Natural Resources, School of


Date of this Version

November 2005


Presented to the National Park Service – Department of Interior, O’Neill, Nebraska.


Freshwater mussel (Bivalvia: Unionida) surveys were conducted on the 39-Mile District of the Missouri National Recreational River (MNRR) between Ft. Randall Dam, South Dakota and Running Water, South Dakota from October 2004 to September 2005. Fortynine locations within the 39-Mile District were inspected for the presence of mussel populations. Mussels (live individuals or dead shells) were collected at only 37% (18 of 49) of the sites. Of the seven mussel species collected during this survey, the fragile papershell Leptodea fragilis and pink papershell otamilus ohiensis were the most common. The paper pondshell Utterbackia imbecillis and mapleleaf Quadrula quadrula were rare and only represented by a few individuals. Most sample locations in the upper half of the 39-Mile District (from Ft. Randall Dam downstream to Verdel, Nebraska) were largely devoid of mussels. Similarly, areas with an unstable, shifting sand substrate, such as the Niobrara River delta, were devoid of mussels. Overall, mussel abundance and diversity was low compared to mussel populations found within the 59-Mile District of the MNRR.