Comparison of physical-chemical conditions for seaweed cultivation in the Spermonde Archipelago, Indonesia

Seaweed cultivation is one of the alternative livelihoods that could support the economy of the small island communities. However, the good growth of seaweed is intrinsically linked to the physicalchemical conditions of the seaweed cultivation area. Therefore, the objectives of this study were to assess and compare the physical-chemical conditions of seaweed farming areas and their relationship with seaweed growth in the Spermonde Archipelago, one of the major seaweed cultivation areas in South Sulawesi, Indonesia. The physical-chemical parameters measured in the field or through laboratory analysis included temperature, salinity, pH, dissolved oxygen (DO), phosphate (PO4), nitrate (NO3), and carbon dioxide (CO2). Data were collected from June to September 2019 from the waters around the islands of Balang Caddi (BC), Polewali (Pw), and Laiya (Ly), and in the coastal areas of Bonto Pannu (BP) and Punaga (Pg) villages. Data on seaweed growth was collected from seaweed (Kappaphycus alvarezii) farming trials using different culture methods (longlines, polyethylene nets, and baskets) at two sites (BC and Ly Islands) starting in June with further monthly planting from July to September. The physicalchemical parameters were similar for all sites and in general, met the acceptance criteria for K. alvarezii growth; however, seaweed growth was affected by the cultivation method applied. The growth of seaweed cultivated with the longline method was constrained by the presence of epiphytes attached to the thallus. However, with the polyethylene net and basket methods, the epiphytes were much reduced, resulting in improved growth and bright green seaweed thalli