Nitrogen, Phosphorus Absorption Rate and Growth of Gracillaria verrucosa Based on Integrated Multi-Trophic Aquaculture (IMTA) in Ekas Bay Waters, East Lombok, Indonesia

The development of marine aquaculture based on Integrated Multi-Trophic Aquaculture (IMTA) is a method designed to overcome environmental problems associated with feed use in aquaculture activities. This study aims to analyze the growth performance, production and absorption rate of N and P of Gracillaria verrucosa seaweed cultivated by floating raft method around floating net cages. This study used an experimental method with 3 repetitions with the location of the floating raft system seaweed cultivation around the floating net cage (FNC) system cultivation activities placed at a distance of 40 meters from the FNC in the north (N), in the south (S), in the east (E), in the west (W) and floating rafts at a distance of 250 meters from the FNC as a control (C). The results showed that seaweed cultivated around FNC had better growth and production performance compared to those cultivated without FNC or controls. The N absorption rate of seaweed cultivated around FNC sites with a range between 0.41 - 0.88 g N/m2/day or 1.51 - 3.20 tons of N/ha/year was higher than in the control location of 0.49 g N/m2/day or 1.78 tons N/ha/year. While the level of P absorption of seaweed cultivated around the FNC location with a range between 0.69 - 1.38 g P/m2/day or 2.51 - 5.05 tons of P/ha/year is higher than in the control site of 0.49 g P/m2/day or 1.78 tons P/ha/year. The application of IMTA-based seaweed cultivation of Gracilaria verrucosa clearly provides economic and ecological benefits with an increase in biomass and improved environmental conditions.