A synoptic survey of musty/muddy odor metabolites and microcystin toxin occurrence and concentration in southeastern USA channel catfish ( Ictalurus punctatus Ralfinesque) production ponds

Abstract

A synoptic profile was conducted in July–August 2000 to assess the occurrence of off-flavor compounds beta-cyclocitral, 2-methylisoborneol (MIB), and geosmin, and the cyanobacterial toxin microcystin in catfish production ponds. A total of 485 ponds were sampled during a 1-week period; sample collections were weighted to reflect state area in production. Over 47% of ponds had detectable toxin concentrations, although less than 10% of ponds exceeded 1 ng/ml microcystin. MIB and/or geosmin off-flavors occurred in 25% of the samples. Beta-cyclocitral was detected in over 98% of ponds, and was strongly correlated with presence of myxoxanthin ( r=0.94) and zeaxanthin ( r=0.82), both indicative of cyanobacterial production of this compound. Off-flavor compounds (geosmin and MIB) were correlated to a lesser degree with zeaxanthin production ( r=0.78), whereas aphanizyphyl was better correlated with MIB and geosmin ( r=0.89 and 0.56, respectively), again suggesting cyanobacterial production of these compounds.