Most ecotoxicity studies on microplastics (MPs) have focused on the single species testing, however environmentally relevant risk assessment of MPs requires different approach. The present study conducted an interspecific competition experiment between Daphnia magna and Daphnia pulex under MP fragments (MP) or MP fragments with UV filter benzophenone-3 (MP/BP-3) exposure. In MP exposure, smaller sized D. pulex was more advantageous, showing a significantly (p < 0.05) lower MP uptake and a higher population growth rate. On the other hand, in MP/BP-3 exposure, larger sized D. magna was more advantageous with a significantly (p < 0.05) lower BP-3 bioconcentration and a higher population growth rate. Transcriptomic analysis showed that expression levels of genes related to energy metabolism were significantly (p < 0.05) increased in D. pulex but significantly (p < 0.05) decreased in D. magna under MP exposure. For MP/BP-3 exposure, defense-related genes were significantly (p < 0.05) upregulated in D. magna but significantly (p < 0.05) downregulated in D. pulex. This study highlights different effects of MPs and plastic additives on interspecific interaction in the zooplankton community.

Division of Environmental Science and Ecological Engineering Korea University Seoul 02841 Republic of Korea

University of Ljubljana Faculty of Chemistry and Chemical Technology 113 Večna pot Ljubljana SI 1000 Slovenia

University of Ljubljana Faculty of Chemistry and Chemical Technology 113 Večna pot Ljubljana SI 1000 Slovenia; Faculty of Mechanical Engineering Brno University of Technology Brno Czech Republic

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