FIG 6.

Distribution of RAS-associated microbes in Salmon hatcheries. (a) RAS are designed to recycle nitrogenous waste, primarily from uneaten feed and fish feces, using a series of nitrification and denitrification steps through microbial filters. The primary microbes involved in these processes and detected in the systems (AOB [ammonia-oxidizing bacteria], NOB [nitrite-oxidizing bacteria], and denitrification) are listed. (b to f) The distributions of these RAS-associated microbes are listed as mean relative counts per 1,000 according to each hatchery type (FT, orange; RAS 1, purple; RAS 2, yellow) across each particular sample type, i.e., (b) gill, (c) skin, (d) digesta, (e) tank water, and (f) tank biofilm.