南極極海におけるメソスケールの植物プランクトンの開花は,鉄の受精によって刺激された
P W Boyd1, A J Watson, C S Law
1National Institute of Water and Atmosphere, Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin, New Zealand. pboyd@alkali.otago.ac.nz
Nature
|October 26, 2000
まとめ
南洋における鉄の肥料化により,植物プランクトンの増殖と二酸化炭素の排出が促進された. しかし,藻類の炭素の輸出の減少は観察されず,その最終的な運命は不明である.
科学分野:
- マリン・バイオロジーの海洋生物学
- 海洋学 海洋学とは
- バイオジオケミストリー バイオジオケミストリー
背景:
- "鉄の仮説"は,海洋プランクトンへの鉄の供給が,二酸化炭素の吸収率を変えることで大気中の二酸化炭素レベルに大きく影響すると仮定している.
- 鉄濃縮に対するペラジック生物の反応を理解することは,この仮説を検証し,気候フィードバックを予測するために不可欠です.
研究 の 目的:
- 鉄の受精が植物プランクトンの動態と南極海における炭素の輸出に及ぼす影響を調査する.
- この栄養価が高く,クロロフィルが低い地域における初次生産とコミュニティの組成の制御における鉄の役割を評価する.
主な方法:
- 南極海でメソスケール鉄の受精実験が行われました.
- 植物プランクトンのバイオマス,光合成速度,二酸化炭素とマクロ栄養素濃度,およびジメチル硫化物レベルをモニターした.
- 衛星観測を用いて,花の広がりや鉄の貯蔵量を追跡した.
主要な成果:
- 鉄の供給の増加は,植物プランクトンのバイオマスと光合成率の上昇につながった.
- 13日以内に二酸化炭素とマクロ栄養素の大幅な減少が観察され,これは主に藻の増殖によって引き起こされた.
- 生物学的炭素の輸出の減少は増加せず,衛星データは30日後に地表水域に鉄が大量に留まっていることを示した.
結論:
- 鉄の供給は,夏の間,南極海における植物プランクトンの成長とコミュニティ構造の重要な規制者である.
- 鉄の肥料化が初次生産と二酸化炭素の排出を刺激する一方で,その結果生じる藻類の炭素の運命は,輸出,再鉱化,水質の沈殿プロセスに依存し,未決定のままである.
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