[Spatio-temporal Patterns of Microbial Communities and Their Driving Mechanisms in Subalpine Lakes, Ningwu, Shanxi]

Human activities and climate change cause the degradation of subalpine lake ecosystems, which induce the shift of microbial community structure. The spatio-temporal dynamics and the diversity maintenance mechanisms of bacterial communities in Gonghai Lake in Ningwu, Shanxi, were investigated by using Q-PCR and DGGE. The results showed that the temperature), pH, dissolved oxygen, electrical conductivity salinity, and ammonium nitrogen (NH₄⁺) contestation were significantly different among the different sampling depths during different months. Bacterial abundance was the highest in August and the lowest in November, and the abundance was higher in the middle water layer (2 m, 4 m, and 6 m depths), but relatively low in the surface layer and bottom layer (0 m and 8 m depths, respectively). The α diversity index of bacterial communities had significant differences among the different months and depths, and showed an initial decreasing trend and then an increasing trend from April to December. A PERMANOVA test showed that the spatial distribution of bacterial communities was significantly different among depths (P<0.001). The results of redundancy analysis and variation partitioning indicated that environmental selection and diffusion limitation had an effect on the maintenance of the diversity patterns of bacterial communities at the different depths of GH. However, the relative effect of environmental factors was stronger, of which the concentration of NO₃^-, NO₂^-, and NH₄⁺ were the main influencing factors. In conclusion, the bacterial communities in GH subalpine lake showed clear spatio-temporal distribution patterns, and environmental variables had a significant effect on shaping the community diversity.