Understanding how global warming will select for zooxanthellae phenotypes

了解全球变暖将如何选择虫黄藻表型

• 批准号: 0851982
• 负责人: Paul Falkowski
• 金额: $ 60.67万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0851982&HistoricalAwards=false
• 关键词: Understanding; how; global; warming; will

Symbiodinium (= zooxanthellae) is a cosmopolitan dinoflagellate genus of tropical and subtropical latitudes, and an integral member of coral reef ecosystems. As the obligate endosymbionts of corals and a variety of other reef organisms, Symbiodinium is the main contributor to coral reef primary production by fueling their host's metabolism and growth. In this delicate symbiosis the symbiont functions as an autotroph, releasing most of its photosynthetic products as food for their host, while the corals provide protection, a stable environment, and metabolic waste that the algae use to grow. The fragility of this relationship has become increasingly apparent in recent years due to rising ocean temperatures. Coral 'bleaching' events, a process by which corals release their symbionts in response to stress, are becoming a global environmental crisis. During this process, Symbiodinium becomes stressed, releasing reactive oxygen species and losing photosynthetic abilities. Prolonged exposure causes irreversible damage and expulsion of zooxanthellae from their hosts. Persistent and recurrent bleaching events can have catastrophic consequences to coral reef health, resulting in the death of coral colonies and a collapse of trophic structure. However, some corals appear to withstand these events unharmed, and laboratory research has shown that some Symbiodinium are tolerant of heat stress. While recent work has revealed a vast genetic diversity of Symbiodinium in coral reef ecosystems, how the diversity is related to stress tolerance is poorly understood.The objectives of this research are to describe the relationship of Symbiodinium genetic diversity to stress phenotypes in both free-living and symbiotic strains, and to determine how some strains tolerate high temperature stress and resist bleaching in their hosts. Another goal is to find stress-sensitive genotype markers that can be used to evaluate coral reef health and susceptibility to heat stress. Using a combination of biophysical, molecular biological and biochemical assays, the PIs propose to sample the largest number of Symbiodinium strains to date, to experimentally determine how genotype is related to phenotype diversity. The broader impacts include advancing Ocean Science Literacy by educating the general public about coral physiology, and explaining how anthropogenic activities may impact the health of marine organisms. Education and outreach activities will be developed through current partnerships between Rutgers, the Liberty Science Center, and COSEE-West. The research may also have implications for coral reef management. Finally, results will make significant contributions to the fundamental understanding of the ecology and evolution of Symbiodinium.

共生鞭毛虫是热带和亚热带地区的世界性甲藻属，是珊瑚礁生态系统的重要组成部分。共生菌作为珊瑚和其他各种珊瑚礁生物的专性内共生菌，通过促进宿主的新陈代谢和生长，是珊瑚礁初级生产力的主要贡献者。在这种微妙的共生中，共生体发挥着自养功能，释放出大部分光合作用产物作为宿主的食物，而珊瑚则提供保护、稳定的环境和藻类用来生长的新陈代谢废物。近年来，由于海洋温度上升，这种关系的脆弱性变得越来越明显。珊瑚“漂白”事件，即珊瑚释放共生体以应对压力的过程，正在成为一场全球性的环境危机。在这个过程中，共生菌受到压力，释放出活性氧物种，失去光合作用能力。长时间暴露会造成不可逆转的损害，并将虫黄藻从宿主体内排出。持续和反复的白化事件可能对珊瑚礁健康造成灾难性后果，导致珊瑚群落死亡和营养结构崩溃。然而，一些珊瑚似乎毫发无损地经受住了这些事件，实验室研究表明，一些共生动物对热应激具有耐受性。虽然最近的工作揭示了珊瑚礁生态系统中共生菌的巨大遗传多样性，但这种多样性与胁迫耐受性的关系尚不清楚。本研究的目的是描述共生菌遗传多样性与共生菌株中胁迫表型的关系，并确定一些菌株如何耐受高温胁迫和抵抗宿主的漂白。另一个目标是寻找压力敏感的基因标记，可以用来评估珊瑚礁的健康状况和对热应激的敏感性。利用生物物理、分子生物学和生化分析的组合，PI建议对迄今为止数量最多的共生菌菌株进行采样，以实验确定基因与表型多样性的关系。更广泛的影响包括通过教育普通公众了解珊瑚生理学来提高海洋科学素养，以及解释人为活动可能如何影响海洋生物的健康。教育和外展活动将通过罗格斯大学、自由科学中心和COSEE-WEST之间的现有伙伴关系来发展。这项研究也可能对珊瑚礁的管理有所启示。最后，研究结果将为从根本上理解共生动物的生态和进化做出重要贡献。