Abstract

Seaweed aquaculture beds (SABs), which sustain seaweed production and a variety of associated products, occupy vast coastal regions. They offer numerous ecosystem benefits, including nutrient extraction and CO2 absorption. The process of photosynthesis in seaweed, leading to carbon sequestration, can aid in alleviating the issue of climate change. This research was aimed to determine carbon uptake by Glacilaria verrucosa and Kappahycus alvarezii at seaweed cultivation area, to calculate carbon sequestration from seaweed cultivation area at Takalar, and to examine the impact of nutrient concentration to carbon uptake by G. verrucosa and K. alvarezii. We conducted field (light and dark bottle experiment) and laboratory experiments on November 2023 to March 2024. The parameters were measured for both experiments including biomass, growth rate, and carbon uptake. Field experiment results showed that the biomass of K. alvarezii seaweed reached 546.12±286.65 g while G. verrucosa was only 403.18±72.73 25 g. The specific growth rate of G. verrucosa seaweed reached 8.28 ± 0.90%/day, whereas for the K. alvarezii is lower growth, accounting for 6.22 ± 1.06%/day. The carbon uptake of G. verrucosa seaweed was found to be 0.63±0.09 mg CO2/g/h much higher than the carbon uptake of K. alvarezii, which was found to be 0.10±0.05 mg CO2/g/h. Furthermore, for laboratory experiment results showed that Biomass, growth rate, and carbon uptake of G. verrucosa and K. alvarezii varied between control and nutrient treatment. In conclusion, seaweed cultivation area at Takalar Regency has a high potential as a carbon sequestration; G. verrucosa and K. alvarezii were a seaweed with a high potential for reducing CO2 concentration in the water due to a high capability to take up carbon. Consequently, seaweed cultivation area can contribute to mitigating climate change, in particular increasing CO2 concentration in the atmosphere and waters.