Effects of Cadmium on Some Haematological Parameters of the Mozambique Tilapia, Oreochromis mossambicus (Peters 1852)

摘要

Haematological profiles have been frequently used to assess the health status of fish subject to metallic stress. The present study examined potential alterations that may arise in the haematological profile of the Mozambique Tilapia (Oreochromis mossambicus) due to exposure to cadmium (Cd). Adult female fish collected from an aquarium were housed in glass tanks and exposed to three concentrations (0.2, 2 and 10 mg l~(-1)) of CdCl_2 for five days. At the end of the trial, fish were sacrificed to obtain blood to record five primary (erythrocyte count - RBC, lymphocyte count - WBC, haemoglobin concentration - Hb, packed cell volume - PCV and clotting time) and three secondary (mean cell haemoglobin - MCH, mean corpuscular haemoglobin concentration - MCHC and mean cell volume -MCV) haematological parameters. Results revealed that the observed patterns were erratic and significant changes were observed only at the low (0.2 mg l~(-1)) and high (10 mg l~(-1)) levels of exposure. Significant increases were noted in RBC and WBC counts, Hb, PCV, MCH, MCHC and MCV, while the clotting time was significantly reduced (2.2 minutes in the control and 0.8 at the highest concentration). These results are of particular concern since the lowest test concentration (0.2 mg l~(-1)), which was capable of inducing changes in some of the blood parameters, falls within the ranges recorded in some of the water bodies of Sri Lanka.