Application of marine organisms at multi-trophic level to study the integrated biological responses induced by microplastics through food-chain

Microplastics (MPs, smaller than 5 mm) are ubiquitous and difficult to be degraded in environment. It is more easily to be ingested by the organism and cause a series of harms through the food chain. Based on the survey of MPs distribution in the intertidal zone along our coast and the development of fast MPs detection methods by using Hyperspectral image recognition, we use a typical marine food chain (microalgae-mussels-crabs) to investigate the trophic transfer and the relative toxic effects by environmental MPs. The polyethylene particles (10-45 μm) was selected as representative MPs to investigate the induced biological effects in microalgae, marine mussels and crabs, and the potential mechanisms under different exposure scenarios, including both water-born and trophic transfer exposure. The results showed that the algae could absorb on the surface of MPs, which not only damaged algal cells, but also changed surface characteristics of MPs to affect the feeding of mussels. In addition, MPs could be ingested and accumulated in the consumers with significant exposure concentration dependence and tissue specificity. Biomarkers from different levels in mussels and crabs showed that MPs could induce the increased ingestion rate, decreased lysosomal membrane stability, the changes of the activity of antioxidative responses. In addition, MPs indeed caused more serious stress responses in organisms at higher levels in food chain through the trophic transfer under the mechanism to balance the antioxidant defenses and metabolism system. To our best knowledge, this research is the first study to focus on trophic transfer induced biological responses by MPs in marine organisms. It provides an important research model and scientific basis for the future exploration of eco-toxic effect of environmental MPs.