Counting mussels with the Upper Sangamon River Conservancy

Counting mussels with the Upper Sangamon River Conservancy

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Last weekend I celebrated “It’s Our River Day” with more than 30 other people at the Lake of the Woods Forest Preserve in Mahomet. Among our group were children as young as 10, college students from the UI chapter of the Wildlife Society and volunteers from the East Central Illinois Master Naturalist program.

“Celebrated” may seem like a funny word to describe our activity when you consider what we did in more specific terms. We waded into the murky water of the Sangamon River and squatted or got on hands and knees, then raked our fingers through the sand and gravel of the riverbed. Our goal was to collect all of the freshwater mussels we could find in a stretch of river just downstream of the covered bridge.

And collect mussels we did—314 of them altogether, including representatives of 14 different native species and one introduced one.

Our most massive specimens were plain pocketbooks, some of which probably would have tipped the scales at more than two pounds (although weighing them wasn’t on the agenda). Our biggest specimens for shell circumference were pink heelsplitters, which grow to the size of a small dinner plates. The addition of a hatchet shaped “wing” on the shells of heelsplitters accounts for their name.

[Photos by author: top to bottom--the whole group; "grubbing"; Sarah Bales and Daniel Bernstein examine a specimen; Chuck Berschinski (left), Bruce Colravey, and another volunteer at the sorting table.]

The names for many other species we encountered are equally colorful and descriptive; among them were pistolgrip and pimpleback, threeridge and deertoe, Wabash pigtoe and fatmucket.

Who knew there was so much going on down there in the streambed?

The scientific aspect of our survey was overseen by Sarah Bales, who is a field biologist with the Illinois Natural History Survey, a Division of the Prairie Research Institute at the UI, and she was pleased with what we found.

Our species list included all but one of those that were found in a 2000 mussel census in that stretch of the Sangamon, and the one we missed is rare, so that’s not really a surprise. On top of that, the mussels we collected looked to be in good condition, and they represented a wide range of ages. That indicates they’re living well into maturity and reproducing.

Bales pointed out that our findings also provided other important indications about the health of the river. The continued presence of mussels there suggests the habitat has not been significantly degraded in recent years, and mussel reproduction in the stream also signifies that certain fish species are thriving there, since the larvae of freshwater mussels parasitize specific fish early in their development (with no harm to the fish).

Our day in the river was organized by Bruce Colravey, Chuck Berschinski, Alan  Weith and others. They’re active members of a relatively new conservation group you might want to check out, the Upper Sangamon River Conservancy (USRC).

The mussel survey fits in with the USRC’s goal of helping people—everyday citizens and scientists alike—to better understand and enjoy the Sangamon River. Along those lines, the USRC also participates in River Watch, a statewide program that monitors stream health by an annual survey of aquatic insects and other invertebrates.

Beyond that, USRC sponsors river clean-ups and educational displays at community events. Most importantly, perhaps, the group provides free access to canoes for members and it helps people get out on the river with regular paddling events.

You can find the Upper Sangamon River Conservancy on the Web at sangamonriver.org.

Volunteer outdoors for National Public Lands Day
Saturday, September 29 is National Public Lands Day, billed as “the largest single-day volunteer effort for public lands in the United States.” Local events are being coordinated through the East Central Illinois Master Naturalist program. A list of local events and contacts is available at http://web.extension.illinois.edu/cfiv/mn/3436.html