Water Research Institute, National Research Council of Italy (IRSA-CNR), Monterotondo, Roma, Italy.
PLoS One. 2013 May 31;8(5):e64109. doi: 10.1371/journal.pone.0064109. Print 2013.
In Mediterranean intermittent streams, the hydrological fragmentation in summer and the successive water flow re-convergence in autumn allow exploring how local processes shape the microbial community within the same habitat. The objectives of this study were to determine how bacterial community composition responded to hydrological fragmentation in summer, and to evaluate whether the seasonal shifts in community composition predominate over the effects of episodic habitat fragmentation. The bacterial community was assessed along the intermittent stream Fuirosos (Spain), at different levels of phylogenetic resolution by in situ hybridization, fingerprinting, and 16S rRNA gene sequencing. The hydrological fragmentation of the stream network strongly altered the biogeochemical conditions with the depletion of oxidized solutes and caused changes in dissolved organic carbon characteristics. In the isolated ponds, beta-Proteobacteria and Actinobacteria increased their abundance with a gradual reduction of the alpha-diversity as pond isolation time increased. Moreover, fingerprinting analysis clearly showed a shift in community composition between summer and autumn. In the context of a seasonal shift, the temporary stream fragmentation simultaneously reduced the microbial dispersion and affected local environmental conditions (shift in redox regime and quality of the dissolved organic matter) tightly shaping the bacterioplankton community composition.
在地中海间歇性溪流中，夏季的水文破碎化和随后的水流再汇合使人们能够探索局部过程如何在同一栖息地塑造微生物群落。本研究的目的是确定夏季细菌群落组成如何响应水文破碎化，并评估季节性群落组成变化是否超过偶发性栖息地破碎化的影响。通过原位杂交、指纹图谱和 16S rRNA 基因测序，在不同的系统发育分辨率水平上，评估了西班牙 Fuirosos 间歇性溪流中的细菌群落。溪流网络的水文破碎化强烈改变了生物地球化学条件，氧化溶质耗竭，并导致溶解有机碳特性发生变化。在孤立的池塘中，β-变形菌门和放线菌门随着池塘隔离时间的增加而增加，其丰度逐渐增加，α-多样性降低。此外，指纹图谱分析清楚地显示了夏季和秋季之间群落组成的变化。在季节性变化的背景下，临时的溪流破碎化同时减少了微生物的扩散，并影响了局部环境条件（氧化还原状态和溶解有机物质量的变化），从而紧密地塑造了细菌浮游生物群落组成。
