Evaluation of Glyphosate Toxicity on Arabian Killifish, Aphanius dispar Collected from Southwestern Saudi Arabia
Glyphosate (Tiller 480 SL), which is used extensively to control and inhibit weeds in terrestrial and aquatic ecosystems, has been blamed of harming non-targeted species like fish. This current study evaluated the acute and chronic impacts of glyphosate on the Arabian killifish (Aphanius dispar) collected from Southwestern Saudi Arabia at different levels of biological organization including behavioral and histopathological responses. Glyphosate toxicity (96 h LC50) to Aphanius dispar was determined at 115.25 mg/l after exposure to 60, 90, 120, 150, 180, 210, 240 mg glyphosate/l. Fish during the 96 h displayed abnormal behavioral changes: erratic movements, hyperactivity, rapid opercula and mouth movements, surfacing, hypoactivity, exhaustion and mortality. While, exposure of fish to 1/4th of the 96-h LC50 for two weeks, the gills and liver organs displayed histopathological alterations. The gills revealed: epithelial uplifting, edema, hyperplasia associated with fusion of secondary lamellae, clubbing, thinning and shortening of secondary lamellae. Whereas, the liver exhibited: necrosis, deterioration, hypertrophy of hepatocytes with loss of determined peripheries, pyknotic nuclei, and cytoplasmic vacuolization with a foamy appearance. In conclusion, this current study results revealed that glyphosate is very toxic leading not only to abnormal behavioral responses and tissue alterations, but might cause mass extinction of fish species. Therefore, glyphosate should be used carefully in/or near aquatic systems to avoid extinctions of life forms, particularly Aphanius dispar. Thence, protecting species diversity, which is a key issue for stability and resiliency of aquatic ecosystems.
