The study of stream ecosystems: a functional view

Abstract

Trophic dynamics and energetics formed the conceptional foundation for much stream research in the 1960s and 1970s. Subsequent development has tended to emphasise the integration of stream ecology with geomorphology, hydrology, forestry ecology, etc and the recognition of the fundamental importance of spatial and temporal scales in the investigation of stream ecosystems. Consequences of such a holistic approach include the adoption of a watershed perspective, the notion of streams existing in a state of dynamic equilibrium in time and space, and the river continuum concept: drainage networks of streams and their receiving rivers form a predictable continuum of increasing channel size and attendant biological characteristics. Mid-sized streams (orders 4-6) will tend to be autotrophic, primarily a consequence of reduced shading and increasing nutrient concentrations; the annual excess of production over respiration is transported along the drainage network. Other biological implications are noted. Active lines of enquiry include: dissolved and particulate organic matter interactions; food quality and the nutritional biochemistry of invertebrates; anaerobic habitats; and riparian influences. -P.J.Jarvis