Microplastics across biomes in diadromous species. Insights from the critically endangered Anguilla anguilla

Low microplastic loads in riverine European eel (Anguilla anguilla) from southwest England during their marine–freshwater transition

“…The application of stable isotope analysis to migratory fishes used in microplastic loading studies could thus link the trophic ecology of individuals with levels of environmental contaminants (Garcia et al, 2021;. As Menéndez et al (2022) found that river and seawater microplastic contamination predicted the contamination levels of individual eels from rivers draining into the Bay of Biscay, the differences in plastic loadings with the authors' study might reflect differences in abiotic microplastic loads between the study locations. The use of samples here that had already been collected for a separate study meant that there was no opportunity to concomitantly collect and analyse abiotic water and/or sediment samples to investigate this further.…”

“…Although it is possible that juvenile eels in the system are highly susceptible to microplastic contamination and so survivorship bias prevented the observation of higher incidences and loadings above a single particle, the data presented by Menéndez et al (2022) for eels in the Bay of Biscay suggest eels can have much higher plastic loadings than the authors detected and still survive. This further emphasises that the lower frequency of occurrence and loadings in eels in this study was probably more reflective of a lower microplastic contamination in the sampled fresh waters.…”

“…Eel trophic ecology is intimately linked to their body size, with smaller eels generally feeding on macro‐invertebrate prey but with increasing proportions of fish in their diet with increasing body size and head width (Cucherousset et al ., 2011; Pegg et al ., 2015), which has also been attributed to the accumulation of mercury and several organic pollutants (De Meyer et al ., 2018). The eel life cycle includes their transition from marine to freshwater environments at their glass‐eel (non‐pigmented) and elver (pigmented) stages when there is potential for individuals to transport marine plastics into the freshwater environment (Menéndez et al ., 2022). Studies on incidences of microplastics in eels are conflicting, with no particles in the River Garonne, France (Garcia et al ., 2021), whereas incidences in three rivers discharging into the Bay of Biscay reported 2.74 microplastics per gram of glass eel (Menéndez et al ., 2022), with loadings related to concentrations in the adjacent freshwater and marine environment (Garcia et al ., 2021).…”

“…The eel life cycle includes their transition from marine to freshwater environments at their glass‐eel (non‐pigmented) and elver (pigmented) stages when there is potential for individuals to transport marine plastics into the freshwater environment (Menéndez et al ., 2022). Studies on incidences of microplastics in eels are conflicting, with no particles in the River Garonne, France (Garcia et al ., 2021), whereas incidences in three rivers discharging into the Bay of Biscay reported 2.74 microplastics per gram of glass eel (Menéndez et al ., 2022), with loadings related to concentrations in the adjacent freshwater and marine environment (Garcia et al ., 2021). Given these discrepancies in loadings, the aim here was to investigate the incidence of microplastic contamination within European eel elvers from three rivers in southwest England, with testing of the effects of location and body size.…”

“…The presented incidence and number of confirmed microplastics were much lower than those in a comparable study finding several particles per gram of juvenile eel (Menéndez et al ., 2022). The average load and frequency of occurrence (0.03 particles per eel and 3.3%, respectively) are additionally among the lowest reported within freshwater fishes (Parker et al, 2021; Parker, Andreou, et al, 2022; Parker, Britton, et al ., 2022).…”