Toxic tuna tales: Tracing microplastic pathways in mackerel tuna (Euthynnus affinis), longtail tuna (Thunnus tonggol), and bullet tuna (Auxis rochei).

Abstract

Casting a shadow upon marine ecosystems worldwide, microplastic pollution emerges as a formidable threat, yet its repercussions on commercially significant marine fish remain largely unexplored. This investigation delves into the realm of microplastic contamination within three tuna species (Euthynnus affinis, Thunnus tonggol, and Auxis rochei) inhabiting Malaysian waters, with a keen focus on the gastrointestinal tract (GIT), gills, and edible muscle. These species were chosen due to their significant ecological roles and considerable commercial value, being extensively fished and widely consumed across global regions. Scrutinising 125 tuna specimens uncovers a spectrum of contamination levels across species, with T. tonggol registering the highest concentration (1.22 ± 0.14 microplastics per gram). Remarkably, male tunas exhibit a discernible proclivity towards heightened microplastic accumulation relative to their female counterparts. Noteworthy morphotypes of microplastics predominantly encompass fibres (92.43 %), notably manifesting in black hues (63.25 %). Notably, microplastics spanning the 0.01-1.00 mm size range assert their dominance, constituting a substantial 61.54 % of the total, with rayon emerging as the leading polymer (54.39 %). These findings highlight the pivotal role of the GIT and gills as primary sites of microplastic accumulation in tuna, raising concerns about potential human health implications through seafood consumption. It is crucial to deepen our understanding of microplastic distribution and characteristics in seafood to develop effective mitigation strategies and safeguard human well-being within marine environments. This study advocates for urgent global attention to address the ecological and human health impacts of microplastic contamination in marine ecosystems.