Bioremediation Potential of the Brackishwater Macroalga Gracilaria tenuistipitata (Rhodophyta) Co-cultured with Pacific White Shrimp Penaeus vannamei (Boone)

The rapid development of intensive shrimp culture has aroused increased concerns about its impact on coastal waters. Practicing propensity of a balanced ecosystem based culture approach is the best way towards sustainability. In this context, seaweed based co-culture finds significance but evaluation of its symbiotic nature needs to be ascertained. Accordingly, an outdoor trial was conducted to arrive at the effective biomass intensity of seaweed Gracilaria tenuistipitata for efficient bioremediation as well as growth and survival of Penaeus vannamei. An experiment with five treatments (different biomass intensity, (0, 0.5, 1.5, 2.5 and 3.5 g L-1) revealed that at a biomass intensity of 3.5 g L-1, NH4 - N and PO4 - P significantly (p <0.05) reduced by 95.71% and 95.74%, respectively in three weeks. It was also observed that turbidity was significantly lowest (0.94 NTU) and specific growth rate was significantly higher (2.86% d(-1)) at the same biomass intensity (3.5 g L-1). Average body weight and specific growth rate of P. vannamei were not significantly increased but survival (99.17%) was significantly (p <0.05) higher. Total bacterial count was also significantly (p <0.05) reduced. This study revealed that seaweed (3.5 g L-1) - shrimp when co- cultured, improves the water quality and has bioremedial benefits in the culture system.