Integration of multi-level biomarker responses to cadmium and benzo[k]fluoranthene in the pale chub (Zacco platypus)

• Cd and BkF exposure showed different biomarker responses in Z. platypus.
• Multi-level IBR index was developed to quantify multi-level biomarker responses.
• Multi-level IBR index was more correlated with dose than conventional IBR index.

The Cd exposure for 14 days significantly increased both the molecular (DNA single-strand breaks) and biochemical (metallothionein concentrations) biomarkers in the freshwater pale chub, Zacco platypus, whereas changes in the histological and physiological biomarker responses were negligible. The BkF exposure for 14 days led to significant increases in the mRNA expression of catalase and superoxide dismutase, 7-ethoxyresorufin-O-deethylase enzymatic activity and DNA single-strand breakage at the molecular and biochemical levels. In addition, exposure to 50 μg/L of BkF induced histological alteration in the liver, with significant changes to the liver somatic index and condition factor at the physiological level. The integration of multi-level biomarker responses at the molecular, biochemical and physiological levels was highly correlated with the concentrations of Cd and BkF.