it dies and is transformed to detritus. Thus, stony and rocky intertidal 

 zones are distinguished by significantly greater primary production 

 than consumption, whereas the opposite is true of intertidal zones with 

 loose sediments. 



On all sediments, particularly rocky sediments, sestonophagous 

 animals (barnacles, bivalves, ascidians, sponges, coelenterata , many 

 higher crustaceans, etc.) are quite important. In the Murman intertidal 

 zone mussels and balani make up 55-90% of the total animal biomass (Kussakin, 

 1963). Therefore, the role of the pelagic zone as a food resource for 

 the population of the intertidal zone is exceptionally important. 



The composition of littoral communities is also influenced by the 

 petrographic composition and morphology of the substrate. It has been 

 shown that changes in the abundance of algae and barnacles are freauently 

 related to variations in the hardness of the rock (Moore, Kitching, 1939). 

 Hard granites and gneisses, even where the surf is strong, can support 

 large Laminaria and F ucuses which attach to them (Gurjanova et al., 

 1930a, b). Phoronis larvae select primarily sandstone to settle on. 

 When loose soils are close to rocks, this results in silting and 

 accumulation of sand, which also influences the composition of littoral 

 communities. Slightly jointed rock masses, particularly cliffs exposed 

 to the surf, maintain rather homogeneous and relatively sparse populations. 

 The number of bands here is usually minimal, and there are few animals 

 except for barnacles and bivalve mollusks. Conversely, the more broken 

 up the rock, the richer the population it can support. The presence of 

 pools, clefts, niches, overhangs and grottoes creates a variety of 

 conditions of illumination, wetting and protection from the surf. In 

 these areas, the littoral communities are particularly rich and varied. 

 Here we also see a general upward movement of communities into higher 

 levels and movement of certain sublittoral inhabitants into the intertidal 

 zone. 



The influence of ice on the littoral biota is both harmful and 

 favorable. The negative influence of ice is primarily a result of its 

 mechanical wearing effect. It is manifested most strongly in an inter- 

 tidal zone with surf, particularly where the morphology of the coast is 

 simple and the ice is in constant motion. In these areas, the population 

 is entirely destroyed in the winter, then after the ice melts, ephemeral 

 (spring, summer or autumnal) or annual communities develop, with pre- 

 dominance of diatoms and small macrophytes ( Chordaria , Pterosiphonia , 

 Polysiphonia , Porphyra , Cladophora , Acrosiphonia ) . As the wearing effect 

 of the ice becomes weaker, conversely, the significance of communities 

 with predominance of multiannual forms such as laminaria, focuses 

 or Sargasso algae increases (Gislen, 1930; Stephenson, Stephenson, 1954; 

 Kussakin, 1958h). Where the coastline is broken, only individual projecting 

 sections of rock are exposed to the action of the ice. Apparently, the 

 significant changes in the composition of communities observed with various 

 degrees of surf action result not only from the variations in tolerance 

 of plants and animals of the surf itself, but also their resistance to 

 the wearing effects of ice. 



138 



