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 NO 2 –N h −1 ind −1 ) and oxygen consumption (0.03 ± 0.01 mg O 2  h −1  ind −1 ). RAS showed no significant differences in water quality (0.06 mg TAN  L −1 ; 7.7 mg O 2  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.