Abstract
Research on the fate and uptake of plastic pollutants in tidal marsh ecosystems is sparse. In an attempt to quantify microplastic prevalence in tidal marsh ecosystems along the coast of Mississippi, we sampled marsh sediments and resident tidal marsh bird stomach contents within three marsh complexes along the Mississippi Coast. To investigate the availability of microplastic pollutants in the marsh habitat, we collected marsh sediment samples at 12 sampling locations within the marsh complexes. To investigate possible microplastic ingestion by resident tidal marsh birds, we captured Clapper Rails (Rallus crepitans) and Seaside Sparrows (Ammospiza maritima) near each sampling location and performed non-lethal stomach flushing to obtain a sample of their stomach contents. We used generalized linear models to differentiate microplastic counts in sediment and bird stomach samples among species, marsh complex, the distance from the Gulf of Mexico, and combinations of these variables. We detected microplastics in 64% of marsh sediment samples, 83% of Clapper Rail, and 69% of Seaside Sparrow stomach samples. The dominant types of microplastics detected in sediment and bird samples were fibers. Model selection showed random and highly variable microplastic concentrations in the tidal marsh sediments within and between marsh complexes. The top models for microplastic counts in marsh bird stomach samples included species and microplastics concentration in the nearby sediments. This study provides the first evidence of microplastic ingestion by resident tidal marsh birds and the first study of microplastic prevalence and distribution within tidal marshes along the Mississippi coast.
