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Strong, weak and missing links in a planktonic microbial community
Betteral, Y.; Dolan, J.R.; Hornac, K.; Lemée, R.; Masin, M.; Pedrotti, M.-L.; Rochelle-Newall, E.; Simek, K.; Sime-Ngando, T. (2002). Strong, weak and missing links in a planktonic microbial community. FEMS Microbiol. Ecol. 42: 451-462
In: FEMS Microbiology Ecology. Federation of European Microbiological Societies: Amsterdam. ISSN 0168-6496, more
Peer reviewed article  

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Authors  Top 
  • Betteral, Y.
  • Dolan, J.R., more
  • Hornac, K.
  • Lemée, R.
  • Masin, M.
  • Pedrotti, M.-L., more
  • Rochelle-Newall, E.
  • Simek, K.
  • Sime-Ngando, T.

    Planktonic microbial communities often appear stable over periods of days and thus tight links are assumed to exist between differentfunctional groups (i.e. producers and consumers). We examined these links by characterizing short-term temporal correspondences in theconcentrations and activities of microbial groups sampled from 1 m depth, at a coastal site of the N.W. Mediterranean Sea, in September2001 every 3 h for 3 days. We estimated the abundance and activity rates of the autotrophic prokaryote Synechococcus, heterotrophicbacteria, viruses, heterotrophic nanoflagellates, as well as dissolved organic carbon concentrations. We found that Synechococcus,heterotrophic bacteria, and viruses displayed distinct patterns. Synechococcus abundance was greatest at midnight and lowest at 21:00 andshowed the common pattern of an early evening maximum in dividing cells. In contrast, viral concentrations were minimal at midnightand maximal at 18:00. Viral infection of heterotrophic bacteria was rare (0.5^2.5%) and appeared to peak at 03:00. Heterotrophicbacteria, as % eubacteria-positive cells, peaked at midday, appearing loosely related to relative changes in dissolved organic carbonconcentration. Bacterial production as assessed by leucine incorporation showed no consistent temporal pattern but could be related toshifts in the grazing rates of heterotrophic nanoflagellates and viral infection rates. Estimates of virus-induced mortality of heterotrophicbacteria, based on infection frequencies, were only about 10% of cell production. Overall, the dynamics of viruses appeared more closelyrelated to Synechococcus than to heterotrophic bacteria. Thus, we found weak links between dissolved organic carbon concentration, orgrazing, and bacterial activity, a possibly strong link between Synechococcus and viruses, and a missing link between light and viruses.

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