First evidence of microplastic ingestion by the European grayling, Thymallus thymallus, in sub-Arctic regions: Insights on plastic pollution and preliminary risk assessment in the Teno River (Finland)

Marine litter pollution affects even remote environments such as the Arctic regions and their biodiversity. However, due to the inaccessibility and difficulty of regular observations in these environments, further studies are needed to fill the knowledge gaps. In this regard, the present investigation provides new insights on microplastic contamination levels in Arctic riverfish by analyzing, for the first time, plastic ingestion by the European grayling Thymallus thymallus from the Teno River (northern Finland), an important fishery resource and vulnerable species; and performing a preliminary ecological risk assessment of microplastics in the Finnish river using the European grayling. Plastic abundance and characterization were explored, and microplastic concentrations and polymer hazardous were also used to assess human and environmental risk. The higher frequency of occurrence (%O = 50) observed in the riverfish and the characterization of the extracted plastic confirm that riverine environment is one of the main pathways for microplastic pollution in Arctic regions and suggest the influence of the surrounding environment and human activities, mainly recreational fishing. Finally, the preliminary risk assessment highlights an ecological threat to the Teno River. This research represents a first step for the study of a commercially important Arctic freshwater species as well as in remote Arctic rivers and support identification of priorities, the application of management strategies and further environmental and human-health risk assessments according to the recommendation of Arctic Monitoring Plan and Monitoring Guidelines.