Ocean acidification affects coral growth by reducing skeletal density
Ocean acidification affects coral growth by reducing skeletal density
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DOI：
10.1073/pnas.1712806115
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发表时间：
2018-02-20
影响因子：
11.1
通讯作者：
Solow, Andrew R.
中科院分区：
文献类型：
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作者：
Mollica, Nathaniel R.;Guo, Weifu;Solow, Andrew R.
海洋酸化（OA）被认为是对珊瑚礁生态系统的一个重要威胁，因为它减少了造礁珊瑚产生骨骼所需的碳酸盐离子的可用性。然而，尽管理论预测，随着碳酸盐离子浓度的降低，珊瑚的钙化率会下降，但这一预测在实验室操作实验或对栖息在自然低ph珊瑚礁中的珊瑚的研究中并没有得到一致的证实。珊瑚的骨骼生长包括两个不同的过程：伸展（向上生长）和致密（侧向增厚）。在这里，我们发现骨骼密度对海水碳酸盐离子浓度的变化直接敏感，因此对OA敏感，而延伸则不是。我们提出了一个孔隙体骨骼生长的数值模型，通过骨骼密度对珊瑚钙化流体化学的影响，将骨骼密度与外部海水环境联系起来。我们使用从五个珊瑚礁地点收集的六种Porites物种的现有珊瑚骨骼数据集验证了该模型，并使用该框架来预测21世纪OA对全球热带地区Porites骨骼密度的影响。我们的模型预测，仅OA就会导致造礁珊瑚的骨骼密度下降20.3 +/- 5.4%。
Ocean acidification (OA) is considered an important threat to coral reef ecosystems, because it reduces the availability of carbonate ions that reef-building corals need to produce their skeletons. However, while theory predicts that coral calcification rates decline as carbonate ion concentrations decrease, this prediction is not consistently borne out in laboratory manipulation experiments or in studies of corals inhabiting naturally low-pH reefs today. The skeletal growth of corals consists of two distinct processes: extension (upward growth) and densification (lateral thickening). Here, we show that skeletal density is directly sensitive to changes in seawater carbonate ion concentration and thus, to OA, whereas extension is not. We present a numerical model of Porites skeletal growth that links skeletal density with the external seawater environment via its influence on the chemistry of coral calcifying fluid. We validate the model using existing coral skeletal datasets from six Porites species collected across five reef sites and use this framework to project the impact of 21st century OA on Porites skeletal density across the global tropics. Our model predicts that OA alone will drive up to 20.3 +/- 5.4% decline in the skeletal density of reef-building Porites corals.