Linear and non-linear diffusion models applied to the behavior of a population of an intertidal snail

The flux and continuity equations are presented for a non-linear diffusion of populations. The generalized diffusion-reaction equations are presented for both random and biased diffusion, where a bias is introduced toward the existing gradient of the population density. An ecological field experiment is presented and analyzed in light of the non-linear diffusion models. The dispersion of the population of intertidal snails near the Red Sea has been measured over a period of 20 months. The dispersion can be described by a one-dimensional random motion and the obtained diffusion coefficient 0·1 m² day^-1 is in good agreement with velocity and free path measurements of individual snails.