Integrated approach to assess water quality and risk assessment for aquatic biota in Baía Negra, Pantanal, Brazil

Abstract

The Baía Negra Environmental Protection Area, situated within the Pantanal Sul-Mato-Grossense (BNEPA), represents an important conservation unit subjected to considerable environmental pressures resulting from human activities, such as agriculture and mining. This study evaluated the impact of these activities on water quality and their toxicogenetic effects on native fish. Physicochemical parameters and metals (Cd, Pb, Cr, Ni, Fe, Mn, Cu and Zn) were analyzed in water and macrophytes (Eichhornia sp.) collected from three sites along the Paraguay River. A 20 km buffer zone was used to assess the composition and structure of the landscape in the BNEPA. The results showed that the concentrations of Cd, Pb, Cr, Ni, Fe and Cu exceeded the legal limits established by CONAMA N° 357/2005, with Fe levels reaching a threshold that poses a substantial risk to aquatic biota. Macrophytes accumulated high Fe concentrations, indicating bioavailability and potential trophic transfer. Genotoxic and mutagenic alterations, including nuclear abnormalities and micronuclei in fish erythrocytes, were observed, indicating chronic exposure to contaminants. These findings highlight the urgent need for long-term biomonitoring programs and regulatory measures to mitigate the environmental risks of metal contamination and protect biodiversity in the Pantanal.