Keeping in mind the similarity of the quantitative development of 

 plankton in the Norwegian Sea and the Labrador Basin, and also considering 

 the great extent of the areas of open water in the boreal Atlantic, it is 

 apparently not a great exaggeration to assume that for the entire boreal 

 Atlantic area the production of the zooplankton community is 2 to 2.5 

 times greater than the production calculated for the area of the Norwegian 

 Sea. 



3.3 Planktonic Communities of the Boreal Pacific 



In our analysis of the biology of the North Pacific, it is proper 

 to include in the water area under consideration the actual oceanic 

 waters and the Far Eastern seas: the Bering Sea, Sea of Okhotsk and 

 Japan Sea. The unique features of each of these seas, resulting from 

 differences in their hydrologic modes, latitudinal position and other 

 factors, cause differences in the makeup of their planktonic populations as 

 well. Also, the boundary between two biogeographic areas, the northern 

 Pacific temperate and circumtropical areas, passes through the Japan Sea 

 (Brodsky, 1957; Zenkevich, 1963). This makes it desirable to analyze 

 the planktonic communities for each of these seas individually. 



Sea of Okhotsk . The planktonic communities of the Sea of Okhotsk 

 include cold-water and cold-temperate species, and at the very southern 

 region of the sea adds the oceanic species typical for the warm waters of 

 the northwestern Pacific. It is most efficient to distinguish three 

 communities in the plankton of the sea: the oceanic subarctic, oceanic 

 cold temperate and neritic communities. 



The oceanic subarctic community occupies the entire northern portion 

 of the sea, except for the coastal zone, and extends southward to 56°N, 

 where it is replaced by the next community. Along the shores of Sakhalin, 

 this community extends to the latitude of Cape Patience (Mys Terpenia). 

 The primary components of the zooplankton of this community are: Calanus 

 glacialis , Metridia ochotensis , Parathemisto libellula and Thysanoessa 

 raschii . At the end of the summer, the biomass of C. glacialis in the 

 0-100 m layer in some locations reaches 8000 mg/m3, making up as much as 

 90% of the entire biomass of zooplankton. In the northernmost region of 

 the sea, C. glacialis is found everywhere, but is less numerous. It extends 

 to the south along the shore of Sakhalin together with the cold current, but 

 plunges to a depth of over 200 m, so that its quantity in the upper produc- 

 tive layer is not great (Ponomareva, 1961). 



Metridia ochotensis is widespread, forms concentrations and is im- 

 portant in the diet of the Okhotsk herring (up to 45-50% of the diet). 

 The main concentrations of this crustacean are observed in the northern and 

 western portions of the sea, the biomass sometimes reaching 1000-5000 mg/m3 

 in the 0-100 m layer. In the summer and autumn, when the surface tempera- 

 ture of the water in the southern portion of the sea reaches 15 C, M. 

 ochotensis is encountered individually, but in the spring the number 

 becomes quite high (in the southernmost portion of the sea, up to 5000 mg/m3 

 in the 0-100 m layer) . 



76 



