A Problem of Size and Scale 
The increasing use of relatively small experimental ecosystems or 
microcosms in marine research has raised a number of interesting questions 
related to the importance of size or scale in natural, as well as experimental 
systems. In pelagic marine environments, one of these questions for which we 
have very little relevant information is the importance of turbulence in the 
water. The relationship between turbulence and scale was first formalized by 
Richardson (1926), who distinguished between classical Fickian diffusion (in 
which scale is not a factor) and the mixing that is characteristic of turbulent 
fluids such as the sea. While the nature of turbulence is extremely complex, 
Richardson’s concept of turbulent energy passing through a series of 
progressively smaller eddies from the wavelength at which it is put into the 
fluid until it is ultimately dissipated in viscosity has continued to prove 
valuable in studying the mixing of marine waters (Okubo 1971). In natural 
systems, turbulent energy is added at a rather large scale by winds, tides, and 
major currents. Since none of these is usually effective in microcosm tanks or 
bags, some artificial means of introducing turbulent energy at smaller scale may 
be required to develop pelagic ecosystems that are credible experimental 
analogs of the “real world” (Perez et al 1977). 
There are at least two aspects to the turbulence problem, one involving the 
actual distribution of organisms, particles, or dissolved constituents in the 
water — the problem of patchiness (see Steele 1974), and the other involving 
the metabolic or behavioral responses of organisms to water turbulence. The 
study of plankton patches usually concerns water masses on a scale larger than 
the largest microcosms yet developed (1300 m^, 10 m dia.; see Menzel and 
Case 1977), and it is generally conceded that this aspect of the ecology of 
marine waters is not well represented in microcosm experiments. The 
importance of this omission is not yet known. While there have been numerous 
studies which have documented the response of sessile plants and animals to 
the special case of turbulence in flowing water (Fox et al 1935; Kerswill 1949; 
Whitford 1960; Jaag and Ambiihl 1963; Whitford and Suchumacker 1964; 
Mclntire 1966; Westland 1967; Nixon and Oviatt 1971), the responses of 
pelagic organisms to small scale turbulent energy have received much less 
attention. 
With the exception of an older qualitative study of the morphological 
response of Daphnia to water motion by Brooks (1947), the recent work by 
Pasciak and Gavis (1975) on the relationship between turbulence and nutrient 
uptake by phytoplankton, and our own studies on marine plankton in 
laboratory microcosms (Perez et al 1977), the effect of water turbulence on 
the growth and metabolism of planktonic organisms is almost totally unknown. 
While this situation is largely a result of the difficulties involved in measuring 
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