THE BARENTS SEA 135 



Virgularia mirabilis and Planularia arctica, the polychaetes Placostegus tri- 

 dentatus and Potamilla neglecta, the urchins Echinus esculentus and Brisaster 

 fragilis, the asterids Psilaster andromeda, the cirripiedia Scalpellum strbmi, 

 the amphipods Menigrates obtusifrons, Harpinia antennaria, Erichthonius 

 brasiliensis, Pantopods Pycnogonum littorale, the molluscs Dentalium entale, 

 Poromya gramdata, Astarte sulcata, Scaphander punctostriatus, Triops laser, 

 and others. The following forms are just as characteristic of the cold waters ; 

 the bottom medusa Ptichogastria polaris, the polychaete Glurhanostomum 

 pallescens, the asterid Asterias lincki, the brittle star Stegophiura nodosa, the 

 amphipods Stegocephalopsis ampulla, Acanthostepheia malmgreni, Lepido- 

 pecrewn umbo, Rozinante fragilis, Socarnes bidenticulatus, Pseudalibrotes 

 nanseni, Aegina echinata, the mollusc Acanthodoris sibirica and others. Some- 

 what earlier N. M. Knipovitch (1906) established a similar distribution of 

 bottom-fish of the genera Lycodes and Lycenchelys ; some of them are adapted 

 to cold waters, some to warm. Linko (1907, 1913) gives a very similar picture 

 of some plankton forms Halosphaera, Rhizosolenia, Ceratium, Globigerina 

 and especially the amphipods Hyperia and Euphausiaceae. 



Later M. Virketis (1928) and Kisselev (1928) have also shown that a 

 number of warm-water forms of the zoo- and phyto-plankton are adapted to 

 the streams of Atlantic waters. Among the vegetable forms the following 

 should be noted : Rluzosolenia styliformis, Rh. shrubsolei, Rh. faerocensis, Rh. 

 alata, Corethron criophilum, Ceratium tripos, Thalassiosira decipiens, Chaeto- 

 ceras constrictum, Ch. curvisetum, Coscinodiscus centralis, Nitzschia delicatis- 

 sima and others, and among animal forms : Euchaeta norvegica, Microcalanus 

 pusillus, Temora longicornicus, Metridia lucens, Oithona plumifera v. atlantica 

 and others. 



General distribution of benthos biomass in the open parts of the Sea. The 

 bottom of the Barents Sea is not homogeneous as regards the benthos biomass, 

 both of the total benthos and of its separate component groups (molluscs, 

 worms, echinoderms) (Figs. 51 and 52). 



Areas with particularly small biomass (10 to 25 g/m 2 ) stretch in the Barents 

 Sea from the west to 30° E longitude, extending farther in two tongues — 

 one southeastern and one northeastern ; they also occupy a large area of the 

 depths between the northern part of Novaya Zemlya and Franz Joseph Land ; 

 furthermore the biomass here is still lower than in the western part of the Sea. 

 In contrast to these impoverished areas there are some areas with a most 

 abundant bottom fauna. Five such areas with accumulations of organic 

 matter as living organisms may be pointed out : 



(1) The southeastern slope of the Spitsbergen bank— shallow with biomass 

 up to 1 kg/m 2 or more. 



(2) Separate patches with an increased biomass (300 to 500 g/m 2 or more) on 

 the shores of the northern part of Norway (mostly epifauna). 



(3) The central part of the Barents Sea with a biomass of up to 150 g/m 2 . 

 {4) The Kanin-Kolguev-Pechora shallow with an exceptionally dense patch 



of benthos near Kanin Nos (up to 300 g/m 2 ). 



