CS26 Organic Carbon Dynamics
Date: Thursday, June 13, 2002
Time: 11:45:00 AM
Location: Carson C
 
KuznetsovaMR, Marine Sciences Research Center, Stony Brook, , marina.kuznetsova@sunysb.edu
Lee, C, , Marine Sciences Research Center, Stony Brook, , cindy.lee@sunysb.edu
 
DFAA, DCAA AND BACTERIAL DYNAMICS IN THE SEA SURFACE MICROLAYER OF THE SARGASSO SEA
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Enrichment factors for dissolved free (DFAA) and combined (DCAA) amino acids and bacteria in the sea surface microlayer (ML) were higher where concentrations of dissolved organic matter in subsurface (SS) water were higher. Enrichment factors are defined as ratios of ML to subsurface (10-20 cm) water concentrations. Wind-induced mixing reduced bacterial concentrations, but had little effect on amino acid concentrations or amino acid and bacterial enrichment factors. To ascertain the impact of sunlight on DFAA, DCAA, and bacteria, ML and SS samples were placed at the air-water surface or at 20 cm depth in vials that allowed penetration of ambient sunlight, or prevented either UV light or all sunlight. As we usually observe, extracellular peptide hydrolysis rates were higher in ML than in SS samples. UV light inhibited hydrolysis, but inhibition was less at depth. UV-light exposure caused a small increase in DFAA concentration, and a decrease in bacterial numbers, again smaller at depth. Our results demonstrate that although bulk water is a source of material enriching the microlayer, processes within the ML control the size of the enrichment.