培養実験による相模湾の植物プランクトン群集に対する海洋深層水の肥沃化効果(Fertilization Effects of Deep Ocean Water on the Phytoplankton Community in Sagami Bay using Incubation Experiments)
- 標題
- 培養実験による相模湾の植物プランクトン群集に対する海洋深層水の肥沃化効果(Fertilization Effects of Deep Ocean Water on the Phytoplankton Community in Sagami Bay using Incubation Experiments)
- 作者
- 井関 和夫, 高橋 香菜, 早野 智子, 中嶋さやか(Kazuo Iseki, Kana Takahashi, Satoko Hayano and Sayaka Nakajima)
- 文件屬性
- 日本研究
- 知識分類
- 水產養殖
- 出版年
- 2011
- 刊名
- 海洋深層水研究
- 卷
- 12
- 期
- 1
- 頁
- P1-9
- 點閱數
- 2496
摘要
2005 年9 月上旬に相模湾中央部で採取した表層水（10 m）と深層水（205 m）および両者の混 合水（表層水：深層水＝2 :1) を遮蔽用ネットで覆い光強度の異なる天然光下で培養し，栄養塩 類，クロロフィルα(Chl. a)，粒状有機炭素・窒素（POC ・PON）および生物起源ケイ素（BSi) の日変化を調べ，深層水の肥沃化効果を検証した． 25％光透過率の混合水では，培養開始4 日目 に顕著なChl.αピーク（最大値） と硝酸塩とリン酸塩の枯渇を示したが，ケイ酸塩は実験期間中 に枯渇状態に至らなかった． Chl. a, POC, PON 及びBSi の増加量は栄養塩の減少量に比例し，ま たChl.αの比増加速度は光強度に対して強い依存性を示し，実験開始時の初期栄養塩濃度にも影 響を受けていた． これらの結果は相模湾における海洋深層水の肥沃化ポテンシャルを明瞭に示し， 肥沃化のためには人工揚水した深層水を，夏季表面光量の10％程度以上の水深に少なくとも数日 間以上にわたって滞留させる必要があると推察された．
The response of the surface water phytoplankton community in Sagami Bay by the addi-- tion of deep ocean water (DOW) was examined under natural sunlight in early September 2005. DOW collected from 205 m depth was mixed with surface water (SW) from 10 m in 20 liters polycarbonate bottles and incubated on deck of the R/V Tansei Maru using a deck incubator under different attenuated natural irradiance (25%,13%and 6% attenuation for the mixed water). The DOW and the SW were also incubated at 25% and 50% attenuation, respectively. Chlorophyll a (Chl. a) increased rapidly in the mixed water under 25% attenua-- tion and reached maximum concentration at 4 days later when nitrate and phosphate were depleted but silicate was not depleted until the end of the experiment. Particulate organic carbon (POC),particulate organic nitrogen (PON),and particulate biogenic silicon (BSi) also showed similar increases but did not have as conspicuous a peak within the incubation period as Chl. a. The net increase of particulate matter was well correlated with the net de-crease of nutrients and the specific growth rates of Chl. a increased with the increase of light intensity and the initial nutrient concentration. These results clearly indicate the potential fertility of DOW to phytoplankton community in Sagami Bay and for ocean fertilization the pumped-up DOW should remain at water depths shallower than 20 m (more than 10%at-tenuation of surface irradiance) for several days or more.
The response of the surface water phytoplankton community in Sagami Bay by the addi-- tion of deep ocean water (DOW) was examined under natural sunlight in early September 2005. DOW collected from 205 m depth was mixed with surface water (SW) from 10 m in 20 liters polycarbonate bottles and incubated on deck of the R/V Tansei Maru using a deck incubator under different attenuated natural irradiance (25%,13%and 6% attenuation for the mixed water). The DOW and the SW were also incubated at 25% and 50% attenuation, respectively. Chlorophyll a (Chl. a) increased rapidly in the mixed water under 25% attenua-- tion and reached maximum concentration at 4 days later when nitrate and phosphate were depleted but silicate was not depleted until the end of the experiment. Particulate organic carbon (POC),particulate organic nitrogen (PON),and particulate biogenic silicon (BSi) also showed similar increases but did not have as conspicuous a peak within the incubation period as Chl. a. The net increase of particulate matter was well correlated with the net de-crease of nutrients and the specific growth rates of Chl. a increased with the increase of light intensity and the initial nutrient concentration. These results clearly indicate the potential fertility of DOW to phytoplankton community in Sagami Bay and for ocean fertilization the pumped-up DOW should remain at water depths shallower than 20 m (more than 10%at-tenuation of surface irradiance) for several days or more.