Preface

The seas of the continental shelf where the depth is less than a few hundred metres experience a physical regime which is distinct from that of the abyssal ocean where depths are measured in kilometres. While the shelf seas make up only about 7% by area of the world ocean, they have a disproportionate importance, both for the functioning of the global ocean system and for the social and economic value which we derive from them. Approximately 40% of the human population lives within 100 km of the sea, and the coastal zones of the continents are host to much of our industrial activity. Biologically, the shelf seas are much more productive than the deep ocean; phytoplankton production is typically 3–5 times that of the open ocean, and globally, shelf seas provide more than 90% of the fish we eat. They also supply us with many other benefits ranging from aggregates for building to energy sources in the form of hydrocarbons and we use our coastal seas extensively for recreation and transport. The high biological production of the shelf seas also means that these areas are important sources of fixed carbon which may be carried to the shelf edge and form a significant component of the drawdown of atmospheric CO2 into the deep ocean.

Understanding of the processes operating in shelf seas and their role in the global ocean has advanced rapidly in the last few decades. In particular, the principal processes involved in the workings of the physical system have been elucidated, and this new knowledge has been used to show how many features of shelf sea biological systems are underpinned and even controlled by physical processes. It is the aim of this book to present the essentials of current understanding in this interdisciplinary area and to explain to students from a variety of scientific backgrounds the ways in which the physics and biology relate in the shelf seas. Our motivation to write such a book came from our extensive experience of teaching undergraduate and post-graduate courses in physical oceanography and biological oceanography to students from diverse disciplinary backgrounds and the realisation that there was an unfulfilled need for a textbook to present the maturing subject of shelf sea oceanography combining the physical and biological aspects.