Effect of water spinach floating bed and chlorella pyrenoidosa on water quality and shrimp growth in an aquaponics system

Abstract

Twelve concrete ponds were stocked with pacific white shrimp (Penaeus vannamei) each weighing about 0.1g and grown for 77 days. The effects of autotrophs, floating beds of water spinach (Ipomoea aquatica) and microalgae (Chlorella pyrenoidosa) on water purification and shrimp growth were assessed. The results showed that the water quality of aquaculture water with water spinach (S1), aquaculture water with chlorella (S2), and aquaculture water with water spinach and chlorella (S3) were significantly better than that of Aquaculture water without vegetation and chlorella (S0). The combination of water spinach and chlorella (S3) was able to keep ammonia and nitrite nitrogen levels below 1.0 mg/L and 0.1 mg/L, respectively. These low levels were not lethal or detrimental to the growth of the white shrimp. The roots of the water spinach were the vital organs for the removal of N and P. Sixty percent of the removed portion of N and P accumulated in the roots of the water spinach. The survival rate and mean harvest weight of shrimp from S1, and S3 was significantly higher than that from S0, and S2. In addition, in S3 the immunity of the shrimp was improved due to the formation of similar biological floccules around the roots and thus increasing their survival rate. The present study indicates that a vegetable-microalgae-shrimp system has a good potential for practical application in commercial shrimp production.