many of the diatom chains found in the bay (~0.05-0.1 cm) and smaller than 

 the dominant zooplankton. Moreover, even below this size, the effect of 

 turbulent energy persists. As the time averaged flux of energy through larger 

 eddies is increased, the viscous shear in the Kolmogoroff zone will also increase 

 and this increase in shear wall be felt even at the very small scales seen by the 

 plankton. Moreover, as the energy flux through larger eddies increases, the 

 upper size hmit of the Kolmogoroff zone will decrease, so that larger plankton 

 will begin to experience direct turbulent effects. 



In addition to simple mechanical effects, such as the disruption of feeding 

 or copulation by zooplankton, this turbulent energy flux at small scale may 

 influence the plankton (or other particles) in at least two ways. Around any 

 given cell of size C, there will exist a thin laminar boundary layer in which 

 Ficldan or molecular diffusion must be rehed upon to transport dissolved gases, 

 nutrients, waste products, etc. Since molecular diffusion is much slower than 

 turbulent diffusion, this is often the rate limiting step in exchange processes 

 between the cell and the surrounding medium. As the turbulent energy flux in 

 the medium increases, however, the water just outside of the boundary layer is 

 renewed more rapidly, with the renewal rate being proportional to: 



(2) 



This increase in renewal rate tends to maximize the concentration gradient 

 across the laminar boundary layers and, thus, the diffusion of materials across 

 the layer. In addition, the increase in renewal rate by turbulent velocity will 

 also decrease the thickness of the boundary layer itself, since the boundary 

 layer thickness is proportional to: 



Z — (3) 



Again, the reduced thickness of the laminar layer will increase the exchange 

 rate of materials between the particle and the medium. 



While the cascade of turbulent energy through successively smaller eddies 

 has been studied frequently in the sea (Okubo 1971), the emphasis in the field 

 has generally centered on measurements of eddies larger than 10 m. The nature 

 of the turbulent energy spectrum in small experimental ecosystems has only 

 recently begun to receive attention (Boyce 1974, Steele et al 1977, Gust 



387 



