<DIV><DIV><DIV>Some of the world's most important bodies of water, from the Black Sea to the Bay of Bengal, are classified as ?semi-enclosed marine systems” (SEMS). Separated from the open seas by a strait, island archipelago, or physical process, SEMS are particularly vulnerable to environmental damage and particularly difficult to fully understand and manage.</DIV><DIV> </DIV><DIV><I>Watersheds, Bays, and Bounded Seas</I> provides state-of-the-science information about these complex systems and identifies best management practices to preserve them. With contributions by natural and social scientists, the book examines both the political and biophysical forces affecting semi-enclosed marine systems.</div><DIV> </DIV><DIV>SEMS comprise a substantial portion of the coasts?areas with high population density?and we rely on them for often-competing services such as navigation and transport, disposal of waste, provision of food, extraction of minerals, and leisure. The book describes how human activities could irrevocably alter these fragile ecosystems, exploring threats from runoff to climate change. It also addresses the unique challenges of managing SEMS, including cooperation between multiple  nations.</DIV></DIV></DIV>