Collaborative Research: Development and application of a method using coralline algae to reconstruct past changes in pH and impacts on calcification

最近和未来人类造成的大气二氧化碳增加对浅水冷水海洋环境的酸度（pH值）的影响（这一过程被称为“海洋酸化”），以及对栖息在其中的生物的影响，人们知之甚少。这部分是由于在这些遥远的环境中重建过去海洋化学变化的困难。本研究旨在开发和应用一种技术，通过广泛存在于浅水、冷水海洋环境中的长寿命甲壳珊瑚藻的硼同位素特征来重建过去的海水pH值。此外，该研究将评估海水pH值变化对这些具有重要生态意义的生物生长速度的影响，这些生物被认为特别容易受到海洋酸化的影响，因为它们的骨骼中镁含量很高。总体而言，该项目将促进对浅水、冷水环境下海洋酸化的理解，并提供关键信息，以评估海洋pH值变化对生活在这些环境中的生物的影响。这项工作的结果将为政策制定者和立法者提供重要的信息，以减轻大气中二氧化碳上升对这些脆弱的高纬度海洋生态系统的负面影响。资金支持一名研究生，众多本科生研究人员，以及两名早期职业教师之间的新合作。外展活动包括通过斯克里普斯学院（Scripps College Academy）指导在科学领域未被充分代表的高中生，并制作一部关于海洋酸化对生物影响的教育影片。该研究小组将通过与加拿大和英国科学家的合作加强国际联系，同时帮助美国科学家保持在海洋酸化研究这一重要子领域的前沿。工作计划包括三个主要部分：(1)建立第一个实验室衍生和现场验证的珊瑚藻古海水pH值delta11b代用物定标；(2)建立第一个高纬度海水pH值在公元1365年至1760年之前（即“基线”）和之后（公元1760年至今）的高分辨率、多世纪数据集；(3)评估人为海洋酸化对一种具有重要生态意义的、形成栖息地的珊瑚红藻产生的骨骼的线形延伸、密度和超微结构的影响。相关目标是：(1)提供重建古海水pH值的新工具；(2)生成海洋酸化的历史记录，阐明高纬度海洋酸化的速率和程度，可用于验证预测模型；(3)建立海洋酸化与珊瑚藻钙化之间的经验关系，为预测未来海洋酸化对高纬度海洋钙化物的影响提供信息。

The impacts of recent and future human-caused increases in atmospheric CO2 on the acidity (pH) of shallow cold-water marine environments (a process known as "ocean acidification"), and on the organisms that inhabit them, are poorly understood. This is due, in part, to the difficulty in reconstructing past changes in ocean chemistry in these remote environments. This research seeks to develop and apply a technique to reconstruct past seawater pH from boron isotope signatures in long-lived crustose coralline alga that are widespread throughout shallow, cold-water marine environments. In addition, the research will evaluate the impact of changing seawater pH on the growth rate of these ecologically important organisms, which are thought to be particularly vulnerable to ocean acidification because of the high magnesium content of their skeleton. Overall, this project will advance understanding of ocean acidification in shallow, cold-water environments, and provide key information to evaluate the impact that changes in ocean pH have had on organisms inhabiting these environments. The outcomes of this work will provide important information to policy makers and legislators seeking to mitigate the negative effects of rising atmospheric CO2 on these fragile, high-latitude marine ecosystems. Funding supports a graduate student, numerous undergraduate researchers, and a new collaboration between two early career faculty members. Outreach includes mentoring high school students from groups underrepresented in the sciences through the Scripps College Academy and production of an educational film on the biological impacts of ocean acidification. The research team will strengthen international ties through collaboration with Canadian and UK scientists, while helping maintain US-based scientists at the forefront of this important sub-field of ocean acidification research. The work plan includes three main parts: (1) developing the first laboratory-derived and field-verified calibration of the delta11B-proxy of paleoseawater pH for coralline algae, (2) generating the first high-resolution, multi-centennial dataset of high-latitude seawater pH before (ca. 1365 to 1760 AD; i.e., "baseline") and after (ca. 1760 AD to present; i.e., "anthropogenic signal") the Industrial Revolution, and (3) evaluating the impact of anthropogenic ocean acidification on the linear extension, density, and ultrastructure of skeletons produced by an ecologically important, habitat-forming coralline red alga. The associated objectives are: (1) to provide a new tool for reconstructing paleo-seawater pH, (2) to generate historical records of ocean acidification that would elucidate the rate and magnitude of high-latitude ocean acidification that could be used to verify predictive models, and (3) to establish empirical relationships between ocean acidification and coralline algal calcification that would inform predictions of future impacts of ocean acidification on high-latitude marine calcifiers.