20 September 2009 studied sites are shown in Table 2. Unlike heavy metal levels in the water, the mean concentrations of most of the heavy metals were lower in sediments of the growout ponds than in their water supplies. The mean values for Cd were 0.07, 0.05 and 0. 5 ppm in the ponds and 0.1, 0.08 and 0.06 ppm in the water supplies at sites I, II and III, respectively. The values for Cu were 1.68, 0.77 in the ponds and 2.31, 1.05 and 0.87 ppm in the water supplies, while mean Zn levels were 3.38, 1.75 and 1.74 ppm (ponds) and 4.7, 1.92 and 1.82 (water supplies) and those for Pb were 0.71, 0.26 and 0.17 ppm (ponds) and 0.77, 0.61 and 0.31 ppm in the water supplies at sites I, II and III, respectively. The mean measured concentration of heavy metals in the muscles of Oreochromis niloticus at the three sites are shown in Figure 5. The mean values of Cd were relatively low: 0.15, 0.06 and 0.04 ppm for sites I, II and III, respectively. The highest mean level of Cu in tilapia muscle was recorded at site I (3.90 ppm), followed by site II (2.87 ppm), while the lowest level was recorded in site III (0.01 ppm). The highest mean level of Pb was recorded at site II (7.33 ppm), followed by site I (6.37 ppm) and site III (2.47 ppm). Discussion The future of fish culture in Egypt depends upon healthy fish stocks. The Ataa El Mataraia site represents one of the largest areas in the Suez Canal area that includes commercial fish farming. This area represents the first order of contamination in the areas studied as demonstrated by the highest levels of biological and chemical contamination in the water, sediment, and fish sampled at the site. Bahr El Baqar represents the main water source for aquaculture farms in Ataa El Mataraia. This drain receives the sewage discharge from the city of Cairo. Agriculture drainage water forms the largest input of water to fish farming in Nemra 3. That water contains salts drained from cultivated land, nutrients from fertilizer residue and pesticide residues from pest control programs. Those substances affect the quality of the drain water and its suitability for re-use. This was apparent in contaminated fish that were produced from the fish farming of Nemra 3. Although we were not be able to estimate the impact of pesticides on finfish, it is highly likely that the production from these farms are also contaminated by pesticides. Total viable bacteria, Aero, TC, FC, and FS are considered to have a high degree of association with outbreaks of gastrointestinal diseases and are recommended as the basis for bacterial water quality standards (USEPA 1986). The highest bacterial contamination was recorded in the sewage water supply and its farm. The mean count of FC recorded in pond water of that farm (82x103/ml) greatly exceeded the permissible level (102/100 mL) in effluent (Dixo et al. 1995). World Health Organization (WHO 1989) guidelines consider coasts with 100 cfu FC/100mL as polluted and not safe for recreational activities. Edwards (1990) mentioned that the infestation potential of fish being cultivated in wastewater effluent is very high because of the possibility of pollution by bacteria, viruses and toxic chemicals. The principal risk associated with any water source is that of infectious diseases related to FC and FS (Cabelli et al. 1982, USEPA 1986, Pettibone 1992, Irvine and Pettibone 1996, Laukova and Juris 1997, Pinto et al. 1999). Escherichia coli is often used as an indicator for fecal contamination. Some strains of E. coli are capable of causing food borne disease, ranging from mild enteritis to serious illness and even death (WHO 1999). Where animal manure, particularly bovine manure, is used as pond fertilizer, there is a risk that pathogenic strains of E. coli may be present in pond water. Fecal streptococci are intestinal bacteria and are found in the feces of all warm-blooded mammals. Within the fecal streptococci is a subgroup known as enterococci, characterized by growing both at 10ºC and 45ºC in an environment of 6.5 percent NaCl and pH 9.6. This subgroup has been suggested as a useful indicator for the quality of water for recreational use (Cabelli 1983, Dufour 1984). The lowest bacterial contamination was recorded in the treated sewage water source and its corresponding fishponds. Although only primary treatment was used, it may have helped, to a large extent, to dilute the chemical contamination. Chlorine used for sewage treatment might reduce pathogenic bacteria. This assumption agrees with that reported by Twarowska(1997) who mentioned that the percentage of occurrence of pathogens decreased gradually in sewage during different steps of treatment. The primary and secondary treated waste effluents were used successfully to grow Nile tilapia, O. niloticus, in many areas. The growth rate of fish reared in treated wastewater was significantly higher than that of fish reared in the natural habitat (Khalil and Hussein 1997). No previous data were available for the bacteriological and heavy metal contamination in fish farming, particularly in the Suez Canal area. However, it is more important to compare our data with the research that is available on bacteriological and metals pollution of Lake Timsah because that lake represents the main source of seafood in the Suez Canal area. In the present study, the mean count of TVB in Oreochromis niloticus harvested from site I was extremely high (225x102 cfu /g). Meanwhile FC recorded in muscles of O. niloticus were much higher (ranging 300 to 178x102 cfu/g) than the safe level (100 cfu/gm) recomFig. 5. Mean heavy metal level in cultured finfish (Oreochromis niloticus) at the three studied sites.
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