Temporal and spatial biosonar activity of the recently established uppermost Yangtze finless porpoise population downstream of the Gezhouba Dam: Correlation with hydropower cascade development, shipping, hydrological regime, and light intensity
葛洲坝下游最近建立的长江江豚种群的时空生物声纳活动：与水电梯级开发、航运、水文状况和光照强度的相关性
Abstract
Numerous dams disrupt freshwater animals. The uppermost population of the criticallyendangered Yangtze finless porpoise has been newly formed below the Gezhouba Dam, however, information regarding the local porpoise is scarce. Passive acoustic monitoring was used to detect the behaviors of porpoises below the Gezhouba Dam.The influence of shipping, hydrological regime, and light inten sity on the biosonar activity of dolphins was also examined using Generalized lin ear models. Over the course of 4 years (2019–2022), approximately 848, 596, and 676 effective monitoring days were investigated at the three sites, from upstreamto downstream. Observations revealed significant spatio-temporal biosonar activity.Proportion of days that are porpoise positive were 73%, 54%, and 61%, while por poise buzz signals accounted for 78.49%, 62.35%, and 81.30% of all porpoise biosonarat the three stations. The biosonar activity of porpoises was much higher at the con fluence area, particularly at the MZ site, during the absence of boat traffic, and during the Pandemic shutdown. Temporal trends of monthly, seasonal, and yearly variation were also visible, with the highest number of porpoises biosonar detected in the sum mer season and in 2020. Significant correlations also exist between the hydrological regime and light intensity and porpoise activity, with much higher detections during nighttime and full moon periods. Hydropower cascade development, establishment of a natural reserve, fish release initiatives, and implementation of fishing restric tions may facilitate the proliferation of the porpoise population downstream of the Gezhouba Dam within the Yichang section of the Yangtze River. Prioritizing restora tion designs that match natural flow regimes, optimize boat traffic, and reduce noise
pollution is crucial for promoting the conservation of the local porpoises.
摘要
许多水坝破坏了淡水动物。最重要的群体濒临灭绝的长江江豚在葛洲坝下新形成然而，大坝关于当地海豚的信息很少。被动声监测用于检测葛洲坝下江豚的行为。还使用广义线性模型研究了航运、水文状况和光照强度对海豚生物声纳活动的影响。在4的过程中 年份（2019年至2022年），约848年、596年和在上游的三个地点调查了676个有效监测日到下游。观测揭示了显著的时空生物声纳活动。海豚阳性的天数比例分别为73%、54%和61%，而海豚嗡嗡声信号分别占所有海豚生物声纳的78.49%、62.35%和81.30%在三个车站。在没有船只通行的情况下，在影响区，特别是在MZ现场，鼠海豚的生物声纳活动要高得多疫。月度、季度和年度变化的时间趋势在夏季和2020年检测到的海豚数量最多。水文要素之间也存在显著相关性环境、光照强度和海豚活动，在夜间和满月期间。水电梯级开发、建设自然保护区、鱼类放流倡议和捕鱼限制的实施可能会促进江豚种群在下游的扩散葛洲坝位于长江宜昌段。优先考虑符合自然流态、优化船舶交通和降低噪音的修复设计污染对于促进当地鼠海豚的保护至关重要。
