الفهرس 
AquacultureOnly 14 pages are availabe for public view
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Abstract
Egypt’s fishery sector has been a vital part of the national culture and economy since recorded time. With rich water bodies, lakes, rivers, coastal lagoons and open sea, catches of fish, and increasingly their culture, has been a key ingredient in national food supply and potential export earnings. Most remarkably, in the face of continued population growth and increasing resource pressures, Egypt has managed to increase its domestically produced per capita supply. This is largely due to the substantial growth of aquaculture, at 445,000mt amounting to more than 51% of national production in 2003.(13) The present study was conducted to investigate Heavy Metals Levels and Chemical Composition of Mullet Fish Cultivated in Fish Farms during summer and Winter Seasons.
Sampling was carried out During Summer and Winter Seasons from different farms of Alexandria and El-Behira included different water salinity types at selected three locations during the winter of 2009 to the summer of 2010. Surface water and fish samples have been collected from the study area representing fish farms of Alexandria and El-Behira.
The first season was started during winter 2009, while the second season was started during summer season 2010 in three fish farms different in place and salinity levels, and was conducted on 10 fish from every fish farm. This season was conducted to assessment of the heavy metals Cd, Zn, Cr, Cu and Pb in fish samples of grey mullet, L. ramada in marketing size and water samples, assessment of proximate chemical analysis (moisture, protein, fat and ash) of edible fish tissues (meat) of grey mullet, L. ramada in marketing size and assessment of some physiochemical parameters of water (pH, temperature, salinity).
The most important results obtained in the both season can be summarized as the following: -
A) Heavy metals:-
The accumulation of heavy metals in fishes varied with different species, organs, feeding habits, area and from one metal to another and they also varied in water with different area and water supply. Cu, Zn and Pb were found in highest levels, while Cr and Cd were found in lowest levels, in all farms through the two seasons in both water and fish samples.
Water:-
1- There was insignificant difference in the mean Cu content among the three farms.
2- The lowest mean Pb level (0.092 mg/l) was detected in El-Hager farm, which was significant difference, lower than those detected in Idku and Mariout farm (0.139 mg/l and 0.136 mg/l) and were no significant.
3- There was insignificant difference in the mean Cr and Cd content among the three farms.
4- The highest mean Zn level (0.249 mg/l) was detected during El-Hager farm, which was significant difference, higher than those detected in Mariout and Idku farm (0.169 mg/l and 0.080 mg/l) and were insignificant.
Fish:-
1- The highest Cu level (6.922 mg/kg) was detected in El-Hager Farm, higher than those detected in Mariout farm (2.612 mg/kg) and Idku farm (0.810 mg/kg). There was significantly difference in the mean Cu content among the three farms.
2- The lowest mean Pb level (0.238 mg/kg) was detected in Mariout Farm, which was statistically significant, lower than those detected in El-Hager farm (0.828 mg/kg) and Idku farm (0.789 mg/kg). They were statistically insignificant.
3- The highest mean Cr level (3.008 mg/kg) was detected in Idku Farm, higher than those detected in El-Hager farm (1.948 mg/kg) and Mariout farm (0.551 mg/kg). There were significant differences in the mean Cr content among the three farms.
4- The highest mean Cd level (0.038 mg/kg) was detected in Idku Farm, which was statistically significant, higher than those detected in Mariout farm (0.030 mg/kg) and El-Hager farm (0.024 mg/kg). They were statistically insignificant.
5- The highest mean Zn level (3.173 mg/kg) was detected in Mariout Farm, higher than those detected in Idku farm (2.942 mg/kg) and El-Hager farm (2.520 mg/kg). There were insignificant differences in the mean Zn content among the three farms.
B) Chemical composition:-
1- There was insignificant difference in the mean Ash percentage among the three farms.
2- The lowest Moisture percentage (69.172%) was detected in El-Hager Farm, which was statistically significant, lower than those detected in Idku and Mariout farm (74.299 and 74.36%) and were significant.
3- The highest Protein percentage (22.918%) was detected in Mariout Farm, which was statistically significant, higher than those detected in Idku and El-Hager farm (21.227 and 20.484%) and were significant.
4- The highest Fat percentage (8.777%) was detected in El-Hager Farm, which was statistically significant, higher than those detected in Idku and Mariout farm (3.289 and 1.331%) and were significant.
C) Water quality:-
1- The highest mean Salinity was detected in Mariout Farm (16.133 ppm) which was statistically significant, higher than those detected in El-Hager and Idku farm (1.933 and 7.4 ppm), which were statistically significant.
2- The highest mean pH level (8.088) was detected in Idku farm, which was statistically significant, higher than those detected in El-Hager and Mariout farm (7.828 and 7.563), which were statistically significant.
3- There was no statistically significant among the three farms in Temperature.
It can be concluded that heavy metals concentrations in fish samples were higher than those found in water samples. Also fish collected thorough winter season was better than summer season and El-Hager farm of winter season was the better farm among the three farms through both seasons, because of their low percentage of moisture and high percentage of protein and fat.
According to the study results the following is recommended to:
1. A balanced diet is essential to avoid excessive exposure to contaminants from a small range of food items.
2. Vulnerable groups such as children and pregnant women should be careful in the selection of food.
3. Fish are excellent sources of high-quality protein and low in saturated fat, and moderate consumption is recommended.
4. Public education on general sources, exposure routes and health impacts of heavy metals and other chemicals.
5. Establishment and strengthening of monitoring programmes on environmental and health risk assessment of chemicals and pharmaceuticals.
6. Control of discharge of heavy metals and other toxic chemicals to the environment.
7. Establishment of a food preparation practice and selling environment legislation and enforcement the same.
8. Regular monitoring of these food categories is conducted, to avoid metal build up in the body, whose detrimental impact becomes apparent only after several years of exposure.
9. Further research studies on methods of removal of heavy metals from water and fish should be conducted.