A new type of fish food!

On Friday, May 13, I taught two classes of Manchester Elementary and Middle School 6th graders about macroinvertebrates. Teachers Seth Bonnett and Melissa Rice turned their students over to me for two wet and wonderful hours, one hour per class.

Earlier I'd gone to the Mettawee River, where next Wednesday MEMS students will release their trout, to collect macros. I brought two coolers that I'd adapted with battery-powered aerators and digital thermometers. I also brought a home-made "kick net" (two 3-foot-long sticks with netting/screening stapled to them) and several frozen bottles of water to keep the temperature cooly stable. A rudely timed downpour drenched me as I was right in the middle of my collecting activities.

I used a PowerPoint presentation to  explain macros and, especially, introduce students to the three principal species of living trout food that we hoped to find in the Mettawee: mayflies, caddis flies, and stone flies. One of the PPT slides took us to a four-minute YouTube video (below) that explained how, by collecting macros, one can calculate the Biotic Index of a stream, a measure of its health.

Teacher Bonnett assigned students to one of five groups, each of which got a kit of supplies, including collecting tools, containers, and macro identification charts.

Then I put approximately two quarts of debris- and macro-filled stream water into every group's wash basin and told them to find, classify, and count the macroinvertebrates. Finally, the students used their insect data to calculate the Biotic Index. (Well, actually, not all of the groups got to that point in the time we had available, but some did.) It seemed that the students, even the initially squeamish ones, really enjoyed the activity.

As we were wrapping up, I asked the students how long they thought it would take for the fish to learn to feed on the natural insects in their new environment as opposed to the artificial food they'd been eating for the last few months. Guesses ranged from a month or more to "instantly." So I suggested that we should see what would happen if we put the macros they had in their collecting dishes into the room's trout tank. When the first group poured their bugs into the water, their shrieks and cheers gave away the answer. "Instantly" is right!

I can't think of a more powerful lesson in instinct.

Here's a short video of that moment when a MEMS girl pours her groups macros into the tank.

You can find the "Know Your Macros" PowerPoint slide show, insect identification charts, and the Biotic Index PDF in the "Resources for TIC teachers" folder on the Google Docs site.

resources for tic teachers