In coastal seas, from the tropics to the poles, seaweeds supply the energy required to support diverse coastal marine life and provide habitat for invertebrates and fish. Retaining the highly successful approach and structure of the first edition, this is a synthesis of the role of seaweeds in underpinning the functioning of coastal ecosystems worldwide. It has been fully updated to cover the major developments of the past twenty years, including current research on the endosymbiotic origin of algae, molecular biology including 'omics', chemical ecology, invasive seaweeds, photobiology and stress physiology. In addition to exploring the processes by which seaweeds, as individuals and communities, interact with their biotic and abiotic environment, the book presents exciting new research on how seaweeds respond to local and global environmental change. It remains an invaluable resource for students and provides an entry into the scientific literature of a wide range of topics.

Inorganic carbon, nitrogen and phosphorus are the main elements required by seaweeds for photosynthesis and growth. This review focusses mainly on nitrogen, but the roles of carbon and phosphorus, which may interactively affect seaweed physiological processes, are also explored. Fundamental concepts such as limiting nutrients, sources, and ratios, mechanisms of nutrient uptake, nutrient assimilation and storage, patterns of uptake and preferences for different nitrogen sources are discussed. The roles of abiotic (water motion, light, temperature, salinity and desiccation) and biotic (life stages and age class) factors in nutrient (nitrogen, phosphorous, carbon) uptake are also reviewed. Understanding species-specific nitrogen physiologies and nitrogen source preferences will enable polyculture of different seaweed species and the use of seaweeds as biofilters in integrated multitrophic aquaculture systems.