relationship between organic-matter density and cell volume in bacteria (Fig. 5.7)
such that the carbon per cell is roughly constant at about 20 femtograms C per cell,
(20 × 10−15 g C per cell). For oceanic regions, this is thought by many to be somewhat
too high. Nevertheless, most estimates range from ∼10 to 30 femtograms C per cell.
Note that the typical cell abundance, 10^9 bacteria liter−1 only represents 10−6 g
carbon, or 1 μg C liter−1.
Fig. 5.7 (a) Relation in marine bacterioplankton between carbon density (g C cm−3)
and cell volume. The negative relation causes carbon per cell to be roughly constant at
∼20 fg, as shown in (b).
(^) (After Lee & Fuhrman 1987.)
(^) After converting direct counts to bacterial carbon and TdR- or leucine incorporation
to cells produced per time, a rough relationship emerges between bacterial standing
stock and production rate for all pelagic habitats taken together. For example, Billen
et al. (1990) and Ducklow (1992) converted cell counts to biomass (20 fg C/bacterial
cell), then plotted the result vs. production rates (Fig. 5.8). As put by Thingstad