Age-specific metal and accumulation patterns in different tissues of nase (Chodrostoma nasus) from the Medjuvršje Reservoir

Nase (Chodrostoma nasus L. 1758) specimens of four age classes (1+ to 4+) were caught in July 2013 in the Medjuvršje Reservoir. Concentrations of 14 metals and elements (Al, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Si, Sr, Zn) in the muscle, gills and liver were analyzed by inductively-coupled plasma optical spectrometry (ICP-OES). The highest concentrations of Al, Ba, Co, Cr, Mn, Si, Sr and Zn were detected in gills, while Cd, Cu, Fe and Mo reached the highest values in the liver. The majority of the analyzed elements were found in minimal concentrations in the muscle. Younger age classes (1+, 2+) were differentiated by higher concentrations of Mn, Sr and Zn in muscle tissue, while the older ones were mainly differentiated by higher concentrations for Ni and Cu. The youngest age class (1+) was distinguished by higher concentrations of Zn, while the oldest age class (4+) was distinguished by higher concentrations of Ba, Cu, Mo and Sr in gills. Results obtained were likely caused by differences in the physiology and feeding habits between younger (1-2+) and older (3-4+) age groups of nase