Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/1999
Publication Date: N/A
Interpretive Summary: Certain types of blue-green algae found in catfish ponds in Mississippi produce a musty compound that causes the catfish to become off-flavor and unmarketable. Previous laboratory studies suggest that the natural compound ferulic acid will kill blue-green algae producing the musty compound. The present study was conducted to determine the effectiveness of ferulic acid for controlling the growth of the blue-green algae under field conditions. Catfish ponds had ferulic acid applied to them, and water samples were collected to count blue-green algae to determine if ferulic acid prevented their growth. Blue-green algae were not consistently affected by applications of ferulic acid. Only one of the six ferulic acid applications resulted in a decrease in abundance of the type of blue-green alga producing a musty odor. The ineffectiveness of ferulic acid as a method to prevent the growth of blue-green algae in catfish ponds appears to be caused by rapid disappearance of ferulic acid from pond waters. Ferulic acid was determined to be neither an effective nor economical approach to preventing musty off-flavor in pond-cultured channel catfish.
Technical Abstract: The cyanobacterium Oscillatoria perornata f. attenuata, a common inhabitant of channel catfish(Ictalurus punctatus) aquaculture ponds, produces the musty compound 2-methylisoborneol that causes fish to become off-flavor and unmarketable. Previous laboratory studies suggest that the natural compound trans-ferulic acid (4-hydroxy-3-methoxycinnamic acid) is selectively toxic against O. perornata. The present study was conducted to determine the effectiveness of the compound for controlling the growth of O. perornata under field conditions. The study was conducted in 12, 0.1-ha earthern ponds in northwest Mississippi. Ponds contained 20,000 catfish/ha and were managed according to commercial culture practices. Half of the ponds were treated six times over a 2-month period with 5 (M (0.97 mg/L) trans-ferulic acid and the other half were untreated controls. Water samples obtained from all ponds preceding and following treatment were analyzed for phytoplankton community structure and concentrations of chlorophyll a, ferulate, and 2-methylisoborneol. Abundance of cyanobacteria, including O. perornata, was not consistently affected by applications of ferulic acid. Only one of the six ferulic acid applications resulted in a decrease in abundance of O. perornata in treated ponds relative to untreated ponds (P < 0.1). The ineffectiveness of trans-ferulic acid as a cyanobacterial algicide in catfish ponds appears to be caused by rapid dissipation of ferulic acid from pond waters. Use of trans-ferulic acid was neither an effective nor economical approach to preventing musty off-flavor in pond-cultured channel catfish.