Chapter 4 - Feeding Roles and Food Webs

Abstract

Food webs include herbivores, carnivores, and omnivores, classified on the basis of the category of food ingested. The food sources in rivers are diverse, including algae and macrophytes, coarse (CPOM), fine (FPOM), and dissolved (DOM) organic matter, and the complex biofilm. The functional role of organisms in rivers and streams is largely based on how they obtain and utilize their food resources. The broad categories within food webs are herbivores, organisms which feed on plants (that is, primary production); carnivores, organisms which feed on other organisms; and omnivores, organisms which feed on both plants and animals. A fourth category of detritivores, organisms which feed on organic detritus (small bits of organic matter), is usually included. The final functional group is that of the predators, which are animals that eat other animals. They occur throughout the stream community and have many different adaptations to enable them to pursue and capture prey. Many stoneflies are predators, but only one family of caddisflies, the Rhyacophylidae, are active predators.