Frequency of fish micronuclei to diagnose aquatic environmental conditions from Brazilian megacities: a case study of Iguaçu river, Southern Brazil

Abstract

More sensitive methodologies for detecting alterations in organisms due to the action
of pollutants have been largely used. Among them, studies of genotoxicity with analyses of genomic, such as the frequency
of micronuclei, damaging have been very useful. The present research aimed on using the frequency of micronuclei (MN) for
diagnosing and predicting the environmental conditions from upper Iguaçu river with influences from Southern Brazil megacity
(Curitiba, PR). Peripheral blood smear specimens of the native Rhamdia quelen from 10 sites were analyzed and it was computed
their frequency of MN cells. The results were compared with a control group with the (zero MNs) in the absence of any altered
circumstances. One-way ANOVA and Tukey test (p < 5%, in both tests) was computed in order to verify the statistical robustness
of the variation observed. Three of the 10 evaluated localities showed a high average number of MN cells, as well as, a high
frequency of MN cells. Tukey test (p <5%), revealed the existence of statistically significant differences in 18 apart 55 possible
pairwise comparisons. The results suggest that the species is undergone to genotoxic impact with a large variation in terms of
intensity of the impact depending upon the inhabiting site. Considering that drastic changes in genetic material reduces the biotic
evolutionary potential the results obtained herein suggest that Rhamdia quelen requires differential management programs in
order to preserve the species and their ecosystems.