全世界海洋中的高浓度二氧化碳抑制了正常的珊瑚生长，这提示随着大气中的碳越来越多地溶解到水中，珊瑚礁面临着艰难的时刻。Derek Manzello及其同事研究了在巴拿马和加拉帕戈斯群岛的呈天然酸性、高二氧化碳海水中的珊瑚礁结构。这组科学家发现，与来自海洋二氧化碳浓度更低的巴哈马的珊瑚礁相比，这些地方的珊瑚礁的结构粘合剂几乎不存在。相关论文发表在美国《国家科学院院刊》（PNAS）上。
此前的研究已经表明自从产业革命以来释放到大气层中的碳的大约1/3已经以二氧化碳的形式溶解到了海洋中，这让海洋酸性更强，而且改变了海洋生物的化学结构单元的基本平衡，例如利用碳组装其矿物质骨骼的珊瑚等海洋生物。这组作者证明了在热带东太平洋的富含二氧化碳的水中生长的珊瑚产生的矿物粘合剂很少，常常只能填充珊瑚骨骼中百分之几的小孔，而来自巴哈马的样本中的小孔几乎全部被填充了。由于粘合不良的珊瑚礁容易遭到自然侵蚀，这项研究中的珊瑚礁让人们得以一窥生活在高二氧化碳世界中的珊瑚的未来。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS，doi: 10.1073/pnas.0712167105，Derek P. Manzello，Chris Langdon
Poorly cemented coral reefs of the eastern tropical Pacific: Possible insights into reef development in a high-CO2 world
Derek P. Manzello*,†,‡, Joan A. Kleypas§, David A. Budd¶, C. Mark Eakin‖, Peter W. Glynn†, and Chris Langdon†
+Author Affiliations
*Cooperative Institute of Marine and Atmospheric Studies,
†Rosenstiel School, Marine Biology and Fisheries, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149;
§Institute for the Study of Society and Environment, National Center for Atmospheric Research, Boulder, CO 80307;
¶Department of Geological Sciences, University of Colorado, Boulder, CO 80309; and
‖National Oceanic and Atmospheric Administration, Silver Spring, MD 20910
Edited by David M. Karl, University of Hawaii, Honolulu, HI, and approved May 16, 2008 (received for review December 22, 2007)
Abstract
Ocean acidification describes the progressive, global reduction in seawater pH that is currently underway because of the accelerating oceanic uptake of atmospheric CO2. Acidification is expected to reduce coral reef calcification and increase reef dissolution. Inorganic cementation in reefs describes the precipitation of CaCO3 that acts to bind framework components and occlude porosity. Little is known about the effects of ocean acidification on reef cementation and whether changes in cementation rates will affect reef resistance to erosion. Coral reefs of the eastern tropical Pacific (ETP) are poorly developed and subject to rapid bioerosion. Upwelling processes mix cool, subthermocline waters with elevated pCO2 (the partial pressure of CO2) and nutrients into the surface layers throughout the ETP. Concerns about ocean acidification have led to the suggestion that this region of naturally low pH waters may serve as a model of coral reef development in a high-CO2 world. We analyzed seawater chemistry and reef framework samples from multiple reef sites in the ETP and found that a low carbonate saturation state (Ω) and trace abundances of cement are characteristic of these reefs. These low cement abundances may be a factor in the high bioerosion rates previously reported for ETP reefs, although elevated nutrients in upwelled waters may also be limiting cementation and/or stimulating bioerosion. ETP reefs represent a real-world example of coral reef growth in low-Ω waters that provide insights into how the biological–geological interface of coral reef ecosystems will change in a high-CO2 world.
