Collaborative Research: A combined boron isotope, pH microelectrode and pH-sensitive dye approach to constraining acid/base chemistry in the calcifying fluids of corals

合作研究：结合硼同位素、pH 微电极和 pH 敏感染料的方法来限制珊瑚钙化液中的酸/碱化学

• 批准号: 1437166
• 负责人: Robert Eagle
• 金额: $ 27.06万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1437166&HistoricalAwards=false
• 关键词: Collaborative; Research; combined; boron; isotope

The anthropogenic elevation of atmospheric CO2 is causing the oceans to become more acidic, which may make it more challenging for corals to build their skeletons and, ultimately, entire reef structures. How corals respond to future ocean acidification will largely depend on how the pH of the internal fluid from which they produce their skeletons-their so-called calcifying fluid-is impacted by the surrounding seawater. It is therefore essential that current methods are refined to accurately measure the pH of corals' calcifying fluids in order to understand and, ideally, predict their responses to CO2-induced ocean acidification. In this project, a three-pronged approach to measure calcifying fluid pH within three species of reef-forming corals will be used to assess how their calcifying fluid pH responds to experimentally induced ocean acidification. This research will improve our understanding of corals' responses to ocean acidification and thus has the potential to inform the decisions of policy makers and legislators seeking to mitigate the deleterious effects of rising atmospheric CO2 on marine ecosystems. The work will support the development of three early career scientists, a postdoctoral fellow, graduate students, and undergraduate researcher assistants-several of whom are from underrepresented groups in the earth and ocean sciences. Results will be widely disseminated through publications, conference presentations, the PIs' websites, an educational film, coursework, and outreach activities at area schools, museums, and science centers.Corals and other types of marine calcifiers are thought to begin the mineralization of their calcium carbonate skeletons by actively elevating pH of their calcifying fluid, thereby converting bicarbonate ions (comprising ~90% of seawater dissolved inorganic carbon) to carbonate ions, the form of carbon used in calcification. This project will compare the combined boron isotope, pH microelectrode, and pH-sensitive dye approach to measure the calcifying fluid pH of three species of scleractinian corals, and to assess how their calcifying fluid pH (a primary factor controlling their calcification) responds to experimentally induced ocean acidification. As a result this multi-pronged approach to measuring calcifying fluid pH of the same coral species under equivalent culturing conditions will permit the first systematic cross-examination of the validity of these independent approaches. The combined approach will also yield values of calcifying fluid pH with uncertainties that can be quantified via inter-comparison and statistical treatment of these independent measurements. Importantly, this multi-pronged approach will be used on three coral species that due to differences in the carbonate chemistry of their native waters possess differing capacities for proton regulation at their site of calcification; a deep, cold-water coral (strong proton-pumper); a shallow, temperate coral (moderate proton-pumper); and a shallow, tropical coral (weak proton-pumper). Target outcomes of this research include (1) cross-examination of the validity of three independent approaches to estimating coral calcifying fluid pH, (2) quantification of uncertainty associated with the three approaches to estimating coral calcifying fluid pH, (3) advancement of our mechanistic understanding of coral calcification, (4) exploration of the mechanism by which ocean acidification impacts coral calcification, (5) elucidation why corals exhibit such varied responses to ocean acidification, (6) identification of coral types most vulnerable to ocean acidification, (7) exploration of so-called "vital effects" that limit the use of corals in paleoceanographic reconstructions, and (8) quantitative constraint of existing models of coral biomineralization.

大气中二氧化碳的人为升高正在导致海洋变得更酸，这可能会使珊瑚构建骨架以及最终整个珊瑚礁结构变得更具挑战性。珊瑚对未来海洋酸化的反应将在很大程度上取决于它们产生骨骼的内部液体（所谓的钙化液体）的pH值如何受到周围海水的影响。因此，必须改进现有的方法，以准确测量珊瑚钙化液的pH值，以便了解并在理想情况下预测它们对二氧化碳引起的海洋酸化的反应。在这个项目中，将采用三管齐下的方法来测量三种珊瑚礁形成珊瑚的钙化流体pH值，以评估它们的钙化流体pH值如何响应实验诱导的海洋酸化。这项研究将提高我们对珊瑚对海洋酸化反应的理解，从而有可能为寻求减轻大气中二氧化碳上升对海洋生态系统的有害影响的决策者和立法者提供决策信息。这项工作将支持三名早期职业科学家、一名博士后、研究生和本科生研究员助理的发展，其中一些人来自地球和海洋科学领域代表性不足的群体。研究结果将通过出版物、会议报告、pi网站、教育影片、课程作业以及在地区学校、博物馆和科学中心开展的推广活动广泛传播。珊瑚和其他类型的海洋钙化剂被认为是通过主动提高钙化液的pH值来开始碳酸钙骨架的矿化，从而将碳酸氢盐离子（包括约90%的海水溶解无机碳）转化为碳酸盐离子，碳酸盐离子是用于钙化的碳的形式。本项目将比较组合硼同位素、pH微电极和pH敏感染料方法来测量三种硬核珊瑚的钙化液pH值，并评估它们的钙化液pH值（控制它们钙化的主要因素）如何响应实验诱导的海洋酸化。因此，这种在同等培养条件下测量相同珊瑚物种钙化液pH值的多管齐下方法将允许对这些独立方法的有效性进行首次系统的交叉检查。联合方法还将产生具有不确定性的钙化流体pH值，这些不确定性可以通过这些独立测量的相互比较和统计处理来量化。重要的是，这种多管齐下的方法将用于三种珊瑚物种，由于其原生水域碳酸盐化学的差异，它们在钙化部位具有不同的质子调节能力；深水珊瑚（强质子泵）；一种浅的，温带珊瑚（中等质子泵）；一种浅层的热带珊瑚（弱质子泵）。本研究的目标成果包括：(1)交叉检验三种估算珊瑚钙化液pH值的独立方法的有效性，(2)量化三种估算珊瑚钙化液pH值的方法相关的不确定性，(3)推进我们对珊瑚钙化的机制理解，(4)探索海洋酸化影响珊瑚钙化的机制。(5)阐明为什么珊瑚对海洋酸化表现出如此不同的反应；(6)确定最易受海洋酸化影响的珊瑚类型；(7)探索限制在古海洋学重建中使用珊瑚的所谓“关键效应”；(8)对现有珊瑚生物矿化模型进行定量限制。