Occurrence and Characterization of Microplastics in the Gastrointestinal Tracts of Fish and a Crustacean from the Keralam Coast, Southeastern Arabian Sea.

Microplastics (> 300 µm) ingestion by marine organisms drives trophic transfer and chemical bioaccumulation, posing risk to sea food safety and coastal fisheries. In this study, the gastrointestinal tracts of commercially important finfish species along with a crustacean species, were analyzed to assess microplastic contamination and its potential entry into the food chain. A total of 540 samples (30 individuals from six species per season) were collected from the fishing harbour Kalamukku along the Keralam coast, India, across the pre-monsoon, monsoon and post monsoon season of 2021. Overall, microplastic ingestion was confirmed in 44.25% of the examined samples. Across the year, the prevalence of microplastics in the gastrointestinal tracts followed the order: Rastrelliger kanagurta (56.67%) > Mugil cephalus (50%) > Sardinella longiceps (45.56%) > Nemipterus japonicus (43.33%) > Thryssa malabarica (42.22%) > Fenneropenaeus indicus (27.78%). Season wise analysis revealed the highest prevalence during the post monsoon season (55.56%). The dominance of microplastics in the 300-500 µm size range (37.65%) indicates their greater susceptibility to ingestion by the analyzed species. Four colour types were recorded, with blue being predominant. Urban run-off and harbour related activities likely contribute to microplastic contamination in the study area. Selected microplastics, characterized by stereomicroscopy and Fourier-Transform Infra Red-spectroscopy, were dominated by polyethylene, polyurethane, and polypropylene. Thus, microplastics in edible species may represent a potential pathway into the human food chain, emphasizing the need for effective plastic waste management.