Integrated Physiological and Chemical Analysis of In Vitro CdCl 2 ‐Induced Responses in Mytilus galloprovincialis Cells

ABSTRACT Cadmium (Cd) is a widespread and persistent contaminant in marine environments, able to disrupt organisms' homeostasis even at low concentrations. In this study, haemocytes and digestive gland (DG) cells from Mytilus galloprovincialis were exposed in vitro to CdCl 2 (10 −5 M for 2 hours) to investigate the early physiological and chemical responses associated with Cd 2+ toxicity. Cell viability, haemocyte phagocytic activity and regulatory volume decrease (RVD) in DG cells were evaluated and correlated with scanning electron microscopy coupled to energy‐dispersive X‐ray spectroscopy (SEM/EDX), X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Cd significantly reduced haemocyte phagocytic activity and impaired RVD in DG cells but caused only limited effects on DG cell viability. SEM/EDX revealed moderate changes in elemental composition, whereas XPS showed a redistribution of surface‐associated elements. Raman spectroscopy highlighted early biomolecular alterations involving protein and lipid‐associated bands. Overall, short‐term CdCl 2 exposure induced functional impairment and physicochemical rearrangements in membrane‐associated components.