111 | Plastic contamination in bycaught yelkouan shearwater (Puffinus yelkouan) from the Mediterranean sea

Marco Parolini¹, Federico Tossani¹, Federico De Pascalis², Dimitra Christidi³, Angelos Evangelidis³, Andrea Benvenuti⁴, Sara Di Leo¹, Simona Mondellini¹, Giacomo Dell’Omo⁴, Danae Portolou³, Jacopo G. Cecere², Diego Rubolini¹ | ¹Department of Environmental Science and Policy, University of Milan, Italy; ²Area Avifauna Migratrice, Istituto Superiore per la Protezione e la Ricerca Ambientale ISPRA, Ozzano dell’Emilia, Italy; ³Hellenic Ornithological Society, Athens, Greece; ⁴Animal Tracking, TECHNOSMART EUROPE srl, Guidonia-Montecelio, Roma, Italy.

Plastic pollution has emerged as a pervasive and persistent threat to marine ecosystems. Plastic debris is widely distributed across marine environments and can interact with organisms, leading to potential adverse effects. Seabirds are considered good indicators of plastic contamination and related impact because their interaction through ingestion, entanglement, and trophic transfer. However, up to date the extent of plastic contamination was investigated only on few and common seabird species. The aim of the present study was to assess plastic contamination in the digestive tract of bycaught yelkouan shearwaters (Puffinus yelkouan) individuals collected in two Mediterranean areas. The yelkouan shearwater is an endemic seabird to the Mediterranean Sea suffering different threats, including fisheries bycatch within foraging areas and sea pollution. Bycaught individuals were collected stranded along the coastline, entangled in trammel nets or hooked on longlines. Individuals were dissected using a standardized protocol adapted from the seabird plastic monitoring program and biometric data were recorded. Meso- (<25 mm in size) and microplastics (< 1 mm in size) was isolated from both the proventriculus and gizzard of shearwaters, and they were then grouped according to their shape, colour, polymer composition and abundance or mass. Meso- and microplastics were isolated from all the analyzed individuals, with higher abundance observed in the gizzard compared to the proventriculus. Spectroscopy characterization showed that polyethylene and polyethylene terephthalate were the main polymers composing plastic debris ingested by shearwaters. Our results confirmed the ingestion of differently sized plastics by seabirds, suggesting a potential threat for their health status.