828 



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



Table 325. Two types of distribution of nutrient salts in the northern shallows of the 

 Bering Sea (V. Mokievskaya, 1956) 



Plankton 



One hundred and sixty-three phytoplankton forms have been recorded in the 

 northern part of the Bering Sea and in the Chukotsk Sea : Flagellata 2, Peri- 

 dinea 55, Diatomaceae 104, Chlorophyceae 2 (I. Kisselev, 1937). Boreal 

 peridineans are predominant even in the Bay of Anadyr in summer (Peri- 

 dinium thorianum, P. pallidum, P. depressum, P. ovatum, P. pellucidum, P. 

 granii, Dinophvsis acuta, Ceratium pentagonum and others). Only a few dia- 

 toms develop in large numbers {Chaetoceros concavicomis, Ch. debilis, Ch. 

 radicans, Rhizosolenia hebetata and others). At a depth of 20 to 30 m the 



Fig. 419. Limit of zones of cold water (/) and thermophilic 

 fauna (//) in northern part of the Bering Sea. 



