Low-frequency sound from large vessels is a major, global source of ocean noise that can interfere with acoustic communication in a variety of marine animals. Changes in vessel activity provide opportunities to quantify relationships between vessel traffic levels and soundscape conditions in biologically important habitats. Using continuous deep-sea (890 m) recordings acquired ~20 km from offshore shipping lanes, we observed a quieting of low-frequency noise within Monterey Bay National Marine Sanctuary (California, USA) associated with changes in vessel traffic during the onset of the COVID-19 pandemic. The frequency band 31–100 Hz effectively captured large-vessel noise while minimizing potential biases from geological and biological sources. Monthly median spectrum levels (MSL) in this band decreased during January–June 2020, as much as 2.7 dB re 1 uPa2 Hz-1 below levels in the prior two years, and they began returning to those levels by July 2020. During 2020 MSL were strongly correlated with large-vessel total gross tonnage derived from economic data, summed across all California ports (r = 0.89, p < 0.01). They were also highly correlated with regional presence of large vessels, quantified from Automatic Identification System (AIS) line-of-sight vessel tracking data and weighted by vessel speed and inverse distance from the recorder (r = 0.94, p < 0.01). Within the three-year study period, February–June 2020 exhibited anomalously quiet low-frequency noise and anomalously low statewide port activity and regional large-vessel presence. While likely a short-term change, the maximum 2020 quieting represented nearly a halving of acoustic intensity in a frequency band used by baleen whales to communicate. This illustrates the influence of offshore large-vessel traffic on sound and protected species in marine sanctuary habitats.

中文翻译：

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降低COVID-19大流行期间蒙特雷湾国家海洋保护区的低频船只噪声

大型船只发出的低频声音是海洋噪声的主要全球来源，可能会干扰各种海洋动物的声音交流。船只活动的变化提供了量化重要生物栖息地中船只通行水平与声景条件之间关系的机会。使用从离岸运输线〜20 km处获得的连续深海（890 m）记录，我们观察到蒙特利湾国家海洋保护区（美国加利福尼亚）内低频噪声的消隐与船舶起航期间船舶交通量的变化有关。 2019冠状病毒病大流行。31-100 Hz频带有效地捕获了大容器噪声，同时最大程度地降低了地质和生物来源的潜在偏差。在2020年1月至6月期间，该频段的每月频谱中位数水平（MSL）下降了多达2个。在前两年低于7 dB且低于1 uPa2 Hz-1的水平，并且它们在2020年7月开始恢复到该水平。2020年，MSL与经济数据得出的大型船只总吨位紧密相关，该数据来自加利福尼亚所有港口（r ＝ 0.89，p ＜0.01）。它们还与大型船只的区域存在高度相关，通过自动识别系统（AIS）视线船只跟踪数据进行量化，并通过船只速度和距记录仪的反距离进行加权（r = 0.94，p <0.01）。在为期三年的研究期内，2020年2月至2020年6月表现出异常安静的低频噪声，全州范围内港口活动的异常低以及区域大船只的存在。虽然可能是短期的变化，2020年的最大静默度代表了鲸鱼在交流中所使用的频带中的声强降低了将近一半。这说明了海上大型船只运输对海洋保护区栖息地的良好和受保护物种的影响。