Analysis of Microplastic Contamination in Water, Sediment, and Fish on the Northeastern Coast of Libya

Abstract

Microplastic contamination has become an emerging environmental concern in marine ecosystems worldwide. This study investigated the occurrence, abundance, size, color, and polymer composition of microplastics in surface water, marine sediments, and the gastrointestinal tracts of commercially important fish species collected from the coastal regions of Sousa and Alhaniyah along the northeastern Mediterranean coast of Libya. Microplastics were detected in 10 of 15 (66.7%) surface water samples from Sousa and in 5 of 15 (33.3%) samples from Alhaniyah. In bed sediments, microplastics were detected in 5 of 15 samples (33.3%) at both study sites. Microplastics were detected in 46.73% (71/149) of the fish specimens collected from Sousa and in 20.30% (25/123) of those collected from Alhaniyah. The mean microplastic abundance in surface water was 2.5 ± 2.6 particles/L in Sousa and 0.7 ± 1.3 particles/L in Alhaniyah. Mean sediment abundances were 254 ± 57 and 212 ± 23 particles/kg dry weight, respectively. These findings indicate microplastic contamination at both study sites, with spatial variation in abundance. Microplastic abundance in fish gastrointestinal tracts varied among species, with the highest mean values observed in Epinephelus marginatus (3.0 ± 1.6 particles/fish), followed by Alepes djedaba (2.7 ± 1.2 particles/fish) and Pagrus pagrus (2.3 ± 0.6 particles/fish). This variability revealed the species-specific exposure associated with the feeding behavior and habitat use. The microplastic particles observed were in sizes from 1.0 to 5.0 mm, with larger particles more prevalent in the sediments and smaller particles in fish. Nine different microplastic colors were seen, with blue being the most common, followed by black, green, white, transparent, yellow, glossy, red, and brown. Rayon, alkyd resin, polyamide, and poly(acrylonitrile) were identified at both study sites, whereas poly (ethylene terephthalate) (PET) was detected only at Alhaniyah. The overall similarity in polymer composition suggests that the two locations share common sources of microplastic contamination, while the occurrence of PET exclusively at Alhaniyah may indicate additional local inputs. However, further investigations are required to identify and confirm the specific sources of these polymers. This study provides the first baseline assessment of microplastic contamination in the coastal environments of Alhaniyah and Sousa, northeastern Libya. It offers a valuable reference for future monitoring and mitigation strategies.