Seasonal Changes in Bacterial Flora of Fish Pond Sediments in Saudi Arabia

The goal of this study was to monitor the bacterial flora in pond sediments. Culturable bacteria were enumerated and identified from samples taken from pond sediments in Saudi Arabia at sampling times representative of the four seasons. Bacterial numbers (cfu/g) seemed to be highest in summer. Total viable counts (TVC) of bacteria in the pond sediments varied between 5.2±2.7 × 107 to 1.4±2.3 × 108cfu/g in early summer, 6.6±2.4 × 108 to 8.9±2.0 × 109 cfu/g, significantly higher (P < 0.005) in summer, 4.2±2.8 × 107 to 6.3±1.7 × 108cfu/g, significantly lower (P < 0.005) in autumn, and 7.9±1.9 × 105 to 8.6±2.1 × 106 cfu/g in winter. A total of 20 bacterial species were identified from the sediment. The bacteria were predominantly Gramnegative rods (77%). Aeromonas hydrophila was 27%, significantly higher (P < 0.005) in the population. Seasonal temperature variation could account for some of the bacterial population variation. Aeromonas hydrophila, Shewanella putrefaciens, Corynebacterium urealyticum, Escherichia coli, Pseudomonas sp., Vibrio choleraeand Cellulomonas sp. were the common species in all the bacterial populations of different seasons where the first four bacterial species made up most culturable assemblage (prevalence of > 10%). Flavobacterium sp., Micrococcus sp., Streptococcus sp., Burkholderia glumae and Pasteurella sp. were present in some seasons of the year. Pseudomonas fluorescens and Salmonella sp. were present only in winter, where Pasteurella pneumotropica was found only in summer.