Survival, antioxidant enzyme activities, and bioaccumulation response in freshwater snail Radix plicatula (W. H. Benson, 1842) to arsenic.

Arsenic contamination threatens freshwater aquatic ecosystems; however, integrated studies of bioaccumulation and toxicological mechanisms in gastropods remain limited. This study assessed acute and chronic toxicity in Radix plicatula by integrating survival, antioxidant enzyme activity, and tissue bioaccumulation measurements. We exposed snails to three arsenic concentrations for 21 days. Survival declined dose- and time-dependently from 98.3% (controls) to 83.3% (high concentrations) by day 21. Antioxidant enzymes showed biphasic responses, catalase (CAT) peaked on day 7 and then declined, while superoxide dismutase (SOD) peaked on day 14 at 4-fold above control levels. Tissue arsenic accumulation showed a dose-dependent, strong linear relationship (R² = 0.85-0.97). Bioaccumulation intensified with prolonged exposure (with BSAF shifting from ≤ 1 to ≥ 2). Diffusive gradients in thin films (DGT) measurements correlated strongly with tissue arsenic concentrations (R² = 0.71), confirming DGT as a reliable bioavailability indicator in Arsenic contamination. Radix plicatula is a sensitive bioindicator of arsenic contamination in freshwater ecosystems. This integrated approach advances mechanistic understanding of arsenic toxicity in freshwater gastropods.