The factors influencing habitat selection by juveniles of species within the family Unionidae (i.e., unionids), between post-larval detachment from a fish host and burrowing into the substratum, are largely unknown. Bed shear stress (τw) has been proposed as a critical factor. A laboratory wall jet apparatus generated τw to assess the response of juvenile Epioblasma triquetra, Villosa iris, Lampsilis fasciola, and Ligumia nasuta. The relationships between juvenile unionids, τw, and chemical and physical parameters were also examined in the field. There was a significant relationship between unionid resuspension and τw in the laboratory (resuspension when τw > 0.26 Pa), and adhesion behaviour required greater critical τw. Near-bed velocity and D50 grain size predicted sphaeriid clam density (a proxy for juvenile unionids) in the field. Laboratory experiments confirmed predictions that juvenile unionids cannot establish beyond a critical τw, demonstrating the importance of hydrodynamics in dispersal and for developing unionid conservation measures. / NSERC and Species At Risk Research Fund Ontario (MNR) to J.D.A.

No description available.