Presentation on theme: "WATERBORNE COPPER EXPOSURE IN WHITE CACHAMA (Piaractus brachypomus): HAEMATOLOGICAL AND TOXICOLOGICAL EVALUATION Maria Constanza Lozano 1, Jaime F. Gonzalez."— Presentation transcript:
WATERBORNE COPPER EXPOSURE IN WHITE CACHAMA (Piaractus brachypomus): HAEMATOLOGICAL AND TOXICOLOGICAL EVALUATION Maria Constanza Lozano 1, Jaime F. Gonzalez 1 Carlos A. Moreno 2 1 Laboratory of Aquatic Toxicology – 2 Laboratory of Clinical Pathology - School of Veterinary Medicine and Animal Science UNIVERSIDAD NACIONAL DE COLOMBIA – BOGOTA, D.C. Methodology 72 white cachamas acclimated in 30-gallon glass tanks - Hematology. Hematocrit (PCV), hemoglobin (HB) and total/differential red and white cell counts. - Serum sodium. (Cromolyte ™ (Bayer) on the blood chemistry analyzer RA-50 ® (Bayer). - Wintrobe indices (Mean Corpuscular Volume -MCV; Mean Corpuscular Hemoglobin - MCH- and Mean Corpuscular Hemoglobin Concentration -MCHC-) were calculated based on total erythrocyte count, hemoglobin concentration and hematocrit. - Statistics. Two-way ANOVA test for comparison of central tendency measures (sample mean) of variables Data were processed using SAS ® (Statistical Analysis Software). Tukey’s test. - Daily 50% water change and Cu concentrations readjusted. Behavior (swimming performance, response to feed and general attitude in the tanks) was evaluated. Fish were given commercial feed (Mojarra 32 ® ) every 24 h accounting for 3% of fish biomass h static-renewal bioassays. 4 different waterborne copper (CuSO 4. 5 H 2 O) concentrations (T1= 0, T2= 0.08, T3= 0.17, T4= 0.47 ppm, respectively) (n=18 / treatment). - Tap dechlorinated water for exposures (pH=7.5 ± 0.3; hardness (as CaCO 3 ) = 53.6 ± 8.2 ppm; alkalinity (as CaCO 3 ) = 28.7 ± 4 ppm; temperature = 25.5 ± 0.9 o C). Figure 2. Control fish showing normal appearance of skin pigmentation under laboratory acclimation (top). Copper- exposed cschama (0.47 ppm) displays skin discoloration (bottom) Results & Discussion -Behavior. T3 and T4 (higher Cu concentrations): the most prominent changes. Feed intake and motion were significantly reduced in these treatments during the 96h period. Erratic swimming determined by motionless and depressed fish resting at the bottom of the tanks. T2 showed these same findings during the first 24 h of experiments. Abstract. White cachama, a characin fish from Orinoco and Amazon basins has considerably increased its production in Colombia, Brazil and Venezuela. Copper sulfate is used as a therapeutic agent in the field regardless of low water alkalinity and hardness levels found in regional waters. 18 cachamas (~ 20 g) per treatment were exposed in static-renewal system for 96 h to 0 ppm Cu (as CuSO 4. 5 H 2 O) (T1), 0.08 ppm (T2), 0.17 ppm (T3) and 0.47 ppm (T4). Gills and liver Cu concentrations, hematological, behavioral and post-mortem findings were examined. Liver Cu (ppm) increased as Cu in water was higher. Gills Cu (ppm) also increased in exposed cachamas. Hematological tests showed reductions in hematocrit, hemoglobin, total leukocyte and erythrocyte counts. Wintrobe indices revealed a macrocytic normochromic anemia in T2 and T3 while T4 exhibited a normocytic anemia. Serum sodium (mEq/L) decreased significantly in Cu exposed fish. Cu-exposed fish looked pale, lethargic (T3, T4) and anorectic (T3, T4). Post-mortem findings in these fish showed weight loss, a congestive liver and smaller abdominal organs than those in controls. Hepatosomatic index diminished significantly in exposed fish. This experiment represents a first approach in the evaluation of Cu used as a therapeutic agent in cachamas. Unique physicochemical water parameters in this region make necessary further research in physiological and toxicological implications in native fish when considering Cu as either a water contaminant or a therapeutic agent. It is of our more genuine interest that the information provided by this study helps to make better judgment when opting for the use of copper as a therapeutant in this indigenous species and/or evaluating its effects as a water contaminant. -Necropsy and Cu measurement. Macroscopic most relevant findings. Harvesting of liver and gills allowed copper quantification using an atomic absorption spectrophotometer (Shimadzu AA-680). -Hepatosomatic index (HSI= Liver weight x 100 / wet body weight ) and weight gain were calculated for comparison among treatments. - Haematology. Results of hematology analysis are shown in Table 1. The most remarkable changes account for reduction in PCV, HB and white/red cell total counts as Cu concentrations increased. These parameters along with Wintrobe indices (not shown) revealed that fish were anemic (macrocytic normochromic : T2 and T3 ; normocytic: T4). Conclusions - White cachama showed to be a sensitive species to copper exposure at even therapeutic concentrations reported for other species. - Water physicochemical parameters recorded for this laboratory exposure (hardness, pH, alkalinity) were higher than those normally found in natural conditions. Toxic effects under natural exposure in ponds could be even more deleterious for fish given the very low water hardness/alkalinity levels as well as the rather acidic pH of waters in the Orinoquia and Amazonia regions. - Changes in hematological parameters (reduced red and white cell counts, low serum sodium levels) were good indicators of the stress caused by the copper exposure. Significant reduction of serum sodium in all the Cu-exposed treatments as compared to the controls was a good indicator of the osmotic stress experienced by the fish. Reduction in white cell counts in exposed fish could impair their immune function making them more susceptible to opportunistic pathogens under field exposure conditions. - Although responses in behavioral (swimming pattern, motion) and production parameters (feed intake, body weight gain) in Cu-exposed fish were not specific to be used as a diagnostic tool, showed a considerable effect on general performance of the specimens. This may have significant implications for cachama growers in commercial farms. - Alternatives to copper for therapeutic purposes in cachama are needed and welcome given the results found in the present work. However, validation of present results under natural conditions would help to establish actual sensitivity of the species. - Differential / absolute white cell counts. Statistically significant reduction in lymphocytes (T3, T4). On the other hand, monocytes (T3, T4) and heterophils (T3, T4) were higher in Cu-exposed fish (Table 2). As for Absolute White Cell Counts is evident that the higher the Cu concentration in the water, the most dramatic the reduction in lymphocytes (T2, T3, T4), heterophils (T3, T4) and even thrombocytes (T3, T4). - Gross Lesions: Most of the exposed fish showed at the necropsy a remarkable reduction in viscera size (intestine, liver, mesenteric fat, stomach). This is strongly related to the reduced feed intake that was observed. Gall bladder in exposed fish revealed darker tone. Hepatosomatic index (HSI) diminished significantly in T3 and T4. - Liver and gills copper accumulation: Figure 3 shows liver and gills Cu accumulation after atomic absorption analysis. The higher affinity for Cu in hepatic tissue has been attributed to detoxification processes mediated by metallothionein binding (Roesijadi and Robinson 1994). Branchial affinity for Cu was significantly reduced in comparison to hepatic accumulation. References - Handy, R.D. & F.B. Eddy Effects of inorganic cations Na + absorption to the gills and body surface of rainbow trout, Oncorhynchus mykiss, in dilute solutions. Can J Fish Sci 48: Heath AG Water Pollution and Fish Physiology. CRC Press. Boca Raton, FA. Pp , Hwang, D.F., J.F. Lin & S.S. Jeng Comparative toxicity of copper and zinc to isolated eel hepatocytes. Chemistry and Ecology 12: Jacobson, S.V. & R. Reimschuessel Modulation of superoxide production in goldfish (Carassius auratus) exposed to and recovering from sublethal copper levels. Fish and Shellfish Immunology 8: Lauren, D.J. & D.G.McDonald Acclimation to copper by rainbow trout Salmo gairdneri. Biochem Can J Fish Aquatic Sci 44: Marr, J.C., J. Lipton, D. Cacela, J.A. Hansen, H.L. Bergman, J.S. Meyer & C. Hogstrand Relationship between copper exposure duration, tissue copper concentration and rainbow trout growth. Aquatic Toxicology 36: Noga, E. J Fish Disease: Diagnosis and Treatment. Mosby. Missouri. pp Nussey, G., J.H.J. Van Vuren & H.H. Du Preez Effect of copper on the haematology and osmoregulation of the Mozambique tilapia Oreocromis mossambicus (Cichlidae). Comp Biochem Physiol 111C: Pelgrom, S.M.G., P.H.M. Balm & S. Wendelaar Bonga Integrated physiological response of tilapia, Oreochromis mosambicus, to sublethal copper exposure. Aquatic Toxicology 32: Reimschuessel, R Postmortem examination. In M. Stoskopf (ed) Fish Medicine. W.B. Saunders, Philadelphia. pp Roesijadi, G. & W.E. Robinson Metal regulation in aquatic animals: mechanisms of uptake, accumulation and release In D. Mallins, G.K.Ostrander (eds) Aquatic Toxicology : Molecular, biochemical and cellular perspectives. CRC Press. Florida. Pp Vosyliene, M.Z Haematological parameters of rainbow trout (Oncorhynchus mykiss) during short-term exposure to copper. Ekilogija (Vilnius) 3: Wieber, D.N. & R.E. Spieler Behavioral mechanisms of metal toxicity in fishes. In D. Mallins, G.K.Ostrander (eds): Aquatic Toxicology, molecular, biochemical and cellular perspectives. CRC Press. Boca Raton, FA. pp Table 1. Hematology results for the different experimental treatments (mean +/- standard deviation, C.I.:confidence intervals) (Different letters represent statistically significant difference among treatments, α=0.05) Variable T1 (n=18) T2 (n=18) T3 (n=16) T4 (n=17) Hematocrit (PCV) (%) /- 2.6 a /- 2.6 b /- 2.3 c /- 2.4 d Hemoglobin (g/dL) 7.5 +/- 0.4 a 6.8 +/- 0.5 b 5.8 +/- 0.8 c 5.1 +/- 0.6 d Total red cells count (million cells / mm 3 ) 1.5 +/- 0.1 a 1.2 +/- 0.1 b 1.1 +/- 0.1 c 1.0 +/- 0.1 c Total white cells count (cells / mm 3 ) 17,249 +/- 2,011 a 15,039 +/- 2,004 b 11,082 +/- 1,802 c 8,253 +/- 1,444 c Table 2. Mean values of differential white cells counts in experimental treatments (mean +/- standard deviation. C.I. : confidence intervals) (Different letters represent statistically significant difference among treatments, α=0.05) Cell type (%) T1 (n=18)T2 (n=18)T3 (n=16)T4 (n=17) Thrombocytes44.0 +/- 3.8 a /- 3.0 a /- 3.2 a /- 5.9 a Heterophils6.4 +/- 1.5 a 7.0 +/- 1.8 a /- 2.8 b /- 2.4 c Monocytes2.7 +/- 0.9 a 2.2 +/- 0.7 a 4.7 +/- 1.4 b 5.3 +/- 1.6 b Lymphocytes46.6 +/ a / a / b /- 4.9 c Eosinophils0.3 +/- 0.4 a 0.1 +/- 0.3 a 0.1 +/- 0.5 a 0 +/- 0 a - Serum sodium. Figure 1 depicts serum sodium concentrations in experimental groups. Lower serum sodium levels, as Cu concentration in waters increased., a d cb Necropsy and Cu measurements. T1 (control) and T2 (0.08 ppm Cu) gained weight throughout the experimental phase (2.8 g and 1.7 g on average/ fish, respectively). T3 and T4 lost 0.5 g and 1 g on average/ fish, respectively. - Skin discoloration: Most of the Cu-exposed fish revealed skin discoloration (T2, T3 = 80%, T4 = 100 % of the fish) (Figure 2).