Evaluation of the Effect of Sediment Resuspension on Water Quality and Cultured Shrimp

Abstract

The effects of sediment resuspension on water quality, sediment property, and shrimp were investigated in a closed culture system for black tiger shrimp (Penaeus monodon Fabricius) using 5 m³ rectangular concrete ponds lined with sandy clay loam. Sediment resuspension was done by supplying air from an air compressor through porous PVC pipes positioned 10 cm above the pond bottom. Two rows of small pores were drilled on the underside of the pipe to direct air stream to bottom sediment. Aeration for control units were done through air stones hanging 10 cm above pond bottom. Results of this study showed that sediment resuspension significantly improved pond water quality by inhibiting phytoplankton growth, decreasing daily fluctuation of dissolved oxygen and pH, and decreasing water COD. Weekly averages of phytoplankton number and chlorophyll a content in sediment resuspension treatment were significantly lower (P<0.05) than that of the control from week 11 till the end of the experiment. Significantly lower COD values (P<0.05) were also observed in sediment resuspension treatment compared to that of the control during the fourth month. Average concentrations of ammonia, nitrite, and sulfide in the sediment resuspension treatment were not significantly different (P>0.05) from the control. Significantly higher (P<0.05) values of redox potential of bottom soil in sediment resuspension treatment were also observed at 28% of sampling date. No significant differences (P>0.05) were found among average body weight, average survival rate and average feed conversion ratio of shrimp in sediment resuspension treatments and in the control.