Toward Predicting the Impact of Ocean Acidification on Net Calcification by a Broad Range of Coral Reef Ecosystems: Identifying Patterns and Underlying Causes

预测海洋酸化对广泛珊瑚礁生态系统净钙化的影响：识别模式和根本原因

• 批准号: 1220529
• 负责人: Anne Cohen
• 金额: $ 69.53万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220529&HistoricalAwards=false
• 关键词: Toward; Predicting; Impact; Ocean; Acidification

Intellectual Merit: Much of our understanding of the impact of ocean acidification on coral reef calcification comes from laboratory manipulation experiments in which reef organisms are removed from their natural habitat and reared under conditions of calcium carbonate saturation (Omega) predicted for the tropical oceans at the end of this century. By comparison, there is a paucity of in situ data describing the sensitivity of coral reef ecosystems to changes in calcium carbonate saturation. Yet emerging evidence suggests there may be critical differences between the calcification response of organisms in culture and the net calcification response of a coral reef ecosystem, to the same degree of change in calcium carbonate saturation. In the majority of cases, the sensitivity of net reef calcification to changing calcium carbonate saturation is more severe than laboratory manipulation experiments predict. Clearly, accurate predictions of the response of coral reef ecosystems to 21st century ocean acidification will depend on a robust characterization of ecosystem-scale responses and an understanding of the fundamental processes that shape them. Using existing data, the investigators show that the sensitivity of coral reef ecosystem calcification to Delta calcium carbonate saturation conforms to the empirical rate equation R=k(Aragonite saturation state -1)n, which also describes the relationship between the rate of net abiogenic CaCO3 precipitation (R) and the degree of aragonite supersaturation (Aragonite saturation state-1). By implication, the net ecosystem calcification (NEC) response to ocean acidification is governed by fundamental laws of physical chemistry and is potentially predictable across space and time. When viewed this way, the existing, albeit sparse, dataset of NEC reveals distinct patterns that, if verified, have important implications for how different coral reef ecosystems will respond to 21st century ocean acidification. The investigators have outlined a research program designed to build on this proposition. The project expands the currently sparse dataset of ecosystem-scale observations at four strategically placed reef sites, enabling us to test the following hypotheses: 1. The sensitivity ("n" in the rate equation) of coral reef ecosystem calcification to Delta Aragonite saturation state decreases with decreasing Aragonite saturation state. By implication, the rate at which reef calcification declines will slow as ocean acidification progresses over the course of this century. 2. The energetic status of the calcifying community is a key determinant of absolute rates of net ecosystem calcification ("k" in the rate equation), which, combined with n, defines the Aragonite saturation state value at which NEC approaches zero. By implication, the shift from net calcification to net dissolution will be delayed in healthy, energetically replete coral reef ecosystems and accelerated in perturbed, energetically depleted ecosystems. 3. The calcification response of individual colonies of dominant reef calcifiers (corals and algae) is weaker than the measured ecosystem-scale response to the same change in Aragonite saturation state. By implication, processes not adequately captured in laboratory experiments, such as bioerosion and dissolution, will play an important role in the coral reef response to ocean acidification. Broader Impacts: Ocean acidification threatens the livelihoods of 500 million people worldwide who depend on coral reefs to provide habitable and agricultural land, food, building materials, coastal protection and income from tourism. Yet data emerging from ocean acidification (OA) studies point to critical gaps in our knowledge of reef ecosystem-scale responses to OA that currently limit our ability to predict the timing and severity of its impact on different reefs in different parts of the world. Using existing data generated by the investigators and others, this project will address a series of related hypotheses, which, if verified by the research, will have an immediate, direct impact on predictions of coral reef resilience in a high CO2 world. This project brings together expertise in coral reef biogeochemistry, chemical oceanography and physical oceanography to focus on a problem that has enormous societal, economic and conservation relevance. Support is provided for a young investigator, undergraduate and minority student will participate in research through the WHOI Summer Fellowship Program, the Woods Hole Sea Education Association and PEP programs, and a burgeoning collaboration will be enhanced between the PIs and Pacific Island conservation groups and stakeholders whose goal it is to ensure that conservation decisions are grounded in scientific data. Results of the study will be presented at national and international meetings and workshops and disseminated in a timely manner through peer-reviewed publications. All data produced through this program will be archived in the Biological and Chemical Oceanographic Data Management Office (BCO-DMO) and the Pangaea Open Access library.

智力价值：我们对海洋酸化对珊瑚礁钙化影响的大部分了解来自实验室操纵实验，在这些实验中，珊瑚礁生物被从它们的自然栖息地移走，并在预测本世纪末热带海洋的碳酸钙饱和(Omega)的条件下饲养。相比之下，描述珊瑚礁生态系统对碳酸钙饱和度变化的敏感性的现场数据很少。然而，新出现的证据表明，对于相同程度的碳酸钙饱和度变化，养殖生物的钙化反应与珊瑚礁生态系统的净钙化反应之间可能存在关键差异。在大多数情况下，净礁钙化对碳酸钙饱和度变化的敏感性比实验室操作实验预测的要严重得多。显然，对珊瑚礁生态系统对21世纪海洋酸化反应的准确预测将取决于对生态系统规模反应的有力描述以及对塑造这些反应的基本过程的了解。利用现有数据，研究人员发现珊瑚礁生态系统钙化对三角洲碳酸钙饱和度的敏感性符合经验速率方程R=k(文石饱和态-1)n，该方程还描述了非生物碳酸钙净沉淀速率(R)与文石过饱和度(文石饱和态-1)之间的关系。这意味着，净生态系统钙化(NEC)对海洋酸化的响应受物理化学基本定律的支配，并有可能在空间和时间上进行预测。如果以这种方式看待，现有的NEC数据集虽然稀少，但揭示了不同的模式，如果得到验证，将对不同的珊瑚礁生态系统如何应对21世纪的海洋酸化产生重要影响。研究人员概述了一项旨在以这一命题为基础的研究计划。该项目扩展了目前在四个战略位置的珊瑚礁地点进行的生态系统规模观测的稀疏数据集，使我们能够检验以下假设：1.珊瑚礁生态系统钙化对三角洲文石饱和状态的敏感度(在速率方程中为“n”)随着文石饱和状态的降低而降低。这意味着，在本世纪，随着海洋酸化进程的推进，珊瑚礁钙化的下降速度将会放缓。2.钙化群落的能量状态是净生态系统钙化绝对率(速率方程中的k)的关键决定因素，它与n一起定义了NEC趋近于零的文石饱和状态值。这意味着，在健康、能量充足的珊瑚礁生态系统中，从净钙化到净溶解的转变将延迟，而在扰动、能量耗尽的生态系统中将加速。3.在文石饱和状态下，珊瑚和藻类优势生物的单个群落对相同变化的钙化响应弱于测量的生态系统尺度响应。这意味着，在实验室实验中没有充分捕捉到的过程，如生物侵蚀和溶解，将在珊瑚礁对海洋酸化的反应中发挥重要作用。更广泛的影响：海洋酸化威胁全世界5亿人的生计，他们依赖珊瑚礁提供宜居和农业用地、食物、建筑材料、海岸保护和旅游业收入。然而，海洋酸化研究产生的数据指出，我们对珊瑚礁生态系统规模对海洋酸化的反应的知识存在严重差距，目前限制了我们预测其对世界不同地区不同珊瑚礁影响的时间和严重程度的能力。利用研究人员和其他人产生的现有数据，该项目将解决一系列相关假设，如果研究证实这些假设，将立即直接影响对高二氧化碳世界中珊瑚礁弹性的预测。该项目汇集了珊瑚礁生物地质化学、化学海洋学和物理海洋学方面的专门知识，重点关注一个具有巨大社会、经济和保护意义的问题。为一名年轻的研究人员提供支持，本科生和少数族裔学生将通过WHOI夏季奖学金计划、伍兹霍尔海洋教育协会和PEP计划参与研究，私人投资机构与太平洋岛屿保护组织和利益攸关方之间的合作将得到加强，其目标是确保保护决策以科学数据为基础。研究结果将在国家和国际会议和讲习班上介绍，并通过同行评议的出版物及时传播。通过该计划产生的所有数据将在生物和化学海洋学数据管理办公室(BCO-DMO)和盘古开放获取图书馆存档。