with an increase in temperature, less rapidly with a decrease in 

 temperature. The decrease in Q-^q with increasing temperature is a 

 common phenomenon in "sharp" experiments. The slow decrease in AN with 

 a decrease in temperature apparently results from an adaptive increase 

 in the content of photosynthetic enzymes in the cells. 



Table 2. Values of Q^g for various temperature intervals in waters with 

 low, medium and high content of nitrates. 



Temperature Content of N-NO3, iig«atom/Ji 

 Interval, 



o 



C 



<0.1 0.1-1.0 >1.0 



0- 5 2.2 1.6 1.1 



5-10 3.4 2.3 1.5 



10-15 3.8 3.9 2.6 



15.20 2.1 1.8 1.4 



20-25 1.0 1.0 1.0 



25-30 1.0 1.0 1.0 



0-20 2.7 2.2 1.6 



0-30 2.0 1.7 1.4 



The decrease in the value of Qiq with improvement of the conditions 

 of mineral nutrition is notable. It results, first of all, from the 

 more rapid increase in AN with improvement of the conditions of mineral 

 nutrition in warm waters in comparison with colder waters and, secondly, 

 from the higher limiting concentrations of nitrates in these waters (see 

 Fig. 9d). An analogous relationship between the values of Q^q and the 

 conditions of mineral nutrition can be obtained upon analysis of the 

 curves of the variation in the P/B ratio with phosphate content at 

 various temperatures (Riley et al . , 1949). According to our 

 calculations, Qiq for the 5-25°C interval is 2.7 with a low content of 

 phosphates in the water (0.1 pg«atom/£), and 1.6 with a high phosphate 

 content (0.5 yg«atom/£). These figures are close to those obtained by 

 us for the 0-20°C interval. 



The contradiction between data on the influence of temperature on 

 photosynthesis and AN becomes clear when we compare the temperature and 

 concentration of chlorophyll in the tropical portion of the Pacific, 

 Indian, and Atlantic Oceans (Fig. He). Whereas in the waters with a 

 concentration of NO3 <1.0 yg'atom/£, the content of chlorophyll 

 decreases slightly with an increase in temperature, in waters with a 

 good supply of nitrogen (>1 ug«atom£), it is inversely proportional to 

 temperature. We find that in regions of the ocean with poor and 

 moderate conditions of mineral nutrition (NO3 <1.0 uq-atom/i) , the 

 slight increase in AN with temperature is compensated for by a decrease 

 in the concentration of chlorophyll, as a result of which production is 



252 



