A CASE STUDY ON OPTIMAL CULTURE STRUCTURE OF PRAWN2FISH2SHELLFISH2ALGAE

An optimal culture structure of prawn-fish-shellfish-algae and its water quality manipulation systemwere established and studied in the paper. The systemincludes four such culture areas as prawn,fish,shellfish and macroalgae culture areas,one probiotic and microalgae culture area,one water treatment area and one emergency water drainage canal1Biomanipulation of water quality could be achieved by stocking different economic animals and plants such as prawn,tilapia,oyster and Gracilaria tenuistipitata which are complementary in terms of biotic niche in different ponds within the closed circulating system. Results indicated that the suspending contents,COD and amount of ammoniated nitrogen and total nitrogen in the circulating water culture system were much lower than those of monoculture control ponds. The final drained water did not lie in the state of eutrophication(E< 1).The input of 1kg feed turned out 0.667kg prawns,0.037kg tilapia,0.738kg oyster and 0.437kg Gracilaria tenuistipitata which were equivalent to net profit 2.01. The ratio of input to output was significantly reduced from 0.671 at monoculture to 0.235 at optimal ecoculture of prawns. The proposed culture pattern not only arrived at the self2repair of culture environment and zero drainage of culture water,feed conversion ratio and economic benefits but also increased notably,simultaneously with advantages of disease resisting,environmental friendliness and high efficiency.