Determination of bacterioplankton biomass, net production and growth efficiency in the Southern Ocean

Several conversion factors are r e q w e d for the eshmation of bacterial biomass, net production and carbon demand from epifluorescence microscopy and measurements of 3 H-thymidlne and 3 H-leucine incorporation rates. These conversion factors were evaluated simultaneously in mixed cultures of bacterial assemblages from the Weddell/Scoha Confluence of the Southern Ocean. The cultures were grown in the dark at + l 'C. Conversion factors were calculated for each culture by regression analyses of cumulative parameters. Average conversion factors were: 1.1 X 1018 cells per m01 thymidme incorporated into cold TCA precipitate, 7.5 X 1015 pm3 of biovolume per m01 leucine incorporated into cold TCA precipitate, 0 4 pgC biomass per wm3 of biovolume, and 40% carbon growth yield.