Investigation of thermodynamic properties in an ecological model developing from ordered to chaotic states

In any ecosystem the equilibrium condition may gradually turn into a chaotic situation for different reasons. In this paper a three species (phytoplankton, zooplankton and fish) model is proposed. Rate parameters are changed according to the change of the size of the organisms. The model is run in different conditions with different sizes of zooplankton by increasing the grazing rate and consequently decreasing the half saturation constant of this organisms following allometric principles. The system exhibits different states (equilibrium point–stable limit cycle–doubling and ultimately chaos) by gradual increment of zooplankton grazing rate and decrease of half saturation constant. This paper also tests the high level of exergy (thermodynamic goal function) of the systems at the edge of oscillation before entering into the chaotic situation. This high level of information supports the hypothesis that the system can coordinate the most complex behavior in these situations.