546 CYCLES OF ORGANIC AND INORGANIC SUBSTANCES 



ton. It should be mentioned that Gushing (1959) pointed out the 

 role of the zooplankton in the "scattering layer" and compared it 

 with the bottom living animals in the shallow sea. 



Because of its relatively high metabolic rate, the zooplankton 

 greatly affects the oscillations of the dynamic balance between 

 living and dead material. When a large swarm of copepods grazes 

 on phytoplankton, only 10 to 20% of this food is actually trans- 

 formed into zooplankton biomass. The remaining 80% is utilized 

 during metabolism or becomes detritus. In either case, decompo- 

 sition is relatively rapid. Because of the marked vertical move- 

 ments of the zooplankton, one water layer may become enriched 

 with the products of decomposition just mentioned. It is thus 

 removed from the layer where it originated. We know that such 

 accumulations actually exist at depths of, for example, 200 to 

 400 m. In this way, the oscillating balance is transferred downward. 

 Here, then, the dynamics of the water may serve to distribute 

 materials evenly throughout the mass. 



We should next consider how a population reacts in a balanced 

 system. Even should the individuals within it remain stable, it is 

 possible that a population, composed in certain proportions may 

 almost reach an equilibrium. In a limited body of water the 

 decomposition of the organic substance may equal its assimilation. 

 This process may best be followed by the energy involved. I 

 believe, however, that the oscillating balance of the phytoplankton, 

 which is transferred deeper through grazing by the zooplankton, 

 is always disturbed especially by the difference which is needed to 

 decompose compounds in solution. In order to get a quasi-stable 

 state, we must choose an area and a period of time sufficiently 

 large such as the Atlantic Ocean. Then allochthonous substances 

 will not be important. The general bare line of the population 

 density would be relatively constant there. Unfortunately, there 

 are insufficient analyses of the total biomass to prove this point 

 with actual data. 



Even if we cannot strictly observe a stable balance between 

 living and dead matter in the ocean, we can determine certain 

 irregularities in the population as a result of the action of the 

 many different processes. In a wide sense we may take this web of 



