r-1.7 I 1.5 



Polar water 



SX. 34.00 -34,74 



.1 , W 4 



Atlantic water 



SX.35 -35,16 



r* 



Themisto abyssorxim 



Themisto libellula 



Figure 7 . 



Variation in ratios between Themisto libellula and Themisto abyssorum in 

 dependence on temperature in the polar waters and the Atlantic waters. 

 1. Quantity of organisms 2. Polar waters 3. Atlantic waters. 



Themisto abyssorum 

 Themisto libeUula 



Some Atlantic species are extremely hardy with regard to temperature variations, and this 

 enables them to travel far north into the Greenland Sea with the waters of the Norwegian current. 



However, only those warmth-loving organisms which inhabit the surface water layers pene- 

 trate to the northern latitudes . Among these organisms are the Halosphaera viridis (flagellates). 

 Colonial radlolaria , Collozoum gro^nlandicum , Limacina retroversa , (pelagic mollusc). These 

 species are mostly concentrated in the 0-100 m. layer. In 1951, C. groenlandlcum was found al- 

 most as far as latitude 77°N in the Norwegian current where the temperature was 1.7 C and the 

 salinity 34.04°/oo. It may be assumed that this species penetrates a good deal further. 



None of the warmth-loving plankton organisms which inhabit the Norwegian Sea in the deep- 

 er layers of water were found by us in the Greenland Sea . 



88 



