Mussel watch program for microplastics in the Mediterranean sea: Identification of biomarkers of exposure using Mytilus galloprovincialis

•Biomarkers (BMs) are a useful tool for assessing toxic effects in aquatic organisms.•Mytilus galloprovincialis was selected as bioindicator for microplastic exposure.•The literature search returned 11 studies, mainly related to oxidative stress BMs.•A battery of standardized BMs as well as the inclusion of new ones are needed.