Integrated use of histological and hormonal biomarkers to assess metal contamination in Leporinus friderici from mining areas in the Amazon

Abstract

High natural concentrations of metals in Amazonian soils, combined with rainfall, increase metal availability in rivers and streams. This study objective was the environmental quality of two microbasins using integrated biomarkers in Leporinus friderici. Water, sediment, and fish samples were collected during the rainy and dry seasons from the Parariquara and Potiritá river microbasins, located near an area of mining in Paragominas, Pará, Brazil. Levels of Al, Fe, Cd, and Ti were measured, and plasma concentrations of E2, PROG, T, and 11-KT were evaluated. The results showed that Al and Fe were the most prevalent metals: mean concentrations in water were 0.80 ± 0.38 mg L⁻¹ for Al and 1.22 ± 0.47 mg L⁻¹ for Fe; in sediment, 6.03 ± 5.17 g kg⁻¹ for Al and 3.75 ± 5.14 g kg⁻¹ for Fe. Ti ranged from undetectable to occasionally present, while Cd was not detected. The pH remained acidic across both seasons. The dry season was the most critical for the fish, as it was associated with lower E₂ (60.9 ± 57.3 pg mL⁻¹) and higher 11-KT (25.17 ± 13.9 pg mL⁻¹) levels, coinciding with elevated gonadosomatic index (GSI) values and increased concentrations of Al in the water. PROG and T remained constant in the environment. Al and Fe presents in the gonad possibly influenced the hormonal levels and in the gonad maturation, which explain the high frequency of the individuals in resting stage. Based on biomarker responses, the study indicates that L. friderici exhibits biological plasticity that allows it to persist in microbasins with elevated Al and Fe levels. Finally, we emphasize the importance of studies that monitor trace metal concentrations and fish health in streams, considering the ecological, geological and seasonal dynamics of the Amazon region.