TRANSLATOR'S ABSTRACT 



The copepod fauna of the northwestern Pacific increases in specific richness but decreases 

 in overall mass with increasing depth. This fact is significant in comparing the faunas of the deep 

 Pacific and adjacent shallow, semi-isolated basins. 



The boreal waters of the northwest Pacific are cooled to a depth of 200 m, in winter and 

 considerably warmed in a shallow surface layer in summer, so that a cold layer persists at inter- 

 mediate depths through the year. South of them the warm Kuroshio water shows small seasonal 

 temperature changes and lacks the cold intermediate layer. These differences of temperature and 

 structure of the water masses are expressed in the specific composition and biomass of the zoo- 

 plankton. The boreal waters are characterized by paucity of species and high biomass, the Kuro- 

 shio waters by low biomass and great specific diversity. The summer boundary between these two 

 plankton faunas is the 18 C. surface isotherm. 



The abundance of the boreal plankter Calanus cristatus is at its minimum in the cold 

 intermediate layer in boreal waters and increases below a depth of 200 m. In Kuroshio water, 

 where the cold intermediate layer is lacking, there is no such minimum at 100-200 m. 



In the boreal waters the plankton biomass is greatest in the shallowly warmed surface layer; 

 in the Kuroshio water it is poor at the surface and peaks at 50-100 m. 



Such species as C. cristatus, C. tonsus, and Eucalanus bungii, in the boreal region, 

 become about twice as abundant in spring (May- June) as they are in summer. This biological 

 spring in the plankton fauna seems to coincide v/ith the feeding migration of whales. 



Analysis of plankton collections from sections extending southeast from the Kuriles across 

 the northwestern part of the Kuroshio make possible the distinction of three zones characterized by 

 their copepod faunas: the southern part of the North Pacific Temperate Region, where Calanus 

 tonsus is abundant; a transitional or subtropical zone, marked by the abundance of C. pacificus : 

 and a tropical zone characterized by great specific diversity and low overall abundance. Seasonal 

 presence of neritic forms such as Labidocera japonica in the tropical zone makes it possible to 

 trace the eastward movement of the Kuroshio water. --W. V.C. 



