Carbon Absorption Potential and Environmental Drivers of Eucheuma spinosum Cultivation in Coastal Waters of South Sulawesi, Indonesia

Abstrak Seaweed cultivation is increasingly recognized for its role in blue carbon sequestration and coastal sustainability. Eucheuma spinosum , a fast-growing carrageenophyte, offers high biomass productivity and potential for carbon uptake. This study investigates growth performance and carbon dynamics of E. spinosum across three major cultivation sites in South Sulawesi: Takalar, Jeneponto, and Bantaeng. Water quality parameters—including depth, salinity, turbidity, pH, and nutrients—were measured and analyzed using regression and Principal Component Analysis (PCA). Results show that depth and salinity positively influence biomass and carbon uptake, while turbidity, pH, and excessive light intensity negatively affect productivity. Jeneponto recorded the highest biomass yield but lowest carbon content, whereas Takalar showed the highest carbon uptake per unit area. A non-linear relationship between biomass and carbon content was observed, indicating a metabolic trade-off: optimal conditions promote structural growth, while environmental stress triggers carbon reserve accumulation. This adaptive strategy reflects the complexity of interpreting carbon sequestration solely from biomass metrics. Spatial variation in carbon uptake highlights the need for site-specific management. Integrating environmental assessments and physiological responses into cultivation planning can enhance the role of E. spinosum in Indonesia's blue carbon strategy and climate mitigation efforts.