The proceedings of the joint BMB 15 and ECSA 27 Symposium provides the reader with some of the advances in the study of biology, ecology, and physical and biochemical modelling of enclosed or semi-enclosed marine, brackish and estuarine systems (the Baltic Sea, the North Sea, the White Sea, the Black Sea, and the Ionian Sea). The book covers a wide range of topics in this field, including hydrography and modelling, eutrophication, environmental gradients, pelagic and benthic communities, introduced species and case studies of environmental impact. This volume of 28 papers summarizes current knowledge on the broad-scale topics of enclosed and semi-enclosed marine systems, and should be of interest to scientists, students and administrators within the field of marine ecology, environmental impact control and conservation.