| 英文摘要 |
Marine cage farms are typically open rearing systems with a continuous exchange of water between the cages and the surroundings, characterized by large outputs of suspended solids, increased biochemical oxygen demand, and release of dissolved nutrients. Only about 24% of carbon, 31% of nitrogen and 31% of phosphorus, added through feed, is removed at harvest, the rest being released as fish faces, urinary waste and uneaten feed. Deposition of waste material from intensive fish farming usually exceeds resuspension and sediment decomposition, resulting in organic accumulation causing increased sediment oxygen consumption. Methods for treating aquaculture waste in open cage culture have mainly been built on feeding management. However, the practice of ecologyical engineering as a tool for reducing effluents have now gained new interest and many suggestions for integrated cultivation systems, using different combinations of seaweeds, bivalves and fish have proposed. In fact, in same cases bivalves have been found to grow much better adjacent to salmon fish cages, indicating that they are making use of the particles produced.?
During May and June, 2009, sea cucumbers and red mussels collected from Penghu island, were released into Tunlung sea cage area. In November, dive surveys found that the sea cucumber (Holothuria atra and H. leucospilota) and red mussel (Modiolus auriculatus) grew well, but hard clams and scallops were all dead. Due to the discovery of stool ball, we suggested that sea cucumber has the function to improve the sea sediments of cage area. |