. Biology of the seas of the Marine biology -- Soviet Union; Hydrology -- Soviet Union. THE BERING SEA 833 distribution of the three dominant species of Copepoda: each species is pre- dominant in a certain horizon, therefore, although they feed on the same species of diatoms, their competition for food is less intense since their main habitats belong to different horizons. Eurythermic species—Oithonasimilis, Sagittaelegans, Calanus finmarchicus, Parathemisto libellula—become predominant in winter as a result of the cool- ing of the upper layer (down to 1,000 m) in the western part of
. Biology of the seas of the Marine biology -- Soviet Union; Hydrology -- Soviet Union. THE BERING SEA 833 distribution of the three dominant species of Copepoda: each species is pre- dominant in a certain horizon, therefore, although they feed on the same species of diatoms, their competition for food is less intense since their main habitats belong to different horizons. Eurythermic species—Oithonasimilis, Sagittaelegans, Calanus finmarchicus, Parathemisto libellula—become predominant in winter as a result of the cool- ing of the upper layer (down to 1,000 m) in the western part of the Sea and the total zooplankton biomass is considerably reduced. It increases again by the second half of the summer (Fig. 423), Eucalanus alone producing a biomass of 200 to 1,000 mg/m3. The amount of zooplankton decreases considerably. Fig. 423. Distribution of zooplankton biomass (mg/m3) in the 0 to 100 m layer in June 1952 (Vinogradov). again in autumn. In the Bay of Anadyr, however, zooplankton reaches its highest development in autumn only, mainly on account of Eucalanus bungii. In the north of the Bering Sea the biomass remains low throughout the year, only at certain places does Calanus finmarchicus form great concentrations with a density of up to 100 mg/m3, and 400 specimens per 1 m2. The mass forms of the plankton Calanoida multiply at different times in the Bering Sea, thus making the best use of the food resources available (A. Geinrich, 1955). The multiplication of Calanus finmarchicus takes place at the beginning of the greatest phytoplankton development; Eucalanus bungii develops somewhat later, followed by Calanus tonsus (small race). The multiplication of Calanus tonsus (large race) is not connected with phyto- plankton vegetation. The multiplication of Metridia pacifica proceeds throughout May to November, while Calanus cristatus spawns in December to February. Most of the forms mentioned produce only one generation 3G. Please note that these images are
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