2.5 Investigating Streams
Investigating streams is a really fun way for students to learn some of the techniques in topic 2.5.
First we teach the kick sampling technique, give an overview of identifying freshwater macroinvertebrates and how to measure abiotic factors such as stream flow, dissolved oxygen, temperature, pH and conductivity (a measure of water hardness).
An essential part of this fieldwork is a careful assessment of risks and explaining to students how to behave to ensure everyone's safety. I also emphasise the ethics of handling living organisms and the need to return them to their original habitat as quickly as possible.
The sorts of investigations that can be completed are comparing pools and riffles (speed of water), comparing species richness or diversity upstream and downstream of an inflow such as from a sewage plant, or comparing shade and light areas.
Recently HHMI have published a set of resources on riverine and coastal ecosystems. The video embedded here is a good introduction into the dynamic nature of these systems, how scientists study a river system over time and a simple overview of food chain dynamics.