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



If in summer the temperature of the air and water is higher in the White 

 Sea than on the Murman coast, yet in winter the fauna of the littoral finds itself 

 in much less favourable conditions. For many months the top layer of the 

 littoral of the White Sea freezes, and is covered with a thick crust of ice. The 

 fauna of the littoral part moves for the winter into the sublittoral, and part of 

 it digs itself deeper and buries itself in a dormant state. 



As on the Murman coast the predominant macrophytes are Fucus vesicu- 

 losa in the upper level and Ascophyllum nodosum in the lower. But in the 

 White Sea the biomass is considerably less than off the Murman Peninsula 

 {Table 88). 



Table 88 



The White Sea sea-weeds are also smaller in size than those of the Murman 

 Peninsula. In the Kola Inlet the length of individual strands of Ascophyllum 

 nodosum reaches 1 m, but in the Gulf of Kandalaksha only 05 m. 



Of the other macrophytes on the littoral one may point out Pelvetia canali- 

 culata, Fucus inflatus and F. serratus. Great peculiarity is given to the White 

 Sea littoral by patches of dwarf Zostera nana which settle on the lowest and 

 moistest parts of the littoral, which are usually left covered with water even 

 at low tide. 



The zonation of the main fucoids of the foreshore — F. vesiculosus, Asc. 

 nodosum and F. inflatus — is not so distinct in the White Sea as off the Mur- 

 man Peninsula : all three species are mingled to a considerable degree. 



E. F. Gurjanova and P. Ushakov (1929) give the following scheme for the 

 vertical distribution of organisms in the littoral zone of the Terskiy coast : 



Horizon I: Dead, owing to the grinding effect of ice. 



Horizon II: Sandy beach Scattered boulders 



Zone I — Sand with biocoenosis: Arenicola Littorina rudis, Balanus balanoides. 



marina-Mya arenaria, Littorina rudis. 

 Zone II — Silty sand with biocoenosis: Zos- Fucoids with their biocoenosis: Gono- 

 tera marina, Eteonearctica,Ariciaquadri- thirea loveni, Membranipora piiosa, 

 cuspida, Pygospio elegans, Lineus gesse- Jaera marina, Gammarus spp., Litto- 

 rensis, Amphiporus lactifloreus, Macoma rina palliata, L. rudis, Hydrobia ulvae, 

 baltica, Littorina littorea, L. rudis. Mytilus edulis, Pholis gunellus, Enche- 



liopus viviparus. 

 On bare patches Usually under stones 



Arenicola marina, Fabricia sabella, Mya Lineus gesserensis, Cephalothrix linearis, 

 arenaria. Halicryptus spinulosus. Between stones : 



Macoma baltica, Pygospio elegans, 

 Oligochaeta. Larvae Chironomidae. 



