Short-term variability of heterotrophic bacterioplankton during upwelling off the NW Iberian margin

• Published in: Progress in oceanography 2001-01, Vol.51 (2-4), p.339-359
• Main Authors: Barbosa, A.B, Galvão, H.M, Mendes, P.A, Álvarez-Salgado, X.A, Figueiras, F.G, Joint, I
• Format: Article
• Language: English
• ISSN: 0079-6611
• DOI: 10.1016/S0079-6611(01)00074-X

Short-term variability of heterotrophic bacterioplankton was studied in a recently upwelled water mass at the NW Iberian margin (August 1998). Bacterioplankton abundance (BA), biomass (BB), production (BP), and specific production (SBP) were monitored during two Lagrangian drift experiments, one along the shelf-edge, the other off-shelf along an upwelling filament. Other measurements included chlorophyll a (Chla), primary production (PP), suspended particulate organic carbon (POC) and nitrogen (PON), and dissolved organic carbon (DOC) and nitrogen (DON). Although primary production was significantly higher during the shelf-edge drift experiment, bacterial biomass in the euphotic zone (2.68 to 22.20 mu gC.l super(-1)) was not significantly different from that in the offshore filament. In contrast, bacterial production (0.13-3.52 mu gC.l super(-l).d super(-1)), estimated using an empirically determined super(14)C-leucine to carbon conversion factor, and bacterial growth rates (doubling time, DT: 3.9-29.7d), were significantly higher during the shelf-edge drift (BP; 1.50 plus or minus 0.11 versus 0.50 plus or minus 0.02 mu gC.l super(-1).d super(-1); DT: 6.9 plus or minus 0.3 versus 16.2 plus or minus 0.9 d; p