Ammonia-oxidizing bacteria and archaea within biofilters of a commercial recirculating marine aquaculture system

Schematic diagram for RAS producing hybrid grouper (Epinephelus lanceolatus × E. fuscoguttatus) at Laizhou Mingbo Aquatic Co. The units are: (1) 16 fish rearing tanks, (2) a bowed screen, (3) a sump, (4) two pumps, (5) foam fractionators, (6) series of three biofilters, (7) UV disinfection unit, and (8) dissolved oxygen contact uni