Stream Food Webs
Food webs are graphic representations of the flow of energy and carbon through organisms in ecological systems. In simple ecosystems, energy may flow along a simple food chain consisting of a primary producer (plants), a primary consumer, a secondary consumer, ... and a top predator. In most ecosystems, however, the linkages among organisms are more complex and form a food web.
Primary producers in southern Appalachian streams with autochthonous energy sources are harvested by primary consumers. Another energy pathway comes from organic detritus, primarily from allochthonous energy sources, which is consumed by detritivores such as invertebrates and microbes.
At a higher trophic level, secondary consumers like predatory invertebrates and fishes feed on primary consumers and detritivores.
Food webs in streams can be quite complex, involving a diversity of organisms that consume energy and carbon. In some cases, organisms consume only part of the carbon or feces produced that are metabolized by other organisms. This material becomes fine particulate organic matter (FPOM), either suspended or deposited in the stream. In this simplified view of a food web in a small woodland stream, two abiotic pools of carbon and energy, FPOM and dissolved organic matter (DOM), are included with the biotic producers and consumers.
Encyclopedia ID: p1491
