mg Carbon assim./m^/day 



cr 



LU 

 UJ 



1000 2000 3000 4000 5000 



T 



X 



A - 



1.90 gC/mVday 



B - 



1.56 gC/mVday 



10 



20 



30 



40 



50 



Figure 4. The vertical profile of dally photosynthesis in (A) a sewage oxidation pond in 

 Lemmon, South Dakota (from Bartsch and Allum, 1957) and in the Northeastern Sargasso 

 Sea (from Menzel and Ryther, in press) . 



