Plastic ingestion in Scopoli's shearwater (Calonectris diomedea) from Lampedusa, central Mediterranean Sea (IT)

Plastic pollution is an escalating threat to marine biodiversity. Seabirds are widely recognized as effective indicators of ocean health. The amount of plastic in Scopoli’s shearwaters (Calonectris diomedea), a wide-ranging seabird that breeds throughout the Mediterranean, one of the world’s most plastic-polluted seas, is not well-known. In this study, we analyzed the stomach contents of bycaught Scopoli’s shearwaters collected by local fishers near Lampedusa Island, in the central Mediterranean Sea. A total of 18 carcasses were dissected using a standardized protocol adapted from the seabird plastic monitoring program in the North Sea. Biometric data and additional information such as organ condition, sex, and sexual maturity were recorded for each individual. The contents of both the proventriculus and gizzard were rinsed, sorted, and analyzed by plastic shape, number, and mass. We identified 243 plastic items across all specimens with an average mass (± SD) of 26.02 ± 30.74 mg per bird, with marked differences between stomach sections and sexes. Interestingly, immature/subadult females (n = 4) exhibited higher plastic burdens than adult males (n = 14), although the highest plastic mass was found in a male (128.6 mg). On average, plastic mass in the gizzard was 23.8 ± 32.0 mg, compared to 5.4 ± 9.08 mg in the proventriculus. Future analysis of polymer composition using FTIR will offer deeper insight into the origin and characteristics of the ingested plastics, contributing to a better understanding of marine litter impacts on Mediterranean seabirds.