As we study the light factor, it is quite important to determine 

 the effectiveness of the utilization of light energy in the process of 

 photosynthesis. We know that as one mole of CO2 is fixed into the 

 products of photosynthesis, 112 kcal of light energy is absorbed, or 

 9.36 cal/mg C. Expressing the data from measurements of photosynthesis 

 in energy units and relating them to the quantity of energy available to 

 plants, we can determine the energetic effectiveness of this process. 

 The phytocenosis tends toward the upper, naturally, unattainable limit 

 of this effectiveness during the course of its evolution. The maximum 

 energy yield of photosynthesis under conditions of scattered long-wave 

 radiation is not over 27%, while for white light the limit is considered 

 to be 20%. The maximum quantum effectiveness is estimated as 8-12% 

 (Rabinovich, 1959). In hydrobiology , the concept of energy 

 effectiveness of photosynthesis has not yet been established. Of 6 

 formulas for the calculation of effectiveness (Patten, 1961d) , only one, 

 in the opinion of Piatt (1969) satisfies the basic requirement of 

 nondimensional ity : 



Q = e"o^ / P^dz, 

 



where P, is the photosynthesis at depth z, expressed in cal/m-^, E= is 

 the light energy striking the surface of the sea (cal/m'^). 



This integral effectiveness has been repeatedly estimated by 

 various authors for various points in the World Ocean (Vinberg, 1960; 

 Ryther, 1962). According to calculations for waters with various 

 gradations of primary production, approximately 0.01 to 5% of the 

 incident light energy is actually utilized in the process of 

 photosynthesis; the energy effectiveness of photosynthesis of 

 phytoplankton increases with increasing productivity of a region. 



The true effectiveness of photosynthesis in individual samples 

 taken from various depths VQ^ can be estimated for a layer 1 m thick by 

 the use of an equation similar to that used in plant physiology: 



Q^ 



Pz 



j K p(^)Ez(^)d^ 



itOO 



where E is the penetrating radiation at depth z, cal/m'^;X p is the 

 index of absorption of light energy by phytoplankton pigments, X is wave 

 length. We (Koblentz-Mishke et al . , 1975) have estimated the energy 

 effectiveness Q^ in the equatorial and Peruvian upwel lings of the 

 Eastern Pacific Ocean. In these areas, Q^ increased from 2% at the 

 surface to 20% at the depth reached by 1% of the light (Fig. 7). 



To calculate Q^ , we must obtain absorption spectra of the 

 phytoplankton pigments and detailed spectral characteristics of the 

 penetrating radiation. These measurements have only recently become 



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