Distribution and Biogeochemical Impacts of Viruses in the Laurentian Great Lakes

Viruses are the most abundant biological entities on earth and can have important effects on microbial populations and biogeochemical cycling. Significant efforts have been made to understand the diversity of viruses in natural environments, but freshwater viruses remain understudied compared to oceans. The biogeochemical impacts of viruses are a crucial missing component in the understanding of the microbial communities and nutrient cycling in these ecosystems. The Laurentian Great Lakes are a useful model for studying viral ecology across lake ecosystems because of the wide range of environmental conditions and diverse microbial communities. Using metagenomics, we characterized viral diversity in the Great Lakes across years, seasons, and depths. We recovered thousands of dereplicated viral genome fragments and 196 complete viral genomes which are predicted to infect a range of hosts spanning eight bacterial phyla including the highly abundant heterotroph genus Fonsibacter. Great Lakes viral communities are dominated by double-stranded head-tail bacteriophage and contain a large abundance of mega-viruses. Viral community structure differed by lake, suggesting local-scale infection dynamics predominate in this interconnected system. Auxiliary metabolic genes, including those involved in carbon fixation and photosynthesis, are present in viruses across the lakes, suggesting that phages have the potential to play an important role in carbon cycling. Our findings provide a first step to incorporating the effects of viral infection to predict the ecology and biogeochemistry of the Great Lakes.

Primary Presenter: Alice Turnham, University of Chicago (aturnham@uchicago.edu)

Authors:

Alice Turnham, University of Chicago  (aturnham@uchicago.edu)

Justin Podowski, University of Chicago  (jpodowski@anl.gov)

Maureen Coleman, University of Chicago  (mlcoleman@uchicago.edu)