Microplastics in Antarctic krill from the Antarctic Peninsula: distribution, composition, and exposure

Despite growing concerns about microplastic (MP) contamination in Antarctic environments, polymer-resolved evaluations of MP exposure in Antarctic krill (Euphausia superba) remain limited, particularly with respect to spatial and size-specific variability. This study analyzed MP abundance, polymer composition, and exposure profiles in krill collected from two regions of the Antarctic Peninsula-the Bransfield Strait and the South Orkney Islands-by categorizing individuals into large (≥50 mm) and small groups (<50 mm) based on body length. MPs were detected in most samples, and MP abundance did not differ significantly between regions and remained within the range previously reported for the Southern Ocean. However, abundance was higher in the large group than in the small group. Polymer composition differed by both region and size class. Ethylene-vinyl acetate (EVA) was detected exclusively in smaller individuals, indicating size-dependent variation in ingested polymer types. Regional differences in polymer assemblages were reflected in distinct polymer hazard index (PHI) values despite modest variation in MP abundance, suggesting that derived hazard profiles were structured primarily by polymer composition rather than particle counts. This study characterizes polymer-specific MP exposure across regional and size gradients in Antarctic krill and clarifies compositional patterns that are not evident from abundance metrics alone, providing context for interpreting MP exposure within Antarctic food webs.