Department of Biological Sciences, Kent State University, Kent, OH 44242, USA.
Water Res. 2018 May 1;134:353-369. doi: 10.1016/j.watres.2018.01.045. Epub 2018 Feb 20.
Sediment bacterial communities play a critical role in biogeochemical cycling in lotic ecosystems. Despite their ecological significance, the effects of urban discharge on spatiotemporal distribution of bacterial communities are understudied. In this study, we examined the effect of urban discharge on the spatiotemporal distribution of stream sediment bacteria in a northeast Ohio stream. Water and sediment samples were collected after large storm events (discharge > 100 m) from sites along a highly impacted stream (Tinkers Creek, Cuyahoga River watershed, Ohio, USA) and two reference streams. Although alpha (α) diversity was relatively constant spatially, multivariate analysis of bacterial community 16S rDNA profiles revealed significant spatial and temporal effects on beta (β) diversity and community composition and identified a number of significant correlative abiotic parameters. Clustering of upstream and reference sites from downstream sites of Tinkers Creek combined with the dominant families observed in specific locales suggests that environmentally-induced species sorting had a strong impact on the composition of sediment bacterial communities. Distinct groupings of bacterial families that are often associated with nutrient pollution (i.e., Comamonadaceae, Rhodobacteraceae, and Pirellulaceae) and other contaminants (i.e., Sphingomonadaceae and Phyllobacteriaceae) were more prominent at sites experiencing higher degrees of discharge associated with urbanization. Additionally, there were marked seasonal changes in community composition, with individual taxa exhibiting different seasonal abundance patterns. However, spatiotemporal variation in stream conditions did not affect bacterial community functional profiles. Together, these results suggest that local environmental drivers and niche filtering from discharge events associated with urbanization shape the bacterial community structure. However, dispersal limitations and interactions among other species likely play a role as well.
流水生态系统中的沉积物细菌群落对于生物地球化学循环起着至关重要的作用。尽管它们具有重要的生态意义，但城市排放对细菌群落时空分布的影响仍研究不足。本研究调查了城市排放对俄亥俄州东北部一条溪流中溪流沉积物细菌时空分布的影响。在特大暴雨事件（径流量>100 立方米）后，从高度受影响的溪流（Tinkers Creek，俄亥俄州 Cuyahoga River 流域）和两条参照溪流的各个采样点采集了水样和沉积物样本。尽管 α 多样性在空间上相对稳定，但细菌群落 16S rDNA 图谱的多元分析揭示了 β 多样性和群落组成的显著时空效应，并确定了一些重要的相关非生物参数。Tinkers Creek 的下游采样点与上游和参照采样点聚类，再加上特定位置观察到的优势科，表明环境诱导的物种分选对沉积物细菌群落的组成有很强的影响。与营养污染（即 Comamonadaceae、Rhodobacteraceae 和 Pirellulaceae）和其他污染物（即 Sphingomonadaceae 和 Phyllobacteriaceae）相关的细菌科的明显分组在经历与城市化相关的更高程度排放的地点更为突出。此外，群落组成存在明显的季节性变化，个别分类群表现出不同的季节性丰度模式。然而，溪流条件的时空变化并没有影响细菌群落功能谱。总之，这些结果表明，局部环境驱动因素和与城市化相关的排放事件产生的生态位过滤塑造了细菌群落结构。然而，扩散限制和其他物种之间的相互作用可能也起到了一定的作用。
