X 



t- 



Cl 

 bJ 

 Q 



Figure 4-19. 



Physical conditions of the marine water column during summer 

 (stratified) and winter (well mixed) which affect phytoplankton 

 growth. Arrows indicate mixing; N= nutrients; dots are 

 phytoplankton (C.S, Yentsch 1977). 



4-54 



