查看文章

Lability of the bulk dissolved organic carbon (DOC) pool and the amount available to bacterioplankton on short time scales (hours to days) were examined in oligotrophic Sargasso Sea water (near Bermuda). We examined bacterial growth and DOC utilization using seawater culture methodology in combination with measurements of bacterial abundance, cell volume, and DOC. Bulk DOC concentrations were determined by high temperature combustion (HTC) analysis, which proved to be a sensitive method for detecting small changes in natural concentration of DOC. Measurable bacterial growth and DOC utilization only occurred in unamended cultures when initial DOC concentrations were greater than observed in the mixed layer at the Bermuda Atlantic Time Series station. In unamended cultures exhibiting growth, approximately 6 to 7% of the bulk pool was available and considered a labile component. This …