Collaborative Research: Physiology and Biogeochemistry of Repeatedly Bleached and Recovering Caribbean Corals

合作研究：反复白化和恢复加勒比珊瑚的生理学和生物地球化学

• 批准号: 0825413
• 负责人: Mark Warner
• 金额: $ 37.66万
• 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: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2013-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0825413&HistoricalAwards=false
• 关键词: Collaborative; Research; Physiology; Biogeochemistry; Repeatedly

The overall stability and health of coral reefs is declining world-wide at an unprecedented rate. Mass coral bleaching, wherein exposure to elevated temperature leads to the loss of significant numbers of endosymbiotic dinoflagellates (Symbiodinium spp., commonly called zooxanthellae) and/or photosynthetic pigments, serves as a primary global example of how fragile this symbiosis is. While we have begun to understand the ecological and physiological impacts of bleaching, there remain key fundamental gaps in knowledge. In particular, it is becoming increasingly clear that a) not all corals either respond to, or recover from, bleaching events the same way, and that b) the impact of annual or repeated bleaching events on corals has not been examined in sufficient detail. Several non-mutually exclusive ecological and physiological pathways could impact how a particular coral species succumbs to or recovers from bleaching. Recent evidence suggests that the following features may play key roles for coral survival in the face of future seawater warming and mass bleaching events: 1) shifts in trophic partitioning (e.g., proportional reliance on autotrophy and heterotrophy) and energy reserve utilization, 2) enhanced thermal tolerance through host and algal-mediated physiological responses, and 3) harboring of different Symbiodinium phylotypes. However, these mechanisms have yet to be investigated in a unified approach that covers the entire coral holobiont system (algae, host tissue, and skeleton), or under scenarios of repeated bleaching.The overall objectives of this study are as follows: 1) to determine the effect of single and repeated bleaching on the physiology, biogeochemistry, and recovery of some Caribbean coral species, and 2) to determine which Symbiodinium-type and host-species combinations are more resilient to single and repeated bleaching, what aspects of their physiology and biogeochemistry render them resilient, and to use this information to evaluate the long-term persistence of Caribbean coral reefs. To address these objectives, the following physiological variables will be measured: 1) Symbiodinium type, photochemical function and algal stress physiology, and 2) animal host energy reserves, defense enzyme concentration, skeletal growth, and feeding capacity in the corals Porites porites, Porites astreoides, and Montastraea faveolata. Corals will be examined immediately following thermal stress designed to approximate natural bleaching, and recovery will be monitored over short and long-term time scales. Next, the impact of repeated bleaching will be examined in the subsequent year, followed by examination over the next recovery period. This research is designed to simultaneously evaluate the symbiotic algae, coral host, and skeleton, and to identify patterns of physiological responses and recovery of each Symbiodinium-type and host-species combination that would be indicative of the resilience capacity of Caribbean corals to future more frequent thermal perturbations.The results of this research should significantly increase understanding of how (or if) reef corals can survive future climate change. This is especially critical for Caribbean corals where sensitivity appears to have a very low threshold, and where bleaching is predicted to occur biannually within the next 20-30 years. Such information is key for the effective future management of coral reefs. This project will incorporate the training of two PhD students and several undergraduates, and the PIs will incorporate the research findings into their teaching. Several female and Hispanic students (both minorities in marine sciences) are mentored by the PIs. In addition, collaborative efforts between Grottoli and Warner will be enhanced by the field research monitoring efforts of the Central Caribbean Marine Institute at the Little Cayman Research Center, and the remote-sensing-based products from colleagues at the NOAA Coral Reef Watch Program. Results of the research will be broadly disseminated through peer reviewed publications, presentations at scientific conferences, and online via the PI's respective websites.

全球珊瑚礁的整体稳定性和健康状况正在以前所未有的速度下降。大规模珊瑚白化是这种共生关系多么脆弱的一个主要全球例子，其中暴露在高温下会导致大量内共生甲藻（共生甲藻，通常称为虫黄藻）和/或光合色素的损失。虽然我们已经开始了解白化的生态和生理影响，但在知识方面仍然存在关键的根本差距。特别是，越来越明显的是，a）并非所有珊瑚都以相同的方式对白化事件做出反应或从白化事件中恢复，b）每年或重复的白化事件对珊瑚的影响尚未得到足够详细的研究。几种非相互排斥的生态和生理途径可能会影响特定珊瑚物种如何死于白化或从白化中恢复。最近的证据表明，面对未来海水变暖和大规模白化事件，以下特征可能对珊瑚的生存发挥关键作用：1）营养分配的变化（例如，对自养和异养的比例依赖）和能量储备利用，2）增强通过宿主和藻类介导的生理反应实现热耐受性，3) 拥有不同的共生藻种系型。然而，这些机制尚未以涵盖整个珊瑚全生物系统（藻类、宿主组织和骨骼）的统一方法或在反复白化的情况下进行研究。本研究的总体目标如下：1）确定单次和重复白化对某些加勒比珊瑚物种的生理学、生物地球化学和恢复的影响，以及 2) 确定哪些共生藻类和寄主物种组合对单次和重复白化更有弹性，什么它们的生理学和生物地球化学方面使它们具有弹性，并利用这些信息来评估加勒比珊瑚礁的长期持续性。为了实现这些目标，将测量以下生理变量：1) 共生藻类型、光化学功能和藻类应激生理学，以及 2) 动物宿主能量储备、防御酶浓度、骨骼生长和珊瑚的摄食能力。 astreoides 和 Montastraea faveolata。在模拟自然白化的热应力后，将立即对珊瑚进行检查，并在短期和长期的时间范围内监测恢复情况。接下来，将在接下来的一年中检查反复漂白的影响，然后在下一个恢复期进行检查。这项研究旨在同时评估共生藻类、珊瑚宿主和骨骼，并确定每种共生藻类型和宿主物种组合的生理反应和恢复模式，这将表明加勒比珊瑚对未来更多环境的恢复能力。频繁的热扰动。这项研究的结果应该会显着提高人们对珊瑚礁珊瑚如何（或是否）能够在未来气候变化中生存的了解。这对于加勒比珊瑚来说尤其重要，因为那里的敏感性阈值似乎非常低，而且预计在未来 20-30 年内每年都会发生两次白化现象。此类信息对于未来有效管理珊瑚礁至关重要。该项目将培训两名博士生和几名本科生，PI 将把研究成果融入到他们的教学中。几名女性和西班牙裔学生（均为海洋科学领域的少数群体）接受 PI 的指导。此外，Grottoli 和华纳之间的合作将通过小开曼研究中心的中加勒比海海洋研究所的实地研究监测工作以及 NOAA 珊瑚礁观察计划同事的遥感产品得到加强。研究结果将通过同行评审的出版物、科学会议上的演讲以及通过 PI 各自的网站在线广泛传播。