Safeguarding seagrass blue carbon sinks: An integrated modeling approach projects habitat suitability and carbon...

Seagrass beds are critical blue carbon ecosystems in the Yellow Sea and Bohai Sea currently facing severe degradation. Understanding the linkage between their distribution dynamics and carbon sink function is urgently needed. In this study, we developed an integrated assessment framework coupling ensemble species distribution models (eSDMs) with the InVEST model, using annual carbon accumulation rates for dynamic carbon accounting rather than instantaneous equilibrium to quantitatively evaluate seagrass habitats and carbon storage. Using carbon density data, we analyzed spatio-temporal patterns of suitable habitats and blue carbon stocks. Results indicate: (1) The ensemble model showed excellent predictive performance (TSS > 0.90); (2) Human activity intensity was the dominant driver of seagrass distribution (24% contribution), challenging conventional temperature-salinity paradigms; (3) Suitable habitats concentrate along Liaoning, Hebei, and Shandong coasts; (4) Carbon density displays a latitudinal gradient at 50-100 Mg C·ha⁻¹ and > 100 Mg C·ha⁻¹; (5) Baseline blue carbon storage reached 7.18 × 10⁷ Mg C in high‑suitability and 9.36 × 10⁷ Mg C in moderate‑suitability habitats, with future storage estimated using temporally explicit accumulation rates. Future projections show the high-emission pathway (SSP585) exacerbating habitat fragmentation and undermining carbon sink stability, while the low-emission pathway (SSP126) better maintains stability. Critically, carbon loss from degradation far exceeds gains from new habitats, emphasizing the priority of protecting existing carbon stocks. This study achieves raster-scale quantification of regional seagrass blue carbon sinks. Our eSDM-InVEST framework provides a scientific basis for temperate seagrass conservation and blue carbon management, supporting carbon neutrality and biodiversity conservation goals.