Fig. 3. Diagram of distribution 

 of various trophic links of plank- 

 ton and nekton in the zone of 

 divergence and convergence near the 

 equator. 1, phytoplankton; 



2, phytophagous zooplankton; 



3, predaceous zooplankton; 



4, large fish. 



Rhincalanus cornutus in the rich equaLo; lal divergence is observed in two 

 narrow strips along 0°30"-l°N and S latitude. Thus, as they grow, the 

 crustaceans, which develop in the "juvenile" water, as it diverges, are 

 carried north and south by the meridional components of the currents. The 

 maximum of sexually mature individuals, however, is not shifted as far 

 from the center as is the maximum of predaceous copepoda. 



Naturally, the shift is greater, the longer the time of maturation of 

 a species, the greater the speed of the current or the higher the position 

 of the organism in the food chain. Therefore, accumulations of macroplankton 

 and the large fish which feed on it, as a rule, are located to the side of 

 a zone of divergence and usually fall along the nearest convergence, beyond 

 which they cannot be carried by the meridional component of the equatorial 

 currents (Fig. 3). In the equatorial zone, it is at these convergences 

 that we observe the greatest accumulation of flying fish (Parin, 1968). 



A. G. Timonin (1971) used the example of the tropical regions of 

 the Indian Ocean to study the changes of the roles of various trophic groups, 

 trophic and specific diversity in communities in regions with varying 

 intensity of upwelling, i.e., varying degree of maturity of the population 

 of the community (see Figs. 1, 2). The young communities in regions of 

 intensive upwelling are characterized by high plankton biomass, low trophic 

 and specific diversity, resulting from an increase in the total quantity 

 of zooplankton due to domination by a few species. Filter feeders predominate 

 (up to 58%), among these--coarse filter feeders such as Eucalanus attenuatus , 

 E. subtenuis and Rhincalanus cornutus , which make up as much as 45% of 

 the total biomass and 85% of the biomass of filter feeders. Predators 

 represent 20-25% of the total mass of zooplankton. Where the water ascends 

 upward more slowly, the total biomass of zooplankton is lower. Specific 

 diversity increases, since the degree of domination by individual species 

 decreases. The trophic structure becomes more diverse, but filter feeders 

 still predominate, representing about 40% of the total biomass. The fraction 

 of predators increases to 30-35%. Mature communities, in regions where 



42 



