regeneration, on the average, is proportional to the indices of destruction 

 rate, such as the BOD (Redfield et a1., 1963). Microorganisms have no 

 monopoly on the regeneration of nutrients. Other heterotrophs also take 

 part in the destruction of organic matter. Their share in this process 

 generally corresponds to the share of their participation in the 

 destruction of organic matter, or the fraction of the total energy flow 

 which they expend. There are rather stable relationships between the 

 respiration of zooplankton and the quantity of mineral forms of nutrients 

 which they liberate: they average 80 for phosphorus, 20 for nitrogen 

 (Conover, Corner, 1968). These values in this case are significantly lower 

 than the stoichiometric relationships with total oxidation of matter by 

 phytoplankton, which is related to the selective assimilation of nutrient 

 enriched substances and their incomplete oxidation by zooplankton. During 

 bacterial oxidation of organic matter in sea water which is poor in 

 nitrogen and phosphorus, these relationships may also be lower than the 

 stoichiometric values, particularly since a significant portion of the 

 nutrients is consumed by the bacteria themselves for biosynthesis. The 

 consumption of inorganic nutrients by bacterioplankton in some biotopes 

 makes the bacterioplankton a serious competitor for the phytoplankton. 

 This occurs in surface tropical waters where, even within the euphotic 

 zone, most of the inorganic phosphate is consumed by bacteria, but not by 

 phytoplankton (Sorokin, Vyshkvartsev, 1974), since the microflora oxidizes 

 primarily "old" organic matter, brought in from other regions of the ocean, 

 which is poor in phosphorus. 



The most important function of the microflora in the cycle of 

 nutrients is that they can mineralize or assimilate biogens in such stable 

 dissolved organic compounds as nucleic acids. In a number of biotopes, for 

 example, in the surface tropical waters, the main stock of nutrients is in 

 just these forms. Their inclusion in the metabolism of the plankton 

 community can occur only through the process of biosynthesis of the 

 bacterial biomass, which is then mineralized by the bacteria-consuming 

 planktonic animals, primarily the ciliates and phytophagous Copepoda. It 

 has been established that the ciliate, in a period of 5-15 minutes, 

 liberate a quantity of mineral phosphate equal to its total content in the 

 body. For the calanoids, this time is 5-10 days. The Protozoa, in spite 

 of their relatively low biomass, apparently play a leading role in the 

 mineralization of the biogens in the organic matter of the bacteria and 

 phytoplankton (Johannes, 1964, 1968), since the Protozoa perform a 

 significant fraction of the total metabolism of the community (see Fig. 

 12). 



Studies of the vertical distribution of nitrates and phosphates, the 

 content of organic phosphorus, O2 and CO2 in various regions of the ocean, 

 have revealed regular changes in the relationship of their concentrations, 

 which develop in the course of mineralization of the organic matter of the 

 phytoplankton. Thus, the atomic ratio of nitrates to phosphates in the top 

 300 m of water is close to that in the cells of the phytoplankton--15:l 

 (Redfield et al . , 1963). It has still not been established with certainty 

 just where the processes of mineralization are located in the waters of the 

 ocean (Menzel , 1970). The assumption which was earlier held, that 

 processes of mineralization and related formation of the oxygen minimum 

 occurred due to utilization of locally produced organic suspended matter, 

 cannot explain the regularities of quasi-conservative distribution of 



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