Onuphis pall ida-Potamilla symbiotica-Syncoryne sp.- 

 Ophiophthalamus normani ,~which probably extends from the Gulf of Alaska 

 along the island slope of the Aleutians and the eastern coast of 

 Kamchatka to the Sea of Okhotsk. In the Sea of Okhotsk, this is an 

 independent bathyal -abyssal community, extending over depths of 460- 

 3314 m on the slopes of the Academy of Sciences sea mount and in the 

 southern portion of the sea (Ushakov, 1953; Savilov, 1961). In the Gulf 

 of Alaska, it is encountered at depths of 990-1030 m in clayey silt, 

 with a bottom temperature of approximately 3.0°C. The total biomass of 

 the grouping is 5.3 g/m^. One of the leading forms of this grouping is 

 a clear example of symbiotic adaptation of organisms to life in the soft 

 bottom at great depths. The hydroid Syncoryne sp. overgrows the long 

 (up to 50-80 cm) tube of the sedentary polychaete Potamilla symbiotica , 

 utilizing it as a substrate, while its hydrorhia creates a thick, " 

 circular weave around the lower end of the tube, holding the polychaete 

 in the vertical position (Ushakov, 1950; Tendal, 1971). This represents 

 the "epi fauna of the soft bottoms" in its clearest form. For this 

 grouping, the large Pavonaria pacifica with Chondractinia , many 

 Spiochaetopterus polychaetes, Maldanidae (up to 160 indiv./m^, biomass 

 0.6 g/m^), Melinna ochotica , Travisia pupa , etc., are characteristic, of 

 the decapod--juveni1e Chionecetes opilio , of the bivalve mollusks--the 

 large Delectopecten ra'ndolphi , the smaller Nucula cardara , Yoldiella 

 derjugim and others. 



The lower bathyal biocenosis Onuphis pall ida-Yoldia beringiana- 

 Ophiura leptoctenia is found in the Gulf of Alaska at depths of 1050- 

 2088 m, over a rather large region from the east slopes of the Aleutian 

 trough to the traverse of Baranov Island in soft clayey silts; the 

 temperature at the bottom is 1.9-2.0°C. The total biomass of macrofauna 

 is from 0.9-57.8 g/m^, averaging 13.9 g/m^. This relatively high 

 biomass of benthic fauna in the lower bathyal is explained by the 

 influence of transport of detritus from the highly productive shelf of 

 the Gulf of Alaska and its accumulation in the lower portion of the 

 slope and in the upper levels of the abyssal gulf (Kuznetsov et al . , 

 1973). 



The biocenosis Onuphis pal 1 ida-Yoldia beringiana is typical for the 

 lower bathyal zone of the Gulf of Alaska. Characteristic for it is the 

 presence of a number of bathyal forms also present in the Bering Sea. 



Onuphis pall ida is a mass form (100% occurrence, more than 100 

 individuals in a trawl catch). The large bivalve mollusk 

 Yoldia beringiana is quite characteristic for the biocenosis, although 

 it is somewhat less frequently found in trawl catches than Q. pal 1 i da 

 (occurrence 40-50%). This is a typical bathyal form for the" northern 

 Pacific Ocean and the far eastern seas. Ophiura leptoctenia is also a 

 common form, occurrence about 60%. It is usually distributed in spots, 

 within which its quantity in trawl catches may reach 500-1100 

 individuals. 



One peculiarity of the biocenosis is the presence in its 

 composition of various sea pens (5-6 species, as many as several dozens 

 of individuals in a trawl catch). They are all characteristic for the 

 bathyal and upper abyssal Pacific, surrounding its northern portion in a 



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