Biomonitoring of Microplastics in Izmir Bay (Eastern Aegean Sea): Abundance, Polymer Characterization, and Ecological Risk Assessment in Saddled Seabream, Oblada melanurus (Linnaeus, 1758)

In this study, we aimed to investigate the occurrence, characteristics and temporal dynamics of microplastics (MPs) in the gastrointestinal tracts of saddled seabream (Oblada melanurus) from Izmir Bay (Eastern Aegean Sea). Sampling was carried out monthly during a one-year period (March 2021–February 2022) and MPs were identified by stereomicroscopy and ATR-FTIR spectroscopy. Microplastics were identified in 115 of the 180 examined individuals, representing an overall frequency of occurrence (FO) of 63.89%. A total of 298 microplastic items were recovered, corresponding to a mean abundance of 1.66 ± 0.35 items individual−1 across all examined fish (N = 180) and a mean intensity of 2.59 ± 0.41 items/individual among positive individuals (N = 115). The highest occurrence (100%) was observed during December. Fibers were the most abundant morphotype (58%) followed by fragments (39%). Black (56%) and blue (20%) particles were the most abundant colors. Size distribution was 105–4678 µm with mean length of 1370.08 ± 1122.74 µm. The most frequently identified polymers were polyethylene terephthalate (PET, 29%), polyethylene (PE, 19%) and polypropylene (PP, 18%). We did not find any significant relationships between MP abundance and fish size, weight or sex (p > 0.05). The study area was classified into high-risk category (Category IV) based on the value of Polymer Hazard Index (PHI) (129.52). The results show temporal variability of MP ingestion, likely influenced by seasonal conditions and anthropogenic activities.