title: Viruses in subarctic lakes and their impact on benthic and pelagic bacteria.
abstract: Virus-bacterium interactions were investigated in the pelagic and benthic habitats in a set of lakes along an altitudinal gradient in the subarctic northern Sweden. Viral and bacterial abundances showed a significant variation between the lakes, with the highest benthic microbial abundances recorded in a high-altitude lake [993 m above sea level (a.s.l.)], whereas the highest pelagic microbial abundances were found in a low-altitude lake (270 m a.s.l.). In the pelagic habitat, there was also a distinct difference in microbial abundances between the summer-autumn and the winter sampling occasion. A positive relationship was noted between viruses and bacteria in both the pelagic and the benthic habitats. Visibly virus-infected bacterial cells were uncommon in the pelagic habitat and undetectable in the benthos. Both lytic and lysogenic pelagic viral production rates were undetectable or low; thus, a possible explanation for the relative high viral abundances found in the water column could be an allochthonous input of viruses or release of sediment-derived viruses. Overall, our results provide novel information about the relevance of viruses in the subarctic region and indicate that viruses play only a minor role in the nutrient and carbon cycling in the microbial communities of subarctic lakes.
authors.affiliation: Department of Ecology and Environmental Science, Climate Impacts Research Centre (CIRC), Umeå University, Abisko, Sweden. c.sawstrom@griffith.edu.au
authors.forename: Christin
authors.initials: C
authors.lastname: Säwström
authors.forename: Jenny
authors.initials: J
authors.lastname: Ask
authors.forename: Jan
authors.initials: J
authors.lastname: Karlsson
mesh_terms: D001419:Bacteria / Q000302:isolation & purification* / Q000821:virology; D001435:Bacteriophages / Q000302:isolation & purification*; D005618:Fresh Water / Q000382:microbiology* / Q000821:virology*; D019015:Geologic Sediments / Q000382:microbiology / Q000821:virology; D012621:Seasons; D013548:Sweden; D013696:Temperature; D014867:Water / Q000737:chemistry; D014871:Water Microbiology
chemical_list: D014867:Water