The Contents Of Heavy Metals In Several Fish Species From Upstream Of The Yangtze River And Ecophysiological Effects Of The Dietary Lead(Pb)on Spinibarbus Sinensis

Two experiments were conducted in this study, experiment 1 was the field investigation and experiment 2 was observation for effects of dietary Pb on Spinibarbus sinensis under laboratory condition. In experiment 1, During July to October in 2010 and April in 2011, nine fish species were collected from the Zhuyang section of the Yangtze River. The samples consisted of 3-8 specimens for the fish of 3 year age respectively in Siniperca kneri, Rhinogobio cylindricus, Cyprinus auratus, Cyprinus carpio, Spinibarbus sinensis, Pelteobagrus vachelli and Silus asotus, and 32 specimens for the fish of 1-4 year age in Coreius heterodon and 38 specimens for 1-3 year age in Coreius guichenoti contained. The three heavy metals were detected in the every samples. Experiment 2 was divided two series, series(1):the juvenile Spinibarbus sinensis were fed with experimental diets containing different Pb levels of 0,2500 and 5000μg Pb/g in an indoor rearing system for 8 weeks; series(2):the fish was fed with the dietary Pb of 5000μg Pb/g and 0μg Pb/g for 16 weeks and sampled at 2nd week,4th week,8th week and 16th week. After the end of experiment, the growth performance of the tested fish; the MDA levels, the activity of GST and T-AOC of the hepatopancreas, gut and gill; and the Pb residued in the liver, gut, muscle and carcass were detected.The main results from experiment 1 were follows:The mean contents of Pb in the nine samples for 3 year age ranged from 1.885 to 2.731μg/g, Cd from 0.107 to 0.236μg/g and Cr from 0.514 to 0.918μg/g. Either the concentrations of Pb or that of Cd in the nine species were higher than the national safety criteria for food in China, but not was Cr. The concentrations of Pb, Cd, and Cr were compared among the different age groups in the same species respectively for Coreius heterodon and Coreius guichenoti. There was no significant difference for the concentrations of Pb in Coreius heterodon between 3 and 2 age groups, and also between 2 and 1 age groups. But the concentration of Pb in 3 age groups was significantly higher than that in the 1 age groups (p< 0.05). The concentration of Pb in Coreius guichenoti for 3 age groups was significantly higher than that for the 1 or 2 age groups (p< 0.05), and the difference between 2 and 1 age groups was not statistically significant. There was no significant difference for the concentrations of Cd and Cr in either Coreius heterodon or Coreius guichenoti among different age groups. Regression analysis showed that there was a significant positive correlation for Pb concentrations in either Coreius heterodon or Coreius guichenoti respectively with its body length or body weight (p< 0.01). And such the relationship between the concentrations of Cd and body length or body weight only occured in the Coreius guichenoti (p< 0.05). However, the correlation for the concentrations of Cr with body length or body weight could be found in neither Coreius heterodon nor Coreius guichenoti.The main results from experiment 2 were follows:The tretments exposured with different dietary Pb concentrations:1. The hepatosomatic index (HSI) and condition factor (K) were not significantly different in the treatments with different dietary Pb exposure concentrations. The total weight was significantly lower in the 5000μg Pb/g group than the control group(p< 0.05), but it was no significantly different between the 5000μg Pb/g and 2500μg Pb/g groups and also no significantly difference between the 2500μg Pb/g groups and cotrol group. The feed efficiency (FE) and Specific growth rates of weight (SGR) were decreased with dietary Pb concentrations increased; the feed efficiency in 5000μg Pb/g groups was significnatly lower than the 2500μg Pb/g group or control group(p< 0.05), it was no significantly different for SGR between 5000μg Pb/g and 2500μg Pb/g group, but they were siginificantly lower than control group.2. The concentrations of Pb residued in hepatopancreas, gut, muscle and crass of Spinibarbus sinensis increased with dietary Pb exposure levles.The concentrtion of Pb residued in hepatopancreas, gut, muscle and carcass of Spinibarbus sinensi were significantly higher than that for 2500μg Pb/g group or control group(p< 0.05), and the 2500μg Pb/g groups was significntly higher than the control groups(p< 0.05). Moreover, Pb accumulated from sampled tissues comformed to the following order:gut> hepatopancreas> muscle.3. Malondialdehyde (MDA) levels in hepatopancreas, gut and gill increased with the dietary Pb exposure concentrations, and the contents of MDA in the gut of 5000μg Pb/g group was significantly higher than the control group (p< 0.05), but it was not significnt difference in the hepatopancreas and gill among different dietary Pb concentrtions. The activity of GST in the gut and hepatopancreas were decreased with the dietary Pb exposure concentrations increased, the activity of GST in the gut and hepatopancreas of 5000μg Pb/g group were significantly lower than the control group(p< 0.05); but the activity of GST in the gill was increased with the dietary Pb exposure concentrations, and the 5000μg Pb/g group was significantly lower than the control and 2500μg Pb/g group (p< 0.05). The total antioxidative capacity (T-AOC) in the gut was decreased with the dietary Pb exposure concentrations increased, and it was significantly lower in the 5000μg Pb/g groups than the 2500μg Pb/g and control group(p< 0.05), but it was not significnat difference of the hepatopancreas and gill among the tretments. The tretments fed with 5000μg Pb/g and 0μg Pb/g exposured with periods:4. The hepatosomatic index (HSI),and condition factor(K) were not significantly different in the treatments with different dietary Pb exposure periods, only the total weight of the 16th weeks of 5000μg Pb/g is significantly different with the control(p< 0.05). The feed efficiency(FE) and decreased with periods increased, the feed efficiency at each sampling periods were siginificantly lower than control group expect 8th and 16th week. The SGR of 5000μg Pb/g group decreasd with the periods increased It was significantly difference between 5000μg Pb/g group and the control group at each sampled times.5.The contents of Pb in hepatopancreas, gut, muscle and carcass of Spinibarbus sinensis were significantly higher than the control group at the each sampling periods. It also increased with dietary Pb exposure periods. There is a significnt difference between 8th week and 16th week in gut, hepatopancreas, muscleand carcass.6. Malondialdehyde (MDA) levels in gut was significantly higher than the control group at the each sampling periods, but MDA in hepatopancreas was significantly higher than the control groups only at the 2nd weeks, it was significant higher than that for the control groups only at the 2nd and 4th weeks in gill. The MDA levle, the activity of GST in gut and hepatopancreas and the level of T-AOC in gut were increased in the 2nd week and decreased with futher incresing exposured periods, but the level of T-AOC in the hepatopancreas and gill were not significantly different with futher incresing exposured period.The conclusions suggested in this study were as follows:1. The results suggested that the fish from the Zhuyang section of the Yangtze River were polluted by Pb and Cd. It also suggested that bioaccumulation of Pb increased with age in Coreius heterodon and Coreius guichenoti, and that of Cd was only found in the Coreius guichenoti.2. Long-term dietary Pb intaking may reduce the SGR and FE of Spinibarbus sinensis, and the inhibit the growth of Spinibarbus sinensis. 3. Compared to others fish species, the ration of Pb accumulated was lower in Spinibarbus sinensis, which suggested that Spinibarbus sinensis have better tolerance for lead toxicity.4. The dietary Pb play serious impact on the gut than on the gill and hepatopancreas, the MDA levels and the activity of T-AOC were subjected to more serious damage in the gut. It was suggested that the gut was a major organ that exposured to dietary Pb.