Availability and assessment of microplastic ingestion by marsh birds in Mississippi Gulf Coast tidal marshes

Millions of tons of plastic enter the environment every year, where much of it concentrates in environmental sinks such as tidal marshes. With prior studies documenting harm to marine fauna caused by this plastic pollution, the need to understand how this novel type of pollution affects estuarine fauna is great. Yet, research on the fate and uptake of plastic pollutants in estuarine ecosystems is sparse. Therefore, we quantified plastic prevalence and ingestion by two species of resident marsh bird, Clapper Rails (Rallus crepitans) and Seaside Sparrows (Ammospiza maritima), in coastal marsh ecosystems within Mississippi. We detected microplastics (plastics smaller than 5 mm) in 64% of marsh sediment samples, 83% of Clapper Rail and 69% of Seaside Sparrow proventriculus samples. Dominant types of microplastics detected in sediment and bird samples were fibers. This study provides the first evidence of microplastic ingestion by marsh birds and its distribution in coastal marshes within Mississippi. •We detected evidence of microplastic ingestion by resident tidal marsh birds•We quantified microplastic distribution in tidal marsh sediments of Mississippi•Fibers were the most prevalent type of microplastic detected (98%)•Plastic ingestion by marsh birds may be a novel threat to their conservation