Arctic Amphipods as bioindicators of plastic pollution: identification and simultaneous quantification of small microplastics and microlitter (< 100 μm)

The study aimed to identify and simultaneously quantify the body burden in Arctic Amphipods (Amphipoda, Crustacea) of small microplastics, plastic additives and other microlitter components, focusing on the particles below 100 μm. These are the sizes that can be easily ingested by the organisms, hence entering the trophic web and reaching its upper layers; indeed, these are also the particles sizes that can be easily long-range transported. As part of the Microtracer project (Small MICROplastics (<100 μm) bioindicaToRs in the changing ArctiC EnviRonment), during the summer of 2022, different genera of amphipods were collected at different sites of the Kongsfjorden, the Svalbard Archipelago. Organisms were pseudo-digested to extract microplastics and microliter components, which were then analyzed via Micro-FTIR for characterization and quantification. Preliminary results showed no differences in the abundance of microplastics and microliter components between the sampled sites or genera collected. The most abundant polymers and components were Polypropylene (PP) and Poly -N-Methylacrylamide (PnMA). Markers of tire wear and road particles were frequently detected, along with vulcanizing agents, specifically used in tires. According to the size distribution of microplastics and other microlitter, most particles were smaller than 100 μm. An exception is the site close to the village, where most of the particles exceed the 80-100 μm. This site might be a local source of particles. Analyzing the aspect ratio (AR), the shape of MPs and MLCs were mainly spheroidal or cylindrical. Smaller shapes and dimensions are the most common, however, due to the limits of sampling and analytical methods, these smaller particles are often overlooked. These findings highlight that amphipods can be employed as bioindicators of plastic pollution and that further studies on smaller microplastics and microlitter components are needed.