Resumo Vossoroca é um reservatório localizado no estado Paraná - Brasil. Embora esteja próximo de grandes cidades e possa ser usado para abastecimento de água para população humana, ele permaneceu sem ser estudado. As concentrações de metais tóxicos e arsênico nos sedimentos, água, fígado, brânquias e músculo de Geophagus brasiliensis do reservatório foram analisadas por espectrometria de absorção atômica. As análises histológicas foram realizadas em brânquia e fígado por microscopia eletrônica de varredura e microscopia de luz, respectivamente. Os resultados mostraram que os sedimentos de Vossoroca estão moderadamente poluídos pelo cobre, cromo, níquel e arsênico. O cádmio estava acima dos limites legais na água. A avaliação histopatológica revelou alterações epiteliais na lamela secundária como a anormalidade mais comum observada nas brânquias, e necrose e centros melanomacrófagos, no fígado. Em conclusão, O Geophagus brasiliensis é um bioindicador adequado para estudos de poluição de metais. Embora o reservatório esteja localizado em uma Área de Proteção Ambiental, ele é afetado negativamente pela atividade humana.

Abstract Vossoroca is a reservoir in the Brazilian state of Paraná. Although it is located near big cities and can be used as a human water supply, it has remained unstudied. Concentrations of toxic metals and arsenic in sediments, water, liver, gills, and muscle of Geophagus brasiliensis from the reservoir were analyzed using atomic absorption spectrometry. Histological analyses were performed on the gills and the livers using scanning electron microscopy and light microscopy, respectively. The results showed that Vossoroca sediments were moderately polluted by copper, chromium, nickel and arsenic. Cadmium was above legal limits in the water. Histopathological assessment revealed epithelial alterations in the secondary lamella to be the most common abnormality observed in the gills and necrosis, melanomacrophage centers in the livers. In conclusion, although the reservoir is located in an Environmental Protection Area, it is negatively affected by human activity. Further, Geophagus brasiliensis was a suitable bioindicator for metal pollution studies.

Bioaccumulation of Ag, Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn was determined in the gills and liver of Cyprinus carpio and related to concentrations in the sediment and water of the Alagados Reservoir, Ponta Grossa/Paraná. Cd and Fe exceeded the legal limit for water. Fe was the most abundant metal in the reservoir's water and sediment. The metals in the sediment were below the level of probable adverse effects on biota. There were no significant differences between sampling sites for water and sediment. Liver and gills had higher concentrations of Al, Fe and Zn, with a significant increase in Al (P > 0.05) compared to the increase in weight and size of the specimens. Statistically, gills showed higher concentrations of Al, Cd, Co, Cr, Mn and Zn and liver higher concentrations of Cu and Fe. Co, Cu, Fe, Mn and Zn showed significant differences (P < 0.01) between the organs. The bioaccumulation factors (BAF) showed that the interaction of water with gills promotes greater accumulation of metals in this organ. Despite the low concentrations in the reservoir, bioaccumulation of metals in gills and liver of C. carpio occurs by its interaction with contaminated water and sediment, respectively.