Possibility of environmental improvement by revival of oyster farming in Ariake Bay

• Published in: ENVIRONMENTAL ENGINEERING RESEARCH Vol. 44; pp. 563 - 570
• Main Authors: OGAWA Hiroki, IYOOKA Hiroki, SUSHIMOTO Kenji, KUSUDA Tetsuya
• Format: Journal Article
• Language: English; Japanese
• Published: Japan Society of Civil Engineers 2007; 公益社団法人 土木学会
• Subjects: Ariake bay; modeling; Oyster; Plankton; Rehabilitation
• ISSN: 1341-5115; 1884-829X
• DOI: 10.11532/proes1992.44.563

Possibility of the environmental improvement useing oyster farming in Ariake Bay was examined. Analysis using a BOX model considering physiology of oyster that inhabits Ariake Bay was carried out. Physiologic characteristics of the oyster were observed through experiments using oysters collected in Ariake Bay. The equasions of filtration, assimilation and respiration were established with good precision. The model calculated the quantities of phytoplankton that was decreased by filtering and of nutrients (nitrogen and phosphorus) removed by catching of oyster. That is to say, oyster farming in Ariake Bayshows enough encironmental improvement effects. Oyster catch of 18, 000ton (the highest oyster catch at Ariake Bay in the past) was removes 360t of nitorogen and 20t of phosphorus and make about 80 percent reduction in phytoplankton in August. The effect on pytoplankton decrease is well in summer, theseason of red tides and in winter, the season of Nori laver farming. As the result, the oyster farming is effecteve for the prevention of red tide in summer and enriches the nutrient environment for Nori laver inwinter. かつて有明海で多く行われていたカキ養殖を利用した環境改善の可能性について議論した。室内実験により、有明海産カキの性質を明らかにすることでカキの成長を精度よくモデル化し、有明海ボックスモデルと組み合わせることで、カキによるプランクトンの削減効果と栄養塩系外取り出し効果を算定した。その結果、過去と同程度の養殖量で80%近いプランクトンの削減と、収穫による窒素約360t、リン約20tの系外取り出し効果が見込め、カキ養殖の再興は、現在の有明海に対して十分な環境改善効果があることが確認できた。