Mathematical ecology deals with the development of mathematical model for studying the patron of relationship between organism and their environment. Mathematical modeling is a useful tool to understand the behavior of natural systems. We hope this reference book will meet the needs of theoretical biologist for modeling and analysis of few real world problems. It is well known fact that environment is getting polluted by different types of chemicals, emitted due to various human activities. The biological populations are regularly exposed to several natural and artificial chemicals which are toxic to them and their environment as well. Many of researchers, while developing population models, studied the interacting species systems with nutrient cycling. Further, with the advancement of mathematical ecology, the researchers also developed and studied the effects of pollutant on interacting species system using mathematical models. It may be noted here that a title or no attention has been given towards the study of the effect of pollutant on interacting species systems with nutrient cycling using mathematical models.