Evaluation of sublethal toxicity of pollutants to red sea bream (Pagrus major) by using hematological parameters

Abstract

Hematological analysis for evaluating sublethal toxicity of chemicals is highly developed and reliable in mammalian studies, but the principles and methods have been only partially extended to fish. Therefore, in order to confirm the usefulness of the hematological approach to estimate toxicity of chemicals for fish, we determined the hematological parameters in red sea bream, Pagrus major. Fish were exposed to sublethal concentrations of bis(tributyltin) oxide (TBTO: 0.031, 0.112, 0.52, 1.98, 0.66, or 1.59 μgTBT/L), triphenyltin chloride (TPTC: 0.13, 1.16, or 3.23 μg/L), naphthalene (0.06, 0.21, 0.8, or 2.42 mg/L), and cadmium chloride (Cd: 0.01, 0.06, or 0.37 mg/L) for 8 or 9 weeks. The lowest observed effect concentrations (LOECs) and the no observed effect concentrations (NOECs) of pollutants were determined from red blood cell count, hematocrit (Ht), or hemoglobin concentration. LOECs and NOECs of TBTO, TPTC, naphthalene and Cd determined by Ht were 0.52μg/L and 0.112μg/L, 3.23μg/L and 1.16μg/L, 0.80mg/L and 0.21mg/L, and 0.37mg/L and 0.06mg/L, respectively. These values were similar to the LOEC and the NOEC determined by the growth parameters, which were reported previously. Additionally, Ht was the most sensitive parameter among the hematological parameters described above. These results suggest that hematological parameter, especially Ht, was a very useful parameter to estimate chronic toxicity of chemicals for fish.