Microplastics and organic pollutants in stranded northern gannet (Morus bassanus) from Southern Spain

Plastic pollution poses a major threat to marine ecosystems, affecting seabirds both physically and chemically. This study provides the first comprehensive assessment of macro-, meso-, and microplastic ingestion, together with the analysis of persistent organic pollutants (POPs) in biological tissues of northern gannet (Morus bassanus) stranded along the Andalusian coast (southern Europe). A total of 42 individuals were necropsied to assess body condition, quantify ingested plastics, determine organic contaminants in muscle tissue, and assess potential associations between both types of exposure. The overall frequency of plastic ingestion was 88 % (100.0 % for adults and 85.7 % for juveniles). Microplastics (<5 mm) dominated the plastic debris (>77 %), with transparent fibres being the most prevalent form. Polymer analysis revealed viscose/regenerated cellulose and polyethylene as the predominant materials, highlighting textile-related sources. Chemical analyses detected 42 organic compounds, including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), and personal care products (PCPs). Detections frequencies ranged from 10 to 100 % for PCBs, 50-100 % for OCPs, 0-100 % for PAHs, 5-95 % for PBDEs, and 0-90 % for PCPs. Adults exhibited higher POPs concentrations, consistent with age-related bioaccumulation. Statistical analyses showed no significant relationship between the number of ingested plastics and tissue contaminant burden after accounting for age, indicating that bioaccumulation rather than plastic-mediated transfer explains the observed patterns. These findings provide the first regional baseline for the integrated assessment of plastic ingestion and organic contaminant exposure in northern gannet along the southern Europe (the Andalusian coast), contributing to future monitoring and conservation efforts in the Atlantic and Mediterranean regions.