ORIGINAL ABSTRACT

Cadmium (Cd) and glyphosate (Gly) are widespread aquatic contaminants known to impair reproductive function in freshwater fish. This study evaluated the effects of Cd, Gly, and their combined exposure on sperm quality and fertilization success in Prochilodus magdalenae, a commercially and ecologically important Neotropical species. Adult males were exposed to environmentally relevant concentrations of Cd, Gly, and a Cd + Gly mixture. Sperm motility parameters, membrane and mitochondrial integrity, DNA fragmentation, fertilization rate, and hatching success were assessed. Cd exposure significantly reduced sperm motility at 25 mg/L (45.0%), while Gly induced motility impairment at concentrations above 10 mg/L. Co-exposure to Cd and Gly further exacerbated the decline in motility (p < 0.05). Cd also caused significant mitochondrial and membrane damage at 25 mg/L, whereas Gly produced moderate alterations (p < 0.05). Fertilization rates declined across all treatments, with complete inhibition (0.0%) observed at the highest combined concentrations (Cd 25 mg/L + Gly 40 mg/L). No significant differences were found in sperm DNA fragmentation. This study shows that combined exposure to cadmium and glyphosate has a stronger negative impact on fish sperm quality than individual exposure. The effects depend on concentration, involving oxidative stress and alterations in motility and membrane integrity. These results contribute to understanding how mixed contaminants affect fish reproduction and emphasize the need for long-term studies under realistic environmental conditions.