Dynamics of biofilter and rearing water microbiota in recirculating aquaculture systems (RAS)

Three reciprocal biofilter-exchange experiments were conducted at the Norwegian University of Science and Technology (NTNU) Sealab (Trondheim, Norway). In each experiment, two laboratory-scale recirculating aquaculture systems (RAS) were stocked with equal biomass of Atlantic salmon fry and operated under identical design and management. The two RAS differed only in their biofilter biofilm carriers, which were sourced from geographically distant commercial RAS facilities and were known to harbour distinct biofilm communities. The biofilters were then reciprocally exchanged between the RAS to test whether biofilter biofilm communities determine the composition of the rearing water microbiota.