Field Notes
U.S. Fish & Wildlife Service
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Missouri Mussels Put on Weight for River Homecoming
Midwest Region, November 15, 2007
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A team of mussel experts from the Missouri Department of Conservation (MDC) and U.S. Fish and Wildlife Service’s Missouri Ecological Services office released over 100 dime to golf ball-size endangered pink mucket and black sandshell mussels into the chilly waters of the Meramac River just south of St. Louis this November.


At the same time last year mussel researchers could only release microscopic freshwater mussels into Missouri waters, but these mussels did not stand much chance for survival due to their small size. 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 them to be tagged. By tagging the mussels, researchers will be able to monitor their growth over time. These larger mussels also stand a much higher chance of survival when released back into the wild.


The mussels released in the Meramac River were grown using a device called a “flupsy” that stimulates natural stream flow in hatchery ponds. Originally collected as larvae from female mussels, they were first propagated in a laboratory at Missouri State University.


After propagation, the juveniles were transported to the Kansas City Zoo where some grew over four inches in three months. According to Barnhart, MSU professor and lead researcher on the mussel conservation project, “This is the fastest growth we have ever recorded.”


To celebrate this breakthrough in mussel conservation, the Kansas City Zoo hosted an open house for members of the media to view the four species grown there over the summer, including one federally endangered species.


Black sandshells, pink heelsplitters, fatmuckets and endangered pink muckets were weighed, measured, and tagged by MSU graduate students in preparation for their release.  The pink muckets and black sandshells would return to the home of their broodstock in the chilly waters of the Meramac River. The pink heelsplitter and fatmucket mussels were later released 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.  Fish and wildlife biologist Andy Roberts explains, “Mussels act as sorters of the stream, eating and digesting some food while releasing the rest in a mucus strand that feeds benthic invertebrates.” 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 the sixty-five native mussel species in Missouri, ten are endangered at either 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. Many native mussel species are extremely rare but the environmental conditions they need to survive are improving.


Barnhart’s 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 Missouri waters need.

Contact Info: Larry Dean, 612-713-5312, Larry_Dean@fws.gov
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