江苏镇江长江豚类省级自然保护区长江江豚种群分布与水下噪声的关系探究

THE RELATIONSHIP BETWEEN POPULATION DISTRIBUTION AND UNDERWATER NOISE OF YANGTZE FINLESS PORPOISE IN ZHENJIANG PROVINCIAL NATURE RESERVE,JIANGSU PROVINCE

为探究长江江豚种群分布与水下噪声的关系,研究于2021年江苏镇江长江豚类省级自然保护区针对长江江豚自然种群和水下噪声进行了3个水期连续调查。结果表明保护区目视调查长江江豚数量共计46头次,声学拖曳式水下高频声音事件记录仪记录数量共33头,固定式水下高频声音事件记录仪记录发声事件共2253次,其种群分布具有明显的时空差异;水下噪声强度较高,均方根声压级(SPL_(rms))中值为133.80 dB re 1μPa,90%声压级在125.77—137.42 dB re 1μPa,比水下背景噪声平均高11.50 dB,差值最大可达31.12 dB,水下噪声也具有明显的时空差异;将长江江豚种群分布与水下噪声强度叠加分析,显示二者呈明显的负相关关系,此外人类活动产生的水下噪声24h累计加权声暴露级(SEL_(cumw))超过长江江豚暂时性听力阈移(TTS)的阈值,长时间暴露在高强度噪声下,可能会使其听力下降,甚至造成永久性的损伤。研究可为减缓水下噪声污染提供数据指导,为保护区长江江豚保护和栖息地修复工作提供数据支撑。

With rapid social and economic development in the Yangtze River basin,human activities such as wading are increasing,leading to a rise in underwater noise pollution.This pollution poses significant threats to the Yangtze finless porpoises,as they rely on acoustic signals for survival.To investigate the relationship between their population distribution and underwater noise,a study was conducted over 3 consecutive periods in 2021 within the Zhenjiang Yangtze River Dolphin Nature Reserve,Jiangsu Province.The findings revealed distinct spatiotemporal variations in the population distribution.Visually,Yangtze finless porpoises were observed 46 times within the reserve,while acoustic towed underwater high-frequency acoustic event recorders captured 33 sightings,and fixed underwater high-frequency acoustic event recorders recorded 2253 vocal events.Median root-mean-square sound pressure level(SPL_(rms))was calculated at 133.80 dB re 1μPa,with 90%of SPLrms ranging from 125.77 to 137.42 dB re 1μPa.This is notably 11.50 dB higher than the average underwater background noise,with a maximum discrepancy of 31.12 dB,excluding noise from human activities.Spatially,the distribution of Yangtze finless porpoise was most concentrated and underwater noise intensity lowest in the northeast corner of Hechang Island.The study highlights a negative correlation between Yangtze finless porpoise distribution and underwater noise intensity,indicating that lower noise levels are conducive to their survival and habitat.Furthermore,62%of sites in the reserve exhibited a 24h cumulative sound exposure level(SEL_(cumw))surpassing the threshold for temporary hearing threshold shift(TTS)in Yangtze finless porpoise,suggesting potential hearing damage if exposed to high-noise environments for extended periods.Consequently,addressing underwater noise pollution is imperative for their conservation.This study provides essential data for mitigating underwater noise pollution and supports efforts to protect and restore the habitat of Yangtze finless porpoise in the protected area.