Design and evaluation of recirculating water systems for maintenance andpropagation of freshwater mussels

摘要

A complete system for culturing, rearing, and holding juvenile and adult freshwater mussels (Unionidae) was designed and evaluated for use at hatcheries and research facilities. The system includes air delivery. water conditioning and delivery, algal culturing and automated algal feed delivery, and air-driven water-recirculating units. These systems are appropriate for holding and conditioning adult mussels for spawning, as well as for the grow-out phase of juvenile rearing. In a 41-d trial without water changes in 350-L water-recirculating units, we used 200 adult eastern elliptios Elliptio complanata (average biomass = 1.36 g dry weight/ L): mean values (mg/L) during the trial were 0.02 for NH3, 0.01 for NO2, and 2.7 for NO3. An 8-L mini-recirculating water unit (MRU) also was designed and evaluated for initial culturing of newly metamorphosed juvenile mussels. Survival of juvenile wavy-rayed lamp-mussels Lampsilis fasciola cultured in the MRU was 27.2% at 2 weeks, but this survival was negatively affected by the presence of a predacious flatworm Macrostomum tuba. Survival of the juvenile lamp-mussels through II weeks grow our in the 350-L trough recirculating water unit was 58.8%. We recommend this overall system of holding and rearing adult and juvenile freshwater mussels for use at hatcheries and research facilities because it is effective. low in cost, and easily maintained.