Marine litter pollution on uninhabited islands in Estonia, northeastern Baltic Sea

This paper provides results of marine litter surveys carried out on 14 small uninhabited islands located in the coastal waters of Estonia, northeastern Baltic Sea. The islands were visited four times in total during 2019–2020. On each island, a litter survey was conducted on the beach and in terrestrial vegetation with a focus on macrolitter. Calculated over all surveys, the median value of macrolitter items per 100 m long beach section was 10.65, and the median density was 0.006 items m–2. At the sub-basin level, the three islands located in the Gulf of Finland had the highest number of beach litter items per 100 m and the highest density (items m–2), 38.05 and 0.017, respectively. The main litter material, representing 57.3% of all findings, was plastic; however, there were some variances across islands due to local conditions. The environmental variables most strongly correlated with differences in the composition of macrolitter were related to water movement and depth. Microlitter was found in low amounts (up to 60 items kg–1) in the sediment of all studied islands. Litter items used as nest material were noted on all the islands with seabird colonies.