Integrated Multi-Trophic Aquaculture (IMTA): A Potential Farming System to Enhance Production of the Red Seaweed Agarophyton tenuistipitatum (Chang and Xia) in Brackishwater

Globally, intensification in aquaculture leads to concern on both environmental and economic sustainability. In this context, integrated multi-trophic aquaculture (IMTA) is one of the best solutions to bring in sustainability in aquaculture. Earlier studies suggest that raising the ecosystem capacity, i.e., increasing the succession of trophic levels may enhance the biomass production of seaweed. Therefore, IMTA may impact positively for the production of seaweed biomass, which will help to meet up the immense industrial requirement of raw material. Thus, the present study focused to evaluate the production performance of red alga Agarophyton tenuistipitatum in an IMTA (milkfish-oyster-seaweed) system in comparison to monoculture (only seaweed) in brackishwater tide-fed ponds in Sundarbans. Water salinity ranged between 5 and 7.5 g L−1 during the 90-days study period. It was observed that the biomass production increased as time progressed in both systems, but biomass and specific growth rate were significantly higher in IMTA (1657.98 ± 65.905 g and 2.64 ± 0.049% d−1) compared to monoculture (1287.74 ± 86.003 g and 2.32 ± 0.085% d−1) throughout the culture period. Analysis of tissue C and N contents of A. tenuistipitatum revealed significantly higher percentage of deposition in IMTA seaweed than in monocultured one. In addition, an average final body weight of milkfish was 214.89 ± 1.665 g from initial 14.57 ± 1.66 g in the IMTA system. An average 10% weight gain of edible oyster was obtained from the IMTA during the culture period. It could be concluded that along with higher growth performance, seaweed utilized a significant amount of carbon and nitrogen which maintained the environmental sustainability. Moreover, higher biomass production and diversification of species in IMTA will certainly provide an economic sustainability to farmers through intensive farming.