166 Information Storage and Neural Control 



lethals). That the comparatively loosely organized coinmunity 

 may also derive profit through death of its constituent organisms 

 at an appropriate time is an interesting speculation. 



First of all, planktonic systems such as these have, of course, 

 evolved. One of the important taxonomic characteristics of the 

 algal phyla is the nature of food storage products. It would seem 

 that with such a capability already well developed generally in 

 these groups there could have evolved, in the time available, 

 species able to maintain robust metabolic activity right down to 

 the bottom if it were consistent with community design. This 

 would be especially adaptive in water masses where expectation 

 for return to the trophogenic zone (above the compensation depth) 

 through vertical turbulence would be good. Indeed, evolutionary 

 theory asserts that such foims would enjoy a selective advantage 

 over more labile ones. In phytoplankton, the smaller motile 

 species typically possess rapid dynamics and short generation 

 times, but lack the capacity for sustained yields characteristic of 

 larger forms with more conservative dynamics (15). Clearly, from 

 the standpoint of the York system in summer with its slight vertical 

 density gradient, the latter type of organism would not be nearly 

 so satisfactory a component as the former. Their production rates 

 per unit of biomass would be slower in the upper water column, 

 and their collective respiration higher in the depths; the result 

 might be a net energy loss to the conmiunity. Under winter con- 

 ditions when hydrography is such that vertical turbulence is 

 extreme and the water column thoroughly mixed, larger species 

 with longer generation times, lower light optima, and greater 

 capabilities for food storage niight be more serviceable con- 

 stituents. Perhaps, therefore, the seasonal replacement of summer 

 flagellate floras by diatomaceous communities in winter and spring 

 may be taken to reflect community adaptability in response to a 

 changing environment. In view of this, it does not seem unreason- 

 able that particular species may be selected for occupancy in a com- 

 munity under a specific environmental regime, not only for their 

 Darwinian competence in competition, but as well for their compati- 

 bility as functional components of a goal-adapted "machine" (40). 



This possibility would seem to add another dimension to the 

 classical concept of ecological community because of its implicit 



