THE BARENTS SEA 



113 



Halicryptus spinulosus, Scoloplos armiger, Capitella capitata, Ophelia limacina, 

 Travisia forbesi, Nephthys ciliata, Glycera capitata, Lineus gesserensis, and 

 Amphiporus lactifloreus. 



In the rocky shale facies besides the above-mentioned the following biocoe- 

 noses can be distinguished : Fucus serratus, Spirorbis borealis and Lacuna 

 pallidula ; fauna : the polychaetes Amphitrites johnstoni, Phyllodoce maculata, 

 together with nemerteans and oligochaetes. 



The biocoenoses of Balanus balanoides and Mytilus edulis are most import- 

 ant for the facies of cliff, boulders and large rocks. The first of these forms is 

 most developed at a level of 2-5 to 3-5 m above zero depth, within the zone of 

 the luxuriant fucoid development. A narrow band of Fucus vesiculosus (20 to 

 30 cm in width) extends over all; under it there is a one-metre band of 

 Ascophyllum nodosum. Below this there is a band of Fucus inflatus and F. 

 serratus. Numerous animals find excellent protection from drying out under 

 the large fronds of Ascophyllum when the tide is low. 



Fucus vesiculosus gives a comparatively small biomass of 4 to 7 kg/m 2 . 

 Ascophyllum nodosum, which gives the largest biomass of all the fuci, may 

 yield 10 to 18 kg/m 2 . As a rule the population of Balanus balanoides is most 

 dense directly under the fucus border, where they form a solid white band 

 10 to 20 cm in width and clearly visible even from a distance. The number 

 of young balanus settled on the rocks may reach up to 100 to 200 thousand 

 per square metre, and their biomass up to 1 kg/m 2 . The total biomass of the 

 animal biocoenosis of Balanus on the Murman coast is as high as 3-2 kg/m 2 

 and sometimes even higher (up to 10 kg/m 2 ). The quantitative composition 

 of the given biocoenosis is set out in Table 44. 



With the growth of the young recently-settled balanus, their number con- 

 siderably decreases : during the period from May to September, the loss in 



Table 44 



H 



