46 DECEMBER 2013 • WORLD AQUACULTURE • WWW.WAS.ORG The influence of intensive aquaculture on the quality of discharged water has been the topic of many studies since the second half of the 20th century. However, pond production of common carp Cyprinus carpio, as practiced in Central and Eastern Europe, has not been studied as much, despite many indications that it can have positive or negative effects on the quality of receiving waters. The majority of common carp production in the Czech Republic originates from semi-intensive pond facilities, where fish yield is based on natural food resources supplemented by feeds, mainly cereals in 25-30 percent proportion. In contrast, extensive pond management excludes feeding and fertilization and relies exclusively on natural production (Adámek et al. 2012). Compliance with the legislative limits of water quality parameters poses one of the fundamental problems in pond fish farming in the Czech Republic. Pond water quality is affected by management intensity and many other factors. The quality of supply water belongs among those of particular importance when evaluating the impact of carp pond farming on the surrounding environment. These impacts are an important issue of serious debate between fish farmers on one side and water management and nature protection authorities on the other. Pond farming is tightly linked to its surrounding environment, influencing it and also influenced by it (Fig. 1). Pond management can substantially modify the hydrological regime and ecological quality of receiving waters, usually rivers, canals, reservoirs and ponds downstream, with positive or negative potential impacts on watershed function. The combination of various municipal wastewater treament plants and diffuse agricultural pollution from pond farming intensification has resulted in high rates of nutrient input into pond ecosystems. In ponds surrounded by arable land, agricultural runoff containing fertilizer nutrients has frequently led to pond eutrophication. Under Central European conditions, the trapping and storage of these nutrients is considered an important function of fish ponds, as documented in numerous German, Austrian, Hungarian, Polish and Czech studies (Gergel and Kratochvil 1984, Oláh et al. 1994, Kainz 1985, Knösche et al. 2000, Drabiński et al. 2010). Study Overview and Pond Characteristics To study the potential ecological consequences of carp farming in ponds, water quality at inlet and outlet canals during the fish growing season was evaluated in ponds subjected to a range of pressures and management styles. Selected study sites included ponds supplied partly or fully with unpolluted river water and water discharged from wastewater treatment plants. Ponds with different management intensity (extensive and/or semiintensive), stock biomass (716 -1,112 kg/ha) and inlet water quality (beta- to alphamesosaprobity) were selected. The main goal was to estimate the extent to which the nutrient and bacterial loadings of water discharged continuously from carp ponds during the growing season reflected the water quality of pond inflow. Monitoring was performed from April to October 2009 in four carp ponds in South Moravia (Czech Republic) managed according to different regimes: • On-growing ponds designated for two-year-old fish production — Extensive Kurdějovský pond (KUR; 48°56‘1“N, 16°46‘40“E; Fig. 2) — Semi-intensive Šibeník pond (SIB; 48°47‘0“N, 16°37‘49“E) • Marketing ponds designated for marketable (usually threeyear-old) fish production — Extensive Nesyt pond (NES, the National Nature Reserve 48°45‘59.65“N, 16°44‘8.561“E) with two inlets Environmental Impacts of Carp Pond Farming on Discharged Water Quality Lucie Vseticková, Zdenek Adámek, Milos Rozkosny and Pavel Sedlácek ˇ ˇ ˇ ˇ ˇ ˇ ´ TABLE 1. Basic characteristics of the studied carp ponds (mean values ± SD). Pond Area Inflow Outflow Retention time 2009 fish yield (ha) (L/sec) (L/sec) (days) (kg/ha) KUR 6.6 3±1 1±0.3 441 737 SIB 28.6 17±10 16±10 236 1,071 NES 289.7 84±52 68±120 614 716 VRK 156.1 315±210 26±40 64 1,112 Pond farming is tightly linked to its surrounding environment, influencing it and also influenced by it. Pond management can substantially modify the hydrological regime and ecological quality of receiving waters, usually rivers, canals, reservoirs and ponds downstream, with positive or negative potential impacts on watershed function.
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