State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, 100038, China.
Department of Water Environment, China Institute of Water Resources and Hydropower Research, Beijing, 100038, China.
Sci Rep. 2020 Mar 16;10(1):4819. doi: 10.1038/s41598-020-61569-z.
Water level fluctuations are an inherent feature regulating the ecological structures and functions of lakes. It is vital to understand the effects of water level fluctuations on bacterial communities and metabolic characteristics in freshwater lakes in a changing world. However, information on the microbial community structure and functional properties in permanently and seasonally flooded areas are lacking. Poyang Lake is a typical seasonal lake linked to the Yangtze River and is significantly affected by water level fluctuations. Bottom water was collected from 12 sampling sites: seven inundated for the whole year (inundated areas) and five drained during the dry season (emerged areas). High-throughput 16S rRNA gene sequencing was used to identify the bacterial communities. The results showed that the taxonomic structure and potential functions of the bacterial communities were significantly different between the inundated and emerged areas. Cyanobacteria was dominant in both areas, but the relative abundance of Cyanobacteria was much higher in the emerged areas than in the inundated areas. Bacterial communities were taxonomically sensitive in the inundated areas and functionally sensitive in the emerged areas. Nitrogen, phosphorus, and dissolved organic carbon concentrations and their ratios, as well as dissolved oxygen, played important roles in promoting the bacterial taxonomic and functional compositional patterns in both areas. According to the metabolic predictions based on 16S rRNA gene sequences, the relative abundance of functional genes related to assimilatory nitrate reduction in the emerged areas was higher than in the inundated areas, and the relative abundance of functional genes related to dissimilatory nitrate reduction in the inundated areas was higher. These differences might have been caused by the nitrogen differences between the permanently and seasonally flooded areas caused by intra-annual water level fluctuations. The relative abundance of functional genes associated with denitrification was not significantly different in the inundated and emerged areas. This study improved our knowledge of bacterial community structure and nitrogen metabolic processes in permanently and seasonally flooded areas caused by water level fluctuations in a seasonal lake.
水位波动是调节湖泊生态结构和功能的固有特征。了解水位波动对淡水湖中细菌群落和代谢特征的影响在不断变化的世界中至关重要。然而，关于永久性和季节性淹没区微生物群落结构和功能特性的信息仍然缺乏。鄱阳湖是一个与长江相连的典型季节性湖泊，受水位波动的显著影响。从 12 个采样点采集底层水：7 个全年淹没（淹没区），5 个在旱季排水（露出区）。使用高通量 16S rRNA 基因测序来鉴定细菌群落。结果表明，淹没区和露出区的细菌群落分类结构和潜在功能有显著差异。蓝藻在两个区域都占优势，但在露出区的相对丰度明显高于淹没区。细菌群落对淹没区具有分类学敏感性，对露出区具有功能敏感性。氮、磷和溶解有机碳浓度及其比值以及溶解氧在促进两个区域的细菌分类和功能组成模式方面发挥了重要作用。根据基于 16S rRNA 基因序列的代谢预测，露出区与同化硝酸盐还原相关的功能基因的相对丰度高于淹没区，而淹没区与异化硝酸盐还原相关的功能基因的相对丰度高于露出区。这些差异可能是由年内水位波动引起的永久性和季节性淹没区之间的氮差异造成的。淹没区和露出区的反硝化相关功能基因的相对丰度没有显著差异。本研究提高了我们对季节性湖泊水位波动引起的永久性和季节性淹没区细菌群落结构和氮代谢过程的认识。
