Plastic ingestion in seabirds of the western Indian Ocean

Abstract

**Abstract:** Ingestion of plastic by marine fauna has been reported all around the world and affects a large number of seabirds including albatrosses, petrels, shearwaters, seagulls and boobies. Most of the studies on plastic ingestion by seabirds realized so far have been focusing in the Pacific and Atlantic Oceans but no information has been published on this issue in the western Indian Ocean. In this study we investigated plastic ingestion in nine seabird species breeding or foraging at Reunion Island and at Juan de Nova (Mozambique Channel), among which two species are endemic and endangered (the Barau's Petrel, Pterodroma baraui) or critically endangered (the Mascarene petrel, Pseudobulweria aterrima). We analyzed the stomach contents of 222 individuals and showed the most affected species are tropical shearwaters (79%) and Barau's petrels (59%). The average number of plastic particles per contaminated bird was higher in Barau's petrels (6.10 ± 1.29) than in tropical shearwaters (3.84 ± 0.59) and all other studied species also showed plastic presence in their stomach contents to a lesser extent. We analyzed differences in plastic ingestion between juveniles and adults for three different species: Barau's petrels, tropical shearwaters and white-tailed tropicbirds. We showed significantly more plastic particles in juveniles of Barau's petrels than in adults and a significantly higher mass of plastic particles both in juveniles Barau's petrels and tropical shearwaters than in adults of these two species. These results demonstrate that the foraging areas of seabirds of the western Indian Ocean have a high level of plastic pollution. In Reunion Island, hundreds of tropical shearwaters and Barau's petrels are attracted by urban lights and die each year so we suggest to take advantage of this situation by using these species as long-term indicators of plastic marine pollution in the region. Keywords: plastic ingestion, seabird, marine pollution, Indian Ocean, Pterodroma baraui, Puffinus bailloni. **Authors:** Audrey Cartraud¹, Matthieu Le Corre¹, Jean Turquet¹, Julie Tourmetz¹ ¹Université de La Réunion