠，而打桩产生的噪声存在引发听觉损伤的潜在风险。
2. 本研究针对某海上风电场建设期间开展行为学研究，所用数据来自24头港海豹（Phoca vitulina L.）佩戴的GPS/GSM追踪标签。通过整合打桩作业数据、声传播模型，以及海豹的移动与潜水数据，我们得以对每头海豹的听觉损伤风险进行预测。
3. 我们结合听觉损伤的增长与恢复函数，预测了每头海豹的暂时性听阈偏移（temporary auditory threshold shifts）。此外，我们还计算了加权M累计声暴露级[cSELs(Mpw)]，并将其与水环境中暴露于脉冲声（pulsed sounds）的鳍足类（pinnipeds）永久性听阈偏移（permanent auditory threshold shift）暴露阈值进行比对。
4. 每头海豹与打桩作业的最近距离介于4.7至40.5千米之间，单头海豹的预测最大加权M累计声暴露级[cSELs(Mpw)]范围为170.7至195.3 dB re 1μPa²-s。与暴露阈值比对后发现，半数海豹的暴露量超出了估算的永久性听觉损伤阈值。
5. 海洋哺乳动物听觉损伤预测是一个快速发展的研究领域，其关联多项关键不确定性因素，其中包括声信号在浅水环境中的传播规律，以及脉冲噪声对海豹听觉的影响。因此，本研究的预测结果需结合上述背景进行解读。
6. 政策启示：本研究预测，半数佩戴追踪标签的海豹所接触的打桩噪声级超出了鳍足类动物的听觉损伤阈值。该研究结果对海上风电产业具有参考价值，同时可为制定打桩作业指导规范的政策制定者提供重要依据。通过研发从源头降低噪声的工程解决方案、引导动物远离损伤风险区域的方法，或是调整打桩作业的时间模式，均可有效降低听觉损伤风险。未来的研究应通过采集打桩暴露前后的听觉阈值数据，对本研究的预测结果进行验证。最终，为确保海上风电产业以环境可持续的方式发展，我们还需获取打桩暴露对种群层面影响的相关数据。