THE SEA OF JAPAN 777 



populated by a varied and extremely numerous fauna of small crustaceans : 

 Amphipoda (Caprella spp., Jassa pulchella, Ischyrocerus spp., Parhyale zibel- 

 lina, Allorchestes spp., Pontogensia spp. and others) ; Isopoda (Dynamenella 

 glabra, Janiropsis kincaidi) ; Polychaeta of the families Syllidae and Nereidae ; 

 small Gastropoda (Cingula spp., and others), and a number of other groups. 

 Some of these species are altogether absent from the northern part of the 

 Tartary Inlet ; others are peculiar only to various biocoenoses of the sub- 

 littoral, others again are found only in insignificant numbers. South of the 

 Tartary Strait the number of these inhabitants of the brown sea-weed beds 

 of the sublittoral usually varies from 10,000 to 200,000 specimens per m 2 

 with a small biomass (usually 50 to 150 g/m 2 , rising to 200 to 500 g/m 2 only 

 in Corallina beds). The fauna of the loose soils of the Primor'e also changes 

 considerably. 



Mokievsky explains these marked differences in the composition, and 

 especially in the distribution, of the littoral fauna of the two parts of the Sea 

 of Japan not only by the changes of temperature and climatic conditions, but 

 also by differences in its tidal ranges — the range of the tides in the northern 

 part of the Tartary Strait being over 2 m and in the central and southern 

 Primor'e, on the average, 1 m. 



Mokievsky maintains that moisture conditions are basically different on 

 littorals with low and high tidal ranges, inasmuch as in the first case the tidal 

 effect on the sea-level is commonly moderated by the swell and by seasonal 

 and sporadic fluctuations of the level ; while in the second case there is a 

 precise tidal rhythm — semi-diurnal, diurnal or a mixture of the two. Pointing 

 out that the taxonomic composition of coastal flora and fauna is determined 

 first of all by the temperature factor, Mokievsky attaches very great import- 

 ance to the character of its moistening (in terms of the height of the tide) in 

 the formation of such features of the littoral as its zonality, the nature of its 

 biocoenoses and the quantitative indices and ratios. On this basis he distin- 

 guishes two types of littoral in the Soviet Far Eastern Seas. In his opinion the 

 littoral of the Sea of Okhotsk, of most of the Barents Sea, of the eastern coast 

 of Kamchatka and of almost the whole of the Kuril Range, and also of the 

 northern part of the Tartary Strait, belongs to the type of north-boreal littoral 

 with a long tidal range (from 1-15 m to 10 or even 13 m), while the central 

 and southern Primor'e and the southwestern coast of Sakhalin belong to the 

 south-boreal type with a short tidal range. 



In contrast to other Far Eastern Seas the variety offish in the Sea of Japan 

 is exceptionally great [about 615 species; among them, in the northern part 

 from Peter the Great Bay to Sakhalin and the Tartary Strait, 245 have been 

 distinguished (T. Rass)]. This is a meeting place of cold-water fish and 

 subtropical and tropical fish which have penetrated into the Sea of Japan from 

 the south with the Tsushima current. The tropical and subtropical fish com- 

 prise members of the families Gobiidae (30 species), Chaetodontidae, Ser- 

 ranidae (15 species), Pharyngognathi, Balistidae, Monocanthidae, Ostra- 

 ciidae, Labridae (11 species), Carangidae (12 species) and Tetrodontidae 

 (12 species). 



The number of tropical and subtropical fish decreases sharply as one moves 



