Michelle B. Steg and Richard J. Neves, Virginia Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0321

Abstract. Growth and survival of juveniles of the wavy-rayed lampmussel (Lampsilis fasciola) were compared in two recirculating culture systems, and with two levels of water hardness and organic content of the substrate. The first experiment compared the growth and survival of 4,000 L. fasiola juveniles in two culture systems of different design, one with juveniles held in dishes and one with them free in sediment beds. After four months, the mussels in the dish system had significantly higher survival (P<0.01) than in the bed system. The mussels in the bed system had significantly greater growth (height, P<0.01; width, P<0.01), partially attributable to higher water temperature. The second experiment compared growth and survival of 4,800 juvenile mussels in containers with two levels of substrate organic content and two levels of water hardness. The experiment continued for four months, with subsamples taken every three weeks. At six weeks, mussels in the high water hardness treatment exhibited significantly greater growth (height, P<0.01; width, P<0.05) and survival (P<0.01). There is no significant difference in mussel growth or survival between the two levels of organic content, and no interaction effect between organic content of sediment and water hardness.