Organismal elemental stoichiometry is important at all scales of ecological interactions, particularly in symbiosis. Symbiotic partnerships are found extensively in corals, where coral hosts and their photosynthetic dinoflagellate partners trade essential nutrients. Using an ecological stoichiometry framework, we assessed variations in carbon (C), nitrogen (N), and phosphorus (P) concentrations in coral hosts and symbiotic zooxanthellae. Our aim was to assess whether corals and zooxanthellae differ in the stoichiometry of C, N and P, which may indicate that corals regulate their symbionts by restricting their access to nutrients. We also investigated the influence of biological and environmental factors on the elemental stoichiometry of coral–zooxanthellae symbiosis. Analysing field data from four locations on the Great Barrier Reef using boosted regression tree models, we observed that C:P and N:P ratios are significantly higher in zooxanthellae than in their coral hosts, suggesting P limitation for zooxanthellae, although the degree of P or N limitation in zooxanthellae varied among coral taxa. Coral taxonomy was also a significant driver of coral–zooxanthellae stoichiometry variations at the species level. Geographical location had a small influence on the variations in stoichiometry. Our analyses suggest that coral species may differentially control the access of zooxanthellae to nutrients which may lead to variation in reef coral responses to nutrient enrichment.

中文翻译：

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珊瑚-虫黄藻共生体元素化学计量的变化

有机体元素化学计量在生态相互作用的所有尺度上都很重要，特别是在共生中。共生伙伴关系广泛存在于珊瑚中，珊瑚宿主和它们的光合甲藻伙伴在那里交换必需的营养物质。使用生态化学计量框架，我们评估了珊瑚宿主和共生虫黄藻中碳 (C)、氮 (N) 和磷 (P) 浓度的变化。我们的目的是评估珊瑚和虫黄藻在 C、N 和 P 的化学计量方面是否不同，这可能表明珊瑚通过限制它们获取营养物质来调节它们的共生体。我们还研究了生物和环境因素对珊瑚-虫黄藻共生的元素化学计量的影响。使用增强回归树模型分析大堡礁四个位置的现场数据，我们观察到虫黄藻中的 C:P 和 N:P 比率显着高于其珊瑚宿主，这表明虫黄藻的 P 限制，尽管 P 的程度或 N 限制在虫黄藻中因珊瑚分类群而异。珊瑚分类学也是物种水平上珊瑚-虫黄藻化学计量变化的重要驱动因素。地理位置对化学计量的变化影响很小。我们的分析表明，珊瑚物种可能会以不同的方式控制虫黄藻对营养物质的获取，这可能导致珊瑚礁对营养物质富集的反应发生变化。表明虫黄藻受磷限制，尽管虫黄藻中磷或氮的限制程度因珊瑚分类而异。珊瑚分类学也是物种水平上珊瑚-虫黄藻化学计量变化的重要驱动因素。地理位置对化学计量的变化影响很小。我们的分析表明，珊瑚物种可能会以不同的方式控制虫黄藻对营养物质的获取，这可能导致珊瑚礁对营养物质富集的反应发生变化。表明虫黄藻受磷限制，尽管虫黄藻中磷或氮的限制程度因珊瑚分类而异。珊瑚分类学也是物种水平上珊瑚-虫黄藻化学计量变化的重要驱动因素。地理位置对化学计量的变化影响很小。我们的分析表明，珊瑚物种可能会以不同的方式控制虫黄藻对营养物质的获取，这可能导致珊瑚礁对营养物质富集的反应发生变化。