Macro Invertebrates and Stream Health

Macro invertebrates are a useful tool to measure the health of a stream. A macro invertebrate is a creature without a backbone that can be seen with the naked eye. Certain macro invertebrates have varying degrees of sensitivity to pollution. The presence of many varieties of macro invertebrate indicates a healthy stream. Inversely the absence of macro invertebrates indicates poor stream health. The over-all health of a stream can be evaluated by enumerating all the species of macro invertebrates found in samples collected from a stream during a set time.

We measured the stream health of Maury Creek using the Michigan Clean Water Corps Stream Macroinvertebrate Data Sheet.  We chose this creek because it is situated below Shanty Creek Resorts, a highly developed area, meaning lots of impervious surfaces and turf grass. On this sheet we recorded the longitude, latitude, date, stream name, and collection start time before collecting samples. We collected samples for thirty minutes timed with a stopwatch. We collected samples by stirring up the mud of the river with our feet and holding a net downstream. We also scraped the banks of the river and logs in the river with our nets. Whatever we caught in our nets we rinsed into the collection bucket with the help of another intern. We switched collectors at the fifteen-minute mark. In this way whoever had been collecting macro invertebrates rinsed nets and whoever rinsed nets and got to collect macro invertebrates as well. Once the half hour was up, we brought the samples back to the Antrim Conservation District where the macro invertebrates were counted and scored.

We found the macro invertebrates in our sample by dipping out a portion of the mud of the sample and pouring it over a sieve that was set onto a white plastic tray. Once we had some of the sample on our tray, we looked for every thing that moved or looked alive. When we had found a creature, we put it into an ice cube tray and identified it by using The Key To Macroinvertebrate Life In The River. Each time we had finished removing all visible living things from the mud sample on our trays, we threw the mud out the back door and refilled our tray with new mud from the collection bucket.

After the collection bucket was empty, we recorded all species and numbers of that species on page 2 of the evaluation sheet where there was a list of common aquatic macro invertebrates.This list was divided by sensitive, somewhat sensitive, and tolerant. In the spaces beside the species names, we tallied the numbers of each species that we found. After that was finished, we wrote “C” for common beside all the species if there were eleven or more and “R” for rare if there were less than eleven. The numbers of R’s and C’s from each group were multiplied by the corresponding constant in the Stream Quality Score area. The totals for each group were added together for the total stream quality score. A score above 48 indicates excellent stream health, good is 48-34, fair is 33-19, and poor is anything below 19. The overall score on Maury Creek was 36.7, which translates into a “Good” stream health score.

No previous recorded studies have been done on Maury Creek. This study will serve as a baseline to evaluate stream health in the future. In later years, we may be able to discover trends concerning pollution of Maury Creek. For now, we know that little if any pollution is in Maury Creek.

The Creek will be evaluated again in the fall and then for the next several years, each spring and fall.

More information see these resources:

Michigan Clean Water Corps (MiCorps)
Shanty Creek, Cold Creek, Maury Creek, Finch Creek and Grass River Macro Data History: Oct 15, 2013
2012 Summer Intern Final Report

This report was submitted by Tineka Witt, September 2013.