Mighty Macros

Grade 4 scientists continued their investigations of water quality by heading to two sections of LaBarque Creek to conduct a macroinvertebrate survey.  Macroinvertebrates are probably what you would call bugs or insects that you find in a creek. They are invertebrates that are large enough to see with the naked eye.  Most of these organisms are the larval stage of flying insects like mayflies and dragonflies.  Some of them are permanent aquatic organisms like crayfish, mussels, snails, and riffle beetles.

 

The organisms we were looking for are considered indicator species because they can tolerate polluted waters to different degrees. They are classified as being sensitive, somewhat tolerant, or tolerant. Macros in the sensitive group can only survive in high quality water that is rich in dissolved oxygen and free of pollution and toxins. The somewhat tolerant group can stand some pollution and other less favorable environmental qualities, but not that much. Those in the tolerant group can survive in poor water quality conditions (pollution, toxins, low dissolved oxygen rates, higher pH, etc.) Using Missouri Stream Team monitoring protocols we can determine the condition of the water in the stream based on the organisms that live there.

     

To carry out this study, our students headed to LaBarque Creek Conservation Area and Hilda Young Conservation Area.  LaBarque is known for being one of the healthiest watersheds in Missouri and typically yields fantastic results when looking for macroinvertebrates.  This trip was no different.  Even though it was a little later in the year than what is ideal we were still able to haul in a diverse cross-section of organisms and determined that LaBarque Creek is indeed a very healthy stream.  The students found the larvae of mayflies, stoneflies, damselflies, dragonflies, crane flies, dragonhunters, scuds, pouch snails, crayfish, and more!

   

Back in the classroom students began to sharpen their skills of observation as we learned how to correctly identify these creatures, which were sometimes as small as a centimeter in length! Students were introduced to dichotomous keys and gained valuable experience in understanding the subtle differences between the various species.  It was awesome to watch their abilities grow.  Just a few weeks ago these were “just bugs”, and now students are talking about being able to “see the feathery gills on the abdomen” or to describe the insects “fleshy, fingerlike appendages”.  All of this ties into our thematic study of water which includes ecology and classification of plants and animals. 

 

Our Grade 4 students kept one macroinvertebrate of each species and learned how to ethically preserve specimens for future studies in class and for educating others about the importance of these indicator species and also water quality in general.  Students used their knowledge of the metric measurement and graduated cylinders to make the solution for preserving the specimens.  We also spent time in class reflecting on the ethical treatment of the organisms we study.  Next the students will begin to dig deeper into how all living things are classified and create a system for labeling our own specimens, beyond just their common names.