Physiological and isotopic responses of scleractinian corals to ocean acidification
Physiological and isotopic responses of scleractinian corals to ocean acidification
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DOI：
10.1016/j.gca.2010.05.023
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发表时间：
2010-09-01
影响因子：
5
通讯作者：
Shemesh, Aldo
中科院分区：
文献类型：
--
作者：
Krief, Shani;Hendy, Erica J.;Shemesh, Aldo
海洋对人为CO2的吸收正在改变海水化学，由于海水pH值和文石饱和状态的降低，可能对珊瑚礁生态系统造成严重后果这项长期研究的目的，是探讨两种具重要生态价值的造礁珊瑚品种─ ─巨型矮珊瑚和Stylophora pistillata ─ ─的生存能力，暴露于高pCO（2）（或低pH值）条件下，并观察生理相关参数以及骨骼同位素组成的可能变化。Ponies sp.和S.将雌蕊在受控的水族箱条件下保存6-14个月，其特征在于正常和升高的pCO（2）条件，分别对应于8.09、7.49和7.19的pH（T）值。与较短的，因此更短暂的实验相比，在这项研究中实现的长实验时间尺度确保了与实验环境的完全平衡和稳定状态，并保证数据提供了对可行和稳定生长的珊瑚的见解。在实验过程中，所有的珊瑚碎片都存活下来并增加了新的骨架，即使在海水Omega（arag）< 1的情况下，这意味着珊瑚骨架是在强烈的生物控制下通过机制形成的。对骨骼的硼（B）、碳（C）和氧（O）同位素组成、珊瑚组织和共生体虫黄藻的碳同位素组成以及生理数据（如骨骼生长、组织生物量、虫黄藻细胞密度和叶绿素浓度）的测量结果沿着，可以与正常条件下生活并同时取样的珊瑚进行直接比较。在高pCO（2）（低pH值）条件下，珊瑚礁的生长和虫黄藻的密度降低，而珊瑚组织的生物量（以蛋白质浓度衡量）和虫黄藻叶绿素浓度增加。两个物种在降低pH值下显示出类似的δ B-11消耗和δ O-18富集趋势，而δ C-13结果表明物种对高pCO（2）条件的特定代谢反应。骨骼δ B-11值绘制在海水δ B-11与pH硼酸盐分馏曲线之上，该曲线使用理论推导的α（B）值1.0194（Kakihana等人（1977）Bull.Chem.Soc.Jpn. 50，158）或经验α（B）值1.0272（Klochko等人（2006）EPSL 248，261）。然而，有效α（B）必须大于1.0200，以便在Ω（arag）>= 1的pH条件下计算珊瑚骨骼δ B-11值。δ B-11与海水δ B-11与pH值分馏曲线的偏移表明，在黑暗和光照钙化和/或内部pH值调节过程中，骨骼材料的比例发生了变化，推测是由离子转运酶控制的。最后，海水pH值显着影响骨骼δ C-13和δ O-18。在根据珊瑚骨骼重建古环境条件时，必须考虑到这一点。(C)2010爱思唯尔有限公司保留所有权利。
Uptake of anthropogenic CO2 by the oceans is altering seawater chemistry with potentially serious consequences for coral reef ecosystems due to the reduction of seawater pH and aragonite saturation state (Omega(arag)) The objectives of this long-term study were to investigate the viability of two ecologically important reef-building coral species, massive Ponies sp. and Stylophora pistillata, exposed to high pCO(2) (or low pH) conditions and to observe possible changes in physiologically related parameters as well as skeletal isotopic composition. Fragments of Ponies sp. and S. pistillata were kept for 6-14 months under controlled aquarium conditions characterized by normal and elevated pCO(2) conditions, corresponding to pH(T) values of 8.09, 7.49, and 7.19, respectively. In contrast with shorter, and therefore more transient experiments, the long experimental time-scale achieved in this study ensures complete equilibration and steady state with the experimental environment and guarantees that the data provide insights into viable and stably growing corals. During the experiments, all coral fragments survived and added new skeleton, even at seawater Omega(arag) < 1, implying that the coral skeleton is formed by mechanisms under strong biological control. Measurements of boron (B), carbon (C), and oxygen (O) isotopic composition of skeleton, C isotopic composition of coral tissue and symbiont zooxanthellae, along with physiological data (such as skeletal growth, tissue biomass, zooxanthellae cell density, and chlorophyll concentration) allow for a direct comparison with corals living under normal conditions and sampled simultaneously. Skeletal growth and zooxanthellae density were found to decrease, whereas coral tissue biomass (measured as protein concentration) and zooxanthellae chlorophyll concentrations increased under high pCO(2) (low pH) conditions. Both species showed similar trends of delta B-11 depletion and delta O-18 enrichment under reduced pH, whereas the delta C-13 results imply species-specific metabolic response to high pCO(2) conditions. The skeletal delta B-11 values plot above seawater delta B-11 vs. pH borate fractionation curves calculated using either the theoretically derived alpha(B) value of 1.0194 (Kakihana et al. (1977) Bull. Chem. Soc. Jpn. 50, 158) or the empirical alpha(B) value of 1.0272 (Klochko et al. (2006) EPSL 248, 261). However, the effective alpha(B) must be greater than 1.0200 in order to yield calculated coral skeletal delta B-11 values for pH conditions where Omega(arag) >= 1. The delta B-11 vs. pH offset from the seawater delta B-11 vs. pH fractionation curves suggests a change in the ratio of skeletal material laid down during dark and light calcification and/or an internal pH regulation, presumably controlled by ion-transport enzymes. Finally, seawater pH significantly influences skeletal delta C-13 and delta O-18. This must be taken into consideration when reconstructing paleo-environmental conditions from coral skeletons. (C) 2010 Elsevier Ltd. All rights reserved.