Date of Graduation

Summer 2021


Master of Science in Biology



Committee Chair

Christopher M. Barnhart


The Asian clam, Corbicula fluminea, is an invasive species that is abundant and often co-occurs with native freshwater mussels. Corbicula is widely suspected of having negative effects on native mussels, but few studies have empirically tested this hypothesis. I used laboratory experiments to evaluate how adult Corbicula affected the survivorship, growth, and drift of juvenile Lampsilis siliquoidea. Survival and growth of newly metamorphosed mussels were tested in downwelling flow-through chambers with glass-bead substrate. Treatments were control (no clams), small adult clams, or large adult clams. After 28 days, large clams slightly but significantly reduced the number of juveniles recovered from the substrate. The proportion recovered alive did not change, suggesting that the missing juveniles were eaten and the shells digested. Small clams did not affect juvenile recovery or survival. Mussels grew nearly threefold in length over 4 weeks. Corbicula had small and inconsistent effects on growth. Mussels exposed to large clams grew 3% larger than the control group at the end of the 4 weeks. In contrast, mussels exposed to small clams grew 3% less than the control group. Tests on drift were carried out in small raceways with glass bead substrate. Drifting behavior (wash-out) of 2-week (0.5 mm) and 6-week-old (1.5 mm) mussels was tested with and without Corbicula over 3 days. Mussel drift increased with increasing clam density: 19%, 33% and 47% of 2-week-old mussels drifted at 0, 500 or 2000 clams/m2, respectively. Drift of 6-week-old mussels increased only at the highest clam density, with 42% of mussels displaced, versus 5% and 8% in the control and low-density treatments. Interactions between Corbicula and native juvenile mussels could help explain why mussel populations continue to decline across the United States.


freshwater mussel, Corbicula fluminea, invasive species, juvenile, conservation, survival, growth, drift

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© Allison Nicole Sieja

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