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Fig. 19. Position of maxima of biomass of various species I'f copepods 

 according to collections from the research vessel OB'. I, Cross section 

 south of New Zealand, March-April 1956; II, Cross section along gS'^E, 

 April 1957; III, Cross section from Mirniy to Aden, May 1956; AC, 

 Antarctic Convergence; 1, Calanoides cutis >25 mg/m^; 2, Calanoides 

 acutus , >50 mg/m^; 3, C alanus propinquus , >25 mg/m^: 4, Calanus 

 p ropinquus , >50 mq/m3; 5, R hincalanus gigas , >25 mg/m3; 6, Rhincalanus 

 g igas , >50 mg/m3 (Voronina, 1970) . 



generations. The spring migration occurs over a large portion of the 

 water area in a rather short time, but is delayed in the south. The 

 summer maximum is observed in the northern zone in February, in the 

 intermediate and southern 2one--in March. Thus, it occurs in the northern 

 and middle zone two months later than the maximum of phytoplankton. The 

 reason for this delay is that the comparatively small overwintered 

 populations of copepods underutil izes the primary production and does 

 not prevent the phytoplankton bloom. Only after breeding and growth of 

 the new generation does effective consumption of algae begin, achieving 

 a balance that is rapidly followed by overutil ization which, in the 

 opinion of many researchers, is the main reason for the seasonal drop in 

 the abundance of phytoplankton. At this time (in April), individual 

 planktonic animals begin to leave the euphotic zone, causing a decrease 

 in biomass. In the northern zone, conditions are still favorable for 

 the vegetation of phytoplankton, and the decrease in consumption leads 



104 



