The aim of this book is to discuss practically useful (operational) bioindicators for sustainable coastal management, criteria for coastal area sensitivity to eutrophication and an approach set a 'biological value' of coastal areas. These bioindicators should meet defined criteria for practical usefulness, e.g., they should be simple to understand and apply to managers and scientists with different educational backgrounds. Central aspects for this book concern effect-load-sensitivity analyses. One and the same nutrient loading may cause different effects in coastal areas of different sensitivity. Remedial measures should be carried out in a cost-effective manner and this book discusses methods and criteria for this. Remedial strategies should generally focus on phosphorus rather than nitrogen because the effects of nitrogen reductions can rarely be predicted well and nitrogen reductions may favour the bloom of harmful cyanobacteria. Three case-studies exemplify the practical use of the bioindicators and concepts discussed in the book. The first concerns how local emissions of nutrients affect the receiving waters when all important nutrient fluxes are accounted for. The second concerns how to find reference values for 'good' ecological status to set targets for remedial actions. The third gives a reconstruction of eutrophication. If the development during the last 100 years can be understood, key prerequisites to turn the development would be at hand. This book should attract considerable interest from researchers in marine ecology, consultants and administrators interested in management and studies of coastal systems.