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

Drs。Grottoli和Pease将通过研究珊瑚宿主的碳获取、分配和利用来研究白化过程中影响珊瑚恢复和死亡的潜在机制。在白化过程中，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，它们必须依靠其他能量来源，如储存的脂质和碳水化合物，或异养获得的碳来维持其能量需求。如果(1)珊瑚通过增加异养摄食能够更好地获取碳，它们可能更有可能在白化中幸存下来并完全恢复。另外，如果(2)珊瑚在非白化期间能够储存大量多余的能量储备（例如，作为脂质），它们可能能够利用这些储备来维持自己，直到完全恢复。如果(3)珊瑚能更有效地利用这些储存的能量储备，它们就更有可能从白化中恢复过来。这三种策略都是珊瑚用来促进白化后恢复的假设机制。为了评估每种机制，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，以及在漂白的Montipora capitata和Porites compressa珊瑚中14个月的恢复过程（相对于未漂白的对照）。实验设计允许同时测量的变量在珊瑚-藻类共生-骨架系统相对于对照组的整体图像中被全面解释。本研究的结果将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胁迫的生理和生物地球化学反应，有助于更好地了解珊瑚漂白的基础生物学。这项工作将为了解珊瑚白化的原因和后果建立一个框架。本项目培养博士生2名（合作研究者各1名），博士后1名，本科生2名。两位研究人员将把这个项目的研究成果纳入他们的教学，并通过公开讲座、建立的K-12外展和在职教师培训讲习班来展示研究成果。

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.