The Toxic Effect Of Copper And Cadmium On Oryzias Latipes

Taking Oryzias latipes as the experimental material, the half lethal concentration and safe concentration were obtained by the single facter acute toxicity experiment of heavy metal to Oryzias latipes. Based on the safe concentration of Oryzias latipes, the subacute acute toxicity experiment was conducted to further investigate the effects of Cu2+, Cd2+to bio-accumulation, bio-enzyme and liver histology in Oryzias latipes. The results were as follows:1. Acute toxicity of waterbome copper and cadmium exposure to Oryzias latipesIn order to explore and compare the toxicity responses of Oryzias latipes at its early developmental stage under the exposure of Cu2+ and Cd2+, static-renewal acute toxicity (48 h) on the embryo of Oryzias latipes and acute toxicity (96 h) on the fry and fingerling were investigated. The results showed that the 24 and 48 h-LCso values of the embryos of Oryzias latipes exposed in Cu2+ were 8.164 and 6.965 mg/L, respectively; and the values exposed in Cd2+ were 63.084 and 53.093 mg/L, respectively. Embryo incubation time of Oryzias latipes was shortened in low Cu2+ concentration (≤1.97 mg/L) while was prolonged in high Cu2+ concentration (≥3.87 mg/L). In contrast, in spite of the concentration of cadmium, all the embryo incubation time of Oryzias latipes exposed to Cd2+ were prolonged significantly.Cu2+ and Cd2+ could decrease the hatchability of the embryos when the concentrations were higher than 1.97 mg/L and 19.68 mg/L, respectively. The 24,48, 72 and 96 h-LCso values for Oryzias latipes larvae exposed to Cu2+ were 5.361,2.844, 2.020 and 1.352 mg/L, respectively; the 24,48,72 and 96 h-LCso values for Oryzias latipes larvae exposed to Cd2+ were 15.907,10.550,7.986 and 6.346 mg/L, respectively; the 24,48,72 and 96 h-LCso values for Oryzias latipes fingerling exposed to Cu2+ were 5.732,4.037,2.498 and 1.955 mg/L, respectively; and the 24,48,72 and 96 h-LCso values for Oryzias latipes fingerling exposed to Cd2+ were 16.419,11.745,8.516 and 6.776 mg/L, respectively. Compared with other freshwater aquatic organisms, the Oryzias latipes fry and fingerling were sensitive to copper and cadmium.2. The subacute toxic effects of copper exposure on accumulation histology and fish’s enzyme in Oryzias latipesIn this study, Oryzias latipes were exposure to O(control),0.04,0.10,0.20 and 0.40 mg/L Cu2+ for 20 days to determine the effects on the accumulation, histology and fish’s enzyme in Oryzias latipes.Copper content in brain, gills, hepatopancreas, gonad and muscle increased with Cu2+ in the water and among these five tissues, hepatopancreas should be the main copper bioaccumulation and the metabolism site for copper in Oryzias latipes. The histological structure lesions of the hepatopancreas in Oryzias latipes were alse observed with the increase of copper concentration.The lesions include nuclear pycnosis, focal necrosis, congestion and fatty degeneration.The enzymatic activities were sensitive to copper exposure.In high Cu2+ concentration, The GSH content of brain, gills, hepatopancreas and gonad, and the SOD, CAT, GR, AKP, ACP, GPT, GOT, GST, TChE and ChAT activities decreased significantly(p<0.05); The Cu2+ didn’t reach the markedness effect on the GPX enzyme activity of brain, gills and gonad.3. The subacute toxic effects of cadmium exposure on accumulation,histology and fish’s enzyme in Oryzias latipesIn this study, Oryzias latipes were exposure to O(control),0.07,0.15,0.37 and 0.74 mg/L Cd2+ for 20 days to determine the effects on the accumulation, histology and fish’s enzyme in Oryzias latipes.Cadmium content in brain, gills, hepatopancreas, gonad and muscle increased with Cd2+ in the water and among these five tissues, gills should be the main cadmium bioaccumulation and the metabolism site for cadmium in Oryzias latipes. The histological structure lesions of the hepatopancreas in Oryzias latipes were alse observed with the increase of cadmium concentration. The lesions include nuclear pycnosis, focal necrosis, vacuolar degeneration, congestion and fatty degeneration.The enzymatic activities were sensitive to cadmium exposure. In high Cd2+ concentration, The GSH content of brain, gills, hepatopancreas and gonad, and the SOD, CAT, GR, AKP, ACP, GST, TChE and ChAT activities decreased significantly(p<0.05); And the GPX enzyme activity of hepatopancreas decreased significantly (p<0.05); The GPX enzyme activity of brain, gills, gonad and GPT, GOT enzyme activity of gonad wasn’t affected by the Cd2+.