This is a book dedicated to show a series of case studies about how benthic habitats are organized and how they function as a tool for any environmental impact studies. The present book documents how the natural condition of these communities is and aims to expand our present knowledge about their organization. The human population growth is driving a very strong pressure over coastal areas, and now more than ever we urgently need elements to evaluate environmental impacts. One of the most striking situations is the loss of biodiversity and the increase of invasive species who modify the trophic networks as well as the community structure. Many endangered species and species related to fisheries depend on the benthic habitat for their basic life cycle stages (reproduction, recruitment, nursery and feeding grounds) who might be impacted by natural and human induced causes. Ranging from species richness studies to population and community structure chapters, this book will bring the reader many options on how to measure environmental impacts. In particular, an analysis of how these environmental studies are made in Mexico provided a good example of how the present report base model is overdue and expresses the need for another approach. Keep in mind the present model does not take into account any statistical approach and is not mandatory in terms of the synergic and accumulative impacts; the lack of this consistency makes evaluation impossible to tell if the impacts are really happening.