Collaborative Research: Stability, flexibility, and functionality of thermally tolerant coral symbioses

合作研究：耐热珊瑚共生体的稳定性、灵活性和功能性

• 批准号: 1635695
• 负责人: Mark Warner
• 金额: $ 46.5万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1635695&HistoricalAwards=false
• 关键词: Collaborative; Research; Stability; flexibility; functionality

All reef-building corals require large numbers of internal symbiotic microalgae (called Symbiodinium) for their survival and growth. These mutualisms have shown considerable sensitivity to changes in the environment in recent decades, especially due to global increases in ocean temperatures. When exposed to severe thermal stress, corals loose their symbionts and often die. However, recent experiments show that some symbionts may be more stress-tolerant. Corals with these heat-resistant symbionts continue to receive high amounts of algal derived nutrients and grow under elevated temperatures. If the global trend in seawater warming continues to increase, these heat-resistant symbioses may become more ecologically prevalent on reef systems around the world and could play a critical role in maintaining healthy and productive coral communities. This project will examine the ecological and physiological attributes of stress-tolerant symbioses from the Indo Pacific where coral communities are the largest, most diverse, and productive in the world. The researchers will conduct a series of experiments to (1) evaluate host and symbiont attributes that contribute to thermal tolerance and (2) characterize the relative flexibility and functionality of various corals and symbionts exposed to typical ambient and stressful temperatures. Broader impacts of the project include the training of several Ph.D. students, undergraduates, and high school students in the disciplines of physiology and ecology. The researchers will partner with Global Ocean Exploration, Inc. to communicate this research to the general public through short documentary videos, editorials, and podcasts. An interactive K-5 program, "Invertebrates on the Road," will introduce elementary students in Pennsylvania to marine invertebrate diversity. Research results will also be disseminated to the public at the University of Delaware via educational seminars, as well as through hands-on research displays and demonstrations presented at the annual open house "Coast Day" festival in each year of the project. This project will examine several attributes important to the functional ecology of coral-dinoflagellate symbioses. Specifically, the research team seeks to understand the interplay between coral and symbiont physiologies under different environmental conditions and determine the relative influence of biotic factors crucial to the performance of stress tolerant symbioses. Results from recent experiments on Indo-west Pacific corals found that Clade D (S. trenchii) symbionts are stress-tolerant. These symbionts are able to maintain function and provide nutrients to their hosts under high temperatures that typically elicit the breakdown of symbioses involving many other species of symbiont. A number of questions arise about how enhanced thermal tolerance symbioses may be aided by a combination of factors; for example: Are symbionts physiologically hardier in corals that are routinely feeding? Do host genotypes that are adapted to high temperatures affect the physiology of their symbionts in ways that make the partnership more stress-tolerant? A series of experiments over three years will examine the functionality of different coral-symbiont pairings exposed to ambient and high temperatures. Reciprocal transplants between inshore (stress-tolerant) and offshore (stress-susceptible) reef sites will be used to produce specific host-symbiont parings. Controlled experiments will test the relative importance of coral trophic status (nutrient content) while holding symbiont type constant and how changes in both coral trophic status and symbiont species identity of the resident affect thermal tolerance. Tank experiments on shore will track rates of photosynthesis as well as carbon translocation and assimilation from symbiont to host tissues and skeletons. Long-term growth rates via skeletal density, linear extension, and biomass gain will also be measured. This project will help elucidate how biochemical, physiological and ecological differences among host-symbiont pairings may respond to rising ocean temperatures and enhance the future viability of coral reefs.

所有造礁珊瑚都需要大量的内部共生微藻（称为共生藻）来维持其生存和生长。近几十年来，这些共生关系对环境变化表现出相当大的敏感性，特别是由于全球海洋温度的升高。当暴露在严重的热压力下时，珊瑚会失去它们的共生体，往往会死亡。然而，最近的实验表明，一些共生体可能更耐压力。具有这些耐热共生体的珊瑚继续接受大量藻类衍生的营养物质，并在升高的温度下生长。如果全球海水变暖的趋势继续加剧，这些耐热共生生物可能会在世界各地的珊瑚礁系统中变得更加生态普遍，并可能在维持健康和多产的珊瑚群落方面发挥关键作用。该项目将研究来自印度洋太平洋的耐应力共生生物的生态和生理特性，那里的珊瑚群落是世界上最大、最多样化和最多产的。研究人员将进行一系列实验，以(1)评估宿主和共生体对耐热性的影响；(2)表征暴露在典型环境和压力温度下的各种珊瑚和共生体的相对灵活性和功能。该项目更广泛的影响包括培养生理学和生态学学科的博士生、本科生和高中生。研究人员将与全球海洋探索公司合作，通过短纪录片、社论和播客向公众传播这项研究。一项名为“路上的无脊椎动物”的互动式K-5课程将向宾夕法尼亚州的小学生介绍海洋无脊椎动物的多样性。研究成果也将在特拉华大学通过教育研讨会向公众传播，并在项目每年的“海岸日”开放日上进行实践研究展示和演示。本项目将研究对珊瑚-鞭毛藻共生的功能生态学重要的几个属性。具体而言，研究小组试图了解珊瑚和共生体生理在不同环境条件下的相互作用，并确定对耐胁迫共生体表现至关重要的生物因素的相对影响。最近对印度-西太平洋珊瑚的实验结果发现，进化枝D （S. trenchii）共生体是耐应力的。这些共生体能够在高温下维持其功能并为其宿主提供营养，而高温通常会导致涉及许多其他共生体物种的共生关系的破裂。关于增强的耐热性共生体如何通过多种因素的组合得到帮助，出现了许多问题；例如：在定期进食的珊瑚中，共生体在生理上是否更顽强？适应高温的宿主基因型是否会影响其共生体的生理机能，从而使它们的伙伴关系更能承受压力？在三年多的时间里，一系列实验将检验不同珊瑚共生对暴露在环境和高温下的功能。在近海（耐压力）和近海（易受压力）珊瑚礁之间的相互移植将用于产生特定的宿主-共生配对。对照实验将测试在保持共生类型不变的情况下，珊瑚营养状态（营养含量）的相对重要性，以及珊瑚营养状态和共生物种身份的变化如何影响居民的耐热性。岸上的水槽实验将跟踪光合作用的速率，以及从共生生物到宿主组织和骨骼的碳转运和同化。通过骨骼密度，线性延伸和生物量增加的长期增长率也将被测量。该项目将有助于阐明寄主-共生体配对之间的生化、生理和生态差异如何对海洋温度上升做出反应，并增强珊瑚礁未来的生存能力。

项目成果

Symbiotic Dinoflagellate Functional Diversity Mediates Coral Survival under Ecological Crisis

共生甲藻功能多样性介导生态危机下珊瑚的生存

• DOI: 10.1016/j.tree.2017.07.013
• 发表时间: 2017
• 期刊: Trends in Ecology & Evolution
• 影响因子: 16.8
• 作者: Suggett, David J.;Warner, Mark E.;Leggat, William
• 通讯作者: Leggat, William