Polyethylene microplastics adhere to Lemna minor (L), yet have no effects on plant growth or feeding by Gammarus duebeni (Lillj.)

Microplastics (1-1000 tim) are ubiquitous in the marine, freshwater and terrestrial environments. These microsized plastics arc considered freshwater pollutants of emerging concern, although the impacts on organisms and ecosystems arc nut yet clear. In particular, effects of microplastics on freshwater aquatic plank and the fate of microplastics in the freshwater trophic chain remain largely unexplored. Here we demonstrate that 10-45 pm polyethylene (PE) microplastics can strongly adsorb to all surfaces of the duckweed species Lemno minor. Despite adsorbance of up to 7 PE microplastics per mm2, seven day exposure experiments showed that photosynthetic efficiency and plant growth are not affected by microplastics. Rather, dense surface coverage suggests L. minor as a potential vector for the trophic transfer of microplastics. Here we show that the freshwater amphipod Gammarus duebeni can ingest 10-45 pm PE microplastics by feeding on contaminated L. minor. In this study, ingestion of microplastics had no apparent impact on amphipod mortality or mobility after 24 or 43 h exposure. Yet, the feeding study showed that the fate of microplastics in the environment may be complex, involving both plant adsorbance and trophic transfer. (C) 2019 Elsevier B.V. All rights reserved.