SECT. 4] 



GEOGRAPHIC VARIATIONS IN PRODUCTIVITY 



Table III 



373 



Mean Amount of Light (g cal/cm 2 /min) in a Water Column with Values of 

 Depth (z) and Incident Radiation (To) and Extinction Coefficient (k) as Indicated. 



(After Riley, 1957.) 



Sep. 



Dec. 



Feb. 



Mar. Apr. 



Jul. 



Fig. 12. Primary production in shallow, intermediate and deep stations of the continental 

 shelf off New York. (After Ryther and Yentsch, 1958.) 



