Mussel experts released more than 100 dime- to golfball-size endangered pink mucket and black sandshell mussels into the chilly waters of the Meramac River south of St. Louis this November. This time last year, the team from the Missouri Department of Conservation and the U.S. Fish and Wildlife Service’s Missouri Ecological Services office could only release microscopic freshwater mussels into Missouri waters. However, due to their small size, these mussels did not stand much chance for survival. Dr. Chris Barnhart from Missouri State University has been testing methods for mussel propagation and rearing since 1999. For the first time this past summer, Barnhart successfully grew out the mussels to a large enough size for researchers to tag them. By tagging the mussels, they will be able to monitor their growth over time. These larger mussels also stand a much higher chance of survival when they release them back into the wild.

In a lab at MSU, researchers used a device called a “flupsy,” to grow out the mussels from larvae they had collected from female mussels. The flupsy stimulates natural streamflow in hatchery ponds. They then transported the juvenile mussels to the Kansas City Zoo, where some mussels grew more than 4 inches in three months. “This is the fastest growth we have ever recorded,” said Barnhart, the lead researcher on the mussel conservation project.

To celebrate this breakthrough in mussel conservation, the zoo hosted an open house for members of the media to view the four species they had grown there over the summer. MSU graduate students weighed, measured and tagged black sandshells, pink heelsplitters, fatmuckets and endangered pink muckets in preparation for the mussels’ release.  The pink muckets and black sandshells would return to the home of their broodstock in the chilly waters of the Meramac River. Researchers later released the pink heelsplitter and fatmucket mussels in the Sac and Silver Fork Rivers.

This breakthrough in mussel conservation is part of a larger effort to increase public awareness of the relationship between freshwater mussels and the health of Missouri streams. Native freshwater mussels serve important roles in stream ecology. “Mussels act as sorters of the stream, eating and digesting some food while releasing the rest in a mucus strand that feeds benthic invertebrates,” explained Andy Roberts. a fish and wildlife biologist. Mussels’ sensitivity to water quality degradation also makes them great indicators of water quality for environmental toxicologists. They are also a food source for fish and small mammals such as raccoons and river otters. However, many native freshwater mussel species are on the decline. Out of 65 native mussel species in Missouri, 10 are endangered at the federal or state level, and more than half are of conservation concern.

Historically, freshwater mussels have been used commercially to make buttons, jewelry, and tools. However, their commercial use has declined along with their numbers. Poor land-use practices, pollution, damming and the introduction of invasive zebra mussels have all disrupted the stable habitat required for native mussels to survive. But in some areas, the environmental conditions these rare mussels need to survive are improving.

The team will return next summer to monitor the growth and weight of the mussels. “We hope to recapture as many as possible, but there’s no way of knowing for sure how many survived the first year,” Roberts said. “However, augmenting populations in areas where environmental conditions are improving will help create strongholds for extremely rare species, like the pink mucket, and buy time for other aquatic areas to improve.” For mussel species on the brink of extinction, that extra time may be just what the mussels, and Missouri waters, need.

Photo 6:

From left to right: Scott Faiman Missouri Department of Conservation; Andy Roberts USFWS; and Steve McMurray, MDC, release pink muckets and scaleshells into the Meramac River. Graduate students from MSU marked the mussels with small tags so the researchers can recapture them in a year to record their growth. Photo by Ashley Spratt, USFWS.