Continental shelves constitute relatively small areas of the ocean (7.6% of ocean area) where water depths are generally less than 200 m. Continental shelves are

those relatively gently grading (average slope of 0.2%; Emery and Uchupi, 1972) platforms which extend from the shore to the point at which the bottom exhibits a more rapid inclination towards the continental slope. Despite their relatively small area, continental shelves provide most of the ocean’s fisheries harvest and oil and gas production. Ironically, though, continental shelf environments have been somewhat of a neutral zone between the “blue water” investigations of the open seas and those of more accessible littoral and estuarine environments. As a consequence, many facets of the oceanography and ecology of continental shelves are less well known than for environments farther inshore or offshore. With the potential of expanded offshore oil and gas development and concerns about dumping of wastes, continental shelves have been the subject of greatly intensified study during the last 10 to 15 years, particularly in the United States. As yet, however, there are few emerging syntheses which provide a scientific framework for a comparative understanding of continental shelf environments.