16 Marine Microbiology 



Anthony (14) often found 10*^ bacteria per gm, 10' to 10^ per 

 gm at core depths of 0.5 to 1 m, and 10" per gm down to 6 m. 



BACTERIAL BIOMASS 



The bacterial biomass is computed from data on the abun- 

 dance of bacteria and theii^ mean weight. The vokune of most 

 marine bacteria faUs within tlie range of 0.1 to 1 /'^. Since smaller 

 cells predominate, 0.2 /--^ is taken as the mean volume of marine 

 bacteria for purposes of estimating their biomass. The weight 

 of such a bacterium is about 2 X 10~^° mg, its dry weight 

 4 X 10~^^ mg, and its organic carbon content about 2 X 10~^^ 

 mg. From these values bacterial biomasses are calculated for 

 different population densities. The second and third columns in 

 Table 4 represent the standing crop or standing stock. Of greater 

 significance is the quantity of organic carbon cycled annually 

 through bacterial cells. The annual production of bacterial carbon 

 is derived by multiplying the standing crop values by the number 

 of bacterial generations per year. The fourth column in Table 4 

 gives orders of magnitude of bacterial carbon for different pop- 

 ulation densities based upon an assumed generation time of 

 twenty-four hours or 365 generations per year. ( See Chapter 65 ) 

 (Zhukova). 



TABLE 4 



Bacterial Biomass Per Cubic Meter of Water For Different 



Population Densities and the Annual Production of Bacterial 



Carbon if the Bacteria Reproduce Every Twenty-Four Hours 



The generation time of marine bacteria varies from less than 

 an hour to several days or maybe many montlis, depending upon 



