水中マイクで記録された15年分の海洋変化(Underwater Microphones Capture 15 Years of Ocean Change)

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2025-06-10 カリフォルニア大学サンディエゴ校(UCSD)

Scripps海洋研究所は、南カリフォルニア沖に設置した6台の水中マイクで15年間にわたり海洋音響を記録。クジラの鳴き声、船舶騒音、風など4周波数帯を分析した結果、2014~16年の海洋熱波時に南部でクジラ音が最大50%減少、北部では増加が確認されました。2008年の金融危機では船舶騒音が40%以上減少し、その後も回復していません。船の活動は午前3時と午後2時にピーク。音響は気候変動や人間活動のモニタリング手段として有望です。

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10年ごとの海洋サウンドスケープが明らかにする気候変動と経済変動
Climatic and economic fluctuations revealed by decadal ocean soundscapes

Vanessa M. ZoBell;Natalie Posdaljian;Kieran L. Lenssen;Sean M. Wiggins;John A. Hildebrand;Simone Baumann-Pickering;Kaitlin E. Frasier
The Journal of the Acoustical Society of America  Published:June 05 2025
DOI:https://doi.org/10.1121/10.0036778

水中マイクで記録された15年分の海洋変化(Underwater Microphones Capture 15 Years of Ocean Change)

Decadal variations of ocean soundscapes are intricately linked to large-scale climatic and economic fluctuations. This study draws on over 15 years of acoustic recordings at six sites within the Southern California Bight, investigating interannual, seasonal, and diel variations. By examining acoustic energy from fin and blue whales along with sounds from ships and wind, we identified changes in soundscape over time and space. This study reveals that sound levels associated with both biological and non-biological sound sources varied seasonally and correlated with large-scale climatic patterns and long-term oceanographic fluctuations. Baleen whale sound levels before, during, and after a marine heatwave were assessed; sound levels decreased in southern sites and increased in northern sites adjacent to the California Current, underscoring the potential for range shifts and habitat compression during warm years for these species. Ship-generated sound levels at high-traffic sites reflected economic events such as recessions, labor shortages and negotiations, and changes to port activities. Marine soundscapes offer an approach to assess the ocean’s condition amid ongoing climatic and economic fluctuations.

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