16 September 2009 Study on bacteriological and heavy metal contamination and its potential risk in fish farms in the Suez Canal Area, Egypt Howaida R. Gabr1 and Sahar El Alfy2 Currently, Egypt is actively involved in aquaculture. Most Egyptian aquaculture is conducted in freshwater ponds, with some use of brackishwater systems and cages in rivers. In a survey of Egyptian aquaculture, Shehadeh and Feidi (1996) found that pond fish culture amounted to 65 percent of production, with culture in rice fields comprising 32 percent and cage culture three percent. Private farms accounted for 89 percent and government farms for 11 percent. About 69 percent of the total pond area consisted of unlicensed farms (farms using arable land). The main cultured species are tilapia, mainly Oreochromis niloticus, about 35 percent of total aquaculture production; carp, mostly Cyprinus carpio (35 percent); mullet, mainly Mugil ramada and M. cephalus (23 percent); African catfish, Clarias gariepinus (three percent); gilthead sea bream, Sparus auratus (two percent); and sea bass, Dicentrarchus labrax (two percent, Barrania and Sadek 1994, FAO 1994). Water use for aquaculture is restricted to irrigation drainage water of variable salinity and water drawn from coastal and inland lakes. Use of water from the Nile and from irrigation canals for fish farming is prohibited. Use of ground water is permitted mainly for fish hatcheries (Balarin 1986, Shehadeh and Feidi 1996). For this reason and in line with the country’s policy to control pollution, the aquaculture authorities have directed their efforts for obtaining new water resources toward recycling and reuse of wastewater. In some regions of Egypt, where there is a shortage of freshwater, fish growers in some private farms use untreated sewage wastewater and agriculture drainage water for fish culture. This water may pose a health risk to handlers and consumers (Sadek 1984). For this reason, health authorities have not yet approved the use of those effluents for aquaculture. According to Twarowska (1997), the largest problem regarding aquaculture in wastewater effluent is the accumulation of heavy metals, pathogens and pesticides in the fish and as a result, the possible transmission of diseases to humans. Among the metals that can be toxic under certain conditions are arsenic, cadmium, chromium, copper, lead, mercury, silver and tin. Moreover, the hazards associated with human pathogenic bacteria in the finfish and crustaceans produced in aquaculture can be divided into two groups: bacteria naturally present in the aquatic environment, (indigenous bacteria) and those present as a result of contamination with human or animal feces, or otherwise introduced to the aquatic environment. Hazards may also arise through the introduction of bacteria during postharvest handling and processing. Although the prevalence of bacterial pathogens appears to be higher in coastal and inland aquaculture environments than in the open seas, it is uncertain if these differences affect the safety of products originating from the different areas (WHO 1999). Fish farming ponds are one of the main sources for finfish supply in Ismailia city. The main source of water for the farms is coming from either sewage water or agricultural water. Although this kind of water is hazardous to aquatic life and poses a public health threat, there is a shortage in our knowledge, particularly on the effect of biological and chemical contamination on production of the farms. In view of the lack of research carried on finfish farming in the Suez Canal area, this research focused on: 1. Investigating the different kinds of bacteria which are highly sensitive indicators of biological contamination and 2. Estimation of the concentrations of heavy metals (cadmium, cupper, lead and zinc). Those two points were studied in both biotic (cultured fish) and abiotic compartments (water and sediment) of fish farming ponds and water supplies. The quality and integrity of fish farming products were evaluated by comparing their level of contamination on farms with the levels of contamination in the fish of Lake Timsah, a lake that is one of the main sources of seafood supplied by fisheries in the Suez Canal area. Study Sites The study was conducted on three farms based on their source of water. The first farm (Site I) was located in Ataa El Mataria, Bahr El-Baqar. This represented the main water source for this area. The second farm (Site II) was located in Nemra 3 just before El Quntara by about 5 km. Agricultural drainage was the main water source for the area. The third farm (Site III) was located in Kilo 11 and the farm received treated sewage water (Figure 1). The size of the growout ponds in all three farms ranged from 0.5 to 1 ha, with average water depth 1.5 m. Oreochromis niloticus was the main cultured species on the three farms. The (Continued on page 18)
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