Acute exposure of a glyphosate-based herbicide affects the gills and liver of the Neotropical fish, Piaractus mesopotamicus

The aim of this study was to determine the acute toxicity of Roundup® Ready (RR) in Piaractus mesopotamicus, and evaluate the effects on the morphology of the gills and liver of exposed surviving fish. Fish were exposed to 3.0, 3.5, 4.0 and 4.5 mg L−1 of glyphosate, and the LC50;48 h was estimated at 3.74 ± 0.2 mg L−1. Gill histopathology was rare, and the activity of Na+/K+-ATPase enzyme did not change, suggesting normal function. However, the damage to the liver was classified as moderate to severe. Cytoplasmic vacuolization, lipid accumulation, nuclear and cellular membrane alterations and glycogen depletion were found in the liver, suggesting a reduction in the liver function. The glyphosate in the RR formulation was classified as moderately toxic for P. mesopotamicus, and the severe damage in the liver may affect the detoxification and/or tissue repair process and contribute to fish death.

► Determination of LC50;48 h of glyphosate, Roundup® Ready formulation, to Neotropical fish species.
► Histopathological index and Na+/K+-ATPase activity evidenced normal gill function.
► Histopathological index evidenced moderated to irreparable liver damage.
► Glycogen depletion indicates energy mobilization.