Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility?
Metabolically induced pH fluctuations by some coastal calcifiers exceed projected 22nd century ocean acidification: a mechanism for differential susceptibility?
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DOI：
10.1111/j.1365-2486.2011.02473.x
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发表时间：
2011-10-01
影响因子：
11.6
通讯作者：
Boyd, Philip W.
中科院分区：
文献类型：
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作者：
Hurd, Catriona L.;Cornwall, Christopher E.;Boyd, Philip W.
人为介导的 pH 值下降（称为海洋酸化 (OA)）可能是对海洋生物和群落的主要威胁。研究主要集中在热带珊瑚礁上，但温带珊瑚礁在较寒冷的水域中发挥着同样重要的生态作用，在这些水域中，OA 的影响可能首先显现出来。在此，我们报告了三种具有重要生态意义的冷水钙化器（初级生产者和食草动物）表面的 pH 值趋势，在一系列流体流量下，彼此之间存在很大差异，并且对于这三个钙化器中的两个，在黑暗期间的 pH 值低于由于 OA 对 2100 年以后全球海洋表层水的 OA 造成的平均预测 pH 值。使用微电极，我们表明每个钙化器在其表面和主流之间具有不同的 pH 梯度海水，即在扩散边界层 (DBL) 内，它似乎充当主流 pH 值的环境缓冲区。鲍鱼只遇到主流海水pH值，而海胆表面的pH值降低了大约0.35个单位。对于珊瑚藻来说，与周围主流海水相比，光照下的 pH 值大约高 0.5 个单位，黑暗下的 pH 值则低 0.35 个单位。一些钙化器 DBL 内的 pH 值范围很宽，预计未来由于 OA 导致 pH 值降低，可能会影响其性能。不同的表面 pH 值范围可能会导致钙化剂对 OA 的敏感性不同。这种波动无疑受到水运动、形态和代谢率（例如呼吸、钙化和/或光合作用）的相互作用的调节。我们的研究通过考虑物理（流态）、化学（pH 梯度与 OA 未来预测）和生物学（营养级、生理学和形态学）表明，预测物种特异性反应和随后对 OA 的生态系统重建是复杂的，需要一种整体的生态机械方法。
Anthropogenically mediated decreases in pH, termed ocean acidification (OA), may be a major threat to marine organisms and communities. Research has focussed mainly on tropical coral reefs, but temperate reefs play a no less important ecological role in colder waters, where OA effects may first be manifest. Herein, we report that trends in pH at the surface of three ecologically important cold-water calcifiers (a primary producer and herbivores), under a range of fluid flows, differ substantially from one another, and for two of the three calcifiers, the pH, during darkness, is lower than the mean projected pH due to OA for the surface waters of the global ocean beyond the year 2100. Using micro-electrodes, we show that each calcifier had a different pH gradient between its surface and mainstream seawater, i.e. within the diffusion boundary layer (DBL) that appears to act as an environmental buffer to mainstream pH. Abalone encountered only mainstream seawater pH, whereas pH at the sea urchins' surface was reduced by similar to 0.35 units. For coralline algae, pH was similar to 0.5 units higher in the light and similar to 0.35 units lower under darkness than in ambient mainstream seawater. This wide range of pH within the DBL of some calcifiers will probably affect their performance under projected future reductions in pH due to OA. Differing exposure to a range of surface pH may result in differential susceptibility of calcifiers to OA. Such fluctuations are no doubt regulated by the interplay of water movement, morphology and metabolic rates (e. g. respiration, calcification and/or photosynthesis). Our study, by considering physics (flow regime), chemistry (pH gradients vs. OA future projections) and biology (trophic level, physiology and morphology), reveals that predicting species-specific responses and subsequent ecosystem restructuring to OA is complex and requires a holistic, eco-mechanical, approach.