Abstract:
This study was investigated the roles of the seaweed C. lentillifera for treatment of inorganic nitrogen compounds in different kinds of aquaculture system. The seaweed was cultured in a plastic container with no soil and contained with soil in which occupied internally by 5 cm thickness of soil and filled with 30 ppt seawater by volume of 25 L. Powdered fish feed was added into all plastic containers as the organic carbon source through the 61 days of the experimental operation. The water quality was evaluated and revealed the same results for the both control operation conditions of outdoor without seaweed and soil and indoor without seaweed and soil. The amount of ammonia quantities in the water was detected from the result of powdered fish feed decomposition by ammonification process. Accordingly, it significantly led the accumulation of ammonia in the water at the 8th days of the experiment. Then the amount of nitrite concentration was rarely detected after the 40th days after that it was turned to be nitrate through nitrification process. In outdoor condition with seaweed, the amount of ammonia quantities founded in water illustrated the major role of seaweed in nitrogen uptake rather than the indoor condition. In the container which contained with soil, the accumulation of nitrate was found because of nitrogen conversion through nitrification and denitrification processes by bacterial culture in sediment. The results clearly illustrated that the natural bacterial culture in soil has the major role in biological nitrogen conversion in aquaculture system. Roles of using C. lentillifera for treatment in Lates calcarifer culture tanks showed that, In condition control with seaweed and soil and outdoor. This could provide water quality with low ammonia and without the accumulation of nitrite, nitrate and phosphate in the system.