Mutagenic effects of mercury pollution as revealed by micronucleus test on three Amazonian fish species.

Genotoxic effect of mercury pollution over Amazonian fish species was evaluated by using the micronucleus test (MNT). Distinct mean frequencies of micronuclei (MN) were observed in three trophically distinct characin fish species collected in two riverine environments in the Amazon Basin: the Madeira (polluted area) and the Solimões (unpolluted area) rivers. Mean frequencies of MN observed in Prochilodus nigricans (detritivore), Mylossoma duriventris (omnivore), and Hoplias malabaricus (piscivore) from the Madeira River were significantly higher compared to the frequencies from the same species from the Solimões River. In addition, mean frequencies of MN from piscivore species were almost fivefold higher than the detritivore and/or omnivore species. We conclude that MNT in fish erythrocytes may be useful for indicating genotoxity of mercury in Amazon rivers.