Improvement of Water Chemistry with <i>Bacillus</i> Probiotics Inclusion during Simulated Transport of Yellowfin Tuna Yolk Sac Larvae

Abstract

Abstract The effects of adding a probiotic Bacillus spp. blend on shipping bag water quality and survival of yolk sac larvae of yellowfin tuna Thunnus albacares during a 24-h mock shipment were investigated. To better detect effects on water quality, the trial was designed without the utilization of available chemical water quality or temperature modulators. Shipping water salinity (30.7–31.0‰) and temperature (24.0–26.7°C) reflected conditions utilized during larval rearing. Probiotic incorporation (15 mL/L, about 1.5 × 106 colony-forming units/mL) resulted in significantly lower final concentrations of total ammonia nitrogen and un-ionized ammonia in comparison with the control. Significantly higher final mean dissolved oxygen concentration observed in the probiotic treatment could have resulted from stress reduction. Although no statistical difference was detected in larval survival upon termination of the trial, improvements in water quality (reduced total ammonia nitrogen and increased dissolved oxygen) resulting from incorporation of Bacillus probiotics would yield added levels of safety during shipping and would reduce the chances of negative results while incurring minimal increases in shipping costs. Received January 28, 2010; accepted May 1, 2010