Figure 2. Surfece temperature distribution in May 1953 . 1. Calanus hyperboreus ; 2. 

 Metridia longa; 3 . Limacina retro versa; 4 . Nematoscelis megalops . 



Some species of plankton organisms are widespread in the North Atlantic, and these are the 

 species which occur in the greatest quantities. They include the following: Calanus finmarchicus , 

 Pseudocalanus elongatus , Microcalanus pusillus , Spinocalanus abyssalis , Oithona similis , O. 

 atlantica, Oncea borealis, Themisto sp. 



Calanus finmarchicus is the most numerous species of plankton in the Norwegian Sea, but 

 its quantitative distribution varies from place to place. C. finmarchicus is not plentiful in the 

 southern part of the Norwegian Sea and its quantity begins to increase only as it travels northward 

 with the current. Very large quantities of Cj finmarchicus have been noted in the path of the con- 

 tinental current. The biomass of plankton in May 1953, during the season of mass development of 

 C. finmarchicus , reached 4, 509 mg/m3. It should be noted that in the more northerly parts of the 

 central areas of the Norwegian Sea, where polar and Atlantic waters are intermingled, the ratio 

 of Calanus finmarchicus and C. hyperboreus is 1:2 in the 50-100 m. layer at less -than- zero C. 

 temperature. 



On the other hand, in the central areas of the Norwegian Sea, where the salinity is hi^er 

 (35 /oo and more) and where the temperati , freezing point, the quantity of C. fin- 



marchicus increases considerably whilst that ,. ^. i.yperboreus decreases, giving the inverted 

 ratio of 2:1 (Table 1). The no less numerous species of Copepoda - Pseudocalanus elongatus - is 

 found together with C . finmarchicus , and the quantity of it increases in the courses of the currents . 

 This species is also unequally distributed in the individual areas of the North Atlantic (Table 2^). 



J/ Translator's note: Table 1, rather than Table 2, contains information on P. elongatus . 



81 



