达里诺尔湖夏季水体浮游细菌群落垂向变化特征差异

浮游细菌是湖泊水生态系统关键组成部分,在元素、能量迁移转化过程中作用明显.基于16S rRNA基因高通量测序技术,以夏季内蒙古达里诺尔湖(简称"达里湖")为研究区,对内陆封闭型湖泊水体浮游细菌群落垂向变化特征及影响因素进行了对比分析.结果显示:夏季达里湖浮游细菌群落多样性在表层水中最高,中层水最低;而丰富度则在底层水中最高,中层水最低.此外,浮游细菌群落组成也存在一定程度的垂向差异:在纲类水平上,Actinobacteria丰度优势明显,表层水为24.70%、中层水为21.06%、底层水为24.77%.冗余分析(RDA)结果表明不同深度水体中优势菌群受理化指标影响不同:表层水优势菌群结构受总溶解性固体含量、电导率等理化指标的影响最明显;不同形态营养元素则是中层水优势菌群结构的主要影响因素;在底层水中,优势菌群则受叶绿素、化学需氧量等理化指标的影响最明显.整体上,水深变化引起的湖水理化性质垂向差异成为影响达里湖夏季水体浮游细菌群落结构特征的关键因素之一.

Vertical Changes of Planktonic Bacteria Community and Predictive Functional Analysis in Summer Dali-Nor Lake

Planktonic bacteria is the key component of water ecosystem, playing an important role in processes of materials and energy cycle. In this study, we have collected 43 water samples from the surface water, middle water and bottom water in the summer Dali-nor lake, an inland closed lake in the Inner Mongolia Plateau. Based on 16S rRNA gene-based high throughput sequencing technology, the vertical variation characteristics and ecological function of planktonic bacterial community have been analyzed in detail. The results show that: in summer, the diversity of phytoplankton community in Dali lake is the highest in surface water, the lowest in middle water, and the richness is the highest in bottom water, and the lowest in middle water. In addition, the Actinobacteria is the most dominant class, which is 24.70% in the surface water, 21.06% in the middle water, and 24.77% in the bottom water respectively. Redundancy analysis results show that the dominant microbial acceptance indicators in different depths of water have different effects. The dominant microflora in surface water of Dali-nor lake is most affected by TDS and EC, which represent exogenous input. The dominant microflora in middle water is mainly affected by different forms of nutrient elements. In bottom water, the dominant microflora is most obviously affected by Chla and COD. And the change of water depth is also one of the key factors affecting the structure of dominant flora in middle and bottom water. On the whole, the vertical difference of the physical and chemical proxies caused by the change of water depth, has become one of the key factors affecting the structural characteristics of planktonic bacteria in summer Dali-nor lake.