The beginning of breeding of the Calanus and euphausiids and the 

 rise of the biomass (Fig. 6) coincide with the beginning of blooming of 

 phytoplankton and is also unrelated to the absolute temperature index 

 (Zelickman, 1958; Kamshilov, 1952, 1955). Since the spermatophores of 

 the male of Calanus and euphausiids are formed long before the spring 

 rising of animals to the surface water, it is possible that spawning 

 occurs only after a certain period which the mature individuals must 

 spend in the light. Breeding may occur over a broad temperature range, 

 approximately identical for all the mass species: for Thysanoessa raschii , 

 from -1 C to 7-10 C, for T. inermis , from 0-7-10 C, for Calanus , from 

 -1 to n C. The prespawning concentrations of euphaisiids and Calanus are 

 formed in the euphotic layer, where their young will later feed. The 

 oceanic, primarily predatory, forms ( Thysanoessa longicaudata , Pareuchaeta 

 spp. , Metridia spp. ) are less closely related to the phytoplankton; 

 therefore, their area of breeding is broader and more continuous, their 

 breeding period more extended. The breeding peaks of the three massive 

 phytophages are displaced with respect to time; for example, in the 

 Barents Sea, the Calanus breeds in April, T. inermis in May, T. raschii in 

 June. 



Since the phytoplankton bloom begins in various sections of the water 

 masses at different times, naturally an alternation develops in the zones 

 of abundance of the young, then of the mature individuals of the massive 

 species. Therefore, the relative significance in the increase of the 

 biomass of the deep water regions and the shallow-water regions changes by 

 seasons: During the spring-summer season, the biomass of zooplankton is 

 higher in the shallow water during the fall and winter--in the deep-water 

 regions. This process of redistribution of living matter is related to 

 the seasonal ontogenetic migrations and cycles of breeding of the holo- 

 and meroplankton animals (Fig. 7). The neritic waters (in the comparatively 

 productive layer) are richer. 



The separation of the zones of large numbers of Calanus and young 

 euphausiids in May-June in waters with abundant phytoplankton bloom can 

 be explained not only by the competition for food, but also by exocrine 

 interactions. Generally, direct and indirect trophic and topical inter- 

 relations of the dominant species of zooplankton with the nannoplanktonic 

 heterotrophs and with the phytoplankton are very close. Sometimes, these 

 bonds are broken at the final, trophic level, bypassing the previous 

 levels. For example, in the neritic communities of colonial birds, 

 the euphausiids and mysids are eaten in large numbers by thick-billed 

 guillemots and kittiwakes, the Calanus by the little auk (Zelickman, 

 1958; Golovkin et al . , 1972). Sometimes, direct expulsion of a species 

 from its ecologic niche is observed, as occurred in 1956 with Pseudocalanus 

 elongatus , developing rapidly in Svyatonosskiy Bay of the Barents Sea after 

 grazing of Calanus finmarchicus there by the Murmanc herring (Zelickman, 

 1961a). 



The summer maximum of zooplankton is created by £. finmarchicus , 

 Pseudocalanus , Oithona , Oncaea , Fritillaria , Oikopleura , and in August- 

 September--by abundant small hydromeduses and ctenophores. In the shallow 



56 



