To the casual observer, one mussel probably looks pretty much like the next. But the recent discovery of a Wabash pigtoe mussel in the West Branch of the DuPage River is cause for jubilation, according to Don LaBrose, a fisheries biologist with the DuPage County Forest Preserve District.
“When I started inventorying mussel species on the West Branch of the DuPage River three years ago, I was aware of only three species that existed there–the fingernail clam, the giant floater and the white heelsplitter,” LaBrose said. “Now there are nine, including the Wabash pigtoe.”
The unexpectedly-rich diversity of bivalve mollusks surfaced during a recent Conservation Foundation event that included stream testing on a 175-yard stretch of the DuPage River near the Naperville Riverwalk. The Wabash pigtoe sighting was especially significant, LaBrose said, because the once-common species had virtually disappeared from the area some years ago due to urban pollution.
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An increase in mussel varieties, and the mollusk population in general, is of interest to environmentalists because the creatures are important indicators of water quality, LaBrose said.
“Mussels are very stationery critters, and they feed by opening their shells and filtering water through in search of plankton,” LaBrose explained. “If there is a lot of pollution in the water, it poisons them.”
“They also will not reproduce if they are uncomfortable with the health of the water system, but we found a lot of different-sized mussels, which indicates that they are reproducing,” LaBrose added. “The fact that there now are a lot of different species of mussels in that stretch of the river and the fact that they are reproducing tells me that the water quality there is very good.”