The domination of various animals and plants within the intertidal 

 zone itself and their vertical distribution Are closely related to their 

 competitiveness and endurance for external factors. The small barnacles 

 Chthamalidae settle higher than the larger Balanidae, and of the latter, 

 such large species as Balanus cariosus settle lower than the smaller _B. 

 balanoides , less capable of competing with the mussel and fucoids. 



The geographic vicariate is also rather clearly expressed, although 

 in different oceans the vicariant species have essentially different 

 areas of distribution. For example, Chthaiiialus stellatus extends in the 

 north to Great Britain, whereas its Pacific vicariance Ch. dalli extends 

 no further than Olyutorskiy Bay. In contrast, Pelvetia canal iculata 

 reaches the shores of Murman, while its western Pacific Ocean vicariance 

 _P. wrighti i extends only to Iturup Island. Many littoral organisms are 

 also asymmetrically distributed with respect to the poles. Thus, Patel- 

 lidae and Si phonari idae in the northern hemisphere do not extend farther 

 than the lower boreal waters, whereas in the southern hemisphere they 

 dre characteristic not only for the Subantarctic, but for the low 

 Antarctic as well . 



The lower boreal coast of Europe characteristically features 

 communities of Chthamalus stellatus + Bostrychia scorpioides and the 

 lichen Lichina pygmaea , extending into the uppermost portion of the 

 intertidal zone. The J., pygmaea community is among the few littoral 

 communities in which most of the animals feed on the dominant plant. To 

 the north, _Ch^. stellatus is gradually replaced by Balanoides balanoides , 

 which settles somewhat lower. Characteristic inhabitants of barnacle 

 communities in the lower boreal intertidal zone of Europe Are the 

 Patel la spp. limpets. In some places, particularly those protected from 

 the surf, the Fucoidae dominate, usually forming several bands-- Pel vetia 

 canal icul ata in the upper intertidal zone, then Fucus spiral is , still 

 lower _F. distichus or _F. vesiculosus . With further weakening of the 

 surf, the Fucusae are frequently replaced by great clusters of 

 Ascophyllum nodosum . In the lower portion of the littoral system, a 

 varied community of small algae usually develops, primarily the red 

 algae ( Laurencia pinnatifida , Gigartina stellata . Coral 1 ina officinal is , 

 Lomentaria articulata , Membranoptera alata , Pulmaria elegans , 

 Rhodymenia palmata ), as well as brown al gae Xi-eathesia difformis , some- 

 times _F. serratus ) . With an increase in surf power, the fucoid cover 

 becomes less prevalent, and the quantity of Mytilus edulis increases; in 

 the lower intertidal zone, the brown algae Himanthalia elongata and 

 Bifurcaria bifurcata frequently dominate. In habitats with heavy surf, 

 the lower portion of the littoral is dominated by 1 i thothamnion, Balanus 

 perforatus and Patella aspera (Southward, 1958). 



The composition of the true littoral communities in high boreal 

 waters of the coast of Murman and the White Sea in its general features 

 is the same, but the species composition is impoverished. The number of 

 bands of fucoids is reduced due to the disappearance of the communities 

 of Fucus spiralis , _F. edentatus and Pelvetia canal iculata . The 

 Patellidae are replaced by Testudinalia tesselata . In the intertidal 

 zone of flirman, below the supral i ttoral edge, a community of 

 Porphyra umbilical is + Balanus balanoides usually develops, with some 

 green al gae Enteromorpha intestinal is . etc . , Li ttorina saxatil is . Hyale 



148 



