Distribution of bacteria in the sediment of an oxbow tropical lake (Lagoa do Infernão, SP, Brazil)

The temporal distribution of bacteria on the surface sediment of the oxbow lake Lagoa do Infernao was studied over a period of one year using different techniques for bacterial counts. Several bacterial groups were differentiated, total and filamentous bacteria, heterotrophic, amylolytic, and lipolytic bacteria. The best defined temporal distribution pattern was obtained by total-AO bacterial counts, with a variation of 1.26 x 10 super(10) to 8.58 x 10 super(10) bacteria (g/dw) during the dry and rainy seasons, respectively. The electrode potential (Eh) of the surface sediment ranged from -148 mV during the rainy season to +371 mV during the dry season. The variations detected on the surface sediment suggest a greater allochthonous contribution of material and bacteria resulting in high decomposing activity during the rainy season.