GENERAL CHARACTERISTICS OF THE NORTHERN SEAS 41 



Kola Guba, thermally one of the most favourable regions of the Barents Sea, 

 attains appreciable intensity during two months — July and August — only at a 

 temperature of 9° to 12° С Even then growth hardly reaches 700 to 800 g/m 2 , 

 whereas in the Black Sea the fouling process is continuous almost throughout 

 the whole year, and as a result of it during the same two months an animal 

 fouling is obtained weighing 8 to 10 kg/m 2 . 



Phytoplankton 



P. Usachev (1947) in his reference work on the phytoplankton of the seas of 

 the u.s.s.r. notes, from data obtained for August and September, the im- 

 poverishment of the qualitative composition of the plankton seaweeds in all 

 their component groups, as one moves from the Barents Sea east and north- 

 ward into the central part of the Arctic Ocean (Table 12). 



Table 12 



As shown in Table 12 the relative variety of species of the diatomaceous 

 algae increases from 51 to 76 per cent while that of peridineans decreases from 

 39 to 11 per cent. This shows the Arctic aspect of the diatoms and the boreal 

 character of the peridineans. 



The character of the two main groups of phytoplankton appears even more 

 clearly in the biomass. The diatoms have a preponderant influence, while the 

 peridineans play a very modest part (Table 13). 



The considerable increase of the role of the flagellates in the plankton bio- 

 mass of the Barents, and partly of the Kara, Sea is caused by a mass develop- 

 ment of Phaeocystis and Dinobryon, which is sometimes observed even in 

 the form of 'bloom' in the Barents Sea and to a lesser degree in the northern 

 part of the Kara Sea. 



The development of the phytoplankton of the Arctic basin is closely bound 

 up with ice conditions. The mass development of the spring plankton (mainly 

 diatoms) coincides with melting of the ice and the penetration of light into the 



