Leucine incorporation rate in the sea surface microlayer and underlying water at the investigated stations. Leucine incorporation rate, representing bacterial production, is shown for the sea surface microlayer (SML, bulk in black bars and >3µm fraction in gray bars) and underlying water (ULW, white bars). Rates were not obtained for stations H5 and H12, except for ULW at H5. DOI: https://doi.org/10.1525/elementa.276.f4