Department of Microbiology, University of Georgia, Athens, GA, USA.
Institute of Bioinformatics, University of Georgia, Athens, GA, USA.
Environ Microbiol. 2018 Oct;20(10):3560-3572. doi: 10.1111/1462-2920.14311. Epub 2018 Sep 13.
The water column of streams hosts a unique microbial community that is distinct from the microbial communities of the stream benthos and surrounding soil. This community is shaped by complex interacting forces, including microbial dispersal from surrounding environments and in-stream selection. However, how the processes structuring stream communities change over space and time remains poorly understood. In this study, we characterize spatial and temporal trends in microbial community composition throughout a stream network spanning first through fifth order streams. We found that the microbial communities of headwater streams are compositionally diverse, with low representation of freshwater microbial taxa and high representation of soil and sediment-associated taxa. In three out of five seasonal samplings, a successional pattern was identified in which phylotype richness and compositional heterogeneity decreased while the proportion of known freshwater taxa increased with increasing cumulative upstream dendritic distance. However, in two samplings, streams instead exhibited uniformly high microbial diversity across the watershed, and the fraction of freshwater taxa showed no relationship with dendritic distance. Overall, our data suggest that the successional processes that drive microbial diversity in streams are highly dynamic and can be disrupted at landscape scales, potentially in response to variation in temperature and precipitation.
溪流的水柱中栖息着一个独特的微生物群落，与溪流底栖生物和周围土壤的微生物群落明显不同。这个群落是由复杂的相互作用力量塑造的，包括来自周围环境的微生物扩散和溪流中的选择。然而，塑造溪流群落的过程如何随空间和时间变化仍然知之甚少。在这项研究中，我们描述了贯穿一级到五级溪流的溪流网络中微生物群落组成的时空趋势。我们发现，源头溪流的微生物群落具有丰富的组成多样性，淡水微生物类群的代表性较低，而土壤和沉积物相关类群的代表性较高。在五次季节性采样中的三次中，我们确定了一个演替模式，即随着累积上游树状距离的增加，生物型丰富度和组成异质性降低，而已知淡水类群的比例增加。然而，在两次采样中，溪流在整个流域表现出均匀的高微生物多样性，而淡水类群的比例与树状距离无关。总的来说，我们的数据表明，驱动溪流中微生物多样性的演替过程是高度动态的，并且可能会在景观尺度上被破坏，这可能是对温度和降水变化的反应。
