0250 



Primary Production 



JFMAMJJASOND 



010 5 

 3 



I 



c 

 o 



05 I 



- 



tr- 2.5 



-2.5 



Excretion 



Detritus Decay 



Phytoplankton I ^ Net Rate 

 Uptake^^ J 



i / 



J i I i V i i 



IOVEDTUDHI 



I L 



JFMAMJJASOND 



Figure 7. Top: Simulated concentration of 

 available phosphorus and rate of gross primary 

 production in the epilimnion. Bottom: Rate 

 plots indicating control of available phosphorus 

 dynamics. Stippled area represents net rate of 

 change. From Scavia (1979). 



:0.069 



■ — U.IU) -— 1 ui -'!__ 



nPo.02= j External S ources H jj 

 ^ ' ". 



Hypolimnion 



Figure 8. Phosphorus flow diagram. Concentration 

 in boxes are in yg P«L _1 «d~ . These values are 

 averaged over the period of July-September for 

 the top 15 m. Phytoplankton, zooplankton, and 

 detritus are evaluated in the model in terms of 

 carbon and are converted to phosphorus for this 

 figure by assuming a Cj^qqPj^ atomic ratio. From 

 Scavia (1979). 



68 



