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Abstract The present study was carried out to assess the impacts of the lining (as a physical mean for water management) on the water quality and Nile tilapia fish, Oreochromis niloticus as bio-indicator species. The present study included two approaches (laboratory study and field investigations). The obtained results could be summarized in the following points: I: The results of the Laboratory studies: 1. After maintaining the fish O. niloticus, for 12 weeks, in aquaria with different substrata (cement, plastic and mud) and control ones (without lining), it was found that there were no significant differences (P>0.05) in the growth performance and the electrophoretic protein banding of the tested fish. The average initial size of the tested fish, of the different groups, was 3 g in weight and 5 cm in length and after 12 weeks the average final size of the fish was 15 g weight and 18 cm length; i.e. their growth rate was nearly the same in all groups. The electrophoretic technique (SDS-PAGE) of the tissue soluble proteins revealed that there were slight variations among the protein banding profiles of the tested fish groups. The number of bands yielded from the fish samples of different lining groups was 11, 14, 14 and 12 for cement, plastic, mud and control fish groups, respectively. The four testing fish groups were sharing 9 bands with each other which may be structural proteins. The dendrogram from cluster analysis showed that the fish of the cement-lined group demonstrate the highest value of the similarity indices ”S” 0.96 and 0.88 with control and mud groups, respectively. 2. The biochemical analysis of the serum samples of fish (30-70 g in weight and 12-17 cm in length) reared in the different substrata for 6 weeks indicated that there were also no significant differences (P>0.05) in the blood parameters (glucose, ALP, ALT, AST, total lipids & total proteins contents, urea and creatinine) and they were all similar to the normal values of the control group. 3. The physicochemical parameters of the water (temperature, pH, dissolved oxygen, electrical conductivity and the total dissolved solids) of the different groups of aquaria also recoded no significant differences (P>0.05) among them. II: The results of the field investigations: The investigated sites were divided into two areas according to the degree of pollution; where the area (2) was more polluted (especially with heavy metals) than the area (1). Area (1) was including site I (lined) and II (unlined), where the sites III (lined) and IV (unlined) were at the area (2). 1. The physico-chemical parameters of the water of the investigated lined and unlined sites in the two areas of study were measured seasonally. The results indicated that: The water temperature of the two study areas (1 and 2) were significantly different (P<0.05), as the water temperature recorded the highest values in the study area (2), especially at the unlined site (site IV: Ismailia canal at Mostorod) during summer; it was 33 ºC. The pH values of the area (1) were neutral at the lined site (site I: El-Bostan canal) and slightly alkaline at the unlined site (site II: Nasser canal). However, the pH values of the area (2) were significantly acidic (P < 0.05) at the unlined site (site IV: Ismailia canal at Mostorod) than the lined one (site III: River Nile at Warraq El-Haddar). The EC and the TDS were also increased significantly (P<0.05) in the unlined sites than the lined ones of the both areas of study. 2. The heavy metal analysis showed that the study area (2) was polluted with heavy metals (Cu, Pb and Cd) than the area (1). Also, it was revealed that the lined sites of both areas are less loaded with heavy metals (if found) than the unlined sites. 3. The performance of fish at the different sites was investigated. It was noticed that the fish inhabiting the area (1) were performing well in the both lined and the unlined sites. However, fish samples collected from the lined site of the area (2) showed a significant (P<0.05) better performance, by a greater growth factor, than of the unlined sites. This was related to the high levels of heavy metals pollution in this site that affected the growth rate. 4. The health of fish represented by the blood analysis of the fish samples collected from the different lined and the unlined sites was significantly (P<0.05) affected by the water quality of each site. The concentrations of glucose, total lipids, urea and creatinine of fish samples were significantly (P<0.05) high in the unlined sites comparing to the lined sites of the both study areas. On the same way ALP, ALT and AST enzymes showed a significant (P<0.05) elevation in the samples of the unlined sites than those of the lined sites at the two study areas. On the other hand, the total protein content of the fish samples of the unlined site at the area (1) showed a significant (P<0.05) increase than those of the lined site of the same area. This may indicate an early stage of tissue damage that allows the proteins to be leaked out of the cells (especially from the damaged hepatocytes) into the blood circulation. On contrast, the fish samples of the unlined site of the area (2) revealed a significant (P<0.05) decrease in the protein content comparing to those of the lined site which may be a result of the late stage of the damaged tissue that no longer able to produce proteins. The present histological study was carried out on two organs; gills and liver of the collected fish samples. The manifested histopathological results of the fish samples collected from the different lined and unlined sites confirm the previous results of the blood analysis. i - The histopathological lesions found in the gills: The gills of the fish samples collected from different sites showed some alterations that were more or less similar but differ in their degree of injury from mild as recorded in the lined site of the area (1) to sever as observed at the unlined site of the area (2). These lesions were including cellular and circulatory changes: The cellular alterations were including shortening/atrophy and curling in the lamellae. Lamellar interstitial oedema that led to epithelial lifting was observed. Hypertrophy of the chloride cells and epithelial hyperplasia of the gill filament led to fusion of neighboring lamellae were also seen. There was also desquamation of the gill lamellae. Necrosis and epithelial degeneration occasionally occurred. While the circulatory disturbances were including lamellar clubbed tips, vasodilation in the gill filament with blood congestion, telangiectasis and aneurism.ii - The histopathological lesions found in the liver: The most prominent alterations of the collected liver samples were cytoplasmic vacuolation, dilation and congestion in the blood vessels and sinusoids. In addition to, irregular arrangements of hepatocytes; i.e.; loss of its characteristic architecture, as a result of the degenerative and necrotic changes were also observed. Also, pyknotic nuclei were one of the most frequent and marked changes observed nearly in all samples. Widen extracellular spaces and loss of contact between hepatocytes and pancreocytes was also seen; especially in the liver samples collected from the unlined site of the area (2); site IV: Ismailia canal at Mostorod. Aggregations of inflammatory cells and hemorrhage of the blood inside the blood vessels were also noticed in liver samples of Ismailia canal. Hemosiderin granules were only seen during winter in the fish samples collected from the El-Bostan canal; the unlined site of the study area (1). CONCLUSION 1. The application of lining (whatever the used material) has no negative effect neither on the physico-chemical parameters of the water nor the health state of fish. 2. However, it plays a significant role in preserving the water with good quality. The mechanism is unknown but it is supposed that the soil nature -especially earthen one with the increased pollution factors today- plays a non negligible role in maintaining the suitable habitat for bacteria, viruses and parasites which are harmful to both aquatic life and human who is the main consumer of the freshwater fish. 3. The histological and biochemical alterations found in the fish samples were due to many types of pollutants; especially heavy metals in the surrounding environment. So these bio-markers with the physico-chemical parameters of the water assist in monitoring and evaluation the state of the aquatic environment. |