Heterotrophic Dinoflagellate Growth and Grazing Rates Reduced by Microplastic Ingestion

Microplastics are ubiquitous contaminants in marine ecosystems worldwide, threatening fisheries production, food safety, and human health. Ingestion of microplastics by fish large zooplankton has been documented, but there few studies focusing on single-celled predators, including heterotrophic dinoflagellates. In laboratory experiments, the dinoflagellate species Oxyrrhis marina Gyrodinium sp. readily ingested both algal prey polystyrene microplastic spheres (2.5–4.5 μm), while Protoperidinium did not ingest microplastics. Compared to algae-only fed dinoflagellates, those that had growth rates reduced 25–35% over course 5 days. Reduced resulted a 30–50% reduction secondary production as measured predator biomass. were also treatments. When given mixture prey, O. displayed higher selectivity for than Observations coastal ocean showed phylogenetically diverse taxa beads, thus dinoflagellates could contribute trophic transfer levels. The results this study may suggest continued increase pollution lead protists due ingestion, altering flow energy matter microbial webs.