Hiệu quả của mô hình nuôi trồng kết hợp gồm bào ngư (Haliotis asinine), cá chẽm (Lates calcarifer), hàu (Saccostrea cucullata) và rong biển (Ulva reticulata)

The  study  was  conducted  to  evaluate  the  potential  for development  of  an  integrated  land-based  semi-closed  recirculating  aquaculture  system  which  consisted  of  abalone,  seabass, oyster  and  Ulva  compartments.  Abalone  and  seabass  fed  artificial  diets.  Water  in  abalone tanks was flushed into the fish tank then filled by water pumped from seaweed tank. Water in the oyster tank was pumped to the seaweed tank then filled by water pumped from fish tank. The system was in three replicates. Water samples were taken from all compartments weekly for  measurement  of  TAN,  NO 2 -N  and  NO 3 -N.  Ulva  and  cultured  animals  were  sampled weekly and bi-monthly to determine their growth. Although Ulva showed a good ability to remove TAN (> 0.3 mg/L/day) to support their growth (> 10% day), nitrogen transformation under  the  effects  of  nitrobacteria  resulted  in  the  lack  of  TAN  (<  0.2  ppm)  and  high concentration  of  nitrite  and  nitrate  nitrogen  (4.5  ppm  maximum)  accumulated  in  culture water.  Therefore,  all  cultured  species  had  poor  growth  and  survival  rates  and  the  loss  of nitrogen in feed supply was as high as in monoculture systems (60%). In order to improve system performance, recirculated water volume should be increased and water retention time should be shortened to maximize nitrogen removal efficiency of Ulva.