Anthropogenic debris accumulated in nests of seabirds in an uninhabited island in West Africa

Abstract

Anthropogenic debris is rapidly spreading in marine environments and poses major problems to biodiversity and humans. However, mitigation strategies are limited by the lack of information on the accumulation patterns of these pollutants both at sea and in marine wildlife. Using observations from an uninhabited island in Delta du Saloum National Park, Senegal, we investigate here the prevalence and abundance of debris in nests of two sympatric seabird species, Caspian terns Hydroprogne caspia and great cormorants Phalacrocorax carbo, and its potential as an indicator of ocean pollution. We recorded debris in 15% of the Caspian terns' nests, and 40% of the great cormorants' nests. Plastics accounted for >95% of items recorded in the nests of both species. Caspian terns collected a diverse array of debris, both in terms of types and colours, with a preference for hard plastics and white items. The great cormorants accumulated in nests mainly greenish fishing gears resembling the vegetation typically used as nest materials. Nests of both bird species contained soft plastic in proportions lower than those observed in the environment. Our results suggest that nests of Caspian terns and great cormorants are not useful indicators of pollution by anthropogenic debris in the surrounding waters of the Delta du Saloum National Park. Nests of great cormorants, however, have the potential to indicate areas vulnerable to plastic pollution associated to fishery. The high amount of debris in nests of this species demonstrates the need for a better implementation of waste management strategies in Senegal.