This August Great Peninsula Conservancy hosted a community science event at Curley Creek Tyner Preserve. The Benthic Sampling Walk & Talk provided people with an opportunity to learn how benthic macroinvertebrates can be used to assess water quality on GPC preserves, as well as get their boots wet in Curley Creek! Benthic macroinvertebrates are invertebrate species, from insect larvae to snails, that live on the bottom of water bodies such as ponds and creeks.
The AmeriCorps VISTA members at GPC facilitated macroinvertebrate sampling of both a pond and Curley Creek on the preserve. Visitors waded in to capture macros such as caddisflies, stoneflies, dragonflies, worms, beetles, and more.
Participants then learned how to identify the species they caught using magnifying lenses to see the fine details needed for identification.
This monitoring work uses a Pollution Tolerance Index (PTI) formula where the species caught are ranked according to their sensitivity to pollution. Below you can see the PTI chart used to determine water quality in this method. The samples from both places had PTI numbers in the 20-22 range, which is within the “Good” range, suggesting that pollution levels are fairly low in the Preserve’s waterways.
To get participants thinking critically, they were asked if they thought this data felt accurate for Curley Creek Tyner Preserve. They pointed out that there could be issues of accuracy in sampling because it was many people’s first time, that the time of year and time of day sampled could influence results, and that this was only one data point. The group suggested testing at different times of year would help create a more accurate picture of water quality on the preserve.
As it turns out, GPC’s environmental education program Land Labs has been facilitating a lesson in the Spring. Students perform the very same benthic sampling while learning how water quality impacts macroinvertebrates and salmon. (You can read more about this lesson on the GPC blog.) Below, are graphs that combine all the student and Walk & Talk data taken at the Preserve. What do you notice about trends in these graphs?
Thanks to all the participants who came out and helped GPC staff continue to monitor the preserve and sample during the Fall, when sampling hasn’t typically happened. By performing these types of water quality assessments, GPC can continue to monitor and respond to potential impacts on this important preserve, where otters raise their families and salmon make the long journey to spawn every Fall.