Today we learned about macroinvertebrates! Macros are aquatic organisms that are large enough to see without a microscope (“macro”) and have no backbone (“invertebrate”). They are often insects in their nymph and larval stages, clams, worms, crayfish, and snails.
To collect our samples, we used D-nets, where part of the net is flat to lay against the bottom of the stream. We stood downstream of the nets, gently tapping the bottom of the creek and under logs and roots. Some of us even grabbed a handful or two of leaves. We grabbed samples from different parts of the Jacks’ Creek because some macros like different environments, like muck or leaf litter, for example.
We then dumped our nets into trays of water to find and sort the macros. When we found a specimen, we used spoons to move them from the large tray to individual cells of ice cube trays. This helps us easily sort, identify, and count the macros. From our samples, we discovered lots of cool organisms–especially scuds that look like tiny shrimp and a fat, wiggly cranefly larva.
Macroinvertebrates are indicators of water quality, as some can tolerate polluted water and others can only survive in clean water. Based on the variety and number of organisms we find, we can calculate how healthy the streams are (using this sheet). Based on our findings today, Jack’s Creek is in good health! We ended the day in the Pine Forest, climbing trees and building our forts. Miraculously, neither of them fell during the wind storm last weekend!
