420 



Marine Microbiology 



a whole. For this reason, it is necessary to Hnk the two categories 

 of curv^es as often as possible. 



ANALYSIS OF RESULTS OBTAINED ON 

 THE MARINE MUDS 



Variations in Nitrification Activity in Relation to Water Depth 



We will consider only the activity of nitrite producing bac- 

 teria, as the nitrate production is subordinate to the former. The 

 interesting data furnished by these curves are the lag phase and 

 the ascending slope of the curves. In Figure 2 are grouped six 

 nitrite curves corresponding to six different depths: 45, 63, 100, 

 185, 325, and 500 m. The rate at 63 and 45 m is rapid and nearly 

 uniform; a medium rate is observed at the depths of 185 and 

 100 m, and finally a slow rate is produced by the sample from 

 depths of 325 and 500 m. In this family of curves, the duration 

 of the lag phase increases when the rate of nitrate foimation 

 decreases. By classifying the sample areas according to the dura- 

 tion of the lag phase, one finds: 



1) A duration shorter than ten days; observed for depths of 

 45, 57, 63, 72 and 80 m. 



20 

 DAYS-> 

 Fig. 2. Effect of water depth on nitrate production. 



