Collaborative Research: Acquisition, Allocation, and Utilization of Carbon in Bleached and Recovering Corals

格罗托利博士和皮斯博士将通过研究珊瑚宿主的碳获取、分配和利用来研究影响漂白过程中珊瑚恢复和死亡的潜在机制。在漂白过程中，当珊瑚失去共生藻类，其光合作用固定碳的供应急剧减少或丧失时，它们必须依赖其他能源，如储存的脂肪和碳水化合物，或异养获得的碳来维持其能量需求。如果(1)珊瑚能够通过增加异养摄食更好地获得碳，它们可能更有可能在漂白中幸存下来并完全恢复。或者，如果(2)珊瑚能够在非漂白期储存更多的过剩能量储备(例如，作为脂质)，它们可能能够通过利用这些储备来维持自己，直到完全恢复。如果珊瑚更有效地利用这些储存的能量储备，它们可能更有可能从漂白中恢复过来。所有这三种策略都是珊瑚用来促进漂白后恢复的假想机制。为了评估每一种机制，这些研究人员将进行一系列13C脉冲标记实验，旨在跟踪固定碳的来源、其在宿主内的分配和储存，以及在14个月的恢复过程中(相对于未漂白的对照)在漂白的头状单孢藻和扁平珊瑚中的利用。实验设计允许同时测量的变量在珊瑚-藻类共生体-骨骼系统相对于对照组的整体情况下得到全面解释。这项研究的结果将有助于更好地理解珊瑚漂白的基础生物学，通过实验评估珊瑚在漂白和恢复过程中对温度诱导的漂白应激源的生理和生物地球化学响应。这项工作将为理解珊瑚漂白的原因和后果建立框架。该项目包括两名博士生(每个合作研究人员一名)、一名博士后和两名本科生的培训。两位调查员都将把这一项目的研究成果纳入他们的教学中，并在公开讲座和既定的K-12外联活动和教师在职培训讲习班上介绍这项研究。

Drs. Grottoli and Pease will investigate the underlying mechanisms influencing coral recovery and mortality during bleaching by studying carbon acquisition, allocation and utilization of the coral host. During bleaching, when corals loose their symbiotic algae and their supply of photosynthetically fixed carbon is dramatically reduced or lost, they must rely on other sources of energy such as stored lipids and carbohydrates, or heterotrophically acquired carbon to sustain their energetic demands. If (1) corals are better able to acquire carbon by increasing heterotrophic feeding, they may be more likely to survive bleaching and fully recover. Alternatively, if (2) corals are able to store larger amounts of excess energy reserves during non-bleaching periods (e.g., as lipids), they may be able to sustain themselves by utilizing these reserves until fully recovered. If (3) corals are more efficient at utilizing these stored energy reserves, they may be more likely to recover from bleaching. All three of these strategies are hypothesized mechanisms used by corals to promote recovery following bleaching. In order to evaluate each mechanism, these investigators will perform a series of 13C-pulse labeling experiments designed to track the source of the fixed carbon, its allocation and storage within the host, and its utilization in bleached Montipora capitata and Porites compressa corals over the course of 14 months of recovery (relative to non-bleached controls). The experimental design allows for simultaneously measured variables to be comprehensively interpreted within the overall picture of the coral-algal symbiont-skeleton system relative to a control group. The results of this research will contribute to a better understanding in fundamental biology of coral bleaching by experimentally evaluating the physiological and biogeochemical responses of corals to temperature-induced bleaching stressors both during bleaching and recovery. This work will build the framework for understanding the causes and consequences of bleaching on corals. This project involves the training of two PhD students (one with each collaborating investigator), a Postdoc, and two undergraduate students. Both investigators will incorporate research results from this project in their teaching and present the research in public lectures and through established K-12 outreach and teacher in-service training workshops.