Abundance and production of bacteria and viruses in the Bering and Chukchi Seas

Grieg F. Steward,David C. Smith,F. Azam

Published 1996 in Oceanographic Literature Review

ABSTRACT

The distribution, abundance, and production of viruses and bactena were investigated during an August to September 1992 cruise aboard the RV 'Alpha Helix' in the Bering and Chukchi Seas. Viruses were abundant in seawater samples at all stations (10' to 10'' I-') and exceeded the bacteria concentration by an order of magnitude on average. Virus-like particles and bacteria were also observed in the pore water of a sed~ment sample at 27 and 2.1 X 10' l.', respectively. The concentrations of viruses and bacteria in pelagic samples were correlated (r = 0.83, n = 43). In a detailed depth profile from the deepest and northernmost station (72' N), bacteria and viruses displayed subsurface maxima in the upper 100 m. Below 100 m, the concentrations declined, but were detectable even in the deepestcollected samples (402 m). Integrated bacterial biomass estimates were similar to results from a previous study in this area, but bacterial production measurements ranging from 0.3 to 0.45 g C m-2 d-' were an order of magnitude higher Production rates of bacterial viruses (also known as bacteriophages or simply phages) measured by radiolabeling ranged from 0.5 to 4.2 X lO%iruses I-' d-l, which are similar to previous estimates for temperate coastal waters. The production measurements ind~cated turnover times ranging from 0.4 to 17 d for bacteria and maximum estimates of 1.2 to 15 d for bacterial viruses. Viral mortality of bactena was estimated from the frequency of visibly infected cells (FVIC) and flagellate grazing was calculated from flagellate and bacterial abundances together with an assumed flagellate clearance rate. Overall, estimated viral lysis was roughly comparable to estimated grazing by flagellates as a source of bacterial mortality. Averaged over the water column, viral mortality of bacteria in the Chukchi Sea was estimated to be 23% of the bacterial production at 2 southern stations and approximately 10% at 2 northern stations. FVIC was correlated with bacterial production (r = 0.75, n = 18) and specific growth rate (r = 0.74, n = 18), but not with bacterial abundance (r = 0.22, n = 27). These data suggest viruses to be a ubiquitous and dynamic feature and a significant source of bacterial mortality in Arct~c marine microbial communities. The implications of bacterial and viral production for C and N cycling in the Chukchi Sea are discussed

PUBLICATION RECORD

  • Publication year

    1996

  • Venue

    Oceanographic Literature Review

  • Publication date

    1996-02-08

  • Fields of study

    Biology, Environmental Science

  • Identifiers
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar

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