The effect of controlled soil sulfur concentration on growth and survival of Litopenaeus vannamei

In a microcosm study, sodium sulfate was mixed with a controlled compositio n soil to yield sulfur concentrations of 100 to 3,000 mg/kg and the mixture was inundated to a depth of 35 cm with 18-ppt salinity water. One juvenile Litopenaeus vannamei with initial weight averaging 0.3 g was placed in eac h soil-water microcosm and fed for 96 d. Dissolved oxygen concentration was maintained at approximately 70% air saturation. Calculated interstitial hy drogen sulfide concentration 0.5 cm below the soil-water interface increase d with time, reaching maximum values ranging from 57 to 113 mg/L. Interstit ial sulfide concentrations 0.5 cm below the soil-water interface increased as a function of soil S. Average weight gain of shrimp ranged from 7.4 to 8 .7 g across treatment groups. Differences in shrimp weight gain and surviva l among treatments were not significant. A higher dissolved oxygen demand d ue to sulfide oxidation implies greater risk of shrimp mortality if the soi l-water boundary is disturbed. Further, this study suggests that shrimp gro wth is not adversely affected by high soil sulfide concentration provided t he sediment surface remains oxidized and that dissolved oxygen concentratio n in the overlying water is maintained at 70% saturation.