CEREGE, CNRS/Université Aix-Marseille, Avenue L. Philibert BP80, 13545 Aix-en-Provence, Cedex 4, France.
Nature. 2011 Aug 3;476(7358):80-3. doi: 10.1038/nature10295.
About one-third of the carbon dioxide (CO(2)) released into the atmosphere as a result of human activity has been absorbed by the oceans, where it partitions into the constituent ions of carbonic acid. This leads to ocean acidification, one of the major threats to marine ecosystems and particularly to calcifying organisms such as corals, foraminifera and coccolithophores. Coccolithophores are abundant phytoplankton that are responsible for a large part of modern oceanic carbonate production. Culture experiments investigating the physiological response of coccolithophore calcification to increased CO(2) have yielded contradictory results between and even within species. Here we quantified the calcite mass of dominant coccolithophores in the present ocean and over the past forty thousand years, and found a marked pattern of decreasing calcification with increasing partial pressure of CO(2) and concomitant decreasing concentrations of CO(3)(2-). Our analyses revealed that differentially calcified species and morphotypes are distributed in the ocean according to carbonate chemistry. A substantial impact on the marine carbon cycle might be expected upon extrapolation of this correlation to predicted ocean acidification in the future. However, our discovery of a heavily calcified Emiliania huxleyi morphotype in modern waters with low pH highlights the complexity of assemblage-level responses to environmental forcing factors.
由于人类活动而排放到大气中的二氧化碳（CO2）约有三分之一被海洋吸收，在海洋中，它会分成碳酸的组成离子。这导致了海洋酸化，这是对海洋生态系统，尤其是对珊瑚、有孔虫和颗石藻等钙化生物的主要威胁之一。颗石藻是一种丰富的浮游植物，它们负责现代海洋碳酸盐产量的很大一部分。对钙化作用的生理响应进行的培养实验研究在物种之间甚至在物种内部产生了相互矛盾的结果。在这里，我们量化了现代海洋和过去四万年中主要颗石藻的方解石质量，并发现钙化作用随 CO2 分压的增加和 CO3（2-）浓度的相应降低而明显减少。我们的分析表明，根据碳酸盐化学，不同钙化的物种和形态在海洋中分布。如果将这种相关性外推到未来海洋酸化预测中，预计对海洋碳循环会产生重大影响。然而，我们在现代低 pH 值水域中发现了一种高度钙化的 Emiliania huxleyi 形态，这突出了群体水平对环境胁迫因素的反应的复杂性。
