Trophic niche influences ingestion of micro- and mesoplastics in pelagic and demersal fish from the Western Mediterranean Sea

Plastic pollution has been extensively documented in the marine food web, but targeted studies focusing on the relationship between microplastic ingestion and fish trophic niches are still limited. In this study we investigated the frequency of occurrence and the abundance of micro-and mesoplastics (MMPs) in eight fish species with different feeding habits from the western Mediterranean Sea. Stable isotope analysis (delta 13C and delta 15N) was used to describe the trophic niche and its metrics for each species. A total of 139 plastic items were found in 98 out of the 396 fish analysed (25%). The bogue revealed the highest occurrence with 37% of individuals with MMPs in their gastrointestinal tract, followed by the European sardine (35%). We highlighted how some of the assessed trophic niche metrics seem to influence MMPs occurrence. Fish species with a wider isotopic niche and higher trophic diversity were more probable to ingest plastic particles in pelagic, benthopelagic and demersal habitats. Addi-tionally, fish trophic habits, habitat and body condition influenced the abundance of ingested MMPs. A higher number of MMPs per individual was found in zooplanktivorous than in benthivore and piscivorous species. Similarly, our results show a higher plastic particles ingestion per individual in benthopelagic and pelagic species than in demersal species, which also resulted in lower body condition. Altogether, these results suggest that feeding habits and trophic niche descriptors can play a significant role in the ingestion of plastic particles in fish species.

Automated summary

Plastic pollution in the marine food web is a significant issue, and this study focuses on the relationship between microplastic ingestion and fish trophic niches in the western Mediterranean Sea. The study finds that certain trophic niche metrics, feeding habits, habitat, and body condition influence the occurrence and abundance of ingested micro- and mesoplastics in fish species. The results suggest that fish with wider isotopic niche and higher trophic diversity are more likely to ingest plastic particles, and zooplanktivorous species tend to have a higher number of ingested plastic particles compared to benthivore and piscivorous species. Additionally, benthopelagic and pelagic species have a higher plastic particle ingestion rate and lower body condition compared to demersal species.