First Assessment of Micro-Litter Ingested by Dolphins, Sea Turtles and Monk Seals Found Stranded along the Coasts of Samos Island, Greece

SIMPLE SUMMARY: This study is the first to assess the presence of micro-litter ingested by four species of marine mammals and two species of sea turtles, found stranded along the coastline of Samos Island, north-eastern Aegean Sea, Greece. Litter particles, identified as microplastics, were ubiquitous throughout all the digestive tracts analysed. This study suggests there is widespread microplastic contamination in marine megafauna in the study area, and proposes a method of standardisation to facilitate comparisons. ABSTRACT: This study is the first to assess the occurrence of micro-litter ingested by marine megafauna in the north-eastern Aegean Sea. A total of 25 specimens from four species of marine mammals, including dolphins and monk seals, and two species of sea turtles, found stranded along the coastline of Samos Island, Greece, were selected for the analysis. Litter particles, identified as microplastics (MPs), were ubiquitous throughout all sections of the gastrointestinal tract (oesophagus, stomach and intestine) in all specimens. Overall, the MPs most frequently found were black fibres 0.21–0.50 mm in size. These results provide insight into the extent of micro-litter ingestion and contamination in marine vertebrates. Here we propose a method of standardisation to establish a baseline for marine taxa in this region of the Mediterranean Sea, where knowledge of the topic is still lacking.