Environmental assessment of Neotropical streams using fish as bioindicators: a multibiomarker and integrated approach

Freshwater ecosystems are among the most threatened habitats on Earth, due mainly to anthropogenic pollutants made up of complex mixtures. The Iguacu River is world famous for the Iguacu Falls and highlighted by its endemism. Unfortunately, it is considered the second most polluted urban river in Brazil. We aimed to perform an environmental evaluation of Neotropical streams in the Iguacu River basin, using a multibiomarker approach from a land use and landscape perspective. A set of biomarkers in the fish Psalidodonbifasciatus was analyzed using an Integrated Biomarker Response (IBR) index and correlated with surrounding land uses. Agricultural and urban sites presented more alterations compared to references sites, with elevated protein carbonyls at agricultural sites, increased DNA damage and depletion of glutathione S-transferase at urban sites and decreased glutathione associated with higher histopathological indices at urban and agricultural sites. The IBR shows a consistent increase in negative effects in anthropized areas, with similar values at agricultural and urban sites. The multibiomarker approach, associated with a well-elaborated sample design and a statistical analysis, is an ideal method to obtain more conclusive results about the effects of human activities, revealing the effective result of exposure in the real world.

Automated summary

The study evaluated the environmental impact on Neotropical streams in the Iguacu River basin, revealing higher pollution levels in agricultural and urban areas. Biomarker analysis showed a consistent increase in negative effects in anthropized areas.