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Freshwater ecosystems, such as lakes, rivers, ponds and wetlands are a precious and critically important form of natural resource. This book highlights the need for a strong scientific approach to biomonitoring and conservation of fresh waters and identifies key shortcomings in the present approach. Pertinent examples of this come from the rapid advances made recently on the relationship between biodiversity and ecosystem processes and in food web research, neither of which have so far informed monitoring and management practices. This book also reviews and describes the morphology and material translocation of emergent plants under a set of different environmental conditions, namely, seasonal, spatial, sediment, water depth and harvesting. Furthermore, the environmental impact of phosphorus (P) waste from the aquaculture industry is increasingly a matter of concern in Japan and elsewhere around the world. This book provides nutritional approaches for the reduction of phosphorus waste from yellowtail, one of the highest of any farmed fish species. Other chapters in this book include a review of the benefits of fish embryo cryopreservation for aquaculture and conservation purposes, a discussion of the position of life-history strategies in community ecology, a comparison of the top-down and bottom-up control philosophies for the food chain model so that the most effective management can be identified, the role of systems theory in sustainable management of freshwater systems and ecosystems and a discussion of the present problems that are related to water and sanitation in Sudan.