Understanding marine pollution and the contamination of coastal environments requires knowledge from a variety of scientific fields. Marine Environmental Quality promotes a multidisciplinary approach to investigations, drawing on not only natural sciences, but also applied mathematics and social sciences. The investigations in this book focus on both organic and inorganic pollutants, firstly in a study conducted in the city of La Rochelle, on the North Atlantic French coast, then expanding the areas under examination to regions of English and Portuguese waters and, lastly, to the Mediterranean Sea. The improvement such research can bring to biomarkers, models and experiments enables equal progress in the quality of seawater in ports and protected areas of coastal regions. The eight chapters of Marine Environmental Quality present many aspects of this research, including experiments with floating barriers, water governance in various areas, sampling sites and sentinel species that act as biomarkers in harbors. Also covered are environmental commitments, both international and local, the risk that marine contamination poses to human health, experimental designs for interactions with microplastics and a study biomonitoring the juveniles of sentinel species. Such results will bring many benefits, to human health, to economic inclusion and to regional development.