Characterization of microplastics in selected commercial marine fishes in Sri Lanka

Abstract

Coastal and offshore fisheries in Sri Lanka are mainly dependent on wild fish stocks, which may have been contaminated with microplastics (MPs) that have a potential risk to transfer subsequently to consumers. However, studies on MPs in commercial fish species are limited, and therefore, we estimated the MPs abundance and composition in three species, i.e., Amblygaster sirm (n = 30 from Dondra), Selar crumenophthalmus (n = 70 from Dondra and Kudawella) and Thunnus albacares (n = 70 from the Indian ocean and the Arabian Sea). MPs were extracted from the gastrointestinal tract by acid digestion and observed under Olympus™ DP21 photomicroscope. All fish samples (100%) were found to be contaminated with microplastics coloured in red, orange, black and blue. Major MPs morphotypes observed in A. sirm and S. crumenophthalmus were microspheres and fragments, whereas fragments and fibers were the commonest in T. albacares. No significant difference (p>0.05) of MPs abundance per individual was identified between A. sirm (54.2 ± 33.0) and S. crumenophthalmus (56.4 ± 33.0). In contrast, MPs abundance per individual in S. crumenophthalmus in Dondra (56.4 ± 33.0) and Kudawella (65.7 ± 89.0) were significantly different (p<0.05). The highest MPs abundance of T. albacares was observed in the Arabian Sea (59.3 ± 79.7 of MPs per 2.5g), followed by the Southern Indian Ocean (19.4 ± 15.2 MPs per 2.5g) and Bay of Bengal (18.1 ± 11.5 MPs per 2.5g). Our findings indicate MPs contamination in marine food fish species A. sirm, S. crumenophthalmus, T. albacares and emphasize the importance of regulation and control of MPs to ensure food safety.