Sulfur - Oxidizing Bacteria as a Potential Method to Improve Water Quality in Aquaculture Ponds

Hydrogen sulfide (H₂S) is produced naturally in aquaculture ponds due to the conditions found in the bottom soils but there is still a need for an effective way to reduce H₂S concentrations.  Previous laboratory studies have shown that the use of the bacteria species Paracoccus pantotrophus at 500 g/ha and 1000 g/ha significantly reduced the H₂S concentrations within study aquaria.  Twelve ponds on a commercial Golden Shiner Notemigonus crysoleucas farm were treated with a P. pantotrophus of 500 g/ha and compared to ten untreated control ponds.  Treated and control ponds were monitored for one year, weekly when water temperatures were at or above 23°C, then biweekly when the temperatures fell below 23°C, recording measurements of water temperature, pH, alkalinity, H₂S concentration and phytoplankton abundance.  Preliminary results suggest that the H₂S concentrations

in the treated ponds were significantly lower than the concentrations within the control ponds (Fig. 1).  Alkalinity levels in the control ponds had significantly more variation than the treated ponds, which remained closer to the desired 100 ppm level. P. pantotrophus was detectable from the soil for only 10 days after treatment.  The results indicated that the use of bacterial treatment reduced the

presence of the harmful blue-green algae compared to the control ponds and a significantly higher abundance of zooplankton was found in the treated ponds.  Overall, the use of P. pantotrophus at the rate of 500 g/ha seems to have a beneficial effect of reducing H₂S concentrations and blue-green algae abundances while buffering the alkalinity and enhancing the zooplankton abundance in Golden Shiner ponds. Ponds need to be treated every 10 days when water temperatures are between 21 and 24⁰C. Further research is needed to determine the concentration of P. pantotrophus needed in sportfish ponds.