Significance of Microorganisms of Upper Sediment Layer 715 



mation of the bacterial biomass observed in the upper sediment 

 of the Azo\' and Caspian Seas. 



The biomass of microorganisms in sediments is not constant. 

 The presence of organic substance changing in different seasons 

 of the year is the principal factor for determining tlie total num- 

 ber of bacteria ( 15 ) . 



But the mere data of bacterial biomass does not lead to an 

 understanding of the process. The cells in the state of tranquility 

 are passive with respect to the transfomiation of organic sub- 

 stance. In the course of the observations we were able to ascertain 

 the abundance of cells which were in the state of anabiosis. 



Besides, the process of decomposition of the bodies of de- 

 funct bacterial cells takes a certain period of time. 



In order to comprehend the actual extent of bacterial ac- 

 tivities, the value of diurnal production of microorganisms in 

 the near bottom water layer was determined both for the North 

 Caspian and Azov Seas. 



Studying the attachment of bacteria to glass plates, it was 

 found that the daily coefficient changed from 1.2 to 6.2. That 

 means that biomass of bacteria can increase by 1.2 to 6.2 times. 



As far as seasonal changes in bacterial propagation are con- 

 cerned, the following has been noted for the Azov Sea: the 

 value of the daily coefficient P/B (production /biomass) kept 

 approximately at the same level both in spring and summer, 

 whereas the percentage of dividing cells increased from 4.7 per 

 cent in spring to 8 per cent in summer. The amount of organic 

 substance in the surface film of the Azov Sea sediments was esti- 

 mated to nearly meet the requirements of microorganisms under 

 the observed rate of summer propagation. 



In order to reveal the connection between microorganisms 

 and the dynamics of biogen elements we have conducted some 

 experiments on the regeneration of bio-microelements from 

 sediments. Simultaneously, observations were made on the d\'- 

 namics of microbe cells. 



The previous works on the North Caspian and Azo\' Sea 

 sediments showed that the rate of regeneration of bio-micro- 

 elements in these seas is proportionate to the quantity of organic 

 substance in sediments and to the amount of biochemical oxygen 



