Predicting the global location of heat tolerant corals: Palau patch reefs as a general model

当珊瑚礁的温度比夏季正常温度高几度时，就会发生一种叫做珊瑚白化的反应，即生活在珊瑚细胞内的单细胞植物被排出体外。珊瑚从正常的棕褐色变成了漂白的白色，因为它被剥夺了从它的植物伙伴那里正常的食物供应，这些珊瑚中的大多数都死了。然而，有些珊瑚天生就能在高温下生存，而高温会导致同一物种的其他珊瑚变白。确定这些耐热珊瑚常见的地方将为保护和恢复耐热珊瑚礁提供一个通用的工具。研究人员将在帕劳的两个泻湖中对30个大小各异的珊瑚礁进行实验，记录400种珊瑚的当地温度，并使用新设计的珊瑚应力箱测试珊瑚的耐热性。由于大型珊瑚礁通常在白天退潮时升温，研究人员假设它们通常是耐热珊瑚的家园。他们还将把耐热珊瑚转移到较冷的地方，以测试珊瑚耐热性的稳定性。应力罐技术可以广泛应用于偏远地区，并将为社区和管理人员在世界各地的珊瑚礁中发现和保护耐热珊瑚提供一套通用的实用工具。这项工作将推动加州和帕劳的本科STEM教育。与帕劳社区学院的伙伴关系将促进太平洋岛屿社区和学生的参与。学生将接受实地研究、基因组学和生物信息学方面的跨学科培训，并学习实用技能，使他们能够收集和解释压力箱和温度数据。更广泛的外联工作将包括制作和传播一系列微型纪录片和博客文章，旨在向全球观众介绍在世界范围内寻找耐热珊瑚的概念。先前的珊瑚礁研究表明，周期性的高水温可以通过许多遗传位点的驯化和选择相结合，诱导造礁珊瑚的高耐热性。关键问题包括这些耐热栖息地是常见的还是罕见的，以及它们的位置是否可以通过识别在退潮时每天温度峰值经常发生的珊瑚礁来预测。该项目将检查400种珊瑚的耐热性，这些珊瑚分布在帕劳30个经历不同温度和流量剖面的斑块珊瑚礁中。本研究将利用多种方法来表征耐热性的时空模式，包括：(1)开发低成本、便携的热应激箱，以快速、经济地评估原位条件；(2)生理条件的基因组分析，以确定负责耐热性的基因和基因表达机制；(3)高分辨率温度作图，追踪温度变化对造礁珊瑚产生稳定、耐高温性的作用；(4)相互移植实验，以评估耐热珊瑚在转移到较冷的地方时是否保持耐热性。这项研究将扩大已知耐热性栖息地的地理地图，并加快定位可能最能抵抗未来海洋变暖的珊瑚种群的能力。

When coral reefs heat up just a few degrees above normal summer temperatures, a reaction called coral bleaching can occur in which single celled plants living inside coral cells are expelled. The coral turns from its normal tan color to bleached white, and because it is deprived of the normal food supply from its plant partner, most of these corals die. Yet, some corals naturally can survive high temperatures that cause others in the same species to bleach. Identifying where these heat tolerant corals are common would provide a general tool for protecting and restoring heat tolerant reefs. The investigators will conduct experiments on 30 patch reefs in Palau of very different sizes in two lagoons, record local temperatures for 400 corals, and test coral heat tolerance using a newly designed coral stress tank. Because large patch reefs generally heat up during daytime low tides, The investigators hypothesize that they are commonly home to heat resistant corals. They will also move heat tolerant corals to cooler locations to test the stability of heat resistance among corals. The stress tank technologies can be widely used in remote settings, and will provide a set of generalizable, practical tools for communities and managers to find and protect heat tolerant corals in reefs around the world. The work will advance undergraduate STEM education in California and Palau. A partnership with the Palau Community College will facilitate the engagement of Pacific Island communities and students. Students will receive interdisciplinary training in field research, genomics and bioinformatics and learn practical skills that will enable them to collect and interpret stress tank and temperature data. Broader outreach efforts will include the production and dissemination of a series of microdocumentaries and blog posts designed to bring the concept of a world-wide search for heat tolerant corals to a global audience.Previous coral reef research has demonstrated that periodic high water temperatures can induce high heat tolerance in reef building corals through a combination of acclimation and selection at many genetic loci. Key questions include whether these kinds of heat tolerant habitats are common or rare, and whether their locations can be predicted by identifying coral reefs where daily temperature spikes regularly occur at low tide. This project will examine heat tolerance of 400 corals in the Acropora hyacinthus species complex across 30 patch reefs in Palau that experience variable temperature and flow profiles. This study will utilize a variety of methods to characterize spatial and temporal patterns of heat tolerance including: (1) the development of low-cost, portable heat stress tanks to quickly and affordably assess in situ conditions, (2) genomic assays of physiological condition to identify the genes and gene expression mechanisms that are responsible for heat tolerance, (3) high resolution temperature mapping to trace the role of temperature variation in producing stable, high temperature tolerance in reef building corals, and (4) reciprocal transplant experiments to evaluate whether heat resistant corals retain heat resistance when moved to cooler locations. This research will expand the geographic map of habitats with known heat tolerance, and expedite the ability to locate coral populations that may be most resistant to future ocean warming.