Hematological findings in neotropical fish Hoplias malabaricus exposed to subchronic and dietary doses of methylmercury, inorganic lead, and tributyltin chloride

• Published in: Environmental research 2006-05, Vol.101 (1), p.74-80
• Main Authors: Oliveira Ribeiro, C.A., Filipak Neto, F., Mela, M., Silva, P.H., Randi, M.A.F., Rabitto, I.S., Alves Costa, J.R.M., Pelletier, E.
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Agnatha. Pisces; Animal, plant and microbial ecology; Animals; Applied ecology; Astyanax; Biological and medical sciences; BIOLOGICAL MARKERS; Biomarkers; CHLORIDES; Diet; DOSES; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Erythrocyte Indices - drug effects; ERYTHROCYTES; Erythrocytes - drug effects; Erythrocytes - physiology; Erythrocytes - ultrastructure; Fishes - physiology; Food Chain; Fundamental and applied biological sciences. Psychology; HEAVY METALS; Hematocrit; HEMATOLOGY; HEMOGLOBIN; Hoplias malabaricus; Lead - toxicity; LEAD IONS; Leukocyte Count; LEUKOCYTES; MERCURY; METHYLMERCURY; Methylmercury Compounds - toxicity; Microscopy, Electron, Transmission; TRANSMISSION ELECTRON MICROSCOPY; Trialkyltin Compounds - toxicity; Tropical Climate; Tropical fish; VEHICLES; Water Pollutants, Chemical - toxicity
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2005.11.005

Hematological indices are gaining general acceptance as valuable tools in monitoring various aspects the health of fish exposed to contaminants. In this work some effects of methyl mercury (MeHg), inorganic lead (Pb 2+), and tributyltin (TBT) in a tropical fish species were evaluated by hematological methods after a trophic exposition at a subchronic level. Forty-two mature individuals of the freshwater top predator fish Hoplias malabaricus were exposed to trophic doses (each 5 days) of MeHg (0.075 μg g −1), Pb 2+ (21 μg g −1), and TBT (0.3 μg g −1) using young fish Astyanax sp. as prey vehicle. After 14 successive doses over 70 days, blood was sampled from exposed and control groups to evaluate hematological effects of metals on erythrocytes, total leukocytes and differential leukocytes counts, hematocrit, hemoglobin concentration, and red blood cell indices mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). Transmission electron microscopy and image analysis of erythrocytes were also used to investigate some morphometric parameters. Results show no significant effects in MCH and MCHC for all tested metals, but differences were found in erythrocytes, hemoglobin, hematocrit, MCV, and white blood cells counts. The number of leukocytes was increased in the presence of MeHg, suggesting effects on the immune system. Also the MCV increased in individuals exposed to MeHg. No ultrastructural damages were observed in red blood cells but the image analysis using light microscopy revealed differences in area, elongation, and roundness of erythrocytes from individuals exposed to Pb 2+ and TBT but not in the group exposed to MeHg. The present work shows that changes in hematological and blood indices could highlight some barely detectable metal effects in fish after laboratory exposure to contaminated food, but their application in field biomonitoring using H. malabaricus will need more detailed studies and a careful consideration of environmental parameters.