Lin Wenzhi, Zheng Ruiqiang, Liu Binshuai, Chen Shenglan, Lin Mingli, Serres Agathe, Liu Mingming, Liu Wenhua, Li Songhai
Marine Mammal and Marine Bioacoustics Laboratory, Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China.
Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, 515063, China; China Blue Sustainability Institute, Haikou, Hainan, 570208, China.
J Environ Manage. 2023 Mar 15;330:117120. doi: 10.1016/j.jenvman.2022.117120. Epub 2022 Dec 29.
It is generally accepted that vessel activity causes various behavioral responses of cetaceans and undermines individual fitness. Whether or how it can lead to a demographic response of populations remains rarely examined. In the northern Beibu Gulf, China, vessel activities have sharply increased in the past two decades, while abnormal demographic dynamics was recently noted for the resident Indo-Pacific humpback dolphins. The present study first examined the humpback dolphins' utilization distribution (UD) from 2003 to 2019. Habitat suitability was then modeled with the sighting data collected before the most recent population reduction. Finally, we tried to disentangle the anthropogenic driver of dolphin demography by cross-referring the spatiotemporal development of dolphins' UD, vessel activities, and habitat suitability. Our results showed that the dolphins' UD shrank substantially during the port expansion in the early 2010s, and we suggest that the consequential increase in vessel activities might impose extra marine stressors on the resident humpback dolphins. To reduce the boat interaction, the dolphins steadily shifted their core area to a less suitable area in the east during 2015-2017, when unnaturally low survivals were recorded. Afterward, the dolphin core area partially shifted back to the more suitable area in the west, which corresponded to the improving dolphin survival in 2018. Our finding suggested that the vessel activity may be responsible for the dolphin displacement, while staying in the less suitable area may further lead to a more severe and acute demographic consequence on the population. The underlying and indirect impact of vessel activities as disclosed by the present study is particularly important for port management, marine planning, and conservation practice regarding coastal cetaceans, especially for those resident and endangered populations inhabiting the urbanized coastal areas.
人们普遍认为，船只活动会引发鲸类动物的各种行为反应，并损害个体健康。然而，船只活动是否会导致种群的人口统计学反应，或者如何导致这种反应，仍鲜有研究。在中国北部湾北部，过去二十年来船只活动急剧增加，而最近发现当地的印太驼背豚出现了异常的种群动态。本研究首先考察了2003年至2019年驼背豚的利用分布（UD）。然后利用最近种群数量减少之前收集的目击数据，对栖息地适宜性进行了建模。最后，我们通过交叉参考海豚利用分布、船只活动和栖息地适宜性的时空发展情况，试图厘清影响海豚种群统计学的人为驱动因素。我们的结果表明，在2010年代初港口扩张期间，海豚的利用分布大幅缩小，我们认为随之增加的船只活动可能给当地的驼背豚带来了额外的海洋压力源。为了减少与船只的互动，海豚在2015年至2017年期间稳步将其核心区域转移到东部一个不太适宜的区域，当时记录到了异常低的存活率。之后，海豚的核心区域部分又转回西部更适宜的区域，这与2018年海豚存活率的提高相对应。我们的研究结果表明，船只活动可能是导致海豚栖息地转移的原因，而停留在不太适宜的区域可能会进一步给种群带来更严重和更直接的人口统计学后果。本研究揭示的船只活动的潜在和间接影响，对于港口管理、海洋规划以及沿海鲸类动物的保护实践尤为重要，特别是对于那些栖息在城市化沿海地区的定居和濒危种群。
