Oxidation of acid-volatile sulfide in surface sediments increases the release and toxicity of copper to the benthic amphipod Melita plumulosa

► Acid-volatile sulfide (AVS) reduces toxicity of copper to deposit feeding amphipod. ► Oxidation of AVS in sediments increases the bioavailability copper. ► Oxidation of AVS increases the toxicity of copper to deposit feeding amphipod. ► Changes in AVS concentrations during toxicity tests should be assessed. ► Dietary copper exposure contributes to toxic effects for epibenthic amphipod.