海洋深層水を利用した多段養殖システムにおける栄養塩濃度の日周変動と収支(Diel fluctuations in nutrient concentrations and flow in an integrated culture system using deep seawater)
- 標題
- 海洋深層水を利用した多段養殖システムにおける栄養塩濃度の日周変動と収支(Diel fluctuations in nutrient concentrations and flow in an integrated culture system using deep seawater)
- 作者
- 辻本 良, 松村 航, 渡辺 健, 大津 順(Ryo Taujimoto, Wataru Matsumura, Ken Watanabe and Jun Ohtsu)
- 文件屬性
- 日本研究
- 知識分類
- 基礎研究
- 出版年
- 2006
- 刊名
- 海洋深層水研究
- 卷
- 7
- 期
- 2
- 頁
- P 13-22
- 點閱數
- 3137
摘要
富山湾の水深321mから汲み上げた海洋深層水を利用して, エゾァワビ, マッカワ, マコンブの順に飼育する多段養殖システムの開発研究を行った.このシステムのなかで, 栄養塩 (アンモニウム塩, 硝酸塩+亜硝酸塩及びリン酸塩) 濃度の日周変動と収支を調べた.エゾアワビは, 屋内水槽 (60 l 容量×2基) に260個体, 6.19kgを収容し, 18℃ に加温した深層水を用いて飼育した.この排水を屋内水槽 (400 e 容量) に注水し, マッカワ30個体, 21.0 kgを飼育した.さらに, マッカワを飼育した排水を屋外水槽 (3600 l 容量) に注水し, マコンブ600藻体, 55.8kgを培養した.マッカワ水槽とマコンブ水槽には, 深層水原水 (3℃) を混ぜることによってそれぞれ14℃ 及び10℃ に調温した.エゾアワビには, マコンブ水槽で培養したマコンブを剪定し, 16: 00に1水槽あたり450gを給餌した.マッカワには, 9: 30に配合餌料95gを給餌した.2004年8月25日にそれぞれの水槽の注水と排水の栄養塩濃度を毎時測定し, 水槽ごとの栄養塩収支を求あた.その結果, エゾアワビ水槽とマッカワ水槽において栄養塩の排出が, マコンブ水槽において吸収が確認された.このシステムにおける栄養塩濃度には2っの特徴が確認された.すなわち,(1) マッカワ水槽排水におけるアンモニウム塩濃度の上昇とマコンブ水槽による吸収 (水槽段階による変化),(2) エゾアワビ水槽におけるマコンブ給餌後の硝酸塩+亜硝酸塩とリン酸塩濃度の上昇 (日周変動) であった.マコンブの栄養塩吸収割合を給水と排水の栄養塩濃度差から算出したところ, 供給量のうちアンモニウム塩, 硝酸塩+亜硝酸塩及びリン酸塩をそれぞれ, 38%, 6%及び12%吸収していた.マコンブによる栄養塩吸収割合が低かったことから, マコンブ培養量を増加させることによって, さらに栄養塩を効率良く利用できるシステムの構築が可能であることが示唆された.
Diel fluctuations in concentrations of nutrients (ammonia-N, nitrate & nitrite-N, phosphate-P) and their flow were determined in an integrated culture system (started on Nov. 18, 2003) using deep seawater (DSW) pipelined from a depth of 321 m in Toyama Bay, Sea of Japan. In the system, ezo-abalone, Nordotis discus hannai (260 shells, 6.19 kg on Aug. 26, 2004) were cultured in two indoor tanks (60l in water volume (w. v.)) by using fresh warmed DSW (18°C) and the wastes were supplied to an indoor tank (14°C, 400l in w. v.) in which barfin flounder, Verasper moseri (30 fishes, 21.0 kg), were cultured. The waste from the latter tank was used in another outdoor tank (10°C, 3600l in w. v.) in which makombu kelp, Saccharina japonica (600 plants, 55.8 kg) were cultured. For chilling, intact DSW (3°C) was supplemented to the barfin flounder and kelp tanks. Nutrient outputs from the abalone and barfin flounder tanks and uptake in the makombu kelp tank were determined every hour on Aug. 25, 2004. On the day, abalones and barfin flounders were fed 450 g/tank of cut-off blade of kelp cultured in the system at 16: 00 and 95 g/tank of artificial compounds at 9: 30, respectively. The two notable features of nutrient variation were (1) increase of ammonium-N level in barfin flounder tank and its uptake in makombu kelp tank and (2) increase of other nutrients in ezo-abalone tank just after feeding. The utilization of ammonia-N, nitrate & nitrite-N and phosphate-P by makombu kelp were calculated to be 38 %, 6 % and 12 % from the difference of nutrient concentrations between supply and drainage. The low utilization rates of nutrients suggest that enlargement of the kelp biomass can improve the nutrient utilization in this system.
Diel fluctuations in concentrations of nutrients (ammonia-N, nitrate & nitrite-N, phosphate-P) and their flow were determined in an integrated culture system (started on Nov. 18, 2003) using deep seawater (DSW) pipelined from a depth of 321 m in Toyama Bay, Sea of Japan. In the system, ezo-abalone, Nordotis discus hannai (260 shells, 6.19 kg on Aug. 26, 2004) were cultured in two indoor tanks (60l in water volume (w. v.)) by using fresh warmed DSW (18°C) and the wastes were supplied to an indoor tank (14°C, 400l in w. v.) in which barfin flounder, Verasper moseri (30 fishes, 21.0 kg), were cultured. The waste from the latter tank was used in another outdoor tank (10°C, 3600l in w. v.) in which makombu kelp, Saccharina japonica (600 plants, 55.8 kg) were cultured. For chilling, intact DSW (3°C) was supplemented to the barfin flounder and kelp tanks. Nutrient outputs from the abalone and barfin flounder tanks and uptake in the makombu kelp tank were determined every hour on Aug. 25, 2004. On the day, abalones and barfin flounders were fed 450 g/tank of cut-off blade of kelp cultured in the system at 16: 00 and 95 g/tank of artificial compounds at 9: 30, respectively. The two notable features of nutrient variation were (1) increase of ammonium-N level in barfin flounder tank and its uptake in makombu kelp tank and (2) increase of other nutrients in ezo-abalone tank just after feeding. The utilization of ammonia-N, nitrate & nitrite-N and phosphate-P by makombu kelp were calculated to be 38 %, 6 % and 12 % from the difference of nutrient concentrations between supply and drainage. The low utilization rates of nutrients suggest that enlargement of the kelp biomass can improve the nutrient utilization in this system.