Microplastics in Commercially Important Marine Fish from Giresun Province, Türkiye: A Baseline Assessment of Tissue Distribution, Polymer Composition, Spatial Patterns, and Potential Environmental and Ecological Risk.

Abstract

This study investigated the occurrence, characteristics, and spatial distribution of microplastics in muscle tissues and guts of commercially important fish species with different feeding habits (Pomatomus saltatrix, Mullus barbatus, Trachurus trachurus, Engraulis encrasicolus, Mugil cephalus, Merlangius merlangus, and Sarda sarda) from Giresun coast of the Black Sea. Microplastic contamination and polymer-associated hazard characteristics were evaluated using the contamination factor (CF), pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk index (PERI). Microplastics were detected in both muscle tissue and gut, with substantial variation among species and tissues. The highest microplastic abundance was observed in the muscle of P. saltatrix (41.3 ± 19.3 particles/g-dw) and in the gut of M. cephalus (230.7 ± 8.2 particles/g-dw). Fibers (FBs) were the predominant morphotype in both muscle tissue and gut, accounting for 92.7% and 97.1% of the detected particles, respectively. Polyethylene terephthalate predominated in muscle tissue (53.4%), whereas polypropylene was predominated in the gut (68.7%). The calculated CF, PLI, PHI, and PERI values revealed marked differences in relative microplastic contamination and polymer-associated hazard among species, tissues, and sampling locations. These differences suggest that feeding behaviour, habitat use, and polymer composition may contribute to species- and tissue-specific microplastic exposure patterns. The detection of microplastics in muscle tissue, together with their variable polymer composition, highlights the ecological relevance of microplastic contamination in commercially important fish and the need for continued monitoring of microplastic occurrence and characteristics in the south-eastern Black Sea.