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Toxicity of microplastics (MPs) in granular form to aquatic animals has been frequently tested, whereas the effects of fibrous MPs remain further explored. In this study, the effects of polyethylene terephthalate granular particles (p-PET, approximately 150 μm in diameter) and fibers (f-PET, approximately 3-5 mm in length and 20 μm in diameter) on the development of zebrafish embryos and their joint effects with cadmium (Cd) were compared. p-PET and f-PET accelerated the velocities of blood flow and heart rate and inhibited hatching in zebrafish embryos because of their barrier effects on the channels in the embryonic chorion and enhanced the mechanical strength of the chorion. The Cd content in the chorion increased by p-PET due to the adsorption of p-PET on the chorion. By contrast, more f-PET dissociated in culture medium and resulted in low Cd content in the chorion. Given that chorion can effectively block p-PET and f-PET, the Cd accumulation in eggs significantly decreased (p < 0.05) under p-PET/f-PET and Cd combined treatment because of the reduction in the bioavailability of Cd. Therefore, p-PET and f-PET decreased the toxicities of Cd on all the target endpoints in this study, and the detoxification effect of f-PET at 72 hpf was more significant than that of p-PET. These results suggest that the toxicity induced by MPs might be form-related., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Microplastics (MPs) are widespread in the environment including coastal wetlands. The influence of different types and intensities of human activities on the occurrence of MPs in coastal wetlands is still unknown. The aim of this study was to investigate the distribution of MPs and the contribution of human activities in different areas of Yellow River Delta wetland. MPs were widely detected in different areas of the wetland even in the protection area with little human activities. Direct human activities resulted in more severe MPs contamination in the protection area than the tourism area. In the soil of different areas, the MPs abundances ranged from 136 to 2060 items/kg. The concentrations of polyethylene terephthalate (PET) ranged from 536 to 660 μg/kg, and the concentrations of polycarbonate (PC) ranged from 83.9 to 196 μg/kg. The MP abundances of the three areas had significant correlations with PET concentrations. These results indicate that the direct influence of human activities has much greater contribution than indirect influence. These results also suggest that PET concentration can be used as a potential marker of MPs contamination in wetland soils., Competing Interests: Declaration of competing interest The authors claim that there is no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The ingestion of petroleum-based microplastics (MPs) by aquatic animals and their toxicological effects are of wide concern. However, the ecological risks of bio-based MPs to aquatic animals remain largely unknown. In the present study, zebrafish (Danio rerio) were exposed to MPs of polylactic acid (PLA), the most widely used bio-based plastic, and polyethylene terephthalate (PET), a high-production volume petroleum-based plastic. PLA MPs were more actively ingested by fish than PET MPs. The abundance of PLA MPs in fish intestines was approximately 170 times greater than that of PET MPs after one day of exposure. The ingestion of PLA MPs caused gastrointestinal damage in zebrafish. In addition, the ingestion of PLA MPs induced specific changes in the diversity of intestinal microbiota and promoted species closely linked with energy metabolism, cellular processes, and fish diseases. This might have been related to the depolymerization of PLA in the digestive tract, which decreased the intestinal pH and changed the carbon source structure. Overall, bio-based MPs may have different ecological effects on aquatic animals than traditional petroleum-based MPs. [Display omitted] • Zebrafish has distinct diet preference for the bio-based PLA in comparing to PET. • High abundance of ingested PLA MPs causes damage on fish intestinal epithelial tract. • The ingested PLA MPs affect the composition of intestinal microbiota. • Ecological risk of bio-based MPs to aquatic organisms deserves more attentions. [ABSTRACT FROM AUTHOR]