Decomposers, Bacteria, and Microbenthos 351 



3- 



'E 

 o 



E 



T 1 1 1 1 1 1 1 1 1 1 — f" 



Glucose, 



T 1 1 T- 



Acetote. 



rilj 2 L 



J I I I I L. 



8 10 12 14 16 



Primory Production, mq C m hr 



FIGURE 8-5. Relationship of velocity of up- 

 take of glucose and acetate to primary produc- 

 tivity of phytoplankton in a transect of 25 

 ponds. 



or lost during photosynthesis and even more will become available during 

 decomposition. 



Attached Bacteria 



The discussion so far has dealt mostly with the free-living bacteria of 

 the plankton or with those bacteria whose activity may be measured by 

 gently mixing radioactive substrate into the sediment. However, a large 

 number of bacteria are attached to the detrital particles of the sediment 

 and many of these may be imbedded in the detritus or covered with masses 

 of adhesive material (Costerton et al. 1978). The result is that many of 

 these bacteria do not come into contact with the radioisotopes. 



Thus, while the attached bacteria were counted by our methods their 

 activity wa^ not measured with the isotope uptake method. The whole- 

 system respiration measurements would measure their activity. 



Production 



The production of bacteria was calculated from the changes in 

 bacterial biomass, from respiration, from production losses, and from 

 methane production (Hobbie and Rublee 1975). Their sum, gross 

 production, was then apportioned to the two input parameters of total 

 uptake of DOC and hydrolysis (breakdown) of detritus (Table 8-6). 



Respiration in the ponds could not be measured in situ for the 

 bacteria alone. In the water column the respiration rate was too low to be 

 measured but there was measurable respiration in the sediments (see 

 Sediment Respiration). The total quantity of about 13.7 g CO2-C m"^ 



