Abstract

Many northern lakes are seasonally ice-covered and it was traditionally thought that microbial communities and processes lay dormant under the ice due to cold temperature and low light levels. In this study, we investigated the spatial patterns of bacterial communities during ice-covered and ice-free periods in three limnologically distinct Canadian lakes using 16S rRNA gene sequencing approaches. Multivariate analyses of community similarity grouped samples first by lake, then by season, demonstrating that community composition was distinct during the ice-covered and ice-free periods and suggesting differences in metabolic strategies of populations living under the ice. 16S rRNA sequences from Verrucomicrobia and Planctomycetes, as well as the methylotrophic LD28 bacteria, were often abundant during ice cover. However, only a small fraction of bacterial taxa were commonly associated with ice-covered conditions across all lakes, suggesting that local lake conditions play a more important role than regional climate conditions in structuring bacterial communities in seasonally ice-covered northern lakes. These preliminary findings will guide further metagenomics-enabled research into the metabolic diversity of these important microbial communities.