THE CHUKOTSK SEA 



263 



Waters flowing into it from the East Siberian Sea through De Long Sound 

 have, in their deeper part, a salinity of 31-7 to 32-6% . To the north their 

 salinity increases, reaching 34-8% . The salinity of the surface layers varies 

 greatly. In summer time in the parts adjacent to the Chukotsk Peninsula the 



Fig. 112. Quantitative benthos distribution in the Chu- 

 kotsk Sea, g/m 3 (Ushakov, 1952). Summer bottom iso- 

 therms are also marked. 



surface layers have a salinity of only 3-5-8% and sometimes even less. In the 

 rest of the Sea it usually remains at 29 to 32-5% in the surface layers, but often 

 it decreases in the regions of the melting ice by a few parts per thousand. In 

 winter time the surface layers must acquire a considerably higher salinity 

 owing to freezing of the water. The ice content of the Chukotsk Sea changes 

 from year to year, and the mean ice limit in August and September, i.e. the 

 warmest season of the year, can be indicated only approximately (Fig. 110). 



Oxygen content 



It is of great interest that the oxygen content in the warmed deep layer of 

 'Atlantic' waters, entering the Chukotsk Sea from the north, is greatly re- 

 duced, in some cases down to 20-47 per cent of saturation. The 1935 data of 

 one of the Krassin stations for the northern part of the Chukotsk Sea are given 

 in Table 114. 



Deep 'Atlantic' water lost 5 or 6 cm 3 of its oxygen per litre, receiving no 

 fresh supply, since the time [in N. Zubov's opinion (1944) no less than four 

 or five years] of its sinking beneath the upper diluted layer of water in the 

 region of Spitsbergen. Such a small oxygen consumption (approximately 



