Distinct bacterial communities in supraglacial snow between monsoon-and westerly-dominated glaciers on the Tibetan Plateau

Atmospheric circulation transports aerosols, nutrients, and microorganisms to cryospheric environments, thereby shaping microbial communities and their ecological functions. Yet, the effects of different circulation regimes on supraglacial microbes remain unclear. Here, we examined the environmental drivers and community assembly mechanisms of snow bacterial communities from 17 glaciers on the Tibetan Plateau, where the Indian monsoon and the westerlies converge. Although bacterial communities in both regions were dominated by Gammaproteobacteria, Bacteroidetes, Actinobacteria, and Alphaproteobacteria, their environmental drivers, community assembly, and network stability differed markedly. In westerly-dominated glaciers, environmental variables explained substantially more variation in diversity and structure, with altitude, dissolved organic carbon (DOC), and wind speed emerging as key drivers. In contrast, monsoon-dominated glacier communities were primarily shaped by wind speed, with stochastic processes prevailing and leading to reduced ecological network stability. These results reveal significant correlations between circulation regimes and the shaping processes of supraglacial bacterial community. Specifically, under the influence of the Indian monsoon, DOC and environmental selection may have relatively weak impacts on glacier communities, which also present weaker interspecific associations and lower community stability. Our findings highlight the overlooked role of atmospheric circulation in shaping cryosphere microbiomes, with implications for microbial resilience under changing climate regimes.