Huttunen Kaisa-Leena, Malazarte Jacqueline, Jyväsjärvi Jussi, Lehosmaa Kaisa, Muotka Timo
Finnish Environment Institute, Nature Solutions Unit, Oulu, Finland.
University of Oulu, Ecology and Genetics Research Unit, Oulu, Finland.
Microb Ecol. 2025 Apr 12;88(1):26. doi: 10.1007/s00248-025-02522-3.
Concern about biodiversity loss has yielded a surge of studies on temporal change in α-diversity, whereas temporal β-diversity has gained less interest. We sampled bacterioplankton, biofilm, and riparian soil bacteria repeatedly across the open-water season in a pristine stream network to determine the level of temporal β-diversity in relation to stream network position and environmental variability. We tested the hypothesis that aquatic bacterial communities in isolated and environmentally heterogenous headwaters exhibit high temporal β-diversity while the better-connected and environmentally more stable mainstem sections support more stable communities, and soil communities bear no relationship to network position. As expected, temporal β-diversity decreased from headwaters toward mainstems for bacterioplankton. Against expectations, an opposite pattern was observed for biofilm. For bacterioplankton, temporal β-diversity was positively related to temporal variability in water chemistry. For biofilm bacteria, temporal variability was negatively related to variability in temperature. Temporal β-diversity of soil communities did not show any response to stream network position, but was strongly related to variability in the soil environment. The two aquatic habitats and riparian soils supported distinctly different bacterial communities. The number of ASVs shared between the soil and the aquatic communities decreased along the network, and more so for bacterioplankton. The higher temporal variability of bacterial communities in the headwaters likely results from temporally variable input of propagules from riparian soil, emphasizing the role of land-water connection and network position to bacterioplankton community composition. Overall, bacterial communities exhibited high temporal variability, highlighting the importance of temporal replication to fully capture their network-scale biodiversity.
对生物多样性丧失的担忧引发了大量关于α多样性随时间变化的研究，而时间β多样性则较少受到关注。我们在一个原始溪流网络的整个开放水域季节对浮游细菌、生物膜和河岸土壤细菌进行了多次采样，以确定与溪流网络位置和环境变异性相关的时间β多样性水平。我们检验了以下假设：在孤立且环境异质的源头水域中，水生细菌群落表现出较高的时间β多样性，而连接性更好且环境更稳定的干流区域支持更稳定的群落，并且土壤群落与网络位置无关。正如预期的那样，浮游细菌的时间β多样性从源头向干流降低。与预期相反，生物膜呈现出相反的模式。对于浮游细菌，时间β多样性与水化学的时间变异性呈正相关。对于生物膜细菌，时间变异性与温度变异性呈负相关。土壤群落的时间β多样性对溪流网络位置没有任何响应，但与土壤环境的变异性密切相关。这两个水生生境和河岸土壤支持着截然不同的细菌群落。土壤和水生生境之间共享的ASV数量沿网络减少，浮游细菌减少得更多。源头水域细菌群落较高的时间变异性可能源于河岸土壤中繁殖体的时间可变输入，这强调了陆地 - 水连接和网络位置对浮游细菌群落组成的作用。总体而言，细菌群落表现出较高的时间变异性，突出了时间重复对于全面捕捉其网络尺度生物多样性的重要性。
