The upper Cedar River was the focus of this year’s annual research project to inventory and map the distribution of Iowa’s mussels, often called clams.
More than 50 biologists, students and volunteers collected 18 species of freshwater mussels in the Cedar River during the three day event held each August since 2005.
Live mussels were inventoried, measured for growth; and then returned to the water. Most of the mussels were found using a technique known as pollywogging, as researchers and volunteers crawl along a stream bed, probing the bottom with gloved hands. “These studies help us learn more about mussels and the areas where they live and thrive,” said Scott Gritters, fisheries biologist with the Iowa DNR. “We knew this area is biologically diverse, but we wanted to study the impact of the many dams on this stretch of the Cedar River. We are also working with the Minnesota Department of Natural Resources to determine the best methods to restore some lost mussels or declining mussel species in our respective stretches of the Cedar River.” The Iowa DNR, the U.S. Fish and Wildlife Service and the U.S. Army Corps of Engineers started researching the disappearance of native fresh-water mussels in Iowa 12 years ago, including the federally endangered Higgins-eye pearly mussel. Once ranging across most of the upper Midwest, this species has been eliminated from most of the river systems it once thrived in. "Historically, there were maybe 54 species of native mussels in Iowa,” Gritters said. “Now, it's about 42. Of those, nine are endangered. Another six are threatened and several more species are very hard to find any more in Iowa.” For more, search "mussel" at iowadnr.gov. 📷: Aaron McFarlane, ACOE
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Image: researcher with goggles holding two mussels while standing in a river