Data from: Microbe biogeography tracks water masses in a dynamic oceanic frontal system

PLEASE NOTE, THESE DATA ARE ALSO REFERRED TO IN ANOTHER PUBLICATION. PLEASE SEE http://dx.doi.org/10.1098/rsos.160829. Dispersal limitation, not just environmental selection, plays an important role in microbial biogeography. The distance–decay relationship is thought to be weak in habitats where dispersal is high, such as in the pelagic environment, where ocean currents facilitate microbial dispersal. Most studies of microbial community composition to date have observed little geographical heterogeneity on a regional scale (100 km). We present a study of microbial communities across a dynamic frontal zone in the southwest Indian Ocean and investigate the spatial structure of the microbes with respect to the different water masses separated by these fronts. We collected 153 samples of free-living microorganisms from five seamounts located along a gradient from subtropical to subantarctic waters and across three depth layers: (i) the sub-surface chlorophyll maximum (approx. 40 m), (ii) the bottom of the euphotic zone (approx. 200 m), and (iii) the benthic boundary layer (300–2000 m). Diversity and abundance of microbial operational taxonomic units (OTUs) were assessed by amplification and sequencing of the 16S rRNA gene on an Illumina MiSeq platform. Multivariate analyses showed that microbial communities were structured more strongly by depth than by latitude, with similar phyla occurring within each depth stratum across seamounts. The deep layer was homogeneous across the entire survey area, corresponding to the spread of Antarctic intermediate water. However, within both the sub-surface layer and the intermediate depth stratum there was evidence for OTU turnover across fronts. The microbiome of these layers appears to be divided into three distinct biological regimes corresponding to the subantarctic surface water, the convergence zone and subtropical. We show that microbial biogeography across depth and latitudinal gradients is linked to the water masses the microbes persist in, resulting in regional patterns of microbial biogeography that correspond to the regional scale physical oceanography.请注意，本数据集相关内容也见于另一篇已发表研究，详情请见http://dx.doi.org/10.1098/rsos.160829。 除环境筛选作用外，扩散限制在微生物生物地理学研究中同样发挥关键作用。学界普遍认为，在扩散能力较强的生境（如远洋环境，洋流可促进微生物扩散）中，距离衰减关系较为微弱。截至目前，多数微生物群落组成相关研究在区域尺度（100千米）下未观测到显著的地理异质性。 本研究聚焦西南印度洋动态锋面带内的微生物群落，探究受锋面分隔的不同水团下微生物的空间结构特征。我们沿亚热带至亚南极水域的梯度，在5座海山采集了153份自由生活微生物样本，采样覆盖3个深度层：(i) 表层下叶绿素最大值层（约40米）、(ii) 真光层底部（约200米）、(iii) 底栖边界层（300–2000米）。 本研究通过Illumina MiSeq平台对16S rRNA基因进行扩增与测序，以此评估微生物操作分类单元（operational taxonomic units, OTU）的多样性与丰度。多变量分析结果显示，相较于纬度，深度对微生物群落结构的塑造作用更为显著：不同海山的同一深度层中，微生物门类组成具有较高相似性。 整个调查区域的深层水体群落组成均一，这与南极中层水的扩散特征相契合。然而，在表层下深度层与中层深度层中，均观测到OTU随锋面发生更替的现象。上述两层的微生物组可划分为三个截然不同的生物群落类型，分别对应亚南极表层水、辐合带与亚热带水体。本研究表明，沿深度与纬度梯度分布的微生物生物地理学特征与微生物所栖息的水团密切相关，由此形成的微生物生物地理区域模式，与区域尺度的物理海洋学特征高度匹配。