RESUMO
Concerned with water quality, specialists have resorted to ecotoxicology as a tool to assess suspected contamination, enabling creation of strategies to repair the observed damage. Organisms such as fish and micro crustaceans are widely used in acute tests due to several characteristics in common among them including (1) accessibility of multiple samples, and (2) enhanced sensitivity when exposed to pollutants. Thus, the objective of this investigation was to determine the degree of toxicity at different points of a dam in Coromandel, Minas Gerais, using Artemia salina and Danio rerio as bioindicator organisms. Water was collected at three points of the dam were subsequently used to expose these organisms to different contaminant concentrations. Following exposure mortality and immobility rates were determined and compared to negative control (only distilled water). Results with exposure of A. salina did not present significant pollution affects. However, in the case of D. rerio the mortality frequency, immobility rate and behavioral alterations was increased at point P3; thus, D. rerio demonstrated greater sensitivity than A. salina. The physical-chemical test indicated that there were changes in parameters including biochemical demand of oxygen, dissolved oxygen and total dissolved solids (in sample at points 2 and 3), confirming toxic potential, and evidence of poor water quality at these locations. Therefore, data demonstrated that water from the dam at certain sites is not suitable for human consumption or leisure activities such as swimming that were previously reported to occur in this reservoir by the local community.