Optimization of Cultivated Seaweed Land Gracilaria sp Using Vertikultur System

The production of Gracilaria sp  is still not optimal and there are some opportunities left for production improvement by developing methods that use depth level as a planting media. A vertikultur method using bag nets is more effective and has higher production levels. This research aims to solve problems in cultivating Gracilaria sp seaweed by doing field optimization. Seaweeds were planted as many as 40 points for each 10 levels depth (BRL); 0, 70, 140, 210, 280, 350, 420, 560, and 630 cm from the surface. Environment and seaweed parameters were measured weekly. This research measures daily and weekly growth rate, absolute growth, and the total production. The data were analyzed using Anota test and BNJ further test . The research result shows that physic-chemistry water parameter is suitable for cultivating Gracilaria sp . The lowest weekly growth rate occurred in level BRL 10 in the first week while gaining weight as much as 9.351 gram/week. The highest growth rate occurred in level BRL 4 on the sixth week while gaining weight as much as 32.25 gram/week. The biggest absolute growth occurred in level BRL 4 with 214.87 gram and the lowest occurred in level BRL 10 with 161.45 gram. The biggest absolute growth rate occurred in level BR1 4 while gaining weight as much as 139.87 gram from the original weight and the lowest occurred in level BRL10 with 86.45 gram from the original weight. The best daily growth rate occurred in level BRL 4 with a growth rate of 2.53%/day and the lowest occurred in BRL 10 with 1.84%/day. Total production of Gracilaria sp from level BR1 1 – BR1 10 is 74,840 gram. The biggest production was obtained from level BRL 4 with the production of 8595 gram and the lowest in BRL 10 with 6458 gram. According to the anova test result and beda nyata jujur (BNJ), it shows that depth level (BR1 1 – BR1 10) gave no influence towards the growth rate of Gracilaria sp in the water of Kelagian Island. The vertikultur method by making use of depth level is both feasible and profitable for seaweed cultivators with production level ten times bigger.