Anthropogenic particles determination in northern krill (Meganyctiphanes norvegica) from the Azores region: A keystone species for marine food webs.

Plastic pollution poses a significant threat to marine ecosystems. Microfibres from fabrics have become the most prevalent shape of microplastic found in the marine environment. The northern krill (Meganyctiphanes norvegica) is the most abundant euphausiid species in the northern hemisphere, playing a crucial role in various pelagic ecosystems. Anthropogenic microparticles in northern krill was assessed for the first time in samples collected in the Azores on two occasions - April 2019 (n = 480) and April 2023 (n = 480). Analysis of all individuals revealed 533 anthropogenic particles, with an average abundance of 0.56 ± 0.14 items per individual and, no significant differences between years. Microfibres were the most common shape (94.8 %), with the remaining items being fragments (5.2 %), and blue and black were the predominant colours. MicroFourier transform infrared spectroscopy analysis (μFTIR) of 22.1 % of the total number of particles, showed that they were mainly cellulosic (65.3 %) - either natural or semisynthetic - followed by polyester (7.6 %). Our finding of microplastics in the northern krill raises important questions due to its crucial role in marine food webs. The intake of anthropogenic particles, particularly those that are 100 % synthetic, suggests that the northern krill may act as a transfer vector of these pollutants to higher trophic levels.