Multi-Scale Patterns of Bacterial Diversity Across Compartments in Remote Arctic Lakes of East Greenland

Lakes are complex ecosystems where aerosols, water, and sediments form interconnected compartments, each hosting microbial communities shaped by distinct environmental conditions. These habitats are often studied in isolation, limiting our understanding of microbial dynamics, transport, and diversity across spatial scales. This study explores bacterial diversity at multiple scales—within and between lake compartments (aerosols, ice cover, water, and sediments) and across a latitudinal gradient—using 12 remote glacial lakes in East Greenland. During a two-week campaign in August 2023, we conducted simultaneous sampling and environmental monitoring, followed by 16S rRNA gene amplicon sequencing. Bacterial abundances peaked in the ice cover (up to 10⁶ genome copies/L), associated with elevated nitrate and ammonia concentrations, while lake water showed the highest taxonomic richness (Chao1 diversity). Beta diversity analyses revealed distinct bacterial communities in each compartment, though shared genera suggest possible microbial transport between environments. Latitudinal differences in community composition aligned with spatial heterogeneity in watershed geology and vegetation, indicating that catchment-scale features influence microbial patterns. These findings highlight the ecological role of ice cover, landscape heterogeneity, and cross-compartmental interactions, offering new insights into microbial biogeography in rapidly changing Arctic lake systems.