長期にわたるクリルの減少と南極海におけるサルプの増加
Angus Atkinson1, Volker Siegel, Evgeny Pakhomov
1British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 OET, UK. aat@ bas.ac.uk
Nature
|November 5, 2004
まとめ
南極クリル (Euphausia superba) の密度は,1970年代以降,海氷の減少と食糧の供給の減少に関連して,南西大西洋で減少しています. このシフトは,南洋の食物網におけるサルプス (Salpa thompsoni) を好む可能性がある.
科学分野:
- 海洋生態学 海洋生態学とは
- 南洋の生態系動態 南洋の生態系動態
- 漁業科学 漁業科学 漁業科学
背景:
- 南極のクリル (Euphausia superba) とサルプス (Salpa thompsoni) は南洋の主要な放牧動物である.
- クリル魚群は,商業漁業と生態系の健康にとって極めて重要です.
- 以前の研究では,1926年から1951年にかけてのクリルの分布を記録し,最近のデータは短期的な変化を示しています.
研究 の 目的:
- 南極のクリルとサルプの分布における長期の空間的および時間的な変化を分析する.
- クリルの密度と広範囲での分布に影響を与える環境要因を特定する.
主な方法:
- 1926年から2003年にかけての科学的なネットサンプリングデータを集めて分析した.
- クリルの密度がクロロフィルの濃度と海氷の範囲と相関している.
主要な成果:
- 生産性の高い南西大西洋地域は,南洋のクリル魚群の50%以上を占めています.
- 南西大西洋のクリル密度は,1970年代以降減少しています.
- クリルの密度は,夏のクロロフィールと,前の冬の海氷の範囲と正に相関しています.
- サルプの個体数は,クリルの密度が減少するにつれて増加しているようです.
結論:
- 夏の食料の利用可能性と冬の海氷の広がりは,南西大西洋のクリル密度の高い状態を維持するために不可欠です.
- クリルとサルプの個体数の変化は,南洋の食物網の構造と機能に大きく影響を与えます.
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