Age and diet-specific trace element accumulation patterns in different tissues of chub (Squalius cephalus): Juveniles are useful bioindicators of recent pollution

Chub (Squalius cephalus L. 1758) specimens of three age groups with different types of diet were collected in November 2013 in the River Szamos/Somes, Hungary. The Ca, K, Mg, Na, Cd, Cr, Cu, Fe, Mn, Pb, Sr and Zn concentrations were analyzed in the muscle, gills and liver samples of chub by microwave assisted plasma-atomic emission spectrometry (MP-AES). The Kruskal-Wallis test revealed significant differences among different age groups based on the trace element concentrations in the liver, muscle and gills. The trace element concentration pattern in muscle and liver of different age groups differed, may be according to the different diet types of the groups. Meanwhile no differentiation among the age groups based on the trace element concentration in the gills was observed, probably because the pattern of trace elements in the gills is related to the habitat preference, which does not differ during the life-span of chub. In contrast to expectations, trace element concentrations in juveniles were the highest in most cases, certainly because of their specific diet, relatively fast metabolic rate and inadequately developed detoxification system. Only the copper concentrations in liver increased with fish age. Considerable concentrations of trace elements in the tissues of juveniles were observed in the case of elements whose concentrations in the River Szamos were higher in 2013 than in previous years. According to this phenomenon, trace element patterns in the tissues of juveniles may be good indicators of recent pollution of watercourses.