Growth Response of Kappaphycus Alvarezii at Different Depth in the Waters of Batu Bao, East Nusa Tenggara

ABSTRACT Seaweed is one of the important fisheries commodities with significant economic value. Kappaphycus alvarezii, commonly known as Eucheuma cottoni in the market, is a type of seaweed that produces kappa carrageenan. This research aims to determine the effective planting depth for the growth, morphological and histological changes, and the environmental parameters influencing the growth of K. alvarezii. The cultivation method used in this research is the longline method, and it employs a Completely Randomized Design consisting of four treatments: 15cm, 30cm, 45cm, and 60cm, with each treatment replicated five times. The data were analyzed using analysis of variance, and if significant differences were found, Duncan's post hoc test was conducted. The research results indicate that an increase in planting depth has a significant impact on specific growth rate (SGR) and average growth rate (AGR). Deeper planting depths result in slower growth. The best depth for the growth, morphology, and histology of K. alvarezii during the study was observed at a depth of 15 cm. Environmental parameters such as temperature, salinity, water flow rate, water clarity, and pH have a positive influence on the growth of K. alvarezii.