Abstract:
Black tiger shrimp culture is one of the most important aquaculture industry in Thailand. Recently, black tiger shrimp culture system is an intensive one, which produces a great amount of wastewater released from shrimp pond. This caused the environment pollution in shrimp pond surroundings and in natural receiving waters. Therefore, shrimp culture management is required for the sustainability of black tiger shrimp culture. In this study, the experiment was classified into 3 phases. In the first phase, development of closed culture system using algae (50, 100 and 200 g/L) and biofilter (1,000, 2,000 and 4,000 cm2 for ammonia, nitrite, nitrate and phosphate removal was established. Results showed that all tested densities of algae were able to decrease concentrations of ammonia and phosphate significantly (p < 0.05), compared to the controls. The highest density (200g/L) of algae showed the greatest ammonia reduction and nitrate reduction, but low concentration of nitrite as accumulated. All three levels of surface area of tested biofilter could reduce the concentration of ammonia significantly, compared to the controls. However, in the biofilter treatment tanks accumulated small amount of nitrite and high amount. In the second phase, the effect of algae and/or biofilter of ammonia, nitrite, nitrate and phosphate removal in simulated shrimp pond was studied. There were 3 treatments in the second phase: shrimp culture with algae only, shrimp with biofilter only and the control (on algae and biofilter). Results showed that shrimp with algae could reduce ammonia, nitrite and nitrate significantly (p < 0.05) than those in shrimp with biofilter and the control. In contrast, biofilter treatment can remove only ammonia and nitrite while the control showed no reduction of all tested nutrients. In the third phase, two treatments (shrimp with biofilter only and shrimp with biofilter and algae) and the control (no algae and biofilter) in earthen shrimp ponds were evaluated. Results demonstrated that there were no difference in removal of all tested nutrients and FCR as well as well as survival rate of shrimps (p < 0.05) among treatments. However, shrimp products, weight and length of shrimp in cultures with biofilter and algae were high. The results of this study concluded the combination of algae and biofilter showed the best performance for black tiger shrimp culture due to the efficiency of higher shrimp products and shrimp growth, compared to the treatment with biofulter only and the control.