Both coral‐associated bacteria and endosymbiotic algae (Symbiodiniaceae spp.) are vitally important for the biological function of corals. Yet little is known about their co‐occurrence within corals, how their diversity varies across coral species, or how they are impacted by anthropogenic disturbances. Here, we sampled coral colonies (n  = 472) from seven species, encompassing a range of life history traits, across a gradient of chronic human disturbance (n  = 11 sites on Kiritimati [Christmas] atoll) in the central equatorial Pacific, and quantified the sequence assemblages and community structure of their associated Symbiodiniaceae and bacterial communities. Although Symbiodiniaceae alpha diversity did not vary with chronic human disturbance, disturbance was consistently associated with higher bacterial Shannon diversity and richness, with bacterial richness by sample almost doubling from sites with low to very high disturbance. Chronic disturbance was also associated with altered microbial beta diversity for Symbiodiniaceae and bacteria, including changes in community structure for both and increased variation (dispersion) of the Symbiodiniaceae communities. We also found concordance between Symbiodiniaceae and bacterial community structure, when all corals were considered together, and individually for two massive species, Hydnophora microconos and Porites lobata , implying that symbionts and bacteria respond similarly to human disturbance in these species. Finally, we found that the dominant Symbiodiniaceae ancestral lineage in a coral colony was associated with differential abundances of several distinct bacterial taxa. These results suggest that increased beta diversity of Symbiodiniaceae and bacterial communities may be a reliable indicator of stress in the coral microbiome, and that there may be concordant responses to chronic disturbance between these communities at the whole‐ecosystem scale.

中文翻译：

---

珊瑚相关的共生植物和受慢性人类干扰的细菌的群落结构增加了多样性，并产生了一致的转变。

珊瑚相关细菌和共生藻类（Symbiodiniaceae spp。）对于珊瑚的生物学功能都至关重要。然而，关于它们在珊瑚中的共生，它们在珊瑚物种中的多样性如何变化，或如何受到人为干扰的影响知之甚少。在这里，我们 从七种物种中取样了珊瑚殖民地（n = 472），涵盖了一系列人类历史特征，跨越了人类慢性干扰（n =位于赤道中太平洋太平洋基里蒂玛蒂环礁（圣诞节环礁）上的11个地点，并量化了其相关的共生菌科和细菌群落的序列组成和群落结构。尽管共生菌科的α多样性不会随着人类的长期干扰而变化，但干扰与细菌香农多样性和丰富度的提高始终保持一致，样本的细菌丰富度几乎是从低干扰到极高干扰位点的两倍。慢性干扰还与共生菌科和细菌的微生物β多样性改变有关，包括两者的群落结构变化和共生菌科群落的变化（分散）增加。当同时考虑所有珊瑚时，我们还发现共生菌科与细菌群落结构之间具有一致性，Hyconophora microconos和Porites lobata，暗示共生菌和细菌对这些物种的人类干扰反应相似。最后，我们发现在珊瑚群落中占优势的共生菌科祖先谱系与几种不同细菌类群的丰度差异有关。这些结果表明，共生菌科和细菌群落的β多样性增加可能是珊瑚微生物组压力的可靠指标，并且在整个生态系统范围内，这些群落之间对慢性干扰的反应可能一致。