CARBON SEQUESTRATION BY CULTIVATED SEAWEEDS: IMPORTANT ROLE OF AQUACULTURE ON CLIMATE CHANGE MITIGATION IN INDONESIA

Erlania*, I Nyoman Radiarta and Ketut Sugama
 
Center for Aquaculture Research and Development
Jl. Ragunan 20 Pasar Minggu, South Jakarta, Indonesia 12540
erlania_elleen@yahoo.com

One of Indonesian government policy is double of national fisheries production in 2019. Seaweeds are considered as one of main commodity to attain the national production target through cultivation activity. Several study show that seaweeds also play an important role in climate change mitigation by using CO2 for photosynthesis process to produce their biomass. This study aimed to analyze and describe the ability of several cultivated seaweed species on CO2 sequestration concerned with climate change mitigation through seaweed aquaculture development in Indonesia.

The study was conducted during three years in 2012 - 2014 in Gerupuk Bay and Ekas Bay, Lombok Island, West Nusa Tenggara, Indonesia. Several seaweed species have been cultivated included Kappaphycus alvarezii var. Tambalang, K. alvarezii var. Maumere, K. striatum, Eucheuma denticulatum, and Gracilaria gigas using long-line methods sized about 50 x 50 m2 in  Gerupuk Bay; and K. alvarezii var. Maumere using 7 x 7 m2 bamboo floating raft in Ekas Bay. Seaweed sampling was held every 15 days during cultivation period which took time about 45 days per cycle. Seaweed sample from 5 random planting point were weighed and then collected for laboratory analysis to measured C content of each species. Carbon sequestration rate was estimated based on total cultivation wide area (ha), standing stock of seaweed (g/m2), C content (%), and production-biomass ratio.

The result showed that G. gigas has the highest rate in carbon sequestration during cultivation period that achieved 631,09 ton CO2/ha/year (Fig. 1). Kappaphycus alvarezii including Tambalang and Maumere variant indicated close value of maximum CO2 sequestration rate which range about 61,11-166,19 ton CO2/ha/year (Fig.1). Different seaweed species have varied capability on CO2 sequestration rate, which also were influenced by condition of different cultivation implementation periods.    Development of seaweed  aquaculture can give  more benefit  not only  biomass production, but also mitigate climate change regarding  blue carbon context.