Hu Yang, Song Yifu, Cai Jian, Chao Jianying, Gong Yi, Jiang Xingyu, Shao Keqiang, Tang Xiangming, Gao Guang
Taihu Laboratory for Lake Ecosystem Research, State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology Chinese Academy of Sciences, Nanjing 210008, China.
Nanjing Forestry University, Nanjing, 210008, China.
Environ Res. 2025 Jan 1;264(Pt 1):120294. doi: 10.1016/j.envres.2024.120294. Epub 2024 Nov 5.
Although the biogeographical pattern and mechanisms underlying microbial assembly have been well-explored in lentic ecosystems, the relevant scenarios in lotic ecosystems remain poorly understood. By sequencing the bacterial communities in bacterioplankton and biofilm, our study detected their distance-decay relationship (DDR), and the balance between deterministic and stochastic processes, along the Kaidu river in an arid and semi-arid region of northwest China. Our results revealed that bacterioplankton and biofilm had significantly contrasting community structures. The bacterioplankton communities showed a gradually decreasing trend in alpha-diversity from the headwater to the river mouth, contrasting with the alpha-diversity of biofilm communities which was constant along the river length. Both bacterioplankton and biofilm showed significant DDRs along the 500-km river corridor with the slope of the bacterioplankton DDR being steeper than that of the biofilm DDR, which implies a stronger biogeography of bacterioplankton than biofilm. Relative to biofilm communities, the species interactions formed a denser and more complex network in the bacterioplankton communities than in the biofilm communities. Our results also revealed that there was a transition of community assembly from deterministic to stochastic processes upstream to downstream, although both the bacterioplankton and biofilm communities were mainly regulated by deterministic processes within the entire river. All these empirical results expand our knowledge of microbial ecology in an arid and semi-arid lotic ecosystem.
尽管在静水生态系统中，微生物组装的生物地理格局和机制已得到充分研究，但流水生态系统中的相关情况仍知之甚少。通过对浮游细菌和生物膜中的细菌群落进行测序，我们的研究在中国西北干旱和半干旱地区的开都河沿线，检测到了它们的距离衰减关系（DDR）以及确定性过程和随机过程之间的平衡。我们的结果表明，浮游细菌和生物膜具有显著不同的群落结构。浮游细菌群落的α多样性从源头到河口呈逐渐下降趋势，而生物膜群落的α多样性沿河流长度保持恒定，两者形成对比。浮游细菌和生物膜在500公里长的河流廊道沿线均呈现出显著的距离衰减关系，浮游细菌距离衰减关系的斜率比生物膜的更陡，这意味着浮游细菌的生物地理学特征比生物膜更强。相对于生物膜群落，浮游细菌群落中的物种相互作用形成了比生物膜群落更密集、更复杂的网络。我们的结果还表明，尽管浮游细菌和生物膜群落在整条河流中主要受确定性过程调控，但群落组装过程从上游到下游存在从确定性过程到随机过程的转变。所有这些实证结果扩展了我们对干旱和半干旱流水生态系统中微生物生态学的认识。
