Abstract:

Background & Aims: The rapid development of the coastal zones poses a serious challenge to global marine biodiversity, highlighting the urgent need for large-scale and long-term quantitative assessments of habitat changes for key species. Using the Chinese white dolphin (Sousa chinensis) as a key indicator species, this study integrates nearly three decades of satellite remote sensing and socioeconomic data to systematically analyze the spatial patterns and drivers of coastal reclamation in southeastern China, along with the resultant habitat loss and conservation gaps for this species. These findings provide scientific evidence for optimizing China’s marine ecological redlines and formulating conservation strategies for endangered marine species. 

Results: Driven primarily by regional population density (r = 0.638, P < 0.001) and per capita regional GDP (r = 0.635, P < 0.001), the cumulative coastal reclamation area in the study region reached 1,683.20 km² between 1990 and 2020, with an annual average reclamation intensity of 0.30 ha·a^–1·km^–1. The reclamation exhibited a distinct spatial pattern characterized by “higher intensity in the north, lower in the south, and significant clustering in estuarine zones.” Extensive reclamation differentially impacted local Chinese white dolphin populations: the Xiamen Bay population experienced the highest proportion of habitat loss and the highest reclamation intensity within its habitat (9.03% and 0.46 ha·a^–1·km^–1, respectively), followed by the Pearl River Estuary population (4.63% and 0.43 ha·a^–1·km^–1), the population in the southwestern waters of Hainan was the least affected (0.06% and 0.02 ha·a^–1·km^–1). Notably, only 8.25% (818.94 km²) of the species’ current habitat was located within protected areas, revealing significant conservation gaps. 

Conclusion & Recommendation: Urgent actions are required to: (1) incorporate the estuarine habitats of Chinese white dolphin population into the natural protected area system; (2) establish an integrated land-sea conservation framework to protect the existing habitats and enhance connectivity.

Key words: remote sensing imagery, MNDWI, coastal reclamation intensity, habitat, conservation gaps