The Food Web
Algae and plants form the basis of the food web. They produce their own energy from sunlight and raw chemicals and provide food for other organisms. In the in-stream environment, aquatic and semi-aquatic flowering plants (macrophytes) and algae are an important source of food for herbivores. Plants along the banks or riparian zone of the river also provide large amounts of organic matter (e.g. leaf litter and woody debris) to the river ecosystem.
Herbivores occupy the next level in the food web. There are two basic types. "Scrapers" graze on algae and decomposers such as fungi and bacteria. "Shredders" consume plant leaves and stems and old or dead plant material or detritus. They include invertebrates such as aquatic snails and yabbies (Click here to find out more about aquatic invertebrates in the Broken River). Above the herbivores in the food web are the predators. These are usually the larger invertebrates and animals such as fish, frogs, lizards and birds. All parts of the food web need to be supported for a healthy ecosystem.
(Source: Gooderham, J, and Jerie, K. 1999. An introduction to stream ecosystems. In Rutherfor, ID, Jerie, K and Marsh, N. A rehabilitation manual for Australian streams, Volume 1. Land and Water Resources Research and Development Corporation and Co-operative Research Centre for Catchment Hydrology.)
