The ratio of the quantity of phytoplankton to the quantity of 

 zooplankton is low. In the Indian Ocean in the 0-200 m layer with 

 observations made once per 2 months it fluctuated, based on the content 

 of C, between 1.4 and 6 (Tranter, 1973). In Guinea Bay, in the 0-100 m 

 layer, with observations made once per month, the ratio of phytoplankton 

 to zooplankton, based on wet weight, was 0.05-0.5 (Gruzov, 1971). In 

 the North Atlantic and Polar basin, the ratio of wet weights of phyto- 

 plankton and zooplankton is 10-100 in the spring, 1-5 in the summer 

 and less than 1 only in the winter (Bogorov, 1938). 



All of this indicates the greater degree of utilization of phyto- 

 plankton by zooplankton in the tropical community. According to Steemann 

 Nielsen (1958), the seasonal stability of the quantity of algae and 

 significant homogeneity of their distribution in space, characteristic 

 for oligotrophic tropical regions, can be achieved only as a result of 

 grazing by herbivores. If grazing did not limit growth, the fluctuations, 

 as observed in cultures, would be significant, and at the moment of 

 utilization of the reserves of nutrients, the growth of algae would stop 

 completely, which is not observed in oligotrophic regions. Certain 

 experimental observations confirm this phenomenon as well. In the 

 Sargasso Sea, after relatively large particles (presumably consumers) 

 are removed from the water, the quantity of small particles, primarily 

 algae, increases (Sheldon et al . , 1973). In the central waters of the 

 North Pacific, primary production in the euphotic layer agrees simultane- 

 ously with the rate of arrival of nutrients from the deeper layers and 

 the rate of excretion of zooplankton (Eppley et al . , 1973). 



A near balanced production cycle is reached in these regions 

 primarily due to the relatively stable abiotic factors. A second important 

 factor is the short delay period of grazing. For most planktonic Copepoda, 

 breeding continues throughout the year (Gueredrat, 1974; Woodmansee, 

 1958; Farran, 1949), one generation following another, with no clear 

 domination of any given stage of development. Therefore, as the quantity 

 of phytoplankton increases, the quantity of herbivores can increase 

 rapidly by the growth of already existing juvenile and middle stages and 

 by breeding and subsequent development of a new generation. As the 

 quantity of phytoplankton increases, the breeding rate of the Copepoda 

 increases (Prasad, Kartha, 1959). Judging from observations in inshore 

 regions, generations of tropical Copepoda are short when food is 

 abundant. Off the coast of India, a generation of Acartia erythraea 

 develops in a week (Subbaraju, 1967). The development of a generation 

 of P aracalanus c rassirostris in culture requires a minimum of 2 weeks 

 (Lawson, Grice, 1973) . Under oceanic conditions, we can expect longer 

 generations, particularly after long periods of starvation, but still, 

 year-round breeding and the varied age composition should help to reduce 

 the delay period. 



The structure of oceanic communities, characterized by a diverse 

 species composition, the lack of strong dominance of a few species and 

 a complex, branched food net with many trophic levels can also facilitate 

 a stable production cycle. 



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