Previous studies suggested that strong positive correlations between microbial taxa destabilized the microbial communities, because high synchrony between taxa caused different taxa responded in tandem to the changes of environmental conditions. In this study, we used nutrient concentrations (nitrogen and phosphorus) as indicators for anthropogenic activities, and explored the effects of anthropogenic activities on the stability of bacterial communities in a subtropical river, Xiyuan River. We also used co-occurrence networks to indicate the synchrony between bacterial taxa. The nutrient concentrations were higher in the midstream and downstream areas than in the upstream area of Xiyuan River. As a result, the average proportion and correlation coefficient of positive correlations were higher in the midstream and downstream networks than in the upstream networks. This indicates that frequent anthropogenic activities increased the synchrony between taxa in the midstream and downstream communities, and therefore destabilized the bacterial communities. To further explore the mechanisms, we found that the changes of community stabilities associated with the changes of bacterial functions. Anthropogenic activity tolerant bacteria (e.g., nutrient removal, aromatic degradation and pathogen bacteria) and their linked bacterial taxa formed large and strong positive modules in the midstream and downstream networks, and thus destabilized the communities. Based on the perspective of microbial correlations, our results provide a new insight in the mechanisms of how anthropogenic activities alter riverine microbial communities.

先前的研究表明，微生物类群之间的强正相关破坏了微生物群落的稳定性，因为类群之间的高度同步导致不同的类群对环境条件的变化做出响应。在这项研究中，我们使用营养物质浓度（氮和磷）作为人为活动的指标，并探讨了人为活动对亚热带河流西源河细菌群落稳定性的影响。我们还使用共现网络来指示细菌分类群之间的同步性。中下游地区养分浓度高于西源河上游地区。因此，中下游网络正相关的平均比例和相关系数高于上游网络。这表明频繁的人为活动增加了中下游群落类群之间的同步性，从而破坏了细菌群落的稳定性。为了进一步探索其机制，我们发现群落稳定性的变化与细菌功能的变化有关。人类活动耐受性细菌（如养分去除、芳香降解和病原体细菌）及其相关的细菌分类群在中下游网络中形成了大而强的阳性模块，从而破坏了群落的稳定。基于微生物相关性的观点，