Injormatwn Concept in Ecology 



163 



In oceanography, there is a prominent and widely accepted 

 theory that energy accrual by a planktonic system cannot exceed 

 respiratory losses in a uniformly mixed water column (37). Vertical 

 stratification of the organisms is therefore necessary for positive 

 energy balance. This theory has never been rigorously developed, 

 however, and as a matter of fact has recently (38) been invalidated 

 by proof for a countertheorem: Vertically homogeneous plankton 

 communities are energetically feasible. Stratification is therefore 

 not essential to positive energy balance. This conclusion makes the 

 foregoing York River observations difficult to understand. Why 

 should a community expend energy to achieve and maintain pro- 

 nounced vertical stratification if it is not thermodynamically 

 essential for it to do so? Consider the following. 



The important variable relating to community energy balance is 

 the cost as defined in Equation [22]. In Figure 12 mean cost data 

 are graphed as a function of collection and suspension depths; 



(6,10,2.671 



(10,10,2.99), 



SUSPENSION DEPTH (ft) 



Fig. 12. Cost, p TT-i as a function of collection and suspension deptlis (means 



for ten experiments). 



