ABSTRACT
A theory of running-water ecosystem functioning has developed in recent years. This theory finds its roots in a series of papers, the most notable of which is by Hynes' in 1975. Taking into account the unity of a river and its valley, to consider them within their catchment, is, in fact, essential for an understanding of the dynamics of running-water ecosystems. The concepts of river continuum 2 and of spiraling of nutrients 3 were largely developed on this notion as was the work on the fish yield of African rivers 4 and the recent syntheses on river ecology. 5 , 6
