Assessing Water Quality Through Macroinvertebrates

There are many different types of bugs found in Iowa’s waterways. When looking for them in the water, the type and variety found in creeks and streams can provide clues about the quality of the water they live in. Macroinvertebrates specifically can help limnologists assess water quality when looking at the biodiversity of a stream. Macroinvertebrates are cold-blooded creatures that lack a visible backbone. Examples include crayfish, snails, mayflies, caddisflies, beetles, and more. Macroinvertebrates can be found in water under rocks and leaves, streambeds, grasses, and in all types of water. But, like all living organisms they need certain conditions to survive in their environment. Some macroinvertebrates are more tolerant to different amounts of pollutants than others. By identifying and counting the different macroinvertebrates, limnologists can determine water quality based on how tolerant the species is to pollutants found in water. Shown are a few different ways to collect macroinvertebrates. This can be done by picking up rocks and wood in streams and collecting the macroinvertebrates in a jar. Later they can be identified and quantified.

• What can the macroinvertebrates you find tell you about water quality?

• What kinds of macroinvertebrates can you find in your local stream?
• What kinds of environments do the macroinvertebrates found in your local stream live in? (Ex. under rocks, logs, undercut banks)?
• How tolerant to pollution are the macroinvertebrates you found?

Students could:

• Collect bugs found in their local streams to bring to class in a bug caddie.
• Use apps or flow charts such as PocketMacros to identify macroinvertebrates.
• Graph the number and types of different species.
• Compare and contrast macroinvertebrates from different bodies of water.
• Calculate the Biotic Index of each of each body of water.

• Leaf Pack Network | Virtual Stream Study: This is a virtual way for classes to look at streams and assess biodiversity if there is no stream available to them.
• Iowa Department of Natural Resources (DNR) | Biological Monitoring and Assessment Database: Bionet is public information about the water quality and biotic life found in nearly all of Iowa’s waterways.
• The Stroud Water Research Center | Build Your Own Macroinvertebrate Discovery Tank: The Stroud Water Research Center is a great source for learning about all things related to water quality. This link provides instructions for making your own macroinvertebrate discovery tank. Where students can observe macroinvertebrates brought to them rather than going out to collect them themselves.
• Izaak Walton League of America | Stream Monitoring 101: The Izaak Walton League of America is a conservation society that is dedicated to protecting natural resources. This link has videos that shows students and teachers how to collect macroinvertebrates in streams and introduces them to common macroinvertebrates found in streams.
• Izaak Walton League of America | Biological Monitoring Data Form for Stream Monitors: Izaak Walton League’s Biological Monitoring Data Form for Stream Monitors allows students to calculate the biotic index of a stream. Educators can focus on the Macroinvertebrate Count and Water Quality Rating sections. If looking for extensions the rest of the form is useful for making observations about the sampling location and surrounding area.