Influence of environmental pH variability and thermal sensitivity on the resilience of reef-building corals to acidification stress

珊瑚礁是非常多样化的生态系统，为沿海社区提供食物、旅游收入和海岸线保护。珊瑚礁继续为社会提供这些服务的能力目前受到气候变化的威胁，气候变化导致海洋温度和酸度上升，可能导致珊瑚死亡，珊瑚是许多物种赖以生存的珊瑚礁框架的动物。该项目研究了温度和酸化压力如何共同影响珊瑚未来的健康和生存。科学家们正在夏威夷进行这个项目，他们在那里发现了生活在不同环境pH条件下的珊瑚，它们对温度压力的敏感性不同。这个项目提高了对单个珊瑚如何？美国的历史影响了它对多种压力源的反应，并有助于确定最有可能支持弹性珊瑚群落的条件。该项目将产生广泛的生物和物理化学数据，这些数据将免费提供。此外，本项目还支持海洋科学和珊瑚礁生态学专业本科生、高中生和博士后1人的教育和培训。针对高中生的动手活动正在被开发成免费的在线教育资源。该项目比较了经历不同pH值动态（高昼夜变化vs低昼夜变化）和不同热耐受性（历史上漂白敏感vs耐受性）的珊瑚对酸化胁迫的反应，以了解珊瑚物种之间和种群内珊瑚对这两个因素的反应是如何不同的。实验的重点是在这些稳定和可变pH值的珊瑚礁中发现的两种主要的珊瑚礁建造者：Montipora capitata和Porites compressa。在2015年全球珊瑚白化事件期间，每个物种的个体表现出不同的热敏性（即漂白与着色）。该系统测试了以下假设：1)生活在pH值波动较大的珊瑚礁上的珊瑚对酸化压力的适应能力更强；2)珊瑚对酸化的适应能力是一种可以通过驯化来促进的塑性特性；3)热敏珊瑚应对pH值压力的能力降低，温度升高会加剧这种能力。从每种环境和漂白历史的菌落中分离出的珊瑚细胞暴露于急性pH胁迫下，并使用共聚焦显微镜检查其在体内恢复细胞内pH的能力，并通过Western blot和免疫定位检查预测参与这种恢复的蛋白质的表达水平（例如质子转运蛋白）。每个pH值历史的珊瑚在受控的水族箱环境中暴露于稳定和可变的海水pH值中，以确定酸化弹性的可塑性水平，并测试该系统中的pH适应性。最后，将不同热敏程度的珊瑚暴露在热应力和恢复中，并随着时间的推移检查它们调节pH值的能力。这些实验的结果有助于确定在日益普遍的热应激事件背景下促进珊瑚对海洋酸化的恢复能力的珊瑚礁条件，同时推进对珊瑚生理学和共生的机制理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Coral reefs are incredibly diverse ecosystems that provide food, tourism revenue, and shoreline protection for coastal communities. The ability of coral reefs to continue providing these services to society is currently threatened by climate change, which has led to increasing ocean temperatures and acidity that can lead to the death of corals, the animals that build the reef framework upon which so many species depend. This project examines how temperature and acidification stress work together to influence the future health and survival of corals. The scientists are carrying out the project in Hawaii where they have found individual corals with different sensitivities to temperature stress that are living on reefs with different environmental pH conditions. This project improves understanding of how an individual coral?s history influences its response to multiple stressors and helps identify the conditions that are most likely to support resilient coral communities. The project will generate extensive biological and physicochemical data that will be made freely available. Furthermore, this project supports the education and training of undergraduate and high school students and one postdoctoral researcher in marine science and coral reef ecology. Hands-on activities for high school students are being developed into a free online educational resource. This project compares coral responses to acidification stress in populations experiencing distinct pH dynamics (high diel variability vs. low diel variability) and with distinct thermal tolerances (historically bleaching sensitive vs. tolerant) to learn about how coral responses to these two factors differ between coral species and within populations. Experiments focus on the two dominant reef builders found at these stable and variable pH reefs: Montipora capitata and Porites compressa. Individuals of each species exhibiting different thermal sensitivities (i.e., bleached vs. pigmented) were tagged during the 2015 global coral bleaching event. This system tests the hypotheses that 1) corals living on reefs with larger diel pH fluctuations have greater resilience to acidification stress, 2) coral resilience to acidification is a plastic trait that can be promoted via acclimatization, and 3) thermally sensitive corals have reduced capacity to cope with pH stress, which is exacerbated at elevated temperatures. Coral cells isolated from colonies from each environmental and bleaching history are exposed to acute pH stress and examined for their ability to recover intracellular pH in vivo using confocal microscopy, and the expression level of proteins predicted to be involved in this recovery (e.g., proton transporters) is examined via Western blot and immunolocalization. Corals from each pH history are exposed to stable and variable seawater pH in a controlled aquarium setting to determine the level of plasticity of acidification resilience and to test for pH acclimatization in this system. Finally, corals with different levels of thermal sensitivity are exposed to thermal stress and recovery, and their ability to regulate pH is examined over time. The results of these experiments help identify reef conditions that promote coral resilience to ocean acidification against the background of increasingly common thermal stress events, while advancing mechanistic understanding of coral physiology and symbiosis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.