THE ROLE OF MACROINVERTEBRATES IN STREAM ECOSYSTEM FUNCTION

This review focuses on some of the roles of macroinvertebrate function al groups, i.e. grazers, shredders, gatherers, filterers, and predator s, in stream-ecosystem processes. Many stream-dwelling insects exploit the physical characteristics of streams to obtain their foods. As con sumers at intermediate trophic levels, macroinvertebrates are influenc ed by both bottom-up and top-down forces in streams and serve as the c onduits by which these effects are propagated. Macroinvertebrates can have an important influence on nutrient cycles, primary productivity, decomposition, and translocation of materials. Interactions among macr oinvertebrates and their food resources vary among functional groups. Macroinvertebrates constitute an important source of food for numerous fish, and unless outside energy subsidies are greater than in-stream food resources for fish, effective fisheries management must account f or fish-invertebrate linkages and macroinvertebrate linkages with reso urces and habitats. Macroinvertebrates also serve as valuable indicato rs of stream degradation. The many roles performed by stream-dwelling macroinvertebrates underscore the importance of their conservation.