Stream Ecosystems

Abstract

Many of us have spent time around and in streams and rivers but perhaps have not given much thought to the ecology and natural history of these aquatic systems. Although each stream or river is unique in its own right, it is the dominant influence of flowing water in these systems that provides a common thread distinguishing streams and rivers as a major class of aquatic resource. At any scale – from local to global – these fluvial ecosystems play a valuable role in the biosphere as habitats and as receptors, transformers, and transporters of water, materials, and energy. In this analysis of stream and river ecosystems, major topics of discussion include environmental conditions in streams and their surrounding watersheds, stream hydrology, habitat structure, stream biota and food webs, energy flow and nutrient-cycling processes, and the ecological effects of disturbances and stress in streams and their drainage basins. In one study from the Mississippi River drainage system, there is a striking example of connections between human farming activities in one region producing adverse ecological impacts in a distant region with a river network acting as the transport medium linking the two locations.