Toxic effects of acute exposure of P. magdalenae at mercuric chloride

Abstract

Young individuals of Prochilodus magdalenae (bocachico) acquired from commercial fish hatcheries were exposed to five acute concentrations of mercury (0.1, 0.13, 0.17, 0.22, 0.29 mg/l) for 96 hour periods in a static system renovated each48 hours. During the acclimation period, fishes were maintained in tap water that had been previously filtered with activated carbon. The circulation rate was 50 l/min and oxygen levels always exceeded 80% of saturation. Fishes were fed daily with Tetramin and feeding was halted twelve hours before the beginning of the toxicity bioassays. During acclimation period and bioassays, the pH and dissolved oxygen levels varied within a narrow range. Lethal mean concentrations (CL₅₀) were calculated for 24, 48, 72 and 96 hours by the moving average angle and probit methods. Results for 96 hours indicated great homogeneity with the lethal mean concentrations varying between 0.132 and 0.133 mg/l of mercury chloride, with P. magdalaneae exhibiting lower sensitivity to this substance than Poecilia reticulata.