Effects of microplastics on energy accumulation in a migratory shorebird in the coastal wetlands of the Yellow Sea, China.

Microplastic pollution has emerged as a significant environmental concern at the global level, potentially threatening biodiversity conservation and human wellbeing. As an important biological group with a wide global distribution, migratory shorebirds face considerable stress due to plastic and microplastic pollution. However, few studies have explored the ecotoxic impact of microplastic pollution on migratory shorebirds. To investigate the physiological effects of microplastic pollution on migratory shorebirds, this study obtained the morphological data of 79 dunlins at a key stopover site at the midpoint of the East Asian-Australasian Flyway in 2023 autumn. Meanwhile, fecal and blood samples were collected to examine the microplastic abundance accumulated in the body and metabolic levels. Microplastics were detected in 100 % of dunlins, comprising 12 distinct polymer types. The average abundance of microplastics ingested by dunlins was 134.50 items/g, which was higher than the reported abundance of environmental sediment. The present study confirmed that individuals with longer bills ingested more microplastics, resulting in significantly decreased body mass for the same shorebird. Compared to the low contamination group, metabolomic analysis also revealed that dunlins with elevated microplastic contamination exhibited the down-regulation of 10 metabolic pathways, including pyrimidine metabolism, beta-alanine metabolism, and vitamin C metabolism. The findings of this study underscore the potential threat microplastics pose to the health of migratory shorebirds. It is recommended that synergies be developed between microplastic management and biodiversity conservation at global and regional scales, with migratory birds serving as pivotal indicator species.