Assessing microplastic distribution within infaunal benthic communities in a coastal embayment

Marine anthropogenic litter is increasing in prevalence in both the marine environment and its inhabitants. This study assesses the levels of anthropogenic microplastics in benthic infauna from 20 subtidal stations in Galway Bay, Ireland. Microplastics were removed from the organisms using an alkaline digestion (KOH) and their synthetic origin was confirmed by μFTIR spectroscopic analysis. The average number of microplastics recorded for all organisms was 0.79 ± 1.14 particles individual-1, similar to previously published results on subtidal fauna of the North Sea. Fibres were the dominant particle type (98%) and the majority were identified as natural (cellulose, cotton). Synthetic polymers identified included PVA (polyvinyl acetate), EPDM (synthetic rubber), PE (polyethylene) and PVC (polyvinyl chloride). Fibres less than 1 mm made up 55% of the recovered lengths. Colours recorded in the organisms were mainly blue and were reflective of the surrounding habitats. Of the five phyla collected, the highest incidence and uptake was associated with the Annelida. A significant difference in ingested MPs was only evident when depth (greater and less than 30 m) was considered as a factor. In addition, no significant differences were found between either the numbers of ingested MPs and phyla or feeding strategies. The results indicate that future studies should follow an ecosystem-based approach to monitor MPs levels in an area where specific bioindicator(s) have not been identified or are unsuitable.