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In this paper, a nonlinear spatial model is proposed and analyzed to study the effect of pollution on biological population. It is assumed that the pollutants enter into the environment not directly by the population but by a precursor produced by the population itself. It is further assumed that larger the population, faster the precursor is produced, and larger the precursor, faster the pollutant is produced. Criteria for nonlinear stability and instability for both spatial and non-spatial models are obtained. The various parameter ranges for stable homogeneous solutions are identified. By the simulation experiments, it is observed that by applying an appropriate effort F , the population density P can be maintained at a higher equilibrium level. It is also shown that the equilibrium level of the concentration of precursor pollutant, concentration of pollutant in the environment and in the population decrease due to the effort F. [ABSTRACT FROM AUTHOR]

In this paper, we have proposed and analysed a mathematical model to figure out possible ways to rescue a damaged eco-epidemiological system. Our strategy of rescue is based on the realization of the fact that chaotic dynamics often associated with excursions of system dynamics to extinction-sized densities. Chaotic dynamics of the model is depicted by 2D scans, bifurcation analysis, largest Lyapunov exponent and basin boundary calculations. 2D scan results show that μ, the total death rate of infected prey should be brought down in order to avoid chaotic dynamics. We have carried out linear and nonlinear stability analysis and obtained Hopf-bifurcation and persistence criteria of the proposed model system. The other outcome of this study is a suggestion which involves removal of infected fishes at regular interval of time. The estimation of timing and periodicity of the removal exercises would be decided by the nature of infection more than anything else. If this suggestion is carefully worked out and implemented, it would be most effective in restoring the health of the ecosystem which has immense ecological, economic and aesthetic potential. We discuss the implications of this result to Salton Sea, California, USA. The restoration of the Salton Sea provides a perspective for conservation and management strategy., (Copyright © 2013 Elsevier Inc. All rights reserved.)