Metagenomic assessment of viral diversity in Lake Matoaka, a temperate, eutrophic freshwater lake in southeastern Virginia, USA

Little is known about the composition and diversity of temperate freshwater viral communities. This study presents a metagenomic analysis of viral community composition, taxonomic and functional diversity of temperate, eutrophic Lake Matoaka in southeastern Virginia (USA). Three sampling sites were chosen to represent differences in anthropogenic impacts: the Crim Dell Creek mouth (impacted), the Pogonia Creek mouth (less impacted) and the main body of the lake (mixed). Sequences belonging to tailed bacteriophages were the most abundant at all 3 sites, with Podoviridae predominating. The main lake body harbored the highest virus genotype richness and included cyanophage and eukaryotic algal virus sequences not found at the other 2 sites, while the impacted Crim Dell Creek mouth showed the lowest richness. Cross-contig comparisons indicated that similar virus genotypes were found at all 3 sites, but at different rankabundances. Hierarchical cluster analysis of multiple viral metagenomes indicated high genetic similarity between viral communities of related environments, with freshwater, marine, hypersaline, and eukaryote-associated environments forming into clear groups despite large geographic distances between sampling locations within each environment type. These results support the conclusion that freshwater viral communities are genetically distinct from virus assemblages in other environments.