Incidence of microplastics in the marine ecosystem of the Cíes Islands & surrounding areas of Atlantic Islands National Park, Galicia (NW Spain): seabirds as vectors of plastic contamination

• Autor(a) principal: Senes, Giovanni Paolo
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/19813
• topic: Microplastics; Larus michahellis; Seabirds; Pellet; Regurgitation; Feces; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

The Atlantic coast of Galicia (Spain) is home to a region called the Rías Baixas where the Atlantic Island National Park and the Cíes Islands lie. These islands are home to the Larus michahellis, or yellow-legged gull. This species is a transport vector for microplastic analysis. The study was conducted in April and focused on cast pellet as well as excrement samples of the yellow-legged gull. KOH and H2O2 digestion and density separation using a ZnCl2 solution were utilized alongside the aid of RAMAN spectroscopy to identify microplastics. Sampling of the sand at Rodas beach was conducted alongside a marine litter survey to quantify the amount of plastic contamination present in the island. The results show that microplastics are present in both the yellow-legged gull samples. Microplastics were present mostly in fiber form (68% of MPs in cast pellets and 48.4% in excrement), with the most common plastic types being sulphones (26% in cast pellets and 29% in excrement), polypropylene (20% in cast pellets and 32.3% in excrement), and cellulose (26% in cast pellets and 19.4% in excrement). Most MP colors were dark (blue, purple, and black; 76% in cast pellets and 71% in excrement) and followed the findings of previous researchers. Additionally, Estimates show that 12.63 million particles of microplastics are deposited each year by the feces of Larus michahellis in the Cíes Islands. The quantity of microplastic items in the sand of Rodas beach can be estimated to be approximately 1.1 million items within the first 5 cm of depth. Sand samples show primarily fibers (49%), with sulphone-based polymers as the most common (52.5%), and dark colors (blue, purple, and black; 78%)