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，本数据集另有相关发表文献，请参考：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中同样发挥重要作用。学界普遍认为，在扩散条件良好的生境（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。迄今为止，多数针对微生物群落组成的研究在区域尺度（100千米）下均未观测到显著的地理异质性。本研究聚焦西南印度洋的动态锋面区微生物群落，探究受这些锋面分隔的不同水团对应的微生物空间结构。本研究从沿亚热带至亚南极水域梯度分布的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) 透光层底部（约200米）以及(iii) 底栖边界层（300~2000米）。通过Illumina MiSeq平台对16S核糖体RNA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, OTUs）的多样性与丰度。多变量分析结果显示，微生物群落的结构受深度的影响远大于纬度，各海山相同深度层的微生物门类组成具有相似性。整个调查区域的深层水体微生物群落均一性较高，对应南极中层水的扩散特征。但在表层下与中层深度层中，均观测到锋面两侧存在OTU周转现象。这些深度层的微生物组可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、辐合带与亚热带水域。本研究证实，沿深度与纬度梯度分布的微生物生物地理学模式与微生物所处的水团密切相关，最终形成与区域尺度物理海洋学特征相匹配的微生物生物地理格局。