Potensi budidaya rumput laut Kappaphycus alvarezii dan Gacilaria gigas dalam penyerapan karbon

Abstract

Carbon sequestration by algae as photoautotrophic organism is potential to reduce CO2 released to the atmosphere, and support to reduce the inclination of global warming. The aim of this study was to analyzed the level of carbon sequestration by seaweed aquaculture of Kappaphycus alvarezii and Gracilaria gigas based on photosynthesis activity included influential variabels, and also analyzed potency of carbon sequestration by seaweed aquaculture area. Seaweed cultivation was conducted at Gerupuk Bay, Central Lombok, West Nusa Tenggara on long-line system with culture area of 2.500 m2. The seaweeds and sea water parameters were analysed on days-0, 10, 20, 30 and 45. Seaweeds parameters was observed included daily growth rate, carbon absorption rate, carbohydrate production, photosynthesis pigment content, aquaculture productivity, and branching index. Water quality parameters was analyzed included temperature, salinity, dissolved oxygen, pH, total dissolved solid, total CO2, NO3-N, NO2-N, NH3-N, PO4-P, transparency and current velocity. Total rate of carbon sequestration based on biomass seaweeds harvesting at the end of cultivation that showed G. gigas (20,67 ton C/ha/year) was almost 335,79% higher than K. alvarezii (90,09 ton C/ha/year), and also higher daily growth rate, carbohydrates production, and photosynthesis rate that supported by higher branching index. The rate of carbon absorption by seaweeds had the highest positive correlation with pigment content as internal factor of seaweeds, as well as water transparency as external factor. Potency of carbon sequestration by seaweeds aquaculture area in Gerupuk Bay reached 6.656,51 tons C/year or 0,36 ton C/ton biomass for K. alvarezii; and 29.008,53 tons C/year or 0,58 ton C/ton biomass for G. gigas cultivation. High potency of carbon sequestration of seaweeds aquaculture could be an alternative of sustainable seaweed aquaculture management. Strategy of seaweeds cultivation might applied based on the highest carbon absorption rate on days 0 – 20 by getting rejuvenation, so that more effective in carbon sequestration as well as increasing of seaweed aquaculture productivity.