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Microplastics are ubiquitous contaminants in marine ecosystems worldwide, threatening fisheries production, food safety, and human health. Ingestion of microplastics by fish and large zooplankton has been documented, but there are few studies focusing on single-celled marine predators, including heterotrophic dinoflagellates. In laboratory experiments, the heterotrophic dinoflagellate species Oxyrrhis marina and Gyrodinium sp. readily ingested both algal prey and polystyrene microplastic spheres (2.5–4.5 μm), while Protoperidinium sp. did not ingest microplastics. Compared to algae-only fed dinoflagellates, those that ingested microplastics had growth rates reduced by 25–35% over the course of 5 days. Reduced growth resulted in a 30–50% reduction of secondary production as measured as predator biomass. Ingestion rates of algal prey were also reduced in the microplastic treatments. When given a mixture of microplastics and algal prey, O. marina displayed a higher selectivity for algal prey than Gyrodinium sp. Observations in the coastal ocean showed that phylogenetically diverse taxa ingested microplastic beads, and thus heterotrophic dinoflagellates could contribute to trophic transfer of microplastics to higher trophic levels. The results of this study may suggest that continued increase in microplastic pollution in the ocean could lead to reduced secondary production of heterotrophic protists due to microplastic ingestion, altering the flow of energy and matter in marine microbial food webs.
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Trophic transfer of microplastics in an estuarine food chain and the effects of a sorbed legacy pollutant
Abstract Microplastics are of increasing concern as they are readily ingested by aquatic organisms. This study investigated microplastic trophic transfer using larval inland silversides (Menidia beryllina) (5 d posthatch) and unicellular tintinnid (Favellaspp.) as a model food chain relevant to North American estuaries. Low‐density polyethylene microspheres (10–20 μm) were used to compare direct ingestion of microplastics by larval fish and trophic transfer via tintinnid prey. Dichlorodiphenyltrichloroethane (DDT)‐treated microspheres were used to determine sorbed pollutant effects on microplastic ingestion. Larval fish exposed directly to microspheres ingested significantly fewer than those exposed via contaminated prey. Larvae ingested significantly more ciliates containing DDT‐treated microspheres than ciliates containing untreated plastics but did not discriminate when exposed directly. Larvae reared for 16 d following a direct 2 h exposure had significantly lower wet weight values than unexposed controls. Our results demonstrate that trophic transfer is a significant route of microplastic exposure that can cause detrimental effects in sensitive life stages.
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- Award ID(s):
- 1935028
- PAR ID:
- 10361046
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography Letters
- Volume:
- 5
- Issue:
- 1
- ISSN:
- 2378-2242
- Page Range / eLocation ID:
- p. 154-162
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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