Heavy metals remain pervasive environmental stressors, yet comparative hazard ranking often relies on single-point metrics (e.g., EC50) and limited test species, potentially obscuring concentration–response (C–R) shape information and cross-trophic variability. Here, acute C–R relationships for ten metals were quantified across four organisms representing distinct trophic levels (Danio rerio, Daphnia magna, Aliivibrio fischeri, and Scenedesmus obliquus). Probit regression was used to derive mult