Toxicity determination of three sturgeon species exposed to glyphosate

Glyphosate, N–(phosphonomethyl) glycine, has been widely used to control agricultural weeds in the north of Iran. However, it is also supposed to have adverse effects on natural sturgeon population. The present study was undertaken to evaluate the acute toxicity of glyphosate to three different sturgeon species (Huso huso, Acipenser stellatus, and A. persicus) under laboratory conditions. Fish were exposed to one of ten glyphosate concentrations (10 to 100 mg l–1 with 10 mg l–1 intervals), along with a control group. The values of the median lethal concentration (LC50) for each experimental species were estimated using a standard probit regression analyses after each 6, 12, 24, 48, 96, and 168 hours as exposure times. Results showed that increase in glyphosate exposure times up to 168 hours was simultaneous to decrease of the lethal concentration (LC50). 96–h LC50 of glyphosate for H. huso, A. stellatus and A. persicus were 26.4, 23.2 and 27.5 mg l–1, respectively. Glyphosate exhibited a slight to moderate toxicity in sturgeon species. However, it may negatively affect the natural population of sturgeons through decreasing of fry mass, smaller size of yolk sac and the initiation of unsafe behaviors.