RAPID: Collaborative Research: Disentangling the effects of heat stress versus bleaching phenotype on coral performance

珊瑚漂白在世界各地的珊瑚礁上变得越来越普遍，因为与气候变化相关的海洋表面温度上升破坏了珊瑚与藻类的共生。这种戏剧性的热应激反应使通常五颜六色的珊瑚变成了明亮的白色，然而在这些热应激事件中，并不是所有的珊瑚都会变白。这个项目的重点是通过比较珊瑚礁上的两对珊瑚来评估漂白的影响，在持续的热浪中，一对珊瑚已经漂白，另一对没有漂白，尽管经历了相同的温度。在过去五年中，在三次漂白事件中对这些珊瑚对进行了监测，提供了一种独特的资源，以研究具有一致不同漂白敏感性的珊瑚是否有能力适应通过遗传变化造成的干扰，或不是由于DNA碱基变化引起的基因表达变化。为了解决这一问题，该项目将利用海洋热浪期间自然栖息地中的珊瑚对来表征漂白或不漂白对珊瑚生理、基因表达和表观遗传模式的影响。该项目还为研究生学员提供研究支持，并为本科生和高中生的研究和培训提供数据和材料。该项目将从URI和UPenn地区的高中和大学本科生中招募未被充分代表的少数族裔学生，从事图像(底栖生物和群落照片、亮场和共焦显微照片)和排序数据的计算机分析工作。它还将支持夏威夷大学ʻI本科生在珊瑚生态学和生理学方面的培训，以及她高级论文的发展。该项目将调查反复的热应激事件对头状单孢藻表现的影响，单孢藻是夏威夷ʻI的主要珊瑚礁建造者。它利用头状单孢藻成对群体的及时背景，这些群体具有漂白和未漂白的历史，通过夏威夷ʻI过去的两次漂白事件(2015年和2019年)和目前正在进行的2020年事件进行监测。这个系统提供了一个独特的机会，可以随着时间的推移，理清热应激和漂白对珊瑚性能的影响，这是珊瑚礁弹性的一个基本特征。这两种表型在热浪中经历的不同的生理和能量过程可能会导致动物体内细胞环境的变化，从而影响表观遗传转录调控。这些调节和能量的变化，如果随着时间的推移而持续下去，有可能在热浪持续之后改变珊瑚的健康状况，区别于具有不同漂白表型的珊瑚。具体地说，该项目将：1)量化2020年热浪对漂白和恢复期间珊瑚生理的影响；2)生成相应的珊瑚组织和核酸档案，作为未来工作的资源，表征漂白表型如何改变能量和非遗传遗传；3)表征漂白表型如何改变表观遗传标记(即DNA甲基化)和基因表达的代内遗传，以及这些标记和表达模式在热应激后的持续时间。这个项目代表了对一种理想系统的紧急评估，以测试珊瑚漂白表型对珊瑚适合性的影响。因此，该项目的结果将为漂白与高温压力的代内和跨代影响奠定基础，这对于了解珊瑚对气候变化的适应能力至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Coral bleaching has become increasingly common on reefs worldwide as rising sea surface temperatures associated with climate change disrupt the coral-algal symbiosis. This dramatic heat stress response turns the normally colorful corals bright white, and yet during these heat stress events not all corals undergo bleaching. This project focuses on assessing the effects of bleaching by comparing pairs of corals side-byside on the reef during an ongoing heat wave, where one has bleached and the other has not, despite experiencing the same temperatures. These coral pairs have been monitored throughout three bleaching events in the past five years, providing a unique resource to address whether corals with consistently different bleaching susceptibilities have the capacity to acclimate in response to disturbances throughepigenetic changes, or changes in gene expression not due to change in DNA bases. To address this, the project will characterize the impacts of bleaching or not bleaching on coral physiology, gene expression, and epigenetic patterns using coral pairs in their natural habitat during a marine heatwave. This project also provides research support for graduate student trainees, as well as data and materials for the research and training of undergraduate and high school students. This project will recruit underrepresented minority students from URI and UPenn area high schools and university undergraduates for work on computer analysis of images (benthic and colony photographs, brightfield and confocal micrographs) and sequencing data. It will also support the training of an undergraduate student at the University of Hawaiʻi in coral ecology and physiology, and the development of her senior thesis.This project will investigate the effects of repeated heat stress events on the performance of Montipora capitata, a dominant reef builder throughout Hawaiʻi. It utilizes the timely context of paired colonies of M. capitata with bleached vs. unbleached histories that have been monitored through two past bleaching events in Hawaiʻi (2015 and 2019) and the currently ongoing 2020 event. This system allows for the unique opportunity to disentangle the consequences of heat stress versus bleaching on coral performance through time, an essential feature of reef resilience. The contrasting physiological and energetic processes these two phenotypes undergo during a heatwave are likely to result in alterations to the cellular environment within the animal that impacts epigenetic transcriptional regulation. These regulatory and energetic changes, if persistent over time, have the potential to alter coral fitness beyond the duration of the heatwave differentially between corals with contrasting bleaching phenotypes. Specifically, the project will: 1) quantify the effect of the 2020 heatwave on coral physiology during bleaching and recovery, 2) generate a corresponding archive of coral tissues and nucleic acids as a resource for future work characterizing how bleaching phenotype alters energetics and non-genetic inheritance, and 3) characterize how bleaching phenotype alters intra-generational inheritance of epigenetic marks (i.e., DNA methylation) and gene expression, and the duration of these marks and expression patterns following heat stress. This project represents an urgent assessment of an ideal system to test the legacy of coral bleaching phenotype on coral fitness. The results of this project will therefore lay the foundation for intra and cross-generational effects of bleaching vs. heat stress, which is essential for understanding coral resilience to climate change.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.