Microplastic contamination in commercially important marine fishes from the Sohar Coast, Sea of Oman: occurrence, characterization, and polymer composition

Abstract

Microplastic (MP) pollution is an increasing concern in marine environments because of its persistence, bioavailability, and potential implications for marine ecosystem health and seafood safety. Despite growing global attention, information on MP contamination in commercially important marine fish from the Sea of Oman remains limited. This study assessed the occurrence, abundance, and characteristics of MPs in four commercially important fish species from the Sohar coast and tested whether MP contamination differed among species and tissues and was associated with habitat group, sex, and biometric characteristics. A total of 120 fish representing Epinephelus areolatus , Lethrinus microdon , Nematalosa arabica , and Rastrelliger kanagurta were examined for MPs in the gastrointestinal tract (GIT) and gills. Microplastics were extracted using alkaline digestion and visually identified under a stereomicroscope. All 316 recovered particles were subjected to ATR-FTIR spectroscopy; 313 (99.1%) met the ≥ 70% spectral-match criterion and were successfully assigned to polymer types. Microplastics were detected in 79.2% of the examined fish, with a mean total abundance of 2.63 ± 2.60 items individual⁻1. Frequency of occurrence ranged from 66.7% to 90.0% among species. Total MP abundance did not differ significantly among species, whereas GIT MP concentration differed significantly among species. GIT–gill differences were significant only in E. areolatus and R. kanagurta . No significant associations were detected between total MP abundance and habitat group, sex, total length, body weight, or condition factor. Fibers were the dominant particle type, most particles measured < 2 mm, and polyester was the predominant identified polymer, followed by polypropylene and ethylene-propylene diene polymer (EPDM). The predominance of fibers and polyester indicates that fibrous synthetic materials constitute an important component of MP exposure in these commercially important fishes. However, specific environmental sources cannot be determined from polymer identity alone, highlighting the need for integrated assessment of fish alongside seawater, sediments, and other potential environmental sources.