PROBLEM TO BE SOLVED: To provide a method of reducing the concentration of nutrient salts in salt water utilizing a marine alga, to provide a system for reducing the concentration of nutrient salts in salt water and to provide an apparatus or the like for reducing the concentration of nutrient salts in salt water.SOLUTION: An immature unialgal culture strain into which the alga sporophyte originating from a specified large-sized red marine alga, for example, the Gracilaria species having the following properties: (1) a matured female gametophyte is not found in nature (2) a matured form of only a tetrasporophyte is found and (3) the Gracilaria species grows up in an area of natural marine water mixed with fresh water, or the alga body into which the immature unialgal culture strain grows is introduced to a nutrient salt reducing device and is used for reduction in concentration of the nutrient salts in salt water.COPYRIGHT: (C)2012,JPO&INPIT【課題】海藻を利用した塩水中の栄養塩類の濃度低減方法、塩水中の栄養塩類の濃度低減システム、塩水中の栄養塩類の濃度低減装置等を提供する。【解決手段】特定の紅藻類大型海藻、例えば、以下(1)~(3)の性質を有するオゴノリ属紅藻類[(1)天然で成熟体として雌性配偶体が検出されず、(2)四分胞子体のみの成熟体が検出される特徴をもち、(3)淡水混入天然海水域で繁殖するオゴノリ属紅藻類)]由来の海藻胞子が生長した非成熟性単藻培養株あるいはその非成熟性単藻培養株が増殖した藻体を栄養塩類低減装置に導入し塩水中の栄養塩類の濃度低減に用いる。【選択図】図1
