Microplastic Ingestion in the Rocky Intertidal Zone: An Assessment of the Grazing Gastropod Phorcus turbinatus

Microplastic (MP) pollution has become a ubiquitous threat to marine ecosystems, yet studies on grazing gastropods in the rocky intertidal zone remain limited. This study investigates the microplastic contamination in the top-shell snail (n=36), Phorcus turbinatus, collected from the highly industrialized İskenderun Bay (Northeastern Mediterranean). The soft tissue of the collected samples underwent chemical digestion, filtration, and extraction processes, after which all suspected microplastic particles were documented. Microplastics were detected in 36% of the individuals, with a mean abundance of 0.42±0.55 MP items/individual and 0.28±0.40 MP items/g (wet weight). Morphological characterization revealed an overwhelming dominance of fibers (92.3%) and black-colored particles (76.9%), with the majority of MPs (72%) being smaller than 1 mm. A moderate positive correlation was observed between shell size and MP burden, suggesting size-dependent accumulation. These results indicate that P. turbinatus is susceptible to microplastic ingestion via grazing which reveal their potential canditance as bioindicators for monitoring benthic pollution in rocky coastal habitats. However, the role of P. turbinatus as a reliable bioindicator remains to be validated through more extensive spatio-temporal monitoring.