Temporal variation in freshwater viral and bacterial community composition

Abstract

Summary 1. The goal of this study conducted in three lakes differing in nutrient content and size was to assess the temporal variation in viral community composition and possible co‐variation with compositional changes in bacterial communities. 2. The viral community composition differed among lakes and changed over the season. Changes could also be detected on short‐time scales, i.e. over a few days. These changes were comparable in magnitude to the changes detected between months or seasons. 3. The most important environmental factors co‐varying with viral community composition, as determined by multivariate analysis, differed over the year and among lakes. Temperature and concentrations of dissolved organic carbon (DOC), total phosphorus and soluble reactive phosphorus were the most important factors. 4. Bacterial community composition also varied over the season and among lakes. The most important factors co‐varying with bacterial community composition, as determined by multivariate analysis, were also temperature and DOC concentration. 5. Correlation between viral and bacterial community composition was weak and appeared to be a result of an indirect connection rather than a direct relationship between bacteria and viruses.