Microplastics in different tissues of wild crabs at three important fishing grounds in China

Crabs are an indispensable component of the benthic ecosystem and represent a type of seafood that is easily obtained and frequently eaten by humans. However, little is known about microplastic (MP) accumulation in different tissues of crabs in important fishing areas. In this study, the abundances and characteristics of MPs in different tissues of four species of wild crabs (Portunus trituberculatus, Charybdis japonica, Dorippe japonica, and Matuta planipes) were investigated across 9 sites at three important fishing grounds (Haizhou Bay, Lvsi and Yangtze River Estuary fishing grounds) in China. Crabs from all sites were found to contain MPs, with a total detection rate of 89.34%. The MP abundance in crabs from all sites ranged from 2.00 ± 2.00 to 9.81 ± 8.08 items/individual and 0.80 ± 1.09 to 22.71 ± 24.56 items/g wet weight. The abundance of MPs exponentially increased with decreasing MP size. The MPs were dominated by fibers in terms of shape, black-gray and blue-green in terms of color and cellophane in terms of composition. MPs were found in the gills and guts of the crabs, but not in the muscles. The abundance and size of the MPs in the guts were significantly higher than those in the gills, but there was no significant difference in color or shape. In addition, crab eating patterns have a significant impact on the abundance of MPs in different species. The abundance of MPs in the saprophytic crabs was significantly higher than that in the predatory crabs. MP contamination in crabs is worthy of attention for human health and the stability of marine ecosystems.