Growth Profile of Kappaphycus Alvarezii Cultivated Using A Vertical Culture System at Different Depths in Concrete Tanks

This study aimed to evaluate the effect of different water depths on the growth performance of K. alvarezii cultivated in concrete tanks using a vertical culture method. The experiment was conducted from June to September 2025 at the National Research and Innovation Agency (BRIN). A completely randomized design (CRD) was applied, consisting of four depth treatments with four replicates: 10 cm (P0), 20 cm (P1), 30 cm (P2), and 40 cm (P3). Seaweed seedlings with an initial weight of 50 g were cultured for 21 days. Observed parameters included absolute weight gain (g), specific growth rate (%/day), thallus length (cm), number of thalli, survival rate (%), and water quality variables. Data were analyzed using analysis of variance (ANOVA) in SPSS at a 95% confidence level. The results indicated that water depth in the vertical culture system did not significantly affect the growth performance or survival of K. alvarezii. Nevertheless, based on mean values, the 10 cm depth treatment (P0) exhibited the highest growth, with an absolute weight gain of 0.73 ± 0.17 g, a specific growth rate of 0.07 ± 0.02%/day, thallus length of 0.95 ± 0.06 cm, number of thalli of 48.3 ± 0.13, and a survival rate of 100%. These outcomes were supported by favorable water quality conditions throughout the culture period, with temperatures ranging from 26.5–27.9 °C, pH values of 7.28–8.00, dissolved oxygen levels of 6.0–8.0 mg/L, and salinity of 32–34 ppt