The influence of the temperature factor on the photosynthetic 

 activity of natural populations of phy topi ank ton has been less 

 studied. The values of Q^q for the phy topi ankton of Japanese lakes and 

 the Oyashio Current in 10-20°C temperature interval is equal to 2.0 

 (Ichimura, Aruga, 1959; Ichimura et al . , 1962). It was found without 

 preliminary adaptation of the algae. After such adaptation, the 

 temperature coefficient in cultures of certain algae may decrease 

 significantly--sometimes by a factor of 2 (Steemann Nielsen, Jorgensen, 

 1968). These authors believe that the reason for this is the great 

 increase in the quantity of photosynthetic enzymes (per unit of active 

 pigment and per cell) at low temperatures. 



Finenko and Lanskaya (1971), using cultures of the same species, 

 taken from different latitude zones, showed that algae adapted to low 

 temperatures decreased the rate of cell division significantly more 

 slowly as the temperature drops than do the same algae which have 

 vegetated at higher temperatures. 



A comparison of temperature and primary production under optimal 

 light conditions was conducted on the basis of the data from almost 200 

 stations in situ in the tropics of the Pacific and Atlantic Oceans 

 (Fig. llaT. THere is a general tendency toward feedback between the 

 level of primary production and temperature. This tendency results from 

 the fact that the temperature is negatively correlated with the 

 concentration of nutrients: a decrease in the temperature of the 

 euphotic layer is observed in areas where the deep waters rise. In 

 zones of different content of nitrates, the temperature has no influence 

 on production (N-NO3 <1.0 ug*atom/£). Apparently, the temperature, in 

 and of itself, has no influence on the level of production in the 

 tropics. 



However, analysis of the data of 360 stations in situ in various 

 latitude areas has shown that the temperature has a"~positive effect on 

 AN. An analysis was conducted of the relationship of temperature with 

 AN for marine phy topi ankton inhabiting waters with poor conditions (N- 

 NO3 <0.1 pg-atom/Ji), moderate conditions (N-NO3 = 0.1-1 ug-atom/Ji) and 

 good conditions of mineral nutrition (N-NO3 >1.0 yg«atom/A) (Fig. lib). 



In all three zones, there is a positive correlation between the 

 values of AN and temperature. As the temperature rises from 5° to 25°C, 

 the values of AN increase, with a low content of nitrates, by a factor 

 of 3.9; with a moderate content of nitrates, the increase is by a factor 

 of 2.9, and when the nitrate content is high, the increase factor is 

 2.2; this increase is reliable with a high level of significance. The 

 curves show that the temperature influences the assimilation activity of 

 the chlorophyll practically only up to 20°C. The range of 20-30°C can 

 be considered optimal for the values of AN. At 20-25°C, they are 1.03- 

 1.13 times higher than at 25-30°C, but the difference between the mean 

 values of AN at these two levels is not reliable, which is probably 

 explained by the adaptation of the algae to high temperatures. A 

 temperature of the surface waters of over 25°C is observed in the 

 tropics, and in summer in the inshore waters of the temperate 

 latitudes. Adaptation to this high temperature is apparently possible 



250 



