Impacts of intensive shrimp cultivation on bacteria in the nitrogen cycle and physicochemical properties of sediments

Abstract

Bacterial numbers involved in the nitrogen cycle and some physicochemical properties in sediments of 4 intensive shrimp ponds, that had been cultivated continuously for 3 and 5 years, were studied between November 2004 to February 2005. The parameters were monitored as follows:, pH, electrical conductivity, organic matter, total Kjeldahl nitrogen (TKN), C/N ratio, ammonium, nitrite, and nitrate. The only significant differences (p 5-10 cm ) for both types of pond. Total numbers were in the order of heterotrophic plate count > azotobacteraceae > ammonifiers > denitrifiers > ammonium oxidizing bacteria > nitrite oxidizing bacteria.No significant difference was found between each bacterial group in the 2 levels of sediments from each sample set. In pond sediments from both sets of ponds organic matter was highly correlated with TKN (r = 0.783, p < 0.05,r = 0.883, p < 0.01 ) indicating that ammonia release and the increase pH in the sediments was to some extent determined by the deposit of organic matter.

Keywords

• impacts
• intensive shrimp cultivation
• bacteria in Nitrogen cycle
• physicochemical properties
• sediments