ABSTRACT
Rivers and lakes, the main focus of this chapter, constitute less than 0.01% of the world’s water resources and cover only ~0.8% of the Earth’s surface. Wetlands (areas where the water table reaches the surface and persists long enough to support aquatic plants) can also be considered as freshwater ecosystems (see Dobson and Frid, 2009) but these are not considered in this chapter. The study of any ‘ecosystem’ unavoidably requires some knowledge of both the living organisms and their effective environment. Where necessary, this chapter makes reference to the aquatic environ - ment to place understanding of the biota into relevant context, but the reader is directed to Chapters 2 and 3 for relevant information on hydrology and Chapters 4 and 5 for a detailed consideration of water quality dynamics.
