Development of a Field Bioassay with Juvenile Mussels

Two embayment sites in Kentucky Lake, an impoundment of the Tennessee River, have low species diversity of mussels. A field bioassay with 6-wk-old laboratory-cultured juvenile mussels (Utterbackia imbecillis Say) was developed and used to compare these sites with a reference site. Mussels exposed to sediment at the test sites exhibited higher mean mortality than those exposed only to overlying water. Results showed significant mortality at both low-diversity sites: 97% mortality at a site where mussels were absent, and 51% in a mussel bed with limited species diversity. Mortality of sediment-exposed juvenile mussels at a reference site with diverse species was only 21%. Based upon the results of this study, field assays with juvenile mussels can be used to assess stress in aquatic ecosystems.