Analysis on ecological status and degradation factors of Halophila beccarii seagrass beds in Huachang Bay, Hainan.

Halophila beccarii is one of the 10 seagrass species at risk of extinction worldwide and is listed as Vulnerable (VU) by the IUCN. To expand the baseline data on H. beccarii seagrass beds and identify the primary factors influencing their spatial distribution, this study investigated the growth and environmental characteristics of H. beccarii seagrass beds in Huachang Bay in 2025. Factor analysis and Spearman correlation analysis were adopted to explore the relationships between seagrass traits and environmental variables. The results showed that the coverage, density and biomass of H. beccarii all exhibited a declining trend. Spatially, seagrass beds near the lagoon inlet and mid-lagoon zones maintained relatively stable ecological status, whereas inner lagoon habitats suffered obvious degradation driven by intensive mariculture. Data analysis revealed that the coverage, density and biomass of H. beccarii were significantly negatively correlated with salinity, indicating that salinity acts as the primary driving factor for the degradation of H. beccarii in this region. Additionally, eutrophication and heavy metal pollution resulting from the discharge of aquaculture wastewater from shrimp ponds around Huachang Bay may also have potential negative impacts on H. beccarii. Given that the H. beccarii seagrass beds in this area have undergone a certain degree of degradation, it is recommended that Huachang Bay Nature Reserve treat seagrasses as equally key protected targets in future management and strengthen relevant conservation and management measures.