An Initial Survey of Unionid Mussels in Lakes East of the Missouri River in South Dakota, USA

This study surveyed freshwater mussels (family Unionidae) in 116 lakes and reservoirs east of the Missouri River in South Dakota, USA, during 2017. Using two-person–hour/site timed searches, evidence of a total of 1789 mussels, including 1053 live mussels, was obtained from 50 waters. Nine species, from two different orders, were found in lakes and reservoirs throughout five of the six major river drainages east of the Missouri River. The native species observed included Giant Floater <i>Pyganodon grandis</i>, Fatmucket <i>Lampsilis siliquoidea</i>, Threeridge <i>Amblema plicata</i>, White Heelsplitter <i>Lasmigona complanata</i>, Wabash Pigtoe <i>Fusconaia flava</i>, Deertoe <i>Truncilla truncata</i>, and Pink Heelsplitter <i>Potamilus alatus</i>. Giant Floater was the most widespread and abundant species observed, representing 63.3% of the live mussels sampled. Two non-native species, Zebra Mussel <i>Dreissena polymorpha</i> and Chinese Basket Clam <i>Corbicula fluminea</i>, were also documented from three water bodies in the lower Missouri River drainage. Overall, mussel abundance was negatively correlated with lake water conductivity and positively correlated with turbidity. No significant correlations were observed between species abundance and water temperature, pH, dissolved oxygen, or substrate particle size.