Optimization of blue mussel (Mytilus edulis) seed culture using recirculation aquaculture systems

By introducing recirculation aquaculture systems (RAS) in the nursery phase of the blue mussel (Mytilus edulis) (17–18 mm), we aimed at a similar growth and survival and a similar water quality compared to the commonly used flow-through systems (FTS). To calculate water flow and size of the biofilter, a series of experiments were done to determine clearance rate (9.26 mL min-1), pseudo faeces threshold (60 000 cells Pavlova lutheri mL-1), nitrogen production (0.00065 mg TAN h-1 ind-1 and 1.6 × 10-5 mg NO2–N h-1 ind-1) and oxygen consumption (0.03 ± 0.01 mg O2 h-1 ind-1). RAS showed no significant differences in water quality (0.06 mg TAN L-1; 7.7 mg O2 L-1) and growth performance of mussel seed specific growth rate (SGR = 5% day-1) after the experimental period of 4 weeks compared with FTS. The low water refreshment, 10% per day, as well as the constant chlorophyll concentrations (9.76 ± 1.06 µg L-1), suggests the potential of RAS as culture system for mussel seed.