Mussel health a clue to river health
LINDENWOOD, Ill. — Sarah Bales spent a recent morning wading through the cold, winding waters of Kilbuck Creek, combing the muddy bottom with her feet and hands, grubbing for freshwater mussels.
The mussel field biologist has been at this for three years.
She and two other field biologists with the Illinois Natural History Survey, a research arm of the University of Illinois, are documenting the presence of mussels in Illinois creeks, rivers and waterways.
Their assignment took them to three sites in the Kishwaukee River watershed, including a stretch of Kilbuck Creek near this Ogle County town about a 30-minute drive south of Rockford.
The data gathered by Bales and her crew could help biologists better understand the health of Illinois waterways. Mussels are often called the livers of rivers because they filter out toxins and chemicals from the water. Their presence also offers clues about aquatic biological diversity. Mussel shells provide shelter for bass and bluegill eggs and macroinvertebrates, an important part of the freshwater food chain.
Illinois waterways are home to myriad mussel species. The Kishwaukee River alone is home to 19 species.
The mussel survey is funded by the Department of Natural Resources and the Illinois Environmental Protection Agency. At each site, Bales and her crew collect, count and measure the mussels they scoop from the bottom of the waterway. They’ll compile a report that details the location of the various mussel species they find.
The morning catch in Kilbuck is healthy, Bales said, about average for a stream of its size.
Field technicians Amy Stultz and John Sherwood spread about 20 mussels, comprising nine species, on the grassy shoreline. A few of the mussels were young, including one less than a year old. That’s a good sign that the mussel population here is healthy and reproducing.
Bales, Stultz and Sherwood documented the size, age and sex of each mussel before returning them to the water. The goal of the survey is to understand the type of mussels in Illinois waterways, not necessarily how many.
“We know we’re not getting all the mussels in this type of sampling,” Bales said. “Basically, we’re trying to get a good assessment of what species we have here.”
She expects to finish her study of the mussel population of Illinois’ 33 watersheds next summer.