Synthetic Microfiber and Microbead Exposure and Retention Time in Model Aquatic Species Under Different Exposure Scenarios

Abstract

Synthetic microfibers have been reported in most aquatic environments and represent a large proportion of environmental microplastics. However, they remain largely underrepresented in microplastic ecotoxicity studies. The present study aims to investigate particle interaction with, and retention time in, aquatic organisms comparing microfibers, and microbeads. We used brine shrimp (Artemia sp.) and fish (Gasterosteus aculeatus) as invertebrate and vertebrate models, respectively. Organisms were exposed to a mixture of microbeads (polyethylene, 27-32 µm) and microfibers (dope dyed polyester; 500 µm-long) for 2 h, at high concentrations (100,000 part./L) in order to maximize organism-particles interaction. Artemia were exposed in the presence or absence of food. Fish were exposed either via the trophic route or directly via water, and water exposures were performed either in freshwater or seawater. In the absence of food, Artemia ingested high numbers of microbeads, retained in their digestive tract for up to 96 h. Microfiber ingestion was very limited, and its egestion was fast. In the presence of food, no microfiber was ingested, microbead ingestion was limited, and egestion was fast (48 h). Limited particle ingestion was observed in fish exposed via water, and particle retention time in gut did not exceed 48 h, both for direct and trophic exposure. However, water exposures resulted in a higher number of particles present in gills, and average retention time was higher in gills, compared to gut. This suggests that gills are organs susceptible to microplastic exposure and should be taken into account in fish exposure and effect studies. Our results show that particle ingestion and retention by organisms differ between microbeads and microfibers, suggesting particle selection based on size, shape, and/or color and species-specific selective feeding. We also showed that the presence of food results in limited particle ingestion and retention in Artemia and that microbeads are more likely to be transferred to organisms from upper trophic levels than microfibers. Finally, fish exposure to particles was not significantly different between freshwater and seawater conditions.

Microplastic Vector Effects: Are Fish at Risk When Exposed via the Trophic Chain?

“…exposures. The absence of MPs in most fish samples is explained by the short particle retention time in three-spined stickleback (<48 h; Bour et al, 2020): the last contamination before fish were sampled was performed more than 48 h and total egestion of MPs could be expected.…”

Ingestion and Depuration of Microplastics by a Planktivorous Coral Reef Fish, Pomacentrus amboinensis

“…Reports of microplasticrelated risks for marine organisms have, for the most part, been associated with their uptake, and specifically direct ingestion of microplastic items (GESAMP, 2019). Other pathways, however, such as passive uptake through the gills (Bour et al, 2020a) or via trophic transfer from prey items (Santana et al, 2017;Miller et al, 2020) have been demonstrated in controlled laboratory experiments. Thus, similar to other contaminants (Blanco et al, 2018;Amoroso et al, 2020;Hassell et al, 2020), depuration is a major factor influencing the potential effects of microplastics following ingestion.…”

Plastic microfibre pollution: how important is clothes’ laundering?

“…Synthetic microfibres have been shown to be ingested by many aquatic species, including zooplankton, polychaetes, bivalves and crustaceans (Alnajar et al, 2021;Chinfak et al, 2021;Mateos-C ardenas et al, 2021;Bour et al, 2020;Avio et al, 2020;Jemec et al, 2016), deep-sea organisms (Pereira et al, 2020;Taylor et al, 2016;Murray and Cowie, 2011), marine, freshwater and farmed fish (Savoca et al, 2021;Avio et al, 2020;Halstead et al, 2018;Horton et al, 2018) and birds (Bourdages et al, 2021;Hamilton et al, 2021;Coughlan et al, 2020). Exposure to microfibers can affect growth, reproduction and survival of water fleas and amphipods (Ziajahromi et al, 2017b).…”

“…This can obviously be a harmful effect in any animal that ingests microfibres. Bour et al (2020) compared the toxic effects of high concentrations of polyester microfibres (500 μm long) and polyethylene microbeads (27)(28)(29)(30)(31)(32) μm) in brine shrimp (Artemia sp.) and fish (Gasterosteus aculeatus), invertebrate and vertebrate aquatic species, respectively.…”

“…The authors considered that the shrimp was acting as a chemical source of prey, stimulating ingestion. In spite of the results of Bour et al (2020), which suggested that microbeads might be more damaging than microfibres, more studies suggest that microfibres have a negative impact on organisms than those that show little impact (Kapp and Miller, 2020, and references therein;Bucci et al, 2019). Examples in which plastic microfibres have been shown to have greater impact than microbeads include studies on the amphipod Hyalella azteca (Au et al, 2015) and the waterflea Ceriodaphnia dubia (Ziajahromi et al, 2017b).…”