The interest in work in oceanography and marine biology and its relevance to global environmental issues creates a demand for authoritative reviews summarizing the results of recent research. Oceanography and Marine Biology: an Annual Review has catered for this demand since its foundation. Its objectives are to consider, annually, basic areas of marine research, returning to them when appropriate in future volumes; to deal with subjects of special and topical importance; and to add new ones as they arise. The 39th volume follows closely the objectives and style of the earlier volumes,...