Characterisation of plastic debris (macro-, meso-, and microplastics) from stranded alcids in southern Spain.

Plastic pollution has become a major issue for marine ecosystems. Seabirds are particularly vulnerable to this pollution and are very good indicators of the ecological state of marine ecosystems. This study aims to analyse the presence of plastics in the digestive tracts of two seabird species: the Atlantic puffin (Fratercula arctica) and the razorbill (Alca torda), collected along the Andalusia coast in Southern Spain. A total of 123 carcasses were collected during the autumn and winter seasons of 2022-2024. The results showed a significantly higher presence of plastics in Atlantic puffin (65.0 %) compared to razorbill (18.4 %). The mean number of plastics per puffin was 2.50 ± 2.75, while per razorbill was 0.31 ± 0.94. The predominant type of ingested plastic was fibres in both Atlantic puffin (38.0 %, n = 19) and razorbill (40.6 %, n = 13), with an average size of 1.58 ± 0.74 mm and 2.13 ± 1.98 mm, respectively. The predominant colour was black in both species (22.0 % in puffin and 46.9 % in razorbill), and polyethylene (39.5 %) was the most common plastic polymer, consisting of highly fragmented particles with low levels of adhering heavy metals. This study supports the growing concern about plastic pollution in marine environment, showing that alcid populations are ingesting plastics, potentially threatening these vulnerable species.