Organic matter reduction using four densities of seaweed (Gracilaria verucosa) and green mussel (Perna viridis) to improve water quality for aquaculture in Java, Indonesia

The high organic waste content of river water in Demak, north coast Java, has caused traditional small-scale pond farmers to stop stocking shrimp. This paper examines whether seaweed and mussel will improve the quality these use. effect Gracilaria verucosa Perna viridis on was assessed by measuring removal rates (RRs) total material (TOM), ammonia nitrogen (TAN), nitrite, nitrate. specific growth (SGRs) were also measured. Thirty-six semi-outdoor tanks containing 800 L brackish 7 cm substrate randomly assigned four replications densities G. : 50 (S50), 100 (S100), 150 (S150), 200 (S200) g m −2 , P. 60 (M60), 90 (M90), 120 (M120), (M150) . Weekly, TOM, TAN, nitrate contents measured, weighted; RRs SGRs calculated at end study. significant for both mussel. more effective reducing TOM (by 38%) than (7%); achieved higher At S200, TAN decreased 7.4% 67%, respectively. M90, 38% 49%, However, nitrite increased significantly S200 M150. SGR lower that S150, S100, S50. best performing S100 M90.