Significance of bacterial biomass in lakes and the ocean: comparison to phytoplankton biomass and biogeochemical implications

We have synthesized the information on marine and lirnnetic bacterial biomass carbon (BOC) and phytoplankton biomass carbon (PhytoC) to examine the relationships between these major biotic carbon pools. On the basis of 6 limnetic and 6 marine studies we found a good similarity for the correlations of BOC vs PhytoC in both systems although the slope was substantially lower than for sim~lar correlations on the basis of bacterial abundance and chlorophyll a. Limnetic systems, however, differed from marine systems In that they supported more BOC relative to PhytoC, as indicated by signlficantly higher y-intercepts of the correlation (p < 0.001). Our dnalysis also generalizes findings from manne to limnetic environments that the food-web structure in oligotrophic systems is fundamentally different from eutrophic systems, e.g that BOC/PhytoC dramatically increases with decreasing PhytoC concentrations. This has impl~cat~ons for the significance of planktonic bacteria in particle abundance and size-dependent properties of lakes and oceans such as trace metal and radionuclide adsorption, biogeochernical dynamics and in light scattering and remote sensing.