Transition to spatiotemporal chaos can resolve the paradox of enrichment

The dynamics and stability of interacting populations in connection to spatial phenomena such as pattern formation and spatiotemporal chaos have recently become a focus of intensive research in theoretical ecology. In this paper, we demonstrate a surprising relation between the long-standing enigma known as Rosenzweig's paradox of enrichment and the formation of chaotic spatiotemporal patterns in an ecological community. Using two different spatially explicit models (a standard diffusion-reaction system and a diffusion-reaction system with cutoff at low population densities), we show by means of computer simulations that transition to spatiotemporal chaos can prevent species extinction in a situation when it would be expected in the case of regular dynamics. The patterns arising in our models are self-organized, and not induced directly by pre-existing spatial heterogeneity of the environment. We also show that the type of the system's response to enrichment essentially depends on the system size and on the rates of eutrophication. (c) 2004 Elsevier B.V. All rights reserved.