Microplastics are ubiquitous on California beaches and enter the coastal food web through consumption by Pacific mole crabs.

Microplastics are commonly found in marine ecosystems, but their distribution, prevalence, and impacts on resident fauna are still not well understood. Microplastics in coastal sediments expose invertebrate infauna to the risk of ingestion of plastic debris and associated toxicants. We assessed the prevalence of microplastics in beach sediments and ingested by Pacific mole crabs (Emerita analoga) at sandy beaches spanning >900 km of the California coast. Microplastics were present in sediments of every one of 51 beaches sampled. At a subset of 38 beaches Pacific mole crabs were collected and crabs at every beach had ingested microplastics. Across all beaches sampled, an average of 35% of Pacific mole crabs examined had microplastics in their guts. Our study demonstrates that microplastics are ubiquitous in sediments on California beaches and they are frequently consumed by a filter-feeding crustacean that is a common prey item in the diet of a wide variety of taxa, including fishes and birds.