Collaborative Research: The physiology and ecology of widespread 'stress tolerant' coral endosymbionts: coral 'saviors' or opportunistic invaders?

海洋变暖正在以多种方式影响我们星球上的生命。高温可以破坏甲藻（Symbiodinium spp.）和造礁珊瑚（即珊瑚白化），从而有可能使全球丧失一个重要的海洋生态系统。珊瑚-甲藻共生体对全球气候变化所带来的环境胁迫的生理、生态和进化响应是复杂的。某些类型的共生藻类的传播可能会增加珊瑚对热应力的耐受力，并帮助它们在温暖的海洋中生存，但可能不会对珊瑚的健康造成损害。这种甲藻暂时被命名为共生沟藻，在整个加勒比海的许多珊瑚中越来越常见，但相对于其他共生体来说，丰度往往很低。而S.在气候变暖期间和之后，沟渠生物的数量会增加，但在恢复正常条件后，它往往会被其他共生体取代。遗传学证据表明S. trenchi最近入侵和/或扩大在加勒比地区，并与许多珊瑚，似乎是不佳的优化，或适应不良，相对于共生关系，它保持在印度-太平洋珊瑚发展协会。本研究旨在探讨该菌的共生生态与生理特性。大西洋和太平洋珊瑚中的海沟。漂白实验将研究温度升高对碳从藻类转移到宿主珊瑚的影响（通过稳定同位素标记），以及光合作用和生长在含有S的殖民地之间。trenchi相比，殖民地窝藏其他共生藻属。将调查共生体群落转变的潜力以及基于漂白严重程度和恢复时间改变的长期菌落生长。互惠移植研究将研究太平洋珊瑚之间共生体的竞争相互作用和稳定性。这些研究将测试是否继续传播的S。海沟将影响加勒比地区的珊瑚生长，如果环境条件恶化，它是否会在印度太平洋地区表现出类似的行为。该项目的结果有可能提供关于广泛分布的共生藻类物种如何（或是否）可能影响造礁珊瑚的复原力及其在气候变化导致的海洋变暖预计增加中生存的潜力的变革性信息。除了培训一名博士后学者和几名研究生外，该项目还将通过与帕劳国家水族馆、帕劳国际珊瑚礁中心和当地学校的几项外联工作，加强科学发现和代表性不足群体的参与。将与几名当地高中教师和学生一起发展海洋共生和科学教育单位，并将向帕劳社区学院的学生提供独特的研究机会。同样，一个新的教育展示，解决全球气候如何可能影响珊瑚礁，并描述目前的研究，以更好地了解珊瑚藻共生的生理学，将开发和介绍在特拉华州大学开放日“海岸日。“该展览随后将捐赠给帕劳水族馆供未来使用。该奖项由NSF的国际和综合活动办公室共同资助。

Ocean warming is affecting life on our planet in many ways. High temperature can disrupt the endosymbioses between dinoflagellate algae (Symbiodinium spp.) and reef-building corals (i.e. coral bleaching), thereby risking the global loss of a critical marine ecosystem. The physiological, ecological and evolutionary responses of coral-dinoflagellate symbioses to environmental stress brought on by global climate change are complex. The spread of certain types of symbiotic algae may increase the thermal stress tolerance among corals and help them persist in warmer oceans, but perhaps not without trade-offs to the health of the coral. The dinoflagellate tentatively named Symbiodinium trenchi has become increasingly more common in numerous corals throughout the Caribbean, but is often at low-abundance relative to other symbionts. While S. trenchi can increase in abundance during and after warming, it is often displaced by other symbionts following a return to normal conditions. Genetic evidence indicates that S. trenchi recently invaded and/or expanded in the Caribbean and has developed associations with many corals that seem to be poorly optimized, or mal-adapted, relative to the symbioses it maintains with corals in the Indo-Pacific. This project will investigate the symbiosis ecology and physiology of S. trenchi in corals from the Atlantic and Pacific Oceans. Bleaching experiments will examine the effects of increased temperature on transfer of carbon from the algae to the host coral (via stable isotopic tagging), as well as photosynthesis and growth among colonies harboring S. trenchi compared to colonies harboring other Symbiodinium spp. The potential for symbiont community shifts as well as altered long-term colony growth based on bleaching severity and recovery time will be investigated. A reciprocal transplant study will examine the competitive interaction and stability of symbionts among Pacific corals. These studies will test if the continued spread of S. trenchi will affect coral growth in the Caribbean and whether it might behave similarly in the Indo-Pacific if environmental conditions worsen. The results from this project have the potential to supply transformative information regarding how (or if) a widely distributed symbiotic algal species may influence the resilience of reef-building corals and their potential to survive projected increases in ocean warming due to climate change. In addition to training one postdoctoral scholar and several graduate students, this project will enhance scientific discovery and participation of underrepresented groups via several outreach efforts with the Palau National Aquarium, Palau International Coral Reef Center, and local schools. Educational units in marine symbioses and science will be developed with several local high school teachers and students, and unique research opportunities will be provided to students at the Palau Community College. Likewise, a new educational display addressing how global climate may impact coral reefs, and describing the current research to better understand the physiology of coral-algal symbioses, will be developed and presented at the University of Delaware open house "Coast Day." The display will be donated subsequently to the Palau Aquarium for future use.This award is co-funded by NSF's Office of International and Integrative Activities.