198 



Marine Microbiology 



thickness, at the almost constant depth of 9 m ( Fig. 3 ) ; only on 

 4 April 1960, at station C, it was encountered at 10 m. 



With regard to the distribution of oxygen and hydrogen 

 sulphide at the different levels (Fig. 4), we can state that until 

 July the gases were present in quantities conforming with tlieir 

 nonnal stratification. At the surface the amounts of dissoKed 

 oxygen varied from a maximum of 6. .54 ml/L, (5 March), to a 

 minimum of 4.23 ml, (4 J"ly)- At 5 m, oxygen concentration was 

 always slightly lower compared to that found on the surface; at 

 8 m instead, i.e., near the transition zone, oxygen oscillated from 

 a maximum of 6.07 ml in March, to a minimum of 0.94 ml, in 

 July. 



1960 



MONTHS 

 Fig. 4. Variations of oxygen and of hydrogen sulphide at station A. 



