A survey on the environmental impact of pond aquaculture in Hungary

Abstract

The aim of the study was to survey the nutrient loads of receiving waters and evaluate the nitrogen, phosphorus and organic matter budget of the conventional fishponds in Hungary. The average nitrogen (N), phosphorus (P) and organic matter (OM) concentrations in the filling-up water of the fishponds were 2.51 ± 1.25, 0.57 ± 0.57 and 23.8 ± 13.4 mg l⁻¹, respectively. Contrarily, the N, P and OM concentrations in the effluents of fishponds were 1.64 ± 2.19, 0.37 ± 0.51 and 30.2 ± 20.5 mg l⁻¹, respectively. The sediment nutrient content in the fishponds during the operation was 5.77 ± 4.42 mg g dry sediment⁻¹ for N, 1.25 ± 0.75 for P and 30.5 ± 43.3 for total organic carbon. The retained nutrients represented on average 53 % (84 kg ha⁻¹ year⁻¹) of N, 74 % (21 kg ha⁻¹ year⁻¹) of P and 74 % (2400 kg ha⁻¹ year⁻¹) of OM, introduced into the fishponds. In the fishponds, the ratio of input N, P and OM accumulated in fish biomass was 18.4 ± 6.7, 10.4 ± 4.4 and 6.8 ± 2.1 %, respectively. The investigated fishponds discharged 48 % less N and 62 % less P into the recipient waters than received with the intake water. However, 78 % more OM was discharged with the effluent from the fishponds than received with the inlet and supplement water.