Coral bacteria are highly dynamic and acutely affected by host health and environmental conditions. However, there is limited knowledge of how the dynamics of coral-associated bacterial communities and interactions among bacterial members change in response to dissolved inorganic nutrient stressors. Here, we used high-throughput sequencing of the 16S rRNA gene to examine dynamic changes in coral-associated bacterial communities under elevated ammonium stress. Short-term exposure to high levels of ammonium does not significantly harm coral holobiont. Physiological parameters such as carbohydrate, chlorophyll a, and lipid content of coral holobiont were not affected. After three weeks of elevated ammonium stress, however, the coral-associated bacterial community changed significantly. The abundance of certain bacterial populations increased significantly, with enrichment of pathogenic and opportunistic bacteria and a decrease in defensive and core bacteria. Keystone bacterial species in the co-occurrence network changed considerably. Under elevated ammonium stress, the abundance of keystone species associated with corals was lower and the complexity of keystone bacterial relationships decreased significantly. Our results indicate that bacteria respond to elevated ammonium stress through changes in abundance and co-occurrence among bacterial members. This precedes visual symptoms of changes in coral physiological conditions and could be used as an early warning indicator of elevated ammonium stress in coastal coral reef management.

珊瑚细菌是高度动态的，并受到宿主健康和环境条件的严重影响。但是，关于珊瑚相关细菌群落的动态变化和细菌成员之间的相互作用如何响应溶解的无机营养胁迫而变化的知识却很少。在这里，我们使用了高通量的16S rRNA基因测序来研究在铵盐胁迫下珊瑚相关细菌群落的动态变化。短期暴露于高水平的铵盐不会严重损害holobiont。生理参数，例如碳水化合物，叶绿素a，并且不影响珊瑚的整体血脂含量。但是，在铵盐胁迫持续三周后，与珊瑚相关的细菌群落发生了显着变化。某些细菌种群的丰度显着增加，致病细菌和机会细菌的富集以及防御细菌和核心细菌的减少。共现网络中的主要细菌种类发生了很大变化。在铵盐胁迫下，与珊瑚有关的梯形藻种类丰富，梯形藻细菌关系的复杂性显着降低。我们的结果表明，细菌通过增加细菌成员之间的丰度和共存来应对铵盐胁迫。