. Biology of the seas of the Marine biology -- Soviet Union; Hydrology -- Soviet Union. GENERAL CHARACTERISTICS OF THE NORTHERN SEAS 45 cus there are large amounts of Metridia longa (II). These two species together form 90 per cent of the total plankton biomass. The total biomass is about 90 mg/m3. In the upper layers of the northern part of the Kara and Laptev Seas Calanus finmarchicus (not exceeding 60 per cent of the total biomass) is still the main constituent of the plankton, but ? hyperboreus (III) is mixed with it to a considerable extent and, what is of special interest, in th
. Biology of the seas of the Marine biology -- Soviet Union; Hydrology -- Soviet Union. GENERAL CHARACTERISTICS OF THE NORTHERN SEAS 45 cus there are large amounts of Metridia longa (II). These two species together form 90 per cent of the total plankton biomass. The total biomass is about 90 mg/m3. In the upper layers of the northern part of the Kara and Laptev Seas Calanus finmarchicus (not exceeding 60 per cent of the total biomass) is still the main constituent of the plankton, but ? hyperboreus (III) is mixed with it to a considerable extent and, what is of special interest, in the deeper layers there is a considerable admixture of forms penetrating from the north along the troughs from the warm intermediate layer of the Arctic basin, such as. Fig. 6. Distribution of main types of zooplankton in northern seas (Jashnov, with certain alterations). /, // Pronounced predominance of Calanus finmarchicus (90 per cent of biomass; many boreal forms present); /// Predominance of Calanus finmarchicus (not more than 60 per cent of total biomass) and C. hyperboreus; a considerable admixture of Atlan- tic forms from intermediate layer; /^Predominance of Pseudocalanus elongatus and a selection of brackish-water forms; V Same as IV but with an admixture of Pacific Ocean forms. Pareuchaeta norvegica and P. glacialis, Conchoecia elegans, Themisto abys- sorum, Eukrohnia hamata, Diphyes arctica and others. The plankton of the less saline littoral waters of the bordering seas is characterized by the great pre- dominance of brackish forms. The sea form of Pseudocalanus and brackish- water Limnocalanus ghmaldi, Drepanopus bungei and Derjuginia tolli (IV) are predominant here. All these copepoda crustaceans comprise 60 per cent of the plankton biomass. About 20 per cent of the plankton consists of Sagitta elegans, mixed with a considerable quantity of fresh-water forms. Finally in the southern part of the Chukotsk Sea, as a result of an increase of salinity, the brackish-wate
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