A laboratory-scale recirculating aquaculture system for juveniles of freshwater pearl mussel Hyriopsis (Limnoscapha) myersiana (Lea, 1856)

Growth and survival rates of juvenile freshwater pearl mussels Hyriopsis (Limnoscapha) myersiana (Lea, 1856) were compared at 0–120 days when reared in two closed recirculating aquacultural systems. System I was composed of a glass aquarium with a filter cabinet (combination of pebbles, ground freshwater mussel shells and nylon fiber), a UV tube, a resting cabinet, and a plastic culture unit. The system II was composed of 5 cabinets: a particulate filter cabinet, a macrophyte (Limnophila heterophylla) filter cabinet, a biological filter cabinet, a water resting cabinet and plastic culture units. Water flowed through the juvenile culture units at 20 ml/min in both systems. In each system juveniles were stocked at day 0 with sand at < 120 μm and were fed twice a day on a 1:1 mixture of Chlorella sp. and Kirchneriella incurvata. Over the 120 days, average growth rate per day and rate of survival were higher in system II. Free carbon dioxide, total ammonia nitrogen, nitrate, phosphate and silica of second system were significantly lower in system II. The relationship between shell length (L) and age of the freshwater pearl mussels cultured in system II was L = 0.6164 − 0.0809 Day + 0.0032 Day2 − 1 × 10− 5 Day3, R2 = 0.983.