Development of phytoplankton communities and common off-flavors in a biofloc technology system used for the culture of channel catfish (Ictalurus punctatus)

• Published in: Aquacultural engineering 2011-11, Vol.45 (3), p.118-126
• Main Authors: Schrader, Kevin K., Green, Bartholomew W., Perschbacher, Peter W.
• Format: Article
• Language: English
• Subjects: 2-Methylisoborneol; Animal and plant ecology; Animal aquaculture; Animal productions; Animal, plant and microbial ecology; aquaculture systems; aquaculture tanks; Bacillariophyceae; Bacillariophyta; Biofloc; Biological and medical sciences; Catfish; Channel catfish; Channels; Chlorophycota; chlorophyll; Communities; Culture; Cyanobacteria; fish culture; fish fillets; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects; Geosmin; Ictalurus punctatus; Microorganisms; off flavors; Phytoplankton; Synecology; Tanks; water quality; Water tanks
• ISSN: 0144-8609; 1873-5614
• DOI: 10.1016/j.aquaeng.2011.08.004

► We examined phytoplankton and common off-flavors in a biofloc technology system. ► Phytoplankton communities in tanks were dominated by green algae and diatoms. ► Water and catfish fillets were analyzed for common off-flavor compounds. ► Earthy and musty compounds were present in many water and catfish fillet samples. ► The microbial sources of earthy and musty compounds in the system remain unknown. The use of biofloc technology production systems continues to increase in the aquaculture industry worldwide. Recent research demonstrated that outdoor biofloc systems can be used to produce high yields of channel catfish (Ictalurus punctatus). However, studies have not yet been performed to determine the development and composition of phytoplankton communities and related off-flavor problems in these biofloc production systems. In this study, water samples were collected biweekly from May to November and channel catfish samples were collected during harvest in November from nine 18.6m2 biofloc culture tanks. Water and fillet samples were analyzed for levels of the common off-flavor compounds geosmin and 2-methylisoborneol (MIB). The development and composition of phytoplankton communities in each culture tank was also monitored. In addition, water and biofloc samples were evaluated to assess the microbial sources of geosmin and MIB within the culture tanks. Phytoplankton (including algae and cyanobacteria attached to bioflocs) biomass, as determined by concentrations of chlorophyll a in the water, gradually increased in all tanks over time. Phytoplankton communities that developed in the culture tanks were dominated by fast-growing, unicellular and small colonial types of green algae (chlorophytes) and diatoms (bacillariophytes) and slower growing, small colonial types of cyanobacteria (cyanophytes). A positive correlation (p