THE BARENTS SEA 149 



include a number of the dominant forms of the middle Barents Sea community. 

 This community can also be divided into nine variations. Among them is the 

 grouping to the east of Kolguev Island, on the silty sand at shallow depths 

 (50 to 70 m) with a sharp preponderance of Pectinaria hyperborea and Yoldia 

 hyperborea, with a considerable deviation from the ordinary phylum ; so also 

 is the grouping in the Novaya Zemlya trough on silty sand and at depths of 

 50 to 200 m. This trough shelters a very large population of a relict mollusc 

 Portlandia arctica. 



The composition of this community, the richest in its biomass, is given by 

 groups in Table 62. 



Table 62 



On the coastal sands of the eastern and southeastern parts of the Sea and in 

 the shallows of the open sea (Gusinaya bank, Kanin shallow) there thrives at 

 depths of 9 to 100 m a hard-bed community mainly on various types of sand, 

 from the slightly silty to the coarse-grained. This community gives a consider- 

 able admixture of shallow-water high Arctic forms, and consists half of epi- 

 fauna. Its dominant forms include among the molluscs: Astarte borealis, 

 Macoma calcarea and Serripes groenlandicus; among the bryozoans: Pelo- 

 naja corrugata; the crustaceans: Eupagurus pubescens and Balanus; and among 

 the echinoderms, Strongylocentrotus. 



Among these characteristic of the first order are Alcyonidium disciforme, 

 Travisia forbesi, Pectinaris hyperborea, Owenia assimilis, Sabellldes borealis, 

 Ampharete vega, Ophelia limaeina, Ophiura nodosa, Myriotrochus rincki, 

 Cucumaria calcigera, Cyprina islandica, Astarte elliptica, A. montagui, Saxi- 

 cava arctica, Mya truncata, Diastylis rathkei, Hyas araneus and Balanus 

 balanus. 



The fauna of the hard sea-floor (13 to 45 m deep) in the Cheshskaya Inlet 

 have a special aspect. 



The dominant forms here are Mytilus edulis and Balanus crenatus. The 

 mass descent into the sublittoral of such a typical littoral form as sea mussel 

 is of special interst. This community has the following group composition 

 {Table 63). 



