turbulent energy levels in the laboratory or in the field, it may also reflect the 
feeling of many ecologists that the small size of plankton generally places them 
below the size scale at which turbulence is “felt”. Both of these considerations, 
along with technical difficulties, have caused almost all marine microcosm 
studies to neglect turbulence as a factor in their experimental design. In the 
simplest terms, the justification appears to have been that since turbulence is 
difficult to measure, hard to mimic, and of unknown importance, it was 
reasonable to avoid the problem of deciding on how to include it in 
microcosms. There is a certain amount of appeal to this argument, especially 
since there are so many other problems to be resolved in developing a 
microcosm. However, the evidence in the papers cited above, as well as the 
experience of anyone who has tried to culture or maintain phytoplankton and 
zooplankton in the laboratory, suggest that turbulence is an important 
consideration in pelagic systems. Our earlier experiments with turbulence in 
marine microcosms also indicated that the scaling of mixing energy in 
laboratory tanks can dramatically influence the results of phytoplankton and 
zooplankton growth studies in the microcosms (Perez et al 1977). The 
argument about plankton being too small to “feel” turbulence is also 
questionable. 
Turbulence 
Following Richardson (1926), Richardson and Stommel (1948), Stommel 
(1949), Batchelor (1950) and others, the flow of turbulent energy from large 
scale motion is passed down through successively smaller eddies until it is 
dissipated in viscosity. Above a certain size, the energy content of eddies is 
solely a function of their size (k) and the rate of energy flux (e) through the 
system. Below this critical size, defined by 
k = 
*3 1/4 
6 
where v = the kinematic viscosity 
e = the energy flux per unit mass 
k = upper limit of the kolmogoroff viscous zone 
viscous forces become important and the energy content decays more rapidly 
with decreasing size as energy is dissipated. In order to give some feeling for the 
scale involved, it is possible to estimate k for the West Passage of Narragansett 
Bay using a value, for the energy dissipation of 4.3 x 10 13 ergs sec' 1 (Levine 
and Kenyon 1975) and an approximate volume of 7.2 x 10 8 m 3 . The result 
su 88 ts ts that k is on the order of 0.06 cm. While this is larger than individual 
phytoplankton cells found in these waters (<0.01 cm), it is about the size of 
384 
