Metal content in muscle, gills and liver tissues of the northern pike Esox lucius (L. 1758) of three age classes in the irrigation channel of the Danube river – case study.

Abstract

Northern Pike is the top piscivore and phytophilic species strongly dependent on backwaters and vegetated river areas for spawning and recruitment. The aim of the present study was to examine dependence between metal concentrations (As, Cr, Cd, Co, Cu, Fe, Sr, Pb, Zn, Hg) and examined fish tissues, as well as of fish age. In June 2013, 26 samples of pike have been collected using electrofishing (HONDA 1,2кW, 6 А). Collection was performed in irrigation Channel Vizelj, runs through the suburban section of Belgrade. The content of heavy metals was determined in samples of fish tissues of different ages using inductively coupled plasma mass spectrometry (ICP-MS). Age analysis indicated that fish belonged to age classes from 0+ to 2+. Metals As, Cd, Co and Pb were not detected in analyzed fish tissues, and Cu was not detected in muscle tissue of 2+ and 1+ specimens. The majority of the analyzed elements were found in minimal concentrations in the muscle, except 0+ specimens with high Fe concentrations. Gills of all analyzed age classes were loaded with very high concentrations of Fe and Sr. In gills of 1+ and 2+ fish were also detected high Zn concentrations while in 0+ fish were detected Fe. The highest concentrations of Cu were detected in liver of all fish age classes. The youngest age class (0+) was differentiated by higher concentrations of Cr, Cu, Fe, Sr and Zn in muscle tissue, while the oldest age class was mainly differentiated by higher concentrations for Zn and Hg in gills.