Journal of the Marine Biological Association of the United Kingdom



Research Article

Viral impacts upon marine bacterioplankton assemblage structure


Ian  Hewson a1p1c1 and Jed A.  Fuhrman a1
a1 Wrigely Institute for Environmental Studies and Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway AHF 107, Los Angeles, CA 90089-0371, USA

Article author query
hewson i   [PubMed][Google Scholar] 
fuhrman ja   [PubMed][Google Scholar] 

Abstract

This study examined the relationship between viral infection and the richness, diversity and composition of bacterial assemblages in the water column. Viruses were enriched by ultrafiltration, added to water column incubation experiments at 15 locations in the North Atlantic, North Pacific, Gulf of Mexico and Southern California. In a separate experiment, viruses were removed from bacterioplankton by diafiltration at the San Pedro Ocean Time Series Station. Bacterial assemblage composition was observed using a high throughput and sensitive molecular fingerprinting analysis, automated rRNA intergenic spacer analysis (ARISA). Diazotrophs were used as a model functional group to represent rare organisms hypothesized to benefit from viral activity, and their richness and diversity was determined by terminal restriction fragment length polymorphism of a nitrogenase gene fragment (nifH). The enrichment and removal experiments demonstrated mixed impacts of viral pressure upon bacterial communities, and we observed significant effects of viruses on several microbial parameters in all but two experiments. However, there was no consistent response of viral enrichment on total bacterial and diazotroph assemblages at stations with similar environmental conditions, suggesting that untested variables, small spatial scale factors, or stochastic processes influence the outcome of viral activities. Across all experiments, the relative abundance of the more common operational taxonomic units (OTUs) in fingerprints were not significantly impacted compared to the abundance of rare OTUs. These data indicate that viruses may have significant influence upon community structure of bacterioplankton; however, effects were not consistent between sampling locations nor water masses.

(Published Online April 10 2006)
(Received December 8 2005)
(Accepted March 7 2006)


Correspondence:
c1 e-mail: hewson@ucsc.edu
p1 Department of Ocean Sciences, University of California, Santa Cruz, 1156 High Street, Earth and Marine Sciences Building D446, Santa Cruz, CA 95054, USA