During the course of the year, the relationships between phytoplankton 

 and zooplankton change. It is impossible to estimate the length of the 

 periods of overutilization and underutilization by the methods now used. 

 The small fluctuations in phytoplankton and its small quantities during 

 the peak period indicate that there is not a long period of underutilization. 

 Overutilization is possible, but since the mean annual balance is obviously 

 not negative, a status near the balanced state is probably predominant. 



In the Indian Ocean, the production cycle in the lower levels of the 

 food chain is apparently better balanced in the equatorial community than 

 in the central community. Due to the shorter delay in the equatorial 

 community, brief periods of underutilization of the phytoplankton are more 

 rapidly eliminated. The high correlations of simultaneously studied 

 zooplankton, nutrients and primary production show that the zooplankton 

 plays the primary role in regeneration of the nutrients. In the central 

 community, the delay in grazing of phytoplankton is longer, and there is 

 no close correlation between zooplankton and the regeneration of nutrients. 



In both parts of the section, Tranter also found anomalous, hard-to- 

 explain relations between trophic levels which, in his opinion, resulted 

 from mixing of waters of different origins, thus disrupting the balance. 



Attempts at direct estimation of the degree of balance of production 

 of phytoplankton and its consumption by zooplankton over the course of an 

 annual cycle were undertaken in the Sargasso Sea (Menzel , Ryther, 1961) 

 and the Guinea Bay (Gruzov, 1971, 1973). In the Sargasso Sea, the daily 

 needs for the metabolism of all zooplankton in the 0-500 m layer was 

 found to be close to the daily primary production throughout the entire 

 period of observation (2.5 years). If we consider the needs for the 

 growth of animals (which was not done), the total consumption of algae would 

 be still higher. In the opinion of the authors, in the Sargasso Sea the 

 cycles of algae production and herbivore grazing are balanced, and 

 practically all of the production of algae is eaten. The comparisons of 

 Menzel and Ryther (1961) were based on approximate calculation; further- 

 more, it was not taken into consideration that some of the animals are 

 predators. The peaks in the curves did not coincide precisely, there were 

 delays of 2-4 weeks in the zooplankton, and some of the small peaks in 

 primary production were not accompanied by peaks on the curve of zooplank- 

 ton respiration. 



L. N. Gruzov (1971, 1973) determined the daily consumption of 

 zooplankton in Guinea Bay, based on the needs for respiration and growth 

 of the animals. It was found that over most of the year the trophic 

 relationships of algae and herbivores were balanced, with underutilization 

 occurring only immediately after the upwelling of the water in June. The 

 large generations of herbivores then formed restored the balanced state. 

 It was not stable, and was replaced by overutilization, which was replaced, 

 in turn, by balance with low primary production and a small number of 

 herbivores. A large number of assumptions were made in the calculations; 

 therefore, their accuracy is low, and we cannot say how long the state of 

 balance was retained during the year. However, there were doubtless 

 fluctuations, and the directions of the deviations were probably properly 



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