Sporting hip waders and armed with tweezers and dip nets, students in science class flipped over rocks along the shoreline and pulled handfuls of muck off the bottom of Little Donahue Lake. What tiny treasures did they find under rocks and embedded in mud? They discovered dobsonfly larvae, mayfly nymphs, dragonfly nymphs, and one snapping turtle. Each of these critters provided information that helped the students piece together an idea of the health of the ecosystem and quality of water in Little Donahue Lake. Dragonfly nymphs cannot tolerate much water pollution, and dobsonfly larvae and mayfly nymphs have an even lower tolerance for pollution. Overall this indicated that the water quality in Little Donahue must be very good for these tiny treasures to call this lake their home.
The students also measured dissolved oxygen in water samples from Little Donahue using a Winkler Titration. You may recall from chemistry class that it’s easy to overshoot a titration, adding too much titrant to the sample and ruining the titration; however, under the guidance of experienced science teacher Andy Milbauer, all of the students completed their Winkle Titration successfully! The students also learned about different forms of pollution such as light pollution, thermal pollution, and chemical pollution and they discovered how a pollutant moves through wells, lakes, different soil types, and groundwater using a model of sand, clay, and dyed water.
This science lesson gave students both the knowledge and skills that they need to help monitor water quality and contribute to efforts to improve water quality so that these tiny treasures can be discovered in more lakes and streams in the future.
~ Graduate Fellow Heather Lumpkin
Thank you Stefan for contributing four of the pictures for this post.