Mapping differential elemental accumulation in fish tissues: importance of fish tissue sampling standardization

The concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se and Zn in the muscle, gills, liver and intestine of the wels catfish (Silurus glanis) from the Danube River were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The aim of the study was to determine whether in complex muscle/skin, gill filament/gill arch, proximal/distal liver and proximal/median/distal intestine samples, particular components differ in concentrations of the analyzed elements. Results indicated that there were no differences in the accumulation of different elements between the proximal and distal liver segments and between the proximal and median intestine sections. Conversely, elemental accumulation patterns in muscle and skin differed significantly. Significant differences were also observed between the gill arch and filaments, as well as between the distal and the two upper intestine sections. Findings indicated the importance of detailed reporting of tissue sampling, i. e. whether the skin was included in the muscle sample, as well as if the gill arch and filaments were analyzed together. Due to a potential bias that can be produced by different muscle/skin or gill arch/filament ratios included in the sample, we strongly recommend that they should not be analyzed together. Results of the present study might be of interest to the scientific community and stakeholders involved in aquatic ecosystem monitoring programs

Age-specific accumulation of toxic metal(loid)s in northern pike (Esox lucius) juveniles

Northern pike specimens of 0(+), 1(+), and 2(+) age classes were collected in June 2013 from the Vizelj channel near Belgrade (Serbia). Inductively coupled plasma optical spectrometry (ICP-OES) and atomic absorption spectrometer SpectrAA 220 were used for analyzing concentrations of As, Cr, Cd, Co, Cu, Fe, Sr, Pb, and Zn, as well as Hg in muscle, gills, and liver. Metal pollution index (MPI) was calculated. Concentrations of As, Cd, Co, and Pb were below the limit of detection. Concentrations of Cu, Hg, and Zn in muscle did not exceed the maximum allowed concentrations. The gills were tissue which was most affected by pollution. The highest concentrations of Fe in muscle, Cr and Fe in gills, and Hg, Sr, and Zn in liver were recorded in 0(+) individuals, as well as Zn in gills of 2(+) individuals. On contrary, the lowest concentrations were recorded for Zn in gills of 0(+) individuals, Hg in gills of 1(+) individuals, and Fe in muscle, Cr and Sr in gills, and Zn in liver of 2(+) individuals. Regarding age classes, 2(+) juveniles had the highest MPI values for all tissues. Correlations between the metal(loid) accumulation and fish condition were not significant, as well as between fish length and weight and Cu and Hg in muscle, Cu, Hg, and Sr in gills, and Cu, Cr, and Fe in liver. Results indicated that young individuals were more sensitive to pollution, but older fish showed higher overall bioaccumulation of toxic elements analyzed in this study