Abstract: Sea is the habitat for marine life and an integral part of human survival and development. Marine ecosystem is an important part of China’s sustainable development. To understand the sustainability of marine ecosystems, we adopted emergy analysis from two aspects, marine ecosystem values and its utility to human beings. Concerning natural capital stock, ecosystem service value, resource consumption and environmental pollution, this study built a comprehensive set of marine ecosystem evaluation index system. Marine ecosystem sustainability in Liaoning Province in 2018 was evaluated. The results showed that: (1) The natural capital stock of marine ecosystem was 1.30E+25 sej and emergy value per unit sea area was 2.03E+14 sej·m^-2, with environmental assets accounting for the largest proportion (58.63%). The emergy monetary value was 3.67E+12 Em＄and emergy monetary value per unit sea area was 57.29 Em＄·m^-2. (2) The emergy monetary value of marine ecosystem services was 1.42E+10 Em＄, which was 2.58 times of the overall market price (5.50E+09 ＄). (3) Comparing the sustainable development index before and after revision (considering ecological economic loss after revision): emergy yield ratio (EYR) was 107, environmental loading ratio (ELR) was 2.97, emergy sustainability indicator (ESI) was 36.10; revised emergy yield ratio (EYR′) was 38.30, revised environmental loading ratio (ELR′) was 3.04, and revised emergy sustainability indicator (ESI′) was 12.60. The lower EYR′ and ESI′ but higher ELR′ indicated that pollution and industry development played a significant role on marine ecosystem sustainability. With the rapid development of marine industry, the problems of marine ecological environment cannot be ignored. Therefore, the relevant policy suggestions were proposed to promote the sustainable development of marine ecosystem in Liaoning Province, including optimizing the pattern of marine spatial development to comprehensively improving the high-quality development of marine economy, protecting marine ecosystem services, paying great attention to their ecological values, and facilitating the marine coordinated development of economy-society-ecology.

Key words: ecosystem valuation, sustainable development, ocean, emergy analysis