Changes in Selected Blood Indices of Common Carp after Acute Exposure to Cadmium

Witeska. 1\1.: Changes in Selected Blood Indices of Common Carp ajier Acute Exposure to Cadmium. Acta vet. Bmo 1998.67: 289-293. Haematocrit. red and white blood cell count. phagocytic index. and viability oflymphocytes were studied in common carp exposed for 3 h to 10 mg dm·3 of cadmium. Hematocrit value and RBC count were elevated in all Cd-exposed (n=IO) and control fish (n=IO). compared to those sampled directly from the rearing tank (non-stressed). This finding indicates that the changes were caused mainly by manipulation stress. and no clear effect of cadmium on red blood cell was observed. White blood cell count was lowered after 48 and 96 h from the end of Cd exposure suggesting an immunological suppresion. Phagocytic response was significantly (P < 0.05) depressed in all stressed fish. and showed also some cadmium-induced elevation. up to 48 h from the end of the exposure. Later a decrease was observed. Preliminary results oflymphocyte viability analysis suggest some supression in 96 h. Only 6 out of 10 fish survived 96 h after the end of exposure which indicates disturbances in physiological functions in fish which were not clearly expressed in their blood. Toxicology. red blood count. white blood count. phagocytic index. viability of lymphocytes Cadmium is extremely toxic to aquatic organisms, and tends to accumulate in living organisms. Cadmium concentration in the water may range from undetectable level (non-polluted water) to 4 mg'dm-3 (strongly contamined mine effluents) (Dojlido 1995). It is readily absorbed by the fish from water, and concentrated in their bodies (Houston and Keen 1984). Among various disturbances, cadmium may affect blood parameters of fish such as numbers blood of cells (Ruparelia eta1.1990; Gill and Epple 1993) as well as their function (Viola etaI.1996). The aim of the present study was an assessment of the influence of short-term cadmium exposure on selected blood indices of common carp fingerlings. Materials and Methods Common carp (C~pri1!us carpio 1.) fingerlings of average body mass 75 g were harvested from the ponds at the beginning of October 1997. and kept under laboratory conditions in the water recirculation system for 6 weeks. Then they were exposed for 3 h to 10 mg'dm-3 of cadmium in the water of total hardness 162 mg CaC03 dm-3• at 17°C. After the exposure. the fish were transferred to metal-free water. Blood was sampled from the heart immediately after exposure (CdO I. and 24, 48, 72. and 96 h later (Cd24. Cd48. Cd72, and Cd96. respectively). Blood sampled from the non-exposed fish (taken directly from the rearing tank· KO), and from the fish exposed in the same way as Cd-treated ones. but in metal-free water (K), were used as controls. Blood from 10 fish of each group was analyzed, except for Cd96. in which only 6 fish survived. Haematocrit. red and white blood cell count. phagocytic activity (l"BT test), and viability of lymphocytes were assessed. Phagocytic activity of neutrophils and monocytes was estimated using nitroblue tetrazolium reduction test: blood was mixed with p-nitro blue tetrazolium chloride solution. incubated for I h at 28°C, and DMF was added. After centrifugation. the absorbance was measured at 540 nm. Address for correspondence: Matgorzata Witeska. PhD. Dept. of Animal Physiology. Siedlce University Prusa 12 08-110 Siedke. Poland Phone: +48 25 -++ 1011 ext. 1230 E-mlil: [email protected]