Microplastic contamination caused by different rearing modes of Asian swamp eel ( <i>Monopterus albus</i> )

At present, research into the impact of microplastic contamination on environmental and food safety in the eel farming industry is insufficient. Here, we investigated the occurrence of microplastics in eels (Monopterus albus), wastewater and soils from recycled-water, cement-pool, net-cage and rice-field rearing systems. Results showed that average microplastic abundances were 2.4 ± 0.8 items/individual, 1.0 ± 0.4 items/L, 27.1 ± 7.0 items/kg in eels, water and soils, respectively. A significant increase in microplastic abundances occurred in all diet-fed eels (recycled-water, cement-pool and net-cage eels) from their pre-rearing to post-rearing stages. Moreover, cluster analysis indicated high similarities in composition of microplastics between fish diets and eels. However, no significant differences in microplastic abundances were observed among the four types of reared eels. Most of the microplastics were found in the foreguts of eels. In addition, wastewater microplastic increased significantly in the cement-pool, net-cage and rice-field farming during eel rearing. This study first revealed microplastic contamination and its characteristics in eels-rearing environments, which suggests the eco-environmental risk of microplastics in aquaculture.