Feeding and Swimming Behavior in Grazing Microzooplankton1,2

ABSTRACT A random-walk model of food-searching behavior is considered for the microzooplankton. It is suggested that in still waters a random walk of the conventional sort, modeled by a Wiener process, is less efficient than a Levy walk (a random walk whose excursions follow a Levy distribution) with Levy parameter less than two. For Levy parameter less than one, however, little advantage is gained by further reduction. In turbulent water, on the other hand, dispersion due to a random walk is dominated by the turbulent diffusion of the medium so that the Levy parameter appears to be less important. The effect of chemosensory responses is considered. It is suggested that these are most useful in still water, whereas in turbulent water their value would be less, and a non-specific filtering behavior might be more plausible.