Characterization of effluents from bullfrog (Lithobates catesbeianus, Shaw, 1802) grow-out ponds Caracteriza o de efluentes de viveiros de engorda de r -touro (Lithobates catesbeianus, Shaw, 1802)

AIM: Current analysis characterizes the effluent from bullfrog-rearing ponds during the grow-out phase; METHODS: Temperature, pH, dissolved oxygen, electric conductivity, turbidity, total phosphorus, N-NH3, N-NO3, BOD5 and COD and the number of thermotolerant coliforms (Escherichia coli) of the inlet and outlet water of the ponds were analyzed twice a week. Assay consisted of a completely randomized experimental design with two treatments (inlet and outlet water) and six repetitions in a split-plot, coupled to collection over time as subplot; RESULTS: All variables were significantly different (p < 0.05) between treatments and over time (p < 0.05). Average rates of temperature, pH and dissolved oxygen levels of the supply water were higher when compared to those of the effluent. The other variables such as conductivity, turbidity, total phosphorus, ammonia, nitrate, biological oxygen demand, chemical oxygen demand and E. coli were higher in the effluent when compared to rates in the supply water; CONCLUSIONS: The management during grow-out phase caused the deterioration of the water quality, with increasing levels of dissolved nutrients and the number of thermotolerant coliform. Ammonia and phosphorus levels in the effluent, caused by waste food, skin and feces, accelerate the eutrophication process of the receiving water body. Further studies on effluent treatment are required. OBJETIVO: Caracterizar a qualidade do efluente na fase de engorda da r -touro; MéTODOS: Quinzenalmente foram mensurados a temperatura, pH, oxigênio dissolvido, condutividade elétrica, turbidez, PT, N-NH3, N-NO3, DBO5, DQO e número de coliformes termotolerantes (Escherichia coli) da água de abastecimento e do efluente das baias de cria o. O delineamento experimental utilizado foi o inteiramente casualizado com dois tratamentos (água de entrada e saída das baias) e seis repeti es, em esquema de parcelas subdivididas, sendo as subparcelas as coletas no tempo; RESULTADOS: Todas as variáveis apresentaram diferen a significativa (p < 0,05) para os tratamentos e entre as coletas (p < 0,05). Os valores médios de temperatura, pH e oxigênio dissolvido da água de abastecimento das baias foram superiores aos do efluente. As demais variáveis; condutividade elétrica, turbidez, fósforo total, am nia, nitrato, demanda bioquímica de oxigênio, demanda química de oxigênio e E. coli foram superiores no efluente, em rela o à água de abastecimento; CONCLUS ES: O manejo realizado na fase de engorda de r -touro deteriora a qualidade da água utilizada, aumentando as concentra es de nutrientes dissol