Impact of water quality on the bacterial populations and off-flavours in recirculating aquaculture systems

Marc Auffret, Étienne Yergeau, Alexandre Pilote, Émilie Proulx, Daniel Proulx, Charles W Greer, Grant Vandenberg, Richard Villemur

Research output: Contribution to journalArticlepeer-review

52 Citations (Scopus)


A variety of factors affecting water quality in recirculating aquaculture systems (RAS) are associated with the occurrence of off-flavours. In this study, we report the impact of water quality on the bacterial diversity and the occurrence of the geosmin-synthesis gene (geoA) in two RAS units operated for 252 days. Unit 2 displayed a higher level of turbidity and phosphate, which affected the fresh water quality compared with unit 1. In the biofilter, nitrification is one of the major processes by which high water quality is maintained. The bacterial population observed in the unit 1 biofilter was more stable throughout the experiment, with a higher level of nitrifying bacteria compared with the unit 2 biofilter. Geosmin appeared in fish flesh after 84 days in unit 2, whereas it appeared in unit 1 after 168 days, but at a much lower level. The geoA gene was detected in both units, 28 days prior to the detection of geosmin in fish flesh. In addition, we detected sequences associated with Sorangium and Nannocystis (Myxococcales): members of these genera are known to produce geosmin. These sequences were observed at an earlier time in unit 2 and at a higher level than in unit 1. This study confirms the advantages of new molecular methods to understand the occurrence of geosmin production in RAS.

Original languageEnglish
Pages (from-to)235-247
Number of pages13
JournalFEMS Microbiology Ecology
Issue number2
Publication statusPrint publication - May 2013
Externally publishedYes

Bibliographical note

© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.


  • Animals
  • Aquaculture
  • Bacteria/genetics
  • Bornanes/analysis
  • Fresh Water/chemistry
  • Naphthols/analysis
  • Nitrification
  • Oncorhynchus mykiss
  • Water Quality


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