Tissue-Specific Biomarkers and Bioaccumulation in Mytilus galloprovincialis: Seasonal Anthropogenic Stress in the North Ionian Sea (Calabria, Italy).

Coastal ecosystems are increasingly threatened by human activities, highlighting the need for sensitive tools to assess environmental risk. An active biomonitoring approach, using the Mediterranean mussel (Mytilus galloprovincialis), was employed to evaluate anthropogenic chemical contamination in the North Ionian Sea, a still poorly studied area, by comparing mussel health status before (PrePT) and after (PostPT) the peak tourist season. Bioaccumulation of metal(loid)s was quantified in whole organisms. Oxidative stress was assessed in the gills and digestive gland through catalase (CAT), superoxide dismutase (SOD), lipid peroxidation (LPO), and oxidized carbonyl proteins (OMP). Neurotoxicity was evaluated via acetylcholinesterase (AChE) activity, while gene expression of stress-related biomarkers was analysed for metallothioneins (mt10, mt20), sod, cat, Glutathione S-transferase (gst), and Heat Shock Protein 70 (hsp70). Results suggest a progressive contaminant accumulation likely associated with intensified summer anthropogenic activity. Biomarker responses revealed clear activation of oxidative stress, with tissue-specific patterns. The findings confirm the effectiveness of active biomonitoring and multibiomarker approach in assessing coastal water quality and provide valuable baseline data for the management of marine ecosystems.