| Planktonic organisms live in the upper waters of aquatic ecosystems where turbulence can be strong. In past years, it was proposed by Margalef that turbulence can play an evolutionary role for plankton, selectively favouring larger phytoplankters due to the suspension effects associated with turbulent motions. This view has been questioned and it is still an open problem. Here I discuss some of these issues by illustrating the possible role of suspension with a simple model of nutrient-phytoplankton-zooplankton where the sinking rate is the control variable, and I review some results on the role of turbulence - as opposed to simple cellular flows - in affecting the motion of inertial particles. |
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