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Cadmium and temperature effect on blood cell counts of freshwater fish Colossoma macropomum

Abstract:

In this work, the cadmium (CD) and temperature effect on the red cell osmotic fragility and blood cells count in the tropical fish Colossoma macropomum were evaluated. The fishes were exposed to 0.5 mg/L of cadmium chloride during 24 days and two temperatures (25 and 30°C). At 0; 10 and 24 days of Cd exposure, blood samples were taken from fishes to determine the osmotic fragility curve, the differential white cell and reticulocyte count. The erythrocytes osmotic fragility began at 90 mmol/L of NaCl and total hemolysis was observed at 10 mmol/L of NaCl. Lymphocytes were the more abundant cells (>62%). These cells increased in Cd-exposed fish; moreover, the lymphocytes absolute percentage (control and exposed) decrease at 24 days of experimentation, being more significant at 30°C. After the granulocytes acidophils, trombocytes were the third cellular type, they were not affect by Cd neither temperature. However, trombocyte absolute number increased than fishes at 25°C/24 d as fishes at 30°C/24. On the other hand, the Cd/30°C exposed fishes showed a significant increase of thrombocytes. Both, cadmium and temperature affect thrombocyte number. The reticulocytes decrease due to cadmium exposed fishes. A synergic effect is produced by Cd and temperature on trombocytes; however, these factors exert an individual effect in fish reticulocytes.