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Microplastics and phagotrophic soil protists: evidence of ingestion
  • Eric Kanold,
  • Matthias Rillig,
  • Pedro Madeira Antunes
Eric Kanold
Department of Biology, Algoma University
Matthias Rillig
Institut für Biologie, Freie Universität Berlin
Pedro Madeira Antunes
Department of Biology, Algoma University

Corresponding Author:[email protected]

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Microplastics (MPs) can now be found in all the Earth's biomes, thereby representing a global change phenomenon with largely unknown consequences for biodiversity and ecosystem functioning. Soil protists are eukaryotic, primarily single celled organisms that play important roles in the soil food web. Microplastics have been shown to affect protist populations in freshwater and marine environments, yet the interactions between soil protists and MPs remain largely unknown. Here we examined whether phagotrophic protists present in a forest soil can ingest MPs and experience declines in abundance. We exposed protists to soil treatments with different concentrations of MPs using commercial polymer fluorescent microspheres and used fluorescence microscopy to find evidence of MP ingestion. In addition, we quantified the total number of active phagotrophic protists over time. We show that most soil protists (>75% individuals) can readily ingest and keep MP within their food vacuoles, even at relatively small MP concentrations (0.1% w/w). There was a trend for higher prevalence of ingestion and for declines in protist abundance at the highest concentration of MPs (1% w/w). However, more data are necessary to further ascertain cause-effect relationships. This is the first report indicating that most soil protists present in a forest soil can ingest MPs, which may have important consequences for the transport and uptake of MPs in the soil food web.
01 Feb 2021Published in Soil Organisms. 10.25674/so93iss2id160