

'^,0 

 J,S 

 3,0 

 2,S 

 2.0 



Htr/bit(g) 



# r^v^y V.::\ff 



"^ 



Fig. 2. Structural changes in the zooplankton communities with changes in 

 the nature of vertical movement of the water (Timonin, 1971). I, Zone 

 of intensive divergence; II, Intermediate zone, weak upwelling of water; 

 III, Zone of convergence or stable stratification of water; B, Total biomass 

 of zooplankton; Hsp, Species diversity; Htr> Diversity in trophic structure; 

 1, Swallowing predators; 2, Biting predators; 3, Sucking predators; 



4, Animals with mixed feeding (omnivores); 5, Coarse filter feeders; 



5, Fine filter feeders. 



in the bodies of its organisms. Soon, processes of dissi 

 to predominate in the community and the total mass of pi a 

 The maximum biomass, as the community develops, tends to 

 trophic chain--first to the herbivores, then to the preda 

 leading to basic changes in the trophic structure of the 

 picture of displacement of the maximum of biomass upward 

 chain is clearly demonstrated by a model of the functioni 

 community (Vinogradov et al., 1971, 1973) (see Fig. 5.4) 

 observations (Vinogradov, Voronina, 1964; Tinomin, 1971; 



milation begin 

 nkton decreases, 

 shift along the 

 ceous forms, 

 community. The 

 along the trophic 

 ng of a tropical 

 and by field 

 Gueredrat, 1971). 



The increase in the mean dimensions of organisms as a community 

 matures touches both phytoplankton and zooplankton. As the community 

 matures, the significance of larger animals (macroplankton and micronekton) 

 increases, while the mean dimensions of the animals of the mesoplankton and 

 microplankton increase. For example, in the South Atlantic as we move from 

 the South African upwelling to the central halistatic regions, the mean 

 weight of microplanktonic and mesoplanktonic organisms increases by a 

 factor of 3-3.5, while the fraction of mesozooplankton in nets and water 

 bottle plankton from the upper 200 meter layer increases from 2/3 to 4/5 of 

 the total mass of animals (Kovalev et al . , 1976). As the biomass decreases 

 and the mean dimensions of organisms increase, as we have seen, the variety 

 of the community increases (see Fig. 2), i.e., these processes act as if 

 they were inversely dependent (Sutcliffe, 1960; Longhurst, 1967; Timonin, 

 1971; etc.). 



19 



