Salinity-modulates Crassostrea hongkongensis physiological efficiency and carbon storage: A case study in Maowei Sea, Guangxi, China

The current research of fishery carbon sinks mainly focusing on the carbon budget in individual marine organisms, but its environmental implications are often overlooked. Hence, this study investigated the complex interplay between environmental parameters and carbon content in C. hongkongensis culture systems in the Maowei Sea, Guangxi, China. Monthly sampling was conducted for 12 months to assess environmental parameters, carbon fractionation in seawater (particulate and dissolved), oyster biological parameters and carbon content cultured in inner and outer bay stations. Results indicated that environmental conditions, water column carbon fractions, oyster condition index, and flesh and shell carbon content showed pronounced temporal variation in Maowei Sea. Spatial differences between the inner and outer bay stations were comparatively limited, with significant station effects detected mainly for water depth and salinity. The condition index and oyster carbon content varied seasonally, indicating that temporal environmental changes exerted a stronger influence than sampling location. Correlations with dissolved organic carbon suggest links between water-column carbon dynamics and oyster physiological condition, although these relationships do not establish causation. Overall, the study provides an annual baseline for carbon dynamics in C. hongkongensis aquaculture in Maowei Sea. These findings of this study not only reveal the influence of spatial and temporal factors on physiological and carbon storage of this oyster species but also provide evidence to show the potential of C. hongkongensis in term of economic value.