132 



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



Fig. 50. Murman Biological Station of the Academy of Sciences of the u.s.s.r. in the 

 Dal'naya Zelenetskaya Guba on the Murman Peninsula coast (1938). 



100 m) and the population of the branched Lithothamnion are found every- 

 where. Both these communities are peculiar to places with vigorous water 

 movement ; the polychaetes Thelepus cincinnatus, Eunice norvegica, the mol- 

 luscs Astarte elliptica, A. crenata, A. sulcata, Cardium fasciatum, C. elegantu- 

 lum, bryozoans of the genera Retepora, Flustra and Defrancia, Porifera of the 

 genera Tethya and Tenthorium, and Ophiopholis aculeata are peculiar to the 

 first one. This community includes quite a number of warm-water forms. 



Among the population of the branched Lithothamnion the following are of 

 significance as regards their numbers — of the echinoderms Ophiopholis acu- 

 leata, Strongylocentrotus droebachiensis, Cucumaria frondosa, of the molluscs 

 Pecten islandicus, Saxicava arctica, Modiola modiolus, of the tunicates Cyona 

 intestinalis, Руша aurantium, of the crustaceans Balanus porcatus and Eupa- 

 gurus pubescens. 



The basic quantitative indices for the three above-mentioned communities 

 are given in Tables 55 and 56. 



When moving east along the Murman coast and north along the Novaya 

 Zemlya coast the fauna suffers considerable impoverishment ; a large number 

 of boreal and sub-Arctic forms disappear, and a series of high Arctic species are 



Table 55 



Biomass, per cent 



Community 



Depth of Mean 



occur- No. of total • 



rence species biomass Infauna Epifauna Bottom Seston 



m g/m 2 feeders feeders 



Porifera-Brachiopoda-Bryozoa 1 00-200 

 Ascidia obliqua 50-100 

 Population of branched Litho- 

 thamnion 5-75 



131 

 93 



170 



524 



321 



23-3 

 4-3 



76-7 

 95-7 



100 



41-3 



7-4 



54-3 

 91-1 



