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



the analogy of the deep-water plankton of the Sea of Japan. While not deny- 

 ing the fact that the penetration of the deep-water plankton forms into the 

 Sea of Japan from the adjacent part of the Pacific Ocean is restricted by the 

 shallowness of the straits leading into it, Vinogradov draws attention also 

 to the contemporary physicochemical characteristics of the Sea of Japan as a 

 possible limiting factor. He confirms the conclusions of previous investigators 

 that only ' those species which, in the adjacent waters of the Pacific Ocean 

 and the Sea of Okhotsk, live at depths of less than 200 to 500 m are found in 

 the deep-water plankton of the Sea of Japan ; they rise during their daily 

 migrations at least to 50 to 100 m'. Many of the plankton and benthos species 

 sink down in the Sea of Japan to much greater depths than those which are 

 usual for them in the Pacific Ocean. Qualitatively and quantitatively, how- 

 ever, the deep-water fauna of the Sea of Japan is considerably impoverished. 

 Vinogradov has remarked on the large number of plankton species found in 

 the upper layers of the Ocean in the areas adjacent to the straits which do not 

 penetrate into the Sea of Japan. 



The deep waters of the Sea of Japan have a lower temperature (0-12° to 

 0-22°) and somewhat lesser salinity (34-08 to 34T4% ) than the adjacent parts 

 of the Pacific Ocean and the Bering and Okhotsk Seas (-1-55° to 2-2°; 

 34-61 to 34-72% ). The main explanation of the absence of a specific deep- 

 water plankton in the Sea of Japan, in Vinogradov's opinion, is associated 

 with this difference in temperature and salinity conditions which might, he 

 thinks, possess the significance of a decisive factor, independently of the 

 geological past of the Sea. 



In recent years the littoral fauna of the Sea of Japan has been investigated 

 by O. Mokievsky (1956, 1959), who has found much similarity between the 

 littoral fauna of the northern part of the Tartary Strait and the Sea of 

 Okhotsk, which are characterized by homogeneous colonies of comparatively 

 large-sized, mainly secular species. The rocks of the sublittoral and the 

 supralittoral here are inhabited by Littorina sitchana subtenebrosa. Differ- 

 ences are observed in the barnacles of the supralittoral : while mixed colonies 

 of Balanus balanoides and Chthamalus dalli, with a predominance of the 

 former, are characteristic of the Sea of Okhotsk, in the Sea of Japan the 

 supralittoral is populated almost exclusively by Chth. dalli. Lower down live 

 organisms which are also characteristic of the Sea of Okhotsk: Acmaea testu- 

 dinalis, Littorina squalida, Thais lima, large Gammaridae {Gammarus locu- 

 stoides, Echinogammarus spasskii and others), Idothea ochotensis; loosely 

 packed soil is inhabited by Nereis vexillosa, Eteone longa, Arenicola claparedi 

 and a few Maeoma baltica. It is to be noted that these last five species have not 

 been observed in the littoral of the central and southern Primor'e. The fauna 

 of fucii and other sea-weed growths, abundant in the northern part of the 

 Tartary Strait, is very poor both qualitatively and quantitatively. The number 

 of specimens is commonly not more than 100 to 2,000 per m 2 , the biomass 

 being from 25 to 150 g/m 2 . 



In the central and southern Primor'e the fauna of the upper horizons of the 

 rocky littoral changes comparatively little. However, Mokievsky describes 

 some marked alterations in the sublittoral. Patchy growths of brown algae are 



