|
All the factors that go into making a stream, as well as the diversity of instream habitats, are extremely complex and interwoven. Factors that go into a stream's composition include: precipitation (seasonal variations), topography (determines stream gradient), geologic substrate (from which minerals are leached), land uses (determine sediment and contaminant loading of surface runoff and groundwater), soil and bedrock types (determine groundwater availability), sunlight or shade (affect temperature and algae growth), and riparian vegetation (for shade, nutrient source, insect habitat, and more). In addition, streams widen and their volumes increase as they are joined by tributaries and other streams.
In these three cross-sections, we are trying to simplify the complex. Three stream types have been categorized using stream size, temperature, and food sources. Characteristic benthic habitats and common fish and insects (Functional Groups) found in each are also noted. (In real life, expect exceptions!) Click on any illustration at right to learn more. Click on italicized words to view Glossary definition in the Resource Center. |