|dc.description.abstract||Four sets of experiments were conducted to evaluate the potential efficacy of bacterial amendments for improving water quality in channel catfish ponds. First, the effects of 12 bacterial amendments from eight companies on reducing total ammonia nitrogen, nitrite nitrogen and organic matter concentration in polluted pond water were evaluated in an environmentally controlled room. Then, a selected bacterial amendment (Waste & Sludge Reducer -WAS) was evaluated in channel catfish ponds at the E. W. Shell Fisheries Center. The third set of experiments was to evaluate selected bacterial amendments (Aqua PE and Oxyless) in channel catfish ponds with ammonium sulfate addition at the E. W. Shell Fisheries Center. The final set of experiments was to evaluate the efficacy of the bacterial amendment (Aqua PE) on water quality in Alabama commercial catfish ponds.
Concentrations of total ammonia nitrogen (TAN), nitrite nitrogen (NO2ˉ–N) and organic matter (as estimated from oxygen demand) in untreated water naturally decreased with time during 16 days. No large improvements were observed in accelerating nitrification or organic matter oxidation from the use of bacterial amendments in the laboratory study.
There were no differences (P>0.05) in total bacterial count after treatment with WAS on most of the days between May and September. Few differences (P<0.05) were observed in pH and concentrations of POM, Cha a, COD, SCOD, TAN and NO2ˉ–N between ponds treated with WAS and control ponds. Channel catfish yield was not improved by treatment with WAS.
No larger improvements were observed in accelerating TAN removal rates in catfish ponds with ammonium sulfate addition from the use of the Aqua PE and Oxyless in combination. There were slightly beneficial effects on TAN removal from day 5 to day 8 in the ponds with high ammonium sulfate addition (225 kg/ha ammonium sulfate applied on day 4) after treatment with the bacterial amendments (Aqua PE and Oxyless).
There was less mean concentration of TAN (P<0.05) in commercial catfish ponds treated with the bacterial amendment (Aqua PE), which may because the dense algal bloom took up the ammonia. Compared to the untreated ponds (controls), Aqua PE gave beneficial effects on TAN removal (P<0.05) on 20 June (week 2) and 27 June (week 3). No differences (P>0.05) in mean concentrations of nitrite nitrogen was observed between ponds treated with Aqua PE and control ponds. However, there were less concentrations of nitrite nitrogen (P<0.05) in the ponds treated with Aqua PE on 27 June (week 3), 18 July (week 6), 1 August (week 8) and 22 August (week 11). There were higher (P<0.05) means of turbidity and Chl a concentration in Aqua PE treated pond. On 18 July (week 6), there were higher (P<0.05) turbidities in Aqua PE treated ponds. No improvements were observed in accelerating organic matter oxidation from the use of Aqua PE. No differences (P>0.05) was observed in pH, and concentrations of TN, TP after treatment with Aqua PE. Catfish yield was not improved by treatment with Aqua PE.||en_US