82 



BIOLOGY OF THE SEAS OF THE U.S.S.R. 



penetrate from the northeast along the trenches from the centre of the polar 

 basin (Fig. 4). In addition there is another very interesting phenomenon to 

 be observed throughout the Barents Sea. In summer the lowest temperature 

 remains at a depth of 50 to 75 m. This is considerably cooled and saline 

 'winter' water which has sunk down. It is called the intermediate cold layer. 

 In the coastal areas of the southern part of the Sea, in its more or less isolated 

 parts, the temperature of the surface layer in summer may be fairly high, 

 owing to local heating, but in the hollows and trenches and over the shallows 

 water may remain very cold all the year round. In the inlets and fjords of the 



Fig. 24. Mean secular limit of ice in the Barents Sea in months 



from April to August (data from Meteorological Institute of 



Denmark). 



northern part of the Sea, if they are separated from the open sea by shallow 

 ridges, cold, low-salinity surface water remains even in summer, as, for 

 example, in Stur-fjord in Spitsbergen. In winter, however, owing to formation 

 of ice in bays and fjords, homothermia and homohalinity may be observed at 

 a temperature below zero and in the presence of high salinity (35 to 37% ). 



The Murman coastal area has a considerably higher temperature (Fig. 26) 

 in summer, but in winter its temperature is above zero. 



The Atlantic waters with a salinity of about 35% at their entrance into the 

 Barents Sea retain the same salinity in the deep layers as they move north 

 and east, while in the surface layers this goes down to 32 to 34% , and only 

 farther up the inlets do they get considerably diluted. 



