| Abstract: | The population sizes of ammonifying, protein mineralizing, nitrogen fixing and nitrifying bacteria, and the rates of ammonification and nitrification (natural and potential) were measured in water and sediments of four fish ponds being used for traditional, mono- and polyculture systems of fish farming. Spatial differences in the microbial density in these ponds were related to the fish culturing practices adopted. The seasonal variation of ammonifying bacteria was found to be positively correlated with the NH4-N level in the water. The natural and potential capacity to generate both nitrite and nitrate in these water bodies was strongly correlated with the concentrations of the different forms of inorganic nitrogen present. The rates of NO2-N and NO3-N formation occurring in these fish ponds were directly proportional to the amount of dissolved oxygen and pH of the environment, respectively. |
