Role of ice cover on the diversity and composition of bacteria communities in warming arctic lakes

Arctic lakes are among the most extreme and least explored freshwater environments, where seasonal ice cover creates unique ecological niches that sustain abundant microbial communities. These microbes are central to nutrient cycling, yet their responses to rapid, climate-driven shifts in ice phenology remain poorly understood. In this study, we examined how lake ice cover structures microbial community composition and function, with a particular focus on nitrogen cycling. Fieldwork was conducted at two lakes in West Greenland during June 2025, when ice cover was still present but undergoing melt. We integrated in situ environmental monitoring, chemical profiling, and 16s rRNA sequencing with physiological and functional assays to characterize microbial assemblages across ice, water column, and bioaerosol compartments. Preliminary findings reveal that ice harbors distinct and metabolically active bacterial communities with elevated nitrogen and ammonia concentrations compared to the underlying water column, suggesting that ice-associated microbiomes may play an overlooked role in Arctic lake biogeochemistry. These results provide new insights into how ice cover sustains specialized microbial communities, their contribution to nitrogen transformations, and how ongoing changes in Arctic ice regimes may reshape ecosystem functioning under climate change.