Microplastic ingestion and diet composition of planktivorous fish

Abstract Planktivorous pelagic fish are susceptible to accumulating microplastics (MP), which have the same size range as their prey and accumulate in their feeding and spawning grounds. We analyzed stomach contents of pelagic fish (European sardine, horse mackerel, anchovy, chub mackerel, Atlantic mackerel, and bogue) from Atlanto‐Iberian waters to investigate the relationship between MP ingestion, their diet composition and select a potential bioindicator. We found significant differences between diet of the studied fish species in terms of prey type and size. MP ingestion was significantly related to diet composition. Species with diets that include smaller prey (European sardine, chub mackerel, and bogue) had lower MP concentration in the stomachs than fish depending on larger mesozooplanktonic prey. Horse mackerel had the highest proportion of larger prey (> 1000 μ m) and the highest MP abundance in the stomachs, and thus are a suitable bioindicator for MP monitoring in the pelagic Iberian ecosystem.