Brain food? Trophic transfer and tissue retention of microplastics by the velvet swimming crab (Necora puber)

Knowledge of the fate and persistence of microplastics within the tissues of marine organisms remains poor, despite their ubiquitous nature in marine habitats and ingestion by a range of species being well understood. Mussels (Mytilus edulis) were fed 50 μl (~4.1 × 106) of 0.5 μm polystyrene fluorescent microplastic spheres. Velvet swimming crabs (Necora puber) were subsequently fed either one or three dosed mussels and were sampled after 1 h, 1, 7 or 21 days post consumption. The stomach, gills, testes and brains were removed and digested. Microplastics were present in all tissues sampled and remained present for the duration of the trial. Only in the stomach and gills was there a decrease in the number of microplastics over time. The stomach and testes showed a significant increase in the number of microplastics present with the number of mussels consumed. The number of microplastics present in the brain remained constant throughout the duration of the trial. Our study is the first to demonstrate the presence of microplastics in the brain of any crustacean species. This has possible implications for a range of behaviours including predator avoidance, foraging and reproduction. Further work is needed to determine whether presence and persistence of microplastics in the brains of crustacean species affects behaviour.