/Or: 





" o o 

 o o 



00 g 





o ^^o'^o 'oo.* "^ 





i:ifk^=^^-•^ 





— — Sr-T 



X 2 



X 



+ 



- - xxx3^ .* 



^ 





X 



o • 

 'x^ o 



2- -i!- 



+0 O + O/ O OX 



/^l? 



/r^ 



N-NO^, ug-atom/i 



Fig. 8. Relationship between logarithm of concentration of ni ,rd^es 

 and phosphates in the surface layer of various regions of the yJjrld 

 Ocean. 1, Indian Ocean; 2, Pacific; 3, Atlantic; 4, Barents Sea; 5, 

 line representing N:P = 15. 



Some hold the opinion that it is hard to find a better "fertilizer" 

 than the deep water which rises in the regions of upwelling. However, 

 the favorable effect of deep water on the photosynthesis of 

 phytoplankton is not immediately felt, due to the depressing influence 

 of nonchelated heavy metals, which disappears when this water is held in 

 darkness. 



Enrichment experiments conducted in the southwest Atlantic and in 

 the Caribbean have shown that the degree of influence of nutrients on 

 the level of primary production in waters of low productivity in the low 

 latitudes is several times greater than in highly productive waters in 

 the higher latitudes (Kabanova, 1972; Kabanova et al . , 1974a, b). 



Comparison of level of primary production and conditions of mineral 

 nutrition . At the present time, it can be considered firmly established 

 that in most regions of the World Ocean, primary production is limited 

 by a shortage of the elements of mineral nutrition. On the global 

 scale, the concentration of nutrients and the level of primary 

 production change over the water area in a similar manner. 



For individual regions of the ocean, the correlation coefficient 

 between production and the concentration of nutrients has been 

 calculated. For example, in the northern part of the Indian Ocean, a 



245 



