Microbial shifts associated to ENSO-derived thermal anomalies reveal coral resilience acclimatation at the holobiont level

The coral microbiome is vital to maintain holobiont homeostasis, conferring important benefits such as nutrient acquisition and disease resistance. Since the microbiome is substantially sensible to the surrounding environment, it conforms a proxy to study effects of changing environmental conditions. However, scarce information exists regarding the microbiome responses to environmental changes. We assessed thermal associated shifts in the bacterial microbiome of Pacifigorgia cairnsi, a sea fan from the remote island of Malpelo in the Tropical Eastern Pacific with absence of direct anthropogenic impacts and considered a hot spot of biodiversity. Analyzing 16S rRNA gene amplicons during 2015, 2017 and 2018, we evaluated the community composition and functional profiles of the bacterial microbiome through different phases of El Nino Southern Oscillation (ENSO) cycle (i.e. El Nino-warming phase, La Nina-cooling phase and the Neutral phase). Our major findings revealed different bacterial community diversity and composition between the warming and cooling phase on the one side, and the neutral phase on the other side.

珊瑚微生物组（coral microbiome）对维持共生联合体（holobiont）的稳态至关重要，可赋予宿主养分获取、抗病性等诸多重要益处。由于微生物组对周围环境具有显著敏感性，其可作为研究环境条件变化影响的替代指标。然而，目前关于微生物组对环境变化的响应的相关研究仍较为匮乏。本研究针对太平洋柳珊瑚（Pacifigorgia cairnsi）——一种栖息于热带东太平洋马尔佩洛偏远岛屿的海扇柳珊瑚，该区域未受直接人为活动影响且被视为生物多样性热点区域——的细菌微生物组，评估了与温度相关的群落变化。本研究于2015、2017及2018年通过分析16S rRNA基因扩增子，针对厄尔尼诺南方涛动（ENSO）循环的不同阶段（即厄尔尼诺增温阶段、拉尼娜降温阶段与中性阶段），评估了该细菌微生物组的群落组成与功能特征。本研究的核心发现表明：增温与降温阶段的细菌群落多样性及组成，与中性阶段存在显著差异。