For the InstructorThese student materials complement the Water Science and Society Instructor Materials. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty (and this box). Or you can download these pages in several formats that you can include in your course website or local Learning Managment System. Learn more about using, modifying, and sharing InTeGrate teaching materials.
A stream channel supports populations of aquatic organisms such as fish and insects. In contrast, upland systems do not provide even temporary habitat for aquatic organisms. Even when stream channels go dry on the surface, fish and other organisms can survive in isolated pools of water or in isolated areas of flow such as springs and perched aquifers.
Source: Brian Laub
Many organisms can survive in the bed of a stream channel even if the surface is dry, due to hyporheic flow, which is water that flows in the sediments of a stream channel beneath the surface.
Source: Top left panel: Jesse Robinson, licensed under Creative Commons. Bottom right panel: Dave Huth, licensed under creative commons [Attribution 2.0 Generic (CC BY 2.0)].
Even if aquatic organisms do not persist in stream channels year-round, temporary flooding can provide productive systems and isolation from predators, favorable for reproduction and development of young organisms, which can then migrate to perennial rivers as the stream dries.
Source: NASA Landsat 5 – TM images