Carbon sequestration in macroalgae Kappaphycus striatum in seaweed aquaculture site, Alaang village, Alor Island, East Nusa Tenggara

Carbon sequestration in macroalgae through photosynthesis can contribute to the mitigation of the climate change problem. This research aimed to analyze carbon sequestration potential on macroalgae Kappaphycus striatum with different harvested ages; i.e. young (25 days) and adult (60 days). Samples were collected randomly from off-bottom seaweed aquaculture system, at Alaang village, Alor island, East Nusa Tenggara. The parameter observed was carbon content determined by using gravimetric analysis. Growth rate measurement and light-dark bottle experiment were also conducted to be further analyzed. Results showed in total area 1,552 m², it was estimated that the carbon sequestration potential of macroalgae Kappaphycus striatum was 13.28 tonnes C/cycle for young and 26.63 tonnes C/cycle for adult. These results were equal to 66.07 tonnes C/ha/cycle and 125.51 tonnes C/ha/cycle, respectively. Therefore, the carbon sequestration potential of adult seaweed was higher about 32.78% than that of young seaweed, followed by its lower growth rate and higher primary productivity. It can be concluded that the carbon sequestration potential was influenced by growth rate and primary productivity. Further study on sustainable management of seaweed aquaculture sites, by considering ecological and economic values, could potentially provide multiple functions both for human and ecosystem.