118 



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



bivalves Macoma baltica, My a truncata and M. arenaria. The main biocoenosis 

 of the infauna Macoma, Arenicola, Phygospio, Polydora, Terebellides and 

 Scoloplos may form fairly individual biocoenotic groupings. 



Large numbers of oligochaetes and especially enhytreides such as Pachy- 

 drillus lineatus, P. profudus, Enchytreus albidus and Marionina crassa some- 

 times swarm under the rocks and washed-up sea-weeds. 



The sea mussel communities Fabricia, Manayunkia and Littorina rudis may 

 be distinguished among the onfauna. 



The zonation in the distribution of the fauna of silty sand littoral on the 

 western Murman coast may be illustrated by Table 50 from the paper of 

 Gurjanova, Zachs and and Ushakov (1930). 



Table 50 



Horizon Zone 



Form 



Depth, m 



I Masses of washed-up seaweed. A mass 



larvae of fly and of Oligochaeta 14-1 



II 1\ [Oligochaeta 2-4 



2 Fabricia Oligochaeta, Macoma baltica, Entero- 



morpha intestinalis, Urospora penicilli- 

 formis 2-1 

 Mytilus edulis, Halicryptus spimdosus, 

 Priapulus caudatits, Macoma baltica, 

 .Arenicola marina 1-3 



1 „_._ (Macoma baltica, Scoloplos armiger, 



| Pygospio elegans, Ophelia limacina, 

 { Travisia for be si, Terebellides strbmi 0-5 



Mya truncata, Axinus flexuosus, Macoma baltica, Chiri- 



dota laevis, Echiurus pallasi 



Fabricia 

 > sabella 

 + Manayunkia 



Pygospio 

 elegans 



A census of the fauna of the soft bed soils of the Kola Inlet littoral reveals 

 a marked preponderance of a few forms (Tables 51 and 52). 



The contamination of the littoral is easily endured by Macoma while 

 Littorina and Priapulus even increase their numbers in it. 



Arenicola and Cardium have a negative reaction to contamination. The 

 qualitative distribution of the dominant forms of the littoral fauna is given 

 in Figs. 44 and 45. As shown by the isobenths given, the biomass increases 

 gradually towards the sea, and then falls again towards zero depth. 



The total benthos biomass of this small section of the littoral, of about 

 25,000 m 2 , is about 13-6 tons, of which 4-5 tons is attributed to plants and 9T 

 tons to animals. The onfauna and infauna are represented about equally : 4-6 

 tons of onfauna and 4-5 tons of infauna. The average benthos biomass is 

 422 g/m 2 , that is approximately double that of the macrophytes. 



During high tide a considerable amount of fish enters the littoral zone to 

 feed; this was pointed out by us for the Kola Tnlet as early as 1933. This 



