The accumulation of microplastics in fish from an important fish farm and mariculture area, Haizhou Bay, China

Marine fisheries and aquaculture can match growing demand for marine protein from an increasing population. However, the microplastics (MPs) in marine environments may pose a threat to human health through food chains by seafood consumption. The MPs have been found lodged in the digestive tracts and other tissues of various sea animals, nevertheless, little is known in regard to the accumulation of MPs in fish from major fish farms and mariculture areas, especially in non-digestive tissues of fishes. This study investigated the accumulation of MPs in six major wild fish species (including Thryssa kammalensis, Amblychaeturichthys hexanema, Odontamblyopus rubicundus, Cynoglossus semilaevis, Chaeturichthys stigmatias and Collichthys lucidus), both in digestive and non-digestive tissues, from an important fish farm and mariculture area, Haizhou Bay, China. All fishes had items that were identified as MPs. The highest abundance of MPs was 22.21±1.70items/individual or 11.19±1.28items/g in T. kammalensis, which is filter-feeding and usually inhabits in estuary. The lowest abundance of MPs was observed in C. semilaevis (13.54±2.09items/individual) and C. stigmatias (1.61±0.56items/g). The abundance of MPs exponentially increased with the decrease of MPs size. The MPs were dominated by fiber in shape, black or grey in colour and cellophane in composition. As to different tissues, the total number of MPs on skin (800) or in gills (746) was higher than that in gut (514). In terms of skin, the abundances of MPs in three species of scaleless fish with mucus (A. hexanema, C. stigmatias and O. rubicundus) were generally higher than other three fishes with scales (C. lucidus, C. semilaevis and T. kammalensis), implying the potential high risk of scaleless fish consumption for human health in Haizhou Bay. More in-depth studies need to focus on the scaleless fish through mucus adsorbing enormous MPs.