THH SEA OF OKHOTSK 813 



colonies of Echinarachnius parma ; silty sands are populated by large-sized 

 bivalves (Macoma calcarea, Tellina, Yoldia traciaeformis); still siltier sands 

 have an abundance of Ophiura sarsi with numerous small Mollusca (Nucula 

 tenuis, Yoldiella derjugini, Axinopsis and others) and Polychaeta (Spio- 

 chaetopterus typicus, Stylarioides plumosa, Sternaspis acutata, Ampharetidae 

 and others). Filter-feeder biocoenoses composed of large-sized Mollusca 

 {Astarte borealis, Sem'pes groenlandicus, Cardium ciliatum, Mya arenaria, 

 M. truncata, Liocyma fluctuosa, Modiolus modiolus and others) characterize 

 the region described. Amphipoda (Ampelisca eschrichti, A. macrocephala, 



A. furcigera) with a biomass of 124-7 g/m 2 and giving about 3,000 specimens 

 per 1 m 2 have been found in large numbers in separate patches. The zone of 

 the predominance of organisms which swallow detritus with the soil should 

 also be noted. Pasternak includes in this group the Polychaeta (Maldanidae, 

 Capitellidae, Ariciidae, Scalibregmidae and Opheliidae), Gephyrea, the 

 Holothuria, the urchin Brisaster latifrons, the starfish Ctenodiscus crispatus 

 and others. 



F. Pasternak (1957) describes the zoogeography of one of the most climatic- 

 ally severe regions of the Far Eastern Seas — the northwestern corner of the 

 Sea of Okhotsk. In this region the Arctic and Arctic-boreal species Ophiura 

 sarsi, Praxilella gracilis, Pr. praetermissa, Spiochaetopterus typicus, Scali- 

 bragma robusta, Chaetozone setosa, Terebellides stroemi, Myriochele heeri, 

 Astarte borealis, A. montagui, Serripes groenlandicus, Mya truncata, Macoma 

 moesta, M. calcarea, M. torelli, Liocyma fluctuosa, Thyasira gouldi and Yoldia 

 myalls play the dominant role in the fauna. Boreal forms are absent. The 

 northern part of the Sea of Okhotsk cannot be included in the boreal province. 



N. Vinogradova (1954) has investigated in detail the bottom-living fauna of 

 the northeastern corner of the Sea. 



Shelekhov Bay in the Sea of Okhotsk, thrusting far up into the Chukotsk 

 Peninsula, is the coldest sector of the Far Eastern Seas. It can be compared 

 only with the northwestern area of the Sea and the Gulf of Anadyr in the 

 Bering Sea. This extensive Bay has an area of about 140,000 km 2 . The distri- 

 bution and composition of its fauna, with its very cold water aspect and a 

 very high mean biomass (470 g/m 2 ) with a predominance of Mollusca, is 

 controlled by the restricted connection of the Bay with the Sea, the feeble 

 penetration of warm waters from the south, its small depth, and the presence 

 of numerous coastal features. 



N. Vinogradova (1954), judging by the composition and distribution of the 

 bottom-living fauna of Shelekhov Bay, distinguishes three main biocoenoses 

 disposed from south to north (Fig. 408): 1 — a biocoenosis of Balanidae- 

 Hydroidea-Bryozoa-Decapoda ; 2 — a biocoenosis of Ophiura sarsi-Macoma 

 calcarea and 3 — a biocoenosis of Leda (pernula type)-Ophiura sarsi-Poly- 

 chaeta. The dominant species of the first biocoenosis are Balanus evermanni, 



B. rostratus dalli, Pagurus pubescens, Ну as coarctatus, and various Hydroidea 

 and Bryozoa. Moreover prawns (Pandalus, Sclerocrangon and others), 

 Echinodermata {Strongylocentrotus droebachiensis, Ophiopholis aculeata, 

 Ophiocantha bidentata, Gorgonocephalus cargi and various Asteroidea) and 

 numerous Porifera (Semisuberites arctica and others) are well represented in 



