Elktoe Mussels in the Pomme de Terre River
Field Day: October 3rd, 2020
By: Peg Furshong, CURE Operations and Director of Programs
My thirteen-year-old daughter is not a fan of rising early on the weekend. Still, this particular Saturday in early October, she woke and declared, “Mom, it is going to be a great day!” Her excitement was that we were headed out to the Pomme de Terre River just south of Morris to meet up with some folks to learn about Minnesota’s freshwater mussels. This Saturday was CURE’s Annual Freshwater Mussel Field Day with malacologist Bernard Sietman from the Minnesota Department of Natural Resources (MNDNR).
By the time we reached our destination, the sun was shining as eager participants arrived. The morning began at 10 am with a brief overview of mussels in Minnesota, their life cycle, and more information about the Elktoe Mussel. Participants helped gather samples of the Elktoe mussel for a research project at the Shedd Aquarium in Chicago, IL. Our goal for the day was to locate 15 mussels for tissue samples to measure the genetic variation of Elktoe populations across its range. In Minnesota, the Elktoe mussel is listed as a threatened species. Elktoe is widespread in the Mississippi and Ohio river systems but is generally uncommon. Our location on the Pomme de Terre River is one of three known active Elktoe mussel beds in Minnesota and the last remaining reproducing population in the Minnesota River watershed.
Freshwater mussels are part of the bivalve mollusk family. There are approximately 50 native to Minnesota rivers and lakes. While mussels live throughout the world, North America supports more species than any other continent, with near 300 unique species. Mussels are fantastic ecosystem engineers that filter and clean our water. As they filter food from the water, they deposit unused particles and metabolic waste essential components of the aquatic food web. Mussels congregate in groups or “beds,” creating biodiversity hotspots similar to the effects of coral reefs in oceans. Some mussels live to be 100 years old and have unique life cycles. Mussels rely on host fish for reproduction and any major migration within the river system. These little eco-engineers are sensitive to pollution and changes in rivers, making them a “canary-in-the-coal-mine” for river health.
Twenty-eight of the roughly 50 native mussel species in Minnesota are considered endangered, threatened, or of special concern. Over the years, there have been various threats to freshwater mussels. In the 1890s, the garment industry relied on the shells for buttons. Millions of shells were harvested and transported down the Minnesota and Mississippi Rivers to factories that would punch buttons out of the shells. Muscatine, Iowa, quickly became the U.S. epicenter for the button industry. In the mid-1900s, the demand for freshwater mussels in the button industry began to decline with the introduction of plastics. Shell remnants were used to seed pearl-making mussels in the freshwater pearl industry in Asia.
The mid-1900s also brought dams to our rivers and streams across the country. Minnesota alone saw 1,100 dams. As these structures were holding water and segmenting off aquatic ecosystems, they also impacted mussels’ life cycles. Because mussels rely on host fish for reproduction when a river is dammed, fish can no longer migrate upstream, and mussels cannot continue to reproduce.
Other present-day threats to mussels include climate change, harmful invasive mussels like zebra mussels, and pesticide runoff from lawns and farm fields.
At the end of the three-hour event, there were smiles all around. When asked what he enjoyed about the day, Sietman replied, “It is seeing the excitement on their face when a participant finds their first live mussel. At the end of the day, it is satisfying to be with people eager to learn about mussels and the important role they play in river health. The Freshwater Mussel Field Days that CURE organizes are by far the longest-running field outreach event we do. It always makes me glad I made the trip out.”
On the trip home, my thirteen-year-old daughter asked if we would have another mussel day again next year? So, for this CURE nature lover and naturalist, I can conclude it was a great day for all involved!
If you would like to see more images of this field day, visit our CURE Facebook page – Mussel Field Day 2020.
Mussels are eco-system engineers
Some mussels can filter as much as 10 gallons of water per day
You can tell the age of a mussel like you can the age of a tree, you count the rings
The physical features in the shell of a mussel records the seasons and changes in climate.
CURE is the only organization outside of the Minnesota Department of Natural Resources (DNR) in Minnesota that hosts freshwater mussel field days.
Minnesota has roughly 50 of the 300 species of freshwater mussels in North America.
REMNANT MUSSEL SHELLS ARE HOME TO MANY THINGS – CADDISFLIES CASING SEEN HERE.
“I AM SO THANKFUL THAT CURE ORGANIZED THIS WONDERFUL EVENT. IT WAS GREAT TO HAVE A CHANCE TO GET OUTDOORS WITH MY SON AND LEARN TOGETHER. WE ALSO MET SOME AMAZING PEOPLE. IT WAS ONE OF MY FAVORITE DAYS THIS YEAR. I AM DEFINITELY A MUSSEL-HEAD NOW!” – TROY GOODNOUGH, MORRIS, MN
THE ELKTOE MUSSEL GETS ITS NAME FROM THE DISTINCTIVE SHAPE OF THE SHELL THAT MIMICS THE SHAPE OF AN ELK HOOF.
SEARCHING UNDER THE BRIDGE FOR LIVE MUSSELS.
BERNARD SIETMAN REVIEWING FRESHWATER MUSSELS OF MINNESOTA