EFFECTS OF PHENOL ON Astyanax bifasciatus AND Daphnia magna

In the present study, we investigated the possible toxic effects of phenol on two bioindicators: the fish Astyanax bifasciatus (Characiformes; Characidae) and the crustacean Daphnia magna (Cladocera; Daphnidae). We performed bioassays with A. bifasciatus (96 h and 15 days of exposure) and D. magna (48 and 96 h of exposure). The bioindicator organisms were exposed to the following concentrations of phenol: 0.003 mg L -1 , 0.01 mg L -1 , 0.03 mg L -1 , 0.06 mg L -1 , and 0.1 mg L -1 ; and the control group was maintained in clear water. We assessed the rate of micronuclei in erythrocytes of fish and evaluated the immobility of D. magna at each concentration of the contaminant. For fish, the 15-day exposure revealed a significant difference between the tested groups (p = 0.0002), showing a tendency for micronuclei to increase at the highest concentrations. For the D. magna test, 96-hour toxicity was evident at all tested concentrations (p < 0.05). A better response of these organisms was observed during the longer exposure period, emphasizing the concern on the long-term effects of phenol. Effects on the lowest concentration of phenol tested (0.003 mg L -1 ) were also observed, and this concentration is permitted by the Brazilian Legislation for Class II waters, demonstrating that the longer time of exposure to phenol can cause damage to the biota.