Time- and concentration-dependent metabolic responses reveal adaptation failure in cadmium-exposed Haliotis...

This study elucidated the time- and concentration-dependent effects of Cd exposure on adult Haliotis diversicolor through an integrated analysis of survival, physiological indices, and metabolomic profiles. Abalones were subjected to varying Cd concentrations for one and two months. While one-month exposure yielded no significant mortality, prolonged exposure to high Cd concentrations for two months substantially elevated mortality risk (hazard ratio = 3.359). Integrated biomarker response values exhibited progressive elevation with both concentration and exposure duration, indicating cumulative perturbation of antioxidant defense and metabolic enzyme systems. Metabolomic analysis revealed distinct temporal and concentration-dependent responses. After one month of exposure, medium concentrations predominantly affected energy and amino acid metabolism with a shift toward anaerobic pathways, while high concentrations activated additional detoxification and stress response mechanisms; after two months of exposure, divergent metabolic strategies emerged, where low concentrations induced lipid remodeling, medium concentrations maintained basic metabolic adjustments, while high concentrations precipitated comprehensive cellular dysfunction. Notably, the observed metabolic focusing at two months represented a forced trade-off under allostatic overload rather than successful adaptation, particularly in high-concentration groups. Combined analysis demonstrated fundamental reorganization of cellular metabolism under prolonged exposure. These findings emphasize the importance of long-term, multi-parameter assessments in evaluating marine ecotoxicological impacts of metal pollution.