Interest in oceanography and marine biology and the relevance of those fields to global environmental issues creates a demand for authoritative reviews that summarize recent research. Oceanography and Marine Biology: an Annual Review has catered to this demand since its foundation, by the late Harold Barnes, more than 35 years ago. It is an annual consideration of basic areas of marine research; it returns to certain topics when appropriate in future volumes and adds new topics as they arise. The favorable reception accorded to all the volumes shows that the series is fulfilling a very real need: both reviews and sales have been gratifying. The 39th volume follows closely the objectives and style of the earlier volumes, continuing to regard marine sciences-in all their various aspects-as a unit. This edition adds commentary on bioturbation, seagrass beds and other topics. The series is an essential reference text for research workers and students in all fields of marine science, so it finds a place in not only the libraries of marine stations and institutes but also universities. It consistently ranks among the highest in the marine biology category of the citation indices compiled by the Institute for Scientific Education.