Common carp ( Cyprinus carpio L.) scales as a bioindicator reflecting its exposure to heavy metals throughout life

Abstract

The aim of the present study was to demonstrate the usefulness of fish scales as a bioindicator reflecting the concentrations of heavy metals in the environment as compared to typical recognized bioindicators such as the liver or kidney. Heavy metal (Zn, Mn, Cu, Cd, Fe, Ni, Pb) concentration analysis (with the atomic absorption technique) was performed in different annuli on the fish scale to characterize the metals’ accumulation in the consecutive years of the fish's life corresponding to individual scale increments. The results confirmed the usefulness of fish scales as a bioindicative tissue reflecting the condition of the environment in subsequent growing seasons. The results of the present study demonstrated that fish scales are more sensitive to the accumulation of Mn, Ni, and Pb, whose concentrations in different parts of the scales were even 10 times higher than in soft tissues, and significantly correlated with their levels in liver or kidney. In light of this finding, further studies involving controlled exposure of fish to different metals could be performed. Their results could allow for obtaining an excellent tool for monitoring the environment inhabited by fish in the present and past without the need to kill the animals.