Some reef corals form stable, dominant or codominant associations with multiple endosymbiotic dinoflagellate species (family Symbiodiniaceae). Given the immense genetic and physiological diversity within this family, Symbiodiniaceae community composition has the potential to impact the nutritional physiology and fitness of the cnidarian host and all associated symbionts. Here we assessed the impact of the symbiont community composition on the metabolome of the coral Montipora capitata in Kāne‘ohe Bay, Hawai‘i, where different colonies can be dominated by stress-tolerant Durusdinium glynnii or stress-sensitive Cladocopium spp. Based on our existing knowledge of these symbiont taxa, we hypothesised that the metabolite profile of D. glynnii-dominated corals would be consistent with poorer nutritional support of the host relative to those corals dominated by Cladocopium spp. However, comparative metabolite profiling revealed that the metabolite pools of the host and symbiont were unaffected by differences in the abundance of the two symbionts within the community. The abundance of the individual metabolites was the same in the host and in the endosymbiont regardless of whether the host was populated with D. glynnii or Cladocopium spp. These results suggest that coral-dinoflagellate symbioses have the potential to undergo physiological adjustments over time to accommodate differences in their resident symbionts. Such mechanisms may involve host heterotrophic compensation (increasing the level of nutrition generated by feeding relative to delivery from the algae), dynamic regulation of metabolic pathways when exchange of metabolites between the organisms differs, and/or modification of both the type and quantity of metabolites that are exchanged. We discuss these adjustments and the implications for the physiology and survival of reef corals under changing environmental regimes.

中文翻译：

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造礁珊瑚 Montipora capitalata 的代谢物池不受共生科群落组成的影响

一些珊瑚礁与多种内共生鞭毛藻物种（共生科）形成稳定的、显性或共显性关联。鉴于该家族内巨大的遗传和生理多样性，共生菌科群落组成有可能影响刺胞动物宿主和所有相关共生体的营养生理和健康。在这里，我们评估了共生体群落组成对夏威夷 Kāne'ohe Bay 珊瑚 Montipora capitalata 代谢组的影响，在那里不同的殖民地可以由耐压的 Durusdinium glynnii 或对压力敏感的 Cladocopium spp 支配。基于我们对这些共生类群的现有知识，我们假设 D. 相对于以 Cladocopium spp 为主的珊瑚，以 glynnii 为主的珊瑚与宿主的营养支持较差是一致的。然而，比较代谢物分析显示宿主和共生体的代谢物库不受社区内两种共生体丰度差异的影响。无论宿主体内是 D. glynnii 还是 Cladocopium spp，宿主和内共生体中个体代谢物的丰度都是相同的。这些结果表明，珊瑚-甲藻共生体有可能随着时间的推移进行生理调整，以适应其常驻共生体的差异。这种机制可能涉及宿主异养补偿（相对于藻类的输送，增加进食产生的营养水平），当生物体之间的代谢物交换不同时，代谢途径的动态调节，和/或交换的代谢物的类型和数量的改变。我们讨论了这些调整以及在不断变化的环境制度下对珊瑚礁的生理和生存的影响。