Sublethal toxicity of heavy metal (Ni, Cu) mixtures on hematological parameters of roach Rutilus rutilus (L.)

Abstract

The aim of the present study was to determine the effect of long-term exposure to binary mixtures of Ni and Cu ions at sublethal concentrations on hematological parameters of roach, Rutilus rutilus (L.). The 10-day toxicity test was conducted under semi-statistic conditions. After exposure the toxicological endpoints, such as various hematological parameters, were investigated. Exposure of fish to respective sublethal concentrations of heavy metal binary mixtures (HMBM) (0.0275 Ni+1.5219 Cu mg/l; 0.0138 Ni+0.7609 Cu mg/l; 0.0077 Ni+0.3805 Cu mg/l; 0.0034 Ni+0.1902 Cu mg/l; 0.0017 Ni+0.0951 Cu mg/l) induced significant alterations in red blood cell parameters, total leukocyte count, and glucose concentration in the blood of fish depending on mixture concentration. The present investigation of sublethal effects of HMBM demonstrated rather high sensitivity of roach to low concentrations of HMBM. Responses of fish were concentration-dependent, higher ones resulted in an anemic status in fish, as demonstrated by the changes in red blood cell parameters; general weakening of the immune system of the test fish and, subsequently, the worsening of their condition. Haematological parameters of roach could be applied as relevant bioassay for evaluation of toxicity of waste or natural waters containing mixtures of heavy metals at low concentrations for estimation of the ecotoxicological status of the water bodies.