Metal contaminants in Largemouth bass (Micropterus salmoides) collected in large dams from Tejo River basin and small irrigation dams

• Autor(a) principal: Andrade, L.P.
• Data de Publicação: 2012
• Outros Autores: Antunes, P., Paulo, L., Pereira, M.E., Rodrigues, A.M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.11/1575
• topic: Metals; Muscle tissue; Micropterus salmoides; Largemouth bass

Largemouth bass (Micropterus salmoides) is a very important fresh water fish in the Portuguese regional cuisine mainly in the countryside (Central region and north Alentejo). Because there’s no aquaculture industry, all eaten largemouth bass in Portugal are collected in large dams (Basins of Tejo and Guadiana rivers) and small irrigation dams. For decades, the Tejo River received environmental pollutants from non-point and point sources that included intensive agriculture, industrial entities, municipalities and nuclear power plant. The aim of this work was to evaluate some metals (Cd, Cr, Cu, Fe, Hg, Mn, Pb, Zn) present on largemouth bass muscle tissue collected in the section of Tejo River that makes border between Portugal and Spain (TR) (N=9) and collected in three irrigation reservoirs (IR) located near Castelo Branco – Portugal (N=11). Individual were weighted and measured. Age was determined by examining fish scales, and sex determined by gonads observation. Samples for liver, dorsolateral muscle and tail muscle were collected from the right side of the fish. TR average weight 435.14g (±109.15), average length 278.33mm (±23.28), average K condition factor 1.98 (±0.09) and average age 3.11 years (±0,78) were similar (P>0.05) to IR average weight 410.84g (±137.71), average length 278.36mm (±31.13), average K condition factor 1.86 (±0.17) and average age 3.18 years (±0,60). Total mercury was determined in freeze-dried samples by atomic absorption spectrometry with thermal decomposition and gold amalgamation. For the other metal analysis, freeze-dried powders were mineralized with a mixture of HNO3 and H2O2, followed by ICP-OES quantification. Cd and Pb presented concentrations below LOQ (0.025 and 0.15mg.kg-1wet.weight, respectively) for all muscle samples. These values are below legal limits in EU (0.05 and 0.3mg.kg-1wet.weight, respectively). Average Hg levels are below legal limits (0.5mg.kg-1wet.weight) and muscle presented higher levels than liver. These contaminant levels indicate that are no contamination sources in the sampling sites. Cu, Cr, Fe, Mn and Zn are essential micronutrients. Their concentrations were not significantly different between dorsal and tail muscle and were higher in liver (P>0.05), with mean concentrations on muscle being, respectively: TR 0.16 (±0.07), <LOQ(0.03), 1.45 (±0.42), 0.04 (±0.04) and 3.76 (±0.39) mg.kg-1wet.weight; IR 0.16 (±0.02), <LOQ(0.03), 1.80 (±0.52), 0.05 (±0.05) and 4.17 (±0.56) mg.kg-1wet.weight. We concluded that metallic concentrations of largemouth bass muscle tissues were below the maximum permissible for a safety utilization of theses fishes in human nutrition.