Skip Navigation



JPR Advance Access published online on December 23, 2005
Journal of Plankton Research, doi:10.1093/plankt/fbi116
This Article
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
28/3/325    most recent
fbi116v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Paoli, A.
Right arrow Articles by Umani, S. F.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Paoli, A.
Right arrow Articles by Umani, S. F.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2005. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org
Received September 1, 2005
Accepted December 20, 2005

Article

Daily variations of highly active bacteria in the Northern Adriatic Sea

A. Paoli 1, A. Karuza 1, C. De Vittor 1, P. Del Negro 1 *, and S. Fonda Umani 1

1 Laboratory of Marine Biology (LBM) - Via A.Piccard, 54 - 34010 Trieste - Italy

* To whom correspondence should be addressed.
P. Del Negro, E-mail: pdelnegro{at}inogs.it


  Abstract

Nowadays it is recognized that only a fraction of aquatic bacteria is actively growing but there is little information about the factors constraining their metabolism. Marine bacterioplankton can rapidly modify their metabolic activity level in response to environmental changes. In this study we focused on the daily changes in abundance and activity of active bacterial fraction, over a 20-day period preceded by intense rainfalls which slightly modified water column conditions. Cells capable of reducing the membrane penetrable dye CTC, estimated by epifluorescence microscopy, are considered very active (CTC+ bacteria). Total bacterial abundance (TBA) ranged from 0.8 to 2.4 x 109 cells L-1 whereas CTC+ bacteria were more variable (1.6-9.2 x 107 cells L-1), accounting for 1.2 to 4.4 % of TBA. Bacterial activity (BA) as the incorporation of [3H]-leucine varied by more than one order of magnitude over the period (25.0-662.5 pmol L-1h-1). BA was strongly related to CTC+ bacteria, suggesting that they were mainly responsible for the bacterial community metabolism. Nevertheless cell specific activity scaled to only CTC+ cells was very high suggesting that a fraction of cells not detectably CTC+ may be able to assimilate [3H]-leucine. The correlation between salinity and TBA, CTC+ bacteria and BA supported the hypothesis of the active role of freshwater input in enhancing cell activity. Our results suggest that freshwater input rather than phytoplanktonic blooms are able to induce shifts in bacterial metabolism over a time scale of days in the area studied.

Communicating Editor: KJ Flynn


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.