E 10 



Q 



Q 25 



45 





1 



"V> 



,/■' 



/ 



Figs. 9-10. 



Vertical distribution of: ( 1 )watertemperaturein°C;(2)dissolved 

 oxygen in mg/1: (3) total bacteria count in millions of cells/ml; 

 and (4) CO, assimilation by bacteria in darkness, in g C 1 ' d '. 

 All data apply to the South China Sea. 



Total bacterial degradation in the water column at individual 

 stations ranged from 41 to 127 (ig C 1 ' d '. The average for a 

 whole of the area studied was 86 U. C 1 ' d" 1 . 



The vertical distribution of bacterioplankton over the 

 water column within the euphotic zone included a clearly 

 evident peak at a depth of 1 m (Figs. 9, 1 0). The mean bacterial 

 density and biomass in this layer were 450 x 10' cells/ml ' and 

 10.1 u.g C 1 ' d "', respectively. Both counts and biomass then 

 decreased with depth. 



Microfloral activity varied considerably over the water 

 column. Two microfloral activity peaks were observed at 

 several stations: one lay at a depth of 10 m, the other at or near 

 the sea bottom. Enhanced production-degradation activity 

 was likewise noted at the corresponding depths. Bacterial 

 biomass production in the peak-activity layers was 2.5 times 

 the bacterial production obtained for the entire sea area studied. 

 The degradation rate OB in the bottom layer was 3.5 times that 

 noted for the surface layer. 



Discussion 



Particular portions of the Pacific Ocean exhibited differing 

 levels of microbiocoenosis development. The equatorial Pacific 

 and South China Sea areas are closely similar with respect to 

 bacterioplankton and biomass parameters in their euphotic 

 zones. On the other hand, the level of development of the 

 bacterial population in the western Pacific was found to be 

 much lower. The South China Sea exhibited relatively high 

 microfloral activity. Values characterizing bacterial production 

 and organic matter degradation in the sea were similar to those 

 reported for the mesotrophic waters of the tropical ocean. The 

 level of production-degradation processes in the western Pacific 

 was almost half of that in both the equatorial ocean and the 

 South China Sea and corresponded to values characteristic of 

 oligotrophic waters. 



n 



n 



in 0-55 m layer 



Station 126 Station 127 



Station 128 



Station 129 Station 130 



Station 131 



Scale: 



I I Bacterial production 

 10 Ug c/l/day EH Organic matter degradation 



Fig. 1 1 . Bacterial production and organic-matter degradation in the South China Sea. 



211 



