Shao Qianwen, Sun Dong, Fang Chen, Feng Yunzhi, Wang Chunsheng
Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, China.
Ningbo Institute of Oceanography, Ningbo, China.
Front Microbiol. 2022 Mar 30;13:839562. doi: 10.3389/fmicb.2022.839562. eCollection 2022.
The levels of chlorophyll and nutrient concentrations in the surface waters of the western subtropical Pacific Ocean are among the lowest globally. In addition, our knowledge of basin-scale diversity and biogeography of microbial communities in this vast extremely oligotrophic environment is still rather limited. Here, high-throughput sequencing was used to examine the biodiversity and biogeography of abundant and rare microbial assemblages throughout the water column from the surface to a depth of 3,000 m across a horizontal distance of 1,100 km in the western Pacific Ocean. Microbial alpha diversity in the 200-m layer was higher than at other depths, with Gammaproteobacteria, Alphaproteobacteria, and Clostridia as the dominant classes in all samples. Distinctly vertical distributions within the microbial communities were revealed, with no difference horizontally. Some microbes exhibited depth stratification. For example, the relative abundances of Cyanobacteria and Alphaproteobacteria decreased with depth, while Nitrososphaeria, Actinobacteria, and Gammaproteobacteria increased with depth in the aphotic layers. Furthermore, we found that environmental (selective process) and spatial (neutral process) factors had different effects on abundant and rare taxa. Geographical distance showed little effect on the dispersal of all and abundant taxa, while statistically significant distance-decay relationships were observed among the rare taxa. Temperature and chlorophyll were strongly associated with all, abundant, and rare taxa in the photic layers, while total inorganic nitrogen was recognized as the crucial factor in the aphotic layers. Variance partitioning analysis indicated that environmental selection played a relatively important role in shaping all and abundant taxa, while the variation in rare taxa explained by environmental and spatial processes was relatively low, as more than 70% of the variation remained unexplained. This study provides novel knowledge related to microbial community diversity in the western subtropical Pacific Ocean, and the analyzes biogeographical patterns among abundant and rare taxa.
西太平洋亚热带海域表层水的叶绿素和营养物质浓度在全球范围内处于最低水平。此外，在这片广阔的极端贫营养环境中，我们对微生物群落的盆地尺度多样性和生物地理学的了解仍然相当有限。在此，利用高通量测序技术，对西太平洋1100公里水平距离内从表层到3000米深度的水柱中丰富和稀有微生物群落的生物多样性和生物地理学进行了研究。200米水层中的微生物α多样性高于其他深度，所有样本中的优势类群为γ-变形菌纲、α-变形菌纲和梭菌纲。微生物群落呈现出明显的垂直分布差异，水平分布无差异。一些微生物表现出深度分层现象。例如，在无光层中，蓝细菌和α-变形菌纲的相对丰度随深度降低，而亚硝化球菌纲、放线菌纲和γ-变形菌纲的相对丰度随深度增加。此外，我们发现环境（选择过程）和空间（中性过程）因素对丰富和稀有类群有不同影响。地理距离对所有类群和丰富类群的扩散影响较小，而在稀有类群中观察到了具有统计学意义的距离衰减关系。温度和叶绿素与光合层中的所有类群、丰富类群和稀有类群都密切相关，而总无机氮被认为是无光层中的关键因素。方差分解分析表明，环境选择在塑造所有类群和丰富类群方面发挥了相对重要的作用，而环境和空间过程对稀有类群变异的解释相对较低，超过70%的变异仍无法解释。本研究提供了与西太平洋亚热带海域微生物群落多样性相关的新知识，并分析了丰富和稀有类群之间的生物地理模式。
