time, three methods are used for determination of phytoplankton 

 carbon: the indirect methods based on ATP (Holm-Hansen, Booth, 1966) 

 and chlorophyll (Vinberg, 1960; Strickland, 1960), and the direct method 

 based on microscopic counting of phytoplankton cells and measurement of 

 their volume, with conversion by equations (Mull in et al . , 1966; 

 Strathmann, 1967). All three methods are based on coefficients obtained 

 in cultures. For the conversion from ATP to Cp|^y^, a single coefficient 

 of 250 is used, regardless of the ecologic conditions (Holm-Hansen, 

 1969), while the conversion from chlorophyll to ^n\)\/t ^^^^ ^^^ 

 coefficient 30 for cultures and nutrient saturated phytoplankton and 

 coefficient 60 for light-inhibited and nutrient-deficient phytoplankton 

 (Strickland, 1960). Obviously, the failure to use differential 

 coefficients for different ecologic conditions must lead to variations 

 in the results of the application of these two methods of estimation of 

 Cp^yt- One shortcoming of the third method is its frequent and 

 significant undercounting of the number of cells and biomass of 

 phytoplankton as a result of losses of fragile forms. 



1.2 Comparison of Results of Determination of Parameters of 

 Primary Production at the Surface of the Ocean . 



In order to estimate the contribution of systematic errors of the 

 methods outlined above to ecologic calculations, we have determined the 

 most probable correlations of production (P), chlorophyll (CI) and cell 

 number of phytoplankton (N) in pairs for the eutrophic, mesotrophic and 

 oligotrophic stations (Fig. 2). The best agreement was produced for the 

 production-phytoplankton relationships. The differences in other 

 relationships fall within the limits of the standard deviations. The 

 similar course of the curves obtained directly and calculated on the 

 basis of the results of two other relationships indicate that the 

 material used was sufficiently representative. 



Conversion coefficients from N to B of phytoplankton (Fig. 3) and 

 ^phyt ^^^^ derived on the basis of a large quantity of material. For 

 approximate estimates, one can assume that 1 mg of carbon is contained 

 in 2 million cells of phytoplankton-- the average for various regions of 

 the World Ocean during various seasons of the year (Koblentz-Mishke, 

 Vedernikov, 1973). Using these relationships, we can approximately 

 estimate the specific production (P/B), and, using the equation n = 

 log(P/B + l)/log 2, we can calculate the rate of cell division n 

 (assuming that each cell division results in a doubling of the content 

 of carbon in the daughter cells). Based on the same graphs, we can 

 calculate the mean content of chlorophyll in the cells of phytoplankton 

 (Cl/N) and in the biomass (Cl/Cp^y^), the assimilation of carbon by one 

 cell (P/N), as well as the daily issimilation number (DAN), separately 

 for the oligotrophic, mesotrophic and eutrophic zones of water (Table 1, 

 Fig. 4). The indices which are calculated without using the quantity of 

 phytoplankton agree rather well with the data from the literature, 

 particularly for the mesotrophic and eutrophic waters. Corrections for 

 possible systematic errors in the determination of primary production 

 and chlorophyll have little influence on the equations produced. The 

 situation is different with the equations whirh include data on cell 

 count and biomass of phytoplankton, and on the content of carbon in the 

 phytoplankton. Authors who have determined C-^y^ by various methods 



233 



