plankton is strongly Influenced by the present as well as the preceding hydrological and metero- 

 logical conditions. 



An earlier development of the vernal biological processes usually is observed in years when 

 the intensity of the Norwegian current is accelerated, especially if the increasing intensity of the 

 current coincides with favorable meteorological conditions . 



For instance, the biological spring started 15-20 days earlier in the spring of 1954 than in 

 1953 in the warm Atlantic waters. This was facilitated by the higt> thermal condition of the waters 

 in March-April, together with calm (in comparison with 1953) and sunny weather. During the peri- 

 od of plankton production in 1954, there were only half as many storms as in 1953. 



Comparing the distribution of the principal plankton complexes (Figures 8, 9, 10, and 11) we 

 see that the biological spring started about a month later in 1951 than in 1954. The plankton devel- 

 oped more actively in the warm waters of the Norwegian current than between the currents (espe- 

 cially on shoals and shallows). It was possible from the qualitative composition of plankton to ident- 

 ify the various branches of the warm current. Approximately the same distribution of plankton was 

 observed by us in 1953 and in 1955. 



It is characteristic that in 1951 such thermophilic Atlantic organisms as Collozoum and 

 Tomopteris were very seldom encountered in the eastern branch of the Norwegian current . This 

 serves as an indicator of a lowering in the flow intensity of Atlantic waters into the Norwegian Sea. 

 It must also be said that in 1951 also cold Arctic waters penetrated into the area between the streams 

 of the warm current. In June, these cold waters carried the cold- loving Calanus hyperboreus, 

 which dwells there at depths of ca. 100 m., into the central regions of the Norwegian Sea. The 

 penetration of these chilled waters, which abound in nutritive substances, into the central regions 

 of the Norwegian Sea facilitated first the production of algae and later of plankton. 



In June 1951, the biomass of plankton was fairly large (800-1, 200 mg/ni3) in the central and 

 northern regions of the Norwegian Sea . 



In the regions of great depths, the main bulk of plankton consisted of spawning Calanus , but 

 near the slope their red fat young were also developing. 



Feeding herring proceed northward very slowly, while feeding in the northern regions of the 

 Norwegian Sea. In July, schools of herring reached Mohn's Threshold and began to enter the Green- 

 land Sea along the continental slope, where, at this time, plankton production had just begun. The 

 amount produced was small (Figure 12). It consisted mainly of the spawning crustaceans, Calanus 

 finmarchicus and Calanus hyperboreus . 



We observed quite different conditions of the development of vernal biological processes in 

 the Norwegian Sea in 1954 . 



The wide dissemination of warm waters as a result of the acceleration of the intensity of the 

 Norwegian current, the small number of stormy days, and the sunny weather in March-April facil- 

 itated the activization of vernal biological processes in the Norwegian Sea . 



The spawning of Calanus was observed in March, i.e. 15 days earlier than in 1953 and ap- 

 proximately a month earlier than in 1951. 



A homogeneity of hydrological conditions in the eastern regions of the Norwegian Sea is 

 characteristic for 1954. A solid stream of Atlantic waters, which carried a large amount of Coll o- 



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