This popular undergraduate textbook offers students a firm grounding in the fundamentals of biological oceanography. As well as a clear and accessible text, learning is enhanced with numerous illustrations including a colour section, thorough chapter summaries, and questions with answers and comments at the back of the book. The comprehensive coverage of this book encompasses the properties of seawater which affect life in the ocean, classification of marine environments and organisms, phytoplankton and zooplankton, marine food webs, larger marine animals (marine mammals, seabirds and fish), life on the seafloor, and the way in which humans affect marine ecosystems. The second edition has been thoroughly updated, including much data available for the first time in a book at this level. There is also a new chapter on human impacts - from harvesting vast amounts of fish, pollution, and deliberately or accidentally transferring marine organisms to new environments. This book complements the Open University Oceanography Series, also published by Butterworth-Heinemann, and is a set text for the Open University third level course, S330.