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

根据骨骼硼和硼同位素重建太平洋珊瑚礁 pH 值变化范围

• 批准号: 1459726
• 负责人: Christopher Charles
• 金额: $ 32.51万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1459726&HistoricalAwards=false
• 关键词: Scales; pH; variability; Pacific; coral

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.

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以及随之而来的海洋酸化相关的最突出的成本之一。然而，尽管存在突出的担忧，目前尚不清楚区域海洋学引起的 pH 值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不同的珊瑚礁系统进行全面监测。 作为现场监测装置的补充方法，斯克里普斯海洋学研究所的一个研究小组将利用 20 世纪末太平洋/大气变化的已知变化作为回顾性监测系统。实际上，来自该目标珊瑚样本网络的测量系统将提供与海洋变化造成的 pH 值变化的事后预期的直接比较。该项目的这些结果将能够直接评估各种海洋环境中的大型珊瑚对区域 pH 值历史变化的实际敏感程度。该项目将作为一名学生的博士研究，扩大代表性严重不足的群体的参与。该项目还将作为通过 SIO Birch 水族馆展览进行公众宣传的平台。研究小组将测量现有珊瑚核心中的珊瑚骨骼化学成分，这些珊瑚核心代表了历史上太平洋盆地变化的不同地理极点。具体来说，他们将应用硼同位素替代 pH 值，并结合一套可能对海水碳化学扰动敏感的其他骨骼示踪剂，以生成季节性解析的环境变化记录。其中两个研究地点帕尔米拉和莫雷阿岛正在安装持续多年的原位 pH 传感器。因此，研究小组将收集并分析这些地点最近的珊瑚生长情况，这将为骨骼代理的现场校准提供最佳可用手段。一般来说，评估钙化部位的 pH 变化范围，特别是其与海洋扰动的关系，对于预测未来人为对珊瑚礁碳化学的影响建立正确的视角至关重要。