Collect insect larvae and other critters from the bottom of the stream to see if there is a variety of both pollution-sensitive and pollution-tolerant species. Insects are good bio-indicators of freshwater health. Typically, the more pollution-sensitive species (and the more individuals within each species) the better the water quality. Note that "pollution-sensitive" and "pollution-intolerant" mean the same thing.
LEARN TO IDENTIFY AQUATIC MACROINVERTEBRATES
Play Ray Swords' online game: "Name That Bug" to test your knowledge of the insect larvae that serve as bioindicators of stream health! View the Isaac Walton League's video on Macroinvertebrate Identification.
If your class does not have nets for collecting specimens, you can make your own nets using $2 paint strainers stretched over bent coat hangers (free from a dry cleaning store).
UNDERSTAND THE PROTOCOL
Play Project Wet's Macroinvertebrate Mayhem simulation, to see how pollution-sensitive species are more likely to be killed by pollutants, so their presence indicates relatively clean water. View the Watershed Science Center's video: Stream Macroinvertebrates: A Love Story.
SAMPLE THE STREAM
COLLECT AND IDENTIFY SPECIMENS
Use nets to collects specimens from the bottom of the stream, under rocks, beneath overhanging streambanks and in leaf packs, using the protocol described in the Georgia Macroinvertebrate Sampling Training Manual. Pour specimens and water into white tubs or ice cube trays to observe and classify them.
Identify the critters you collected. The Stroud Center's Aquatic Macroinvertebrate Key may be helpful. Divide the organisms into categories according to their pollution sensitivity (see chart to left).
Record data on this Macroinvertebrate Observation Form from Georgia AdoptAStream.
RECORD YOUR DATA
Record data on this Macroinvertebrate Observation Form from Georgia AdoptAStream. Score the specimens according to the Macroinvertebrate Water Quality Index (included in the form).
Make a graph that shows your data in a way that makes it easier to spot trends and patterns. Kids CreateAGraph may be helpful. Screenshot and save any graphs you make at this web site.
Report the data in your Portfolio, and convert it to a labelled graph.
Return to Gather to collect more data, or continue to Reason to make sense of your findings.