Mussels on the Move

by Angela Boyer

In August 2010, a major northern riffleshell (Epioblasma torulosa rangiana) translocation project took place in Big Darby Creek within the Prairie Oaks Metro Park of Franklin County, Ohio. Nearly 1,500 adult mussels were released at three locations in the creek, which has been designated as a State and National Scenic River. Big Darby Creek is noted for its tremendous diversity and abundance of both aquatic and terrestrial plants and animals, including 43 species of freshwater mussels.

The northern riffleshell is an endangered freshwater mussel that makes its home in riffles and runs in streams with a sand or gravel substrate.  Prior to 1800, this species was widespread throughout both the Ohio River and Maumee River drainages. It was found in Illinois, Indiana, Kentucky, Michigan, Ohio, Pennsylvania, West Virginia and western Ontario, Canada. Unfortunately, populations have declined dramatically due to habitat degradation and loss.

Like many freshwater mussels, the northern riffleshell is sensitive to silt, agricultural run-off, other forms of water pollution, stream channelization, the conversion of free-flowing stream habitat to impoundments and competition from the non-native zebra mussel (Dreissena polymorpha). The decline of the northern riffleshell is not unique; nearly 70 percent of the nation’s freshwater mussel species are considered endangered, threatened or of special conservation concern.

These aquatic gems are important indicators of water quality. Because of their rapid population decline and habitat fragmentation, augmenting riffleshell numbers is essential to the species’ recovery. For last year’s translocation project, northern riffleshell mussels were collected from the Allegheny River by U.S. Fish and Wildlife Service and Pennsylvania Fish and Boat Commission biologists. The mussels were then transported to the Columbus Zoo and Aquarium mussel facility, where they were quarantined and fitted with passive integrated transponder (PIT) tags.  These tags allow biologists to locate individual mussels using an electronic device and determine the conditions most conducive for long-term survival and reproduction success.

The Columbus Zoo and Aquarium, Ohio State University, Ohio Department of Natural Resources Division of Wildlife, Franklin County Metroparks and Darby Creek Association all took part in this translocation project. A similar translocation of 1,700 northern riffleshells took place in 2008 at Battelle-Darby Creek Metro Park, just a few miles downstream of Prairie Oaks Metro Park. It remains the largest single release of any federally listed species in the state of Ohio.

A large number of these rare mussels became available for both of these projects as a result of a proposed bridge replacement project in the Allegheny River in Pennsylvania. The bridge project requires the translocation of approximately 200,000 endangered northern riffleshells over the next several years.

When the bridge replacement project was first proposed, a northern riffleshell augmentation and reintroduction plan was already being developed in Ohio, and a captive propagation facility was in place at the Columbus Zoo and Aquarium in cooperation with Ohio State University.

These releases are the first steps to reintroducing and augmenting populations with mussels displaced by the bridge replacement project. Biologists hope that focusing augmentation efforts in areas of Ohio already surrounded by protected uplands in the Big Darby Creek watershed will improve the northern riffleshell’s chances for recovery. The information gained from these efforts will also aid future mussel restoration efforts in Ohio and other states in the Midwest.

 

Angela Boyer, an endangered species biologist with the Service’s Columbus, Ohio Ecological Services Field Office, can be reached at angela_boyer@fws.gov or 614-416-8993, ext. 22.
Editor’s note: This article published originally in the Summer 2011 edition of the Endangered Species Bulletin.