Differential responses of Indo-Pacific humpback dolphin populations to climate change: Implications for future habitat shifts and conservation strategies

Understanding species' potential distribution is crucial for informing effective conservation strategies. The Indo-Pacific humpback dolphin (Sousa chinensis, IPHD), a vital indicator of marine ecosystem health, is increasingly threatened by human activities and climate change, and is currently listed as Vulnerable on the IUCN Red List of Threatened Species. By integrating species distribution records with ten environmental variables, we developed species-level (SLDMs) and population-level distribution models (PLDMs) to investigate the habitat preferences of IPHDs in China and evaluate their current and future habitat dynamics under different climate change scenarios. The SLDMs identified mixed layer depth as the primary environmental variable influencing the distribution of IPHDs, while the PLDMs revealed that the key environmental variable influencing distribution differs across different IPHD populations. The SLDMs projected a continuous reduction in suitable habitat for IPHDs over the next 70 years. The PLDMs indicated that larger IPHD populations, such as those in the Pearl River Estuary (PRE), Leizhou Bay (LZB), and Sanniang Bay (SNB), may serve as critical refugia with available habitats for transfer in the future, whereas smaller IPHD populations, including Xiamen-Jinmen (XJ) and Yuedong (YD) populations, are projected to face severe and progressive habitat loss, increasing their risk of local extinction. This research offers valuable insights for future protected area planning and the development of climate-appropriate conservation strategies.