This report addresses coastal ecosystem degradation as a consequence of human driven increases in nutrients such as Nitrogen and Phosphorus. Effects on ecological communities such as algal blooms, loss of seagrass beds, and coral leaching are described. Excess nitrogen is emphasized as being the limiting nutrient in coastal systems. Political and scientific consideration to support the control of Nitrogen pollutions is discussed. Sources of nutrients to coastal ecosystems are listed, as well as a comparison of wastewater and nonpoint sources. Agriculture and fossil-fuel combustion are discussed as sources of nitrogen. Issues in Ecology is an ongoing series of reports designed to present major ecological issues in an easy-to-read manner. This Issue summarizes the consensus of a panel of scientific experts based on the information that was current and available at the time of its publication in 2000.