Belhaoues_2026_Environ.Res__124974

This study evaluated the suitability of the gonads of the sea urchin Sphaerechinus granularis (Lamarck, 1816) as bioindicators for monitoring marine pollution. To this end, a suite of biomarkers including glutathione S-transferase (GST), catalase (CAT), reduced glutathione (GSH), malondialdehyde (MDA), metallothionein (Mt), and acetylcholinesterase (AChE) was investigated at four distinct stations in the Gulf of Annaba (Mediterranean Sea). Concurrently, the concentrations of five trace metals (zinc, cadmium, copper, nickel, and lead) and thirteen physicochemical parameters were measured. A multi-biomarker pollution index (MPI)was subsequently calculated to characterize the spatiotemporal patterns of coastal contamination. The results revealed that the eastern sector of the Gulf, near the El Mafrag River, exhibited the highest contamination levels, with a median multi-biomarker pollution index ranging between 41 and 44 (Level 4: moderately contaminated), and occasional peaks (MPI = 58) reaching Level 5 (highly contaminated) during certain months. Lower pollution levels were observed during the dry season (June, July, and August). Variation partitioning analysis indicated that physicochemical parameters were the main drivers of contamination variability in this coastal ecosystem, rather than trace metals. The multi-biomarker pollution index proved to be a robust and integrative tool for assessing anthropogenic impacts on coastal marine ecosystems, and S. granularis gonads are proposed as a reliable bioindicator for Mediterranean coastal monitoring programs.