The need for a sentinel species: considerations towards regional bioindicators

As we move towards increased policy intervention and mitigation strategies against marine litter and microplastics, there is a need for powerful monitoring data. There is currently no accepted bioindicator for microplastics which is required to understand the bioavailable fraction of litter and inform ecotoxicological experiments and risk models. Commonly suggested bioindicators include fish and shellfish as they are abundant, have a wide geographical range and are of economic importance. The present study explores the suitability of the blue mussel (Mytilus edulis), demersal flatfish common dab (Limanda limanda) and small pelagic fishes European anchovy (Engraulis encrasicolus) and European sardine (Sardina pilchardus) as sentinel species for microplastics. Samples were collected from around the coast of England and Wales between 2019 and 2023 and were digested in a potassium hydroxide and sodium hypochlorite digestion. To increase particle recovery, microplastics were fluorescently tagged with Nile red and samples were searched under blue light and white light. Particles of interest were then analysed with micro-FTIR and LDIR spectrometry to identify the polymers present. Microplastics were detected in all species, but to differing degrees. Over half (53 Also see: https://micro2024.sciencesconf.org/559412/document