Marine Bioturbation Drives Global Microplastic Cycling and Biological Exposure Risks

Marine sediments are the ultimate sink for microplastics that threaten benthic ecosystems. This study establishes the first comprehensive global database of microplastic contamination in benthic environments, comprising 1697 benthic organism samples (203 species) and 3724 sediment samples from marine continental shelves worldwide. Using in situ environmental data, we systematically elucidate the regulatory mechanisms through which benthic bioturbation influences the fate of microplastics. Compared with mobile foragers (e.g., crabs: 4.06 ± 5.80 items/unit), filter-feeding species (e.g., oysters: 7.92 ± 10.54 items/unit) accumulate significantly more microplastics, reflecting functional group differentiation in terms of microplastic-biota interactions. Bioturbation has dual effects: it facilitates the migration of microplastics to deeper sediments for carbon sequestration while increasing organismal exposure. Dissolved oxygen and temperature regulate bioaccumulation by controlling bioturbation intensity, resulting in pronounced spatiotemporal variability. Relatively higher accumulation efficiency occurs in high-latitude regions and semienclosed seas, and areas such as the Asia-Pacific region and the Gulf of Mexico exhibit elevated winter contamination risks. This study provides a global-scale investigation of complex benthic bioturbation transport mechanisms and ecological regulation of microplastic fate, offering critical evidence for predicting contamination risks under climate change and forming adaptive management strategies.