近年の瀬戸内海における有害・有毒渦鞭毛藻の分布拡大とその原因 : 溶存態有機リンの生態学的重要性

Recent Developments and Causes of Harmful Dinoflagellate Blooms in the Seto Inland Sea : Ecological Importance of Dissolved Organic Phosphorus (DOP)

Oh Seok Jin

Matsuyama Yukihiko

Yamamoto Tamiji

Nakajima Masanori

Takatsuzi Hideyuki

Hujisawa Kuniyasu

沿岸海洋研究

過去30年間の瀬戸内海における主要赤潮構成種を概観すると, 珪藻類やラフィド藻から有害・有毒な渦鞭毛藻へと遷移してきている. 1980年から行政の指導の下で取り組まれてきた沿岸域へのリン負荷削減の結果, 瀬戸内海などの閉鎖性海域では溶存態無機リン(DIP)濃度が低下し, 溶存態無機窒素(DIN)との比(DIN:DIP比)が顕著に上昇してきている. 同時に植物プランクトンが利用するリン源として溶存態有機リン(DOP)の重要性が増し, これを利用可能な渦鞭毛藻が増殖するようになってきたと考えられる. 本論文では, そのような一連の現象について, 既存の知見と新しいデータを交えながら考察した,

Data sets obtained in the last three decades reveal that the composition of the major harmful algal bloom (HAB) forming species in the Seto Inland Sea, Japan appears to have changed from a diatom/raphidophyte complex to the dinoflagellate species. Since 1980, a significant decrease in dissolved inorganic phosphorus (DIP) concentration has been observed in the coastal area of the Seto Inland Sea due to administrative regulations in respect to phosphorus loading from land to coastal areas. This selective reduction of DIP has led to an apparent increase in the dissolved inorganic nitrogen (DIN) to DIP ratio in coastal areas. Dissolved organic phosphorus (DOP) is considered an important source of phosphorus for phytoplankton growth. The recent proliferation of the dinoflagellate species can be explained by the availability of DOP rather than DIP. In the present study, we review the changes in water quality and HAB species changes for the last three decades, and discuss the possible process of the sequential phenomena which is thought to occur in the lower trophic ecosystem in coastal areas of the Seto Inland Sea.

瀬戸内海

赤潮

溶存態無機リン(DIP)

溶存態無機窒素(DIN)

DIN:DIP比

溶存態有機リン(DOP)

珪藻

渦鞭毛藻

Earth sciences. Geology [ 450 ]

jpn

日本海洋学会沿岸海洋研究部会

Copyright (c) 2005 日本海洋学会 沿岸海洋研究部会

[ISSN] 1342-2758

[NCID] AN10492259