Buckets of muckets: A compact system for rearing juvenile freshwater mussels

A novel system was developed for the culture of juvenile freshwater mussels (Unionidae). The system can be replicated economically to provide statistical power for experimental investigations of culture conditions. Two nested buckets partition a water volume of 18 l into upper and lower compartments. Water moves from the lower to the upper compartment via a small submersible pump, and returns to the lower compartment through screen-capped chambers containing the juveniles. Each bucket system includes 7 chambers, each of which can accommodate 2000 juveniles (14,000 total). Newly transformed juvenile unionids of 8 species were held in these systems for 9 to 12 wk and continuously drip-fed a monoculture of Neochloris oleoabundans. Survival rates were generally higher than those previously reported for newly metamorphosed unionids and exceeded 95% over 2 mo for Lampsilis siliquoidea and L. reeveiana. Mean growth rates varied among 5 species from 4.2 to 12.5 μm/d at 22 °C. These growth rates are within the range previously reported for lampsiline juveniles in recirculating systems. The bucket rearing system may be particularly useful for conducting studies of water quality and feeding regimes that require replication to account for container effects. It is also useful for short-term culture of juveniles to be used in toxicity testing.