Collaborative Research: Assessing the changing symbiotic milieu on Caribbean coral reefs under climate change: magnitude, tradeoffs, interventions, and implications

气候变化对世界各地的珊瑚礁生态系统构成了生存威胁，海洋持续变暖导致的珊瑚白化是这些生态系统在未来几十年持续存在的最紧迫挑战。鉴于这一威胁的严重性和紧迫性，至关重要的是调查一些珊瑚可能在变暖中幸存下来的机制，评估这种情况在珊瑚礁上发生的程度，并将这些发现应用于可能改善生存轨迹的保护干预措施。这个项目旨在通过测试加勒比海的珊瑚礁是否正在经历藻类共生体的转变，转向更耐热的类型，这些转变可能对珊瑚礁生态系统造成的后果，以及我们可能使用这些信息来帮助保护它们的方式来实现这些目标。将利用科学目标来提高加勒比地区珊瑚礁恢复工作的有效性，方法是将研究结果应用于正在进行的干预试验，这些试验旨在用耐热藻类播种外植珊瑚(包括在苗圃中饲养的成年珊瑚碎片和性衍生珊瑚新兵)，这些藻类耐高温。它还利用在两个主要公共水族馆出现的机会，向积极参与的公众受众强调珊瑚礁的困境，准备接收这一信息，并了解科学在理解和缓解问题方面的作用。最后，许多高中生、本科生和研究生将在这个项目期间得到指导，帮助培养下一代海洋科学家。该项目测试持续的气候变暖是否正在导致耐热藻类共生体(如杜氏藻)在加勒比海的珊瑚礁上变得越来越常见。了解该地区不断变化的共生环境、特伦奇氏吸虫传播的潜在过程以及这种传播的后果，都是非常及时的问题，有可能帮助我们了解未来的珊瑚礁状态。该项目将：(1)在实验室中操纵珊瑚共生环境，包括一些以前从未尝试过的加勒比海珊瑚物种，以标准化的方式评估它们获得耐热共生体的相对能力；(2)将具有操纵共生体群落的珊瑚种植到珊瑚礁，以评估现实世界中对耐热性的生态生理权衡，如生长速度降低；(3)通过组织植入物将耐热共生体引入野外珊瑚群落，以了解环境控制引入的共生体的持续或丧失；(4)通过调查温度和可获得性对在新定居的珊瑚幼虫中获得和建立这些共生体的作用，评估共生环境中的跨代反馈；以及(5)使用来自佛罗里达、巴哈马、伯利兹和百慕大的独特的存档样本，量化过去约20年来加勒比海耐热共生体的发生率和相对丰度的变化。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Climate change represents an existential threat to coral reef ecosystems worldwide, with coral bleaching driven by continued ocean warming presenting the most pressing challenge to the persistence of these ecosystems over the next few decades. Given the severity and urgency of this threat it is critical to investigate mechanisms by which some corals might survive warming, assess the degree to which this is happening on reefs, and apply these discoveries to inform conservation interventions that might improve survival trajectories wherever possible. This project aims to fulfill these objectives by testing whether reef corals in the Caribbean are undergoing shifts in their algal symbionts in favor of more heat-tolerant types, what the consequences of these shifts might be for coral reef ecosystems, and the way in which we might use this information to help conserve them. Scientific objectives will be leveraged to improve the effectiveness of reef restoration efforts in the Caribbean by applying findings to ongoing intervention trials which aim to seed outplanted corals (both adult fragments raised in nurseries, and sexually derived coral recruits) with heat tolerant algae that are climate-resistant. It also takes advantage of emerging opportunities at two major public aquariums to highlight the plight of coral reefs to engaged public audiences primed to receive this message and learn about the role of science in both understanding and mitigating the problem. Finally, numerous high school, undergraduate, and graduate students will receive mentorship during this project, helping to train the next generation of marine scientists. This project tests whether continued climate warming is causing heat-tolerant algal symbionts (such as Durusdinium trenchii) to become increasingly common on coral reefs in the Caribbean. Understanding the changing symbiotic "milieu" in the region, the processes underlying the spread of D. trenchii, and the consequences of this spread, are very timely questions that have the potential to help us understand future reef states. This project will: (1) Manipulate coral symbioses in the laboratory, including a number of Caribbean coral species never before attempted, to assess in a standardized way their relative ability to acquire heat-tolerant symbionts; (2) Outplant corals with manipulated symbiont communities to reefs to assess real-world ecophysiological tradeoffs to heat tolerance, such as reduced growth rate; (3) Introduce heat-tolerant symbionts to coral colonies in the field using tissue implants in order to understand environmental controls on the persistence or loss of introduced symbionts; (4) Evaluate transgenerational feedbacks in the symbiotic milieu by investigating the roles of temperature and D. trenchii availability on the acquisition and establishment of these symbionts in newly settled coral larvae; and (5) Quantify changes in the incidence and relative abundance of heat-tolerant symbionts in the Caribbean over the last ~20 years using unique archived samples dating back to 1995-2002 from Florida, Bahamas, Belize, and Bermuda.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.