Scales of pH variability on Pacific coral reefs reconstructed from skeletal boron and boron isotopes

珊瑚礁生态系统活力的下降经常被认为是与海洋逐渐吸收化石燃料二氧化碳和随之而来的海洋酸化有关的最突出的代价之一。然而，尽管存在突出的担忧，目前尚不清楚区域海洋学诱导的pH变化是否以及如何在珊瑚钙化部位实际表现出来。这种不确定性需要对各种珊瑚礁系统进行全面监测。作为就地监测装置的补充办法，斯克里普斯海洋学研究所的一个研究小组将利用20世纪后期太平洋/大气变率的已知变化作为回顾性监测系统。实际上，这一目标珊瑚样本网络的测量系统将提供一个直接的比较，以预测海洋变化所导致的pH变化。该项目的研究结果可直接评估不同海洋环境下的大型珊瑚对区域ph值历史变化的敏感程度。该项目将作为一名学生的博士研究，以扩大代表性严重不足的群体的参与。该项目还将通过SIO桦木水族馆展览作为公众宣传的平台。研究小组将测量现有珊瑚核的珊瑚骨骼化学成分，这些珊瑚核来自历史上太平洋盆地范围变化的不同地理极点。具体来说，他们将应用硼同位素代替pH值，结合一套其他可能对海水碳化学变化敏感的骨骼示踪剂，生成季节性解决环境变化的记录。两个研究地点，Palmyra和Moorea，具有持续多年的原位pH传感器安装的特点。因此，研究小组将在这些地点收集和分析最近的珊瑚生长情况，这将为实地校准骨骼代用物提供最佳手段。总的来说，评估钙化地点的pH变化尺度，特别是其与海洋扰动的关系，对于建立正确的视角来预测未来人为对珊瑚礁碳化学的影响至关重要。

The decreased vitality of coral reef ecosystems is often cited as one of the most prominent costs associated with the progressive oceanic uptake of fossil fuel carbon dioxide and the consequent ocean acidification. Yet, despite the prominent concerns, it is presently unknown whether and how regional oceanographically-induced pH variability is actually manifested at the site of coral calcification. This uncertainty requires comprehensive monitoring of diverse reef systems. As a complementary approach to in situ monitoring installations, a research team from the Scripps Institution of Oceanography will make use of the known changes in Pacific ocean/atmosphere variability of the late 20th century as a retrospective monitoring system. In effect, the system of measurements from this targeted network of coral samples will provide a direct comparison to hindcast expectations of the pH variability forced by oceanographic change. These results of this project will allow a direct assessment of the extent to which massive corals in various oceanographic settings were actually sensitive to historical changes in regional pH. The project will serve as the doctoral research of a student who broadens participation of severely underrepresented groups. The project will also be used as a platform for public outreach through SIO Birch Aquarium exhibits. The research team will measure coral skeletal chemistry in existing coral cores from locations that represent very different geographic poles of historical Pacific basin-wide changes. Specifically, they will apply the boron isotopic proxy for pH, in conjunction with a suite of other skeletal tracers that might be sensitive to perturbations in seawater carbon chemistry, to generate seasonally-resolved records of environmental changes. Two of the study sites, Palmyra and Moorea, feature on going, multi-year in situ pH sensor installations. Accordingly, the research team will collect and analyze the most recent coral growth at these locations, which will provide the best available means for field calibration of the skeletal proxies. In general, the assessment of the scale of pH variability manifested at the site of calcification--and, especially, its relationship with oceanographic perturbations--is essential for establishing the proper perspective for projections of future anthropogenic effects on reef carbon chemistry.