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Hill, P. G., National Oceanography Centre, Southampton, United Kingdom, polly.hill@noc.soton.ac.uk
Purdie, D. A., National Oceanography Centre, Southampton, United Kingdom, duncan.purdie@noc.soton.ac.uk
Zubkov, M. V., National Oceanography Centre, Southampton, United Kingdom, mvz@noc.soton.ac.uk

HIGH SPATIAL VARIABILITY OF MICROBIAL AMINO ACID UPTAKE IN AN EASTERN BOUNDARY UPWELLING SYSTEM, NORTH-WEST AFRICA

Coastal upwelling introduces nutrients to sunlit waters leading to biologically productive regions. Bacterioplankton recycle organic molecules released from phytoplankton, allowing production to extend offshore from the upwelling source. Microbial metabolic activity, estimated as the uptake rate of amino acids leucine (Leu) and methionine (Met), in surface waters of the Mauritanian upwelling was characterised and compared with that observed in the Atlantic (sub-)tropical gyres and equatorial region. Activity was measured in two upwelled filaments during Lagrangian studies: L1 began at the source of upwelling (depth 63 m), whereas L2 began further offshore (>2 km). Variance in leucine uptake and concentration was significantly higher during L1 than L2. During L2, concentration and uptake rate was stable throughout, suggesting efficient nutrient recycling. Uptake was rapid in the upwelling region (319 ± 132 pmol Leu L-1 h-1 & 131 ± 52 pmol Met L-1 h-1), where variation was considerably higher than in the gyres, despite a smaller sampling area (~6 x104 km2 & ~4x106 km2, respectively). Whereas stable regions may be characterised by mean values, dynamic upwelling regions show high spatial variation of microbial activity.

Session #:S28
Date: 02-16-2011
Time: 15:00

Presentation is given by student: No