Significant differences in the interrelationships of phytoplankton 

 and zooplankton can be found between the equatorial and central com- 

 munities in the Pacific and Indian Oceans. For example, in the equatorial 

 region of the Pacific Ocean (at 174°W), the ratio of the quantity of 

 phytoplankton to zooplankton is higher than in the central regions. In 

 the equatorial region there is a significant and high correlation between 

 the biomass of phytoplankton in the 0-100 m layer and the biomass of 

 zooplankton in the 0-500 m layer (r = 0.84; P = 0.95), while in the central 

 regions this correlation is low and insignificant (r = 0.08; P < 0.95)*. 



In the Indian Ocean, within the equatorial distant neritic community, 

 significant positive correlation has been noted (Tranter, 1973) between 

 zooplankton and primary production, zooplankton and nutrients, which is 

 explained by the high value of immediate regeneration of nutrients through 

 the excretions of the animals. In the "subtropical zone" of Tranter, 

 corresponding to our central community, a positive correlation was noted 

 only between phytoplankton and primary production, which determined their 

 direct functional relation, in spite of the weak influence of other effects. 



It was found that in the equatorial community of the Indian Ocean, 

 the delay in the development of zooplankton and its grazing of phytoplankton 

 was shorter than in the central community. In the equatorial region, 

 there is no significant correlation between the quantity of phytoplankton 

 and zooplankton upon simultaneous observation. When phytoplankton is 

 compared with zooplankton collected at the same station after one or two 

 weeks, the correlation coefficient becomes higher and significant. When 

 phytoplankton is compared with zooplankton collected after 6-8 weeks, the 

 correlation coefficient decreases once again. In the central community, a 

 comparison of simultaneous collections and collections with intervals of 

 3-4 weeks reveals a correlation coefficient which is either positive, 

 but low and statistically insignificant, or negative, but comparison of 

 samples collected with a delay of 6-8 weeks yields a higher positive, 

 significant correlation between phytoplankton and zooplankton. 



The reason for the long delay period in the central community is 

 the less constant enrichment of the surface waters with nutrients, the 

 greater duration of the period of low productivity, during which the 

 herbivores starve, and the greater grazing of herbivores by predatory 

 micronekton, the population of which is supplemented by drift from the 

 north (Tranter, 1973). The long delay retards the remineral ization 

 of nutrients and increases the imbalance. The decrease in the rate of 

 development of animals under conditions of starvation has been proven, 

 at least for neritic Copepoda (Woodmansee, 1958; Ummerkutty, 1967). 



*The decimal logarithms of biomass of phytoplankton and zooplankton 

 were used to calculate the correlation coefficient. The biomass of zoo- 

 plankton was calculated on the basis of the number and individual weight of 

 the animals (Heinrich, 1961a), the biomass of phytoplankton was taken 

 from G. I. Semina). 



120 



