First high-resolution marine natural capital mapping in the coastal waters of Chinese mainland.

Marine ecosystems are complex self-organized systems that generate natural capital stocks and vital ecosystem services (ES) for human well-being. However, the assessment of marine natural capital in coastal countries is often overlooked. In this study, we evaluated the value of marine natural capital in mainland China using existing ES classifications and the emergy method. China's marine natural capital was estimated at 3.29E+24 sej/yr, with coastal waters having 3.2 times higher emergy density than terrestrial ecosystems. The annual economic value of marine natural capital in China's coastal water was approximately 8817.42 billion yuan/yr, nearly equal to China's Gross Ocean Product (GOP) in 2019 (8941.5-billion-yuan). Southern China showed significantly higher natural capital values than northern China. These findings highlight regional disparities in marine resource utilization and socioeconomic status, posing challenges to sustainable ocean development. The results provide a reference for policy and strategy development for sustainable marine resource exploitation.