Lethal and Sublethal Effects of Atrazine to Amphibian Larvae

The effects of Atrazine contamination on amphibian larval stages were assessed, using acute and chronic toxicity in the laboratory. Tadpoles of Ptychadena bibroni at varying post-hatch developmental stages (1, 2, 3, and 4 weeks) were exposed to environmental relevant treatment concentrations of 200, 400, 600μg/L and 3, 30, 100μg/L for acute and chronic toxicity tests respectively. The effects were assessed by comparing mortality, glycogen levels and behavioral response of a control group and a group exposed to the pesticide. The American Society for Testing and Material (ASTM) recommended semi-static renewal bioassay method to beemployed, and LC50 was measured at 96 hours. Percentage of mortality increased with increase in concentration and exposure duration; but decreased as the tadpoles matured. Mean percentage mortality of tadpoles were significantly affected by concentrations and developmental stages . Derived 96 hours LC50 values decreased with increase in exposure duration but increased with each successive developmental stage. Estimated 96 hours LC50 ranged from 230.06 – 431.32μg/L. Glycogen levels varied negatively with concentrations, but it increased with each successive developmental stage. Mean glycogen level of tadpoles, exposed to Atrazine, were significantly different in the developmental stages but showed no significant difference with concentrations (F= 1.493, P 0.05). The above results of acute and chronic exposure to Atrazine indicate marked behavioral and physiological effect of Atrazine on Ptychadena tadpoles. Results obtained from this study would serve as a fundamental platform for development of Atrazine safety limits for monitoring the waters of the Niger Delta ecological zones of Nigeria