The surface water microplastic concentration found in our study was similar (0.79 ± 1.75 mg m -3 ) to the global average found (0.79 mg m -3 Isobe et al. 2021). However, it should be noted that data in our study reflect surface water only, while Isobe et al reported it for the entire water column not including sediment. Thus, extrapolating our data to the entire water column would certainly lead to a higher mean concentration than the global average. Our data showed that surface water microplastics concentrations higher than that found in the Mediterranean Sea The methods used for the study of microplastics in sediment often differed in sampling techniques, (corers, Van-Veen grabs, box-corers) laboratory methods used for extraction, analysis of particles, (digested or non-digested) and the units for reporting concentrations found (pieces/kg dry sediment or pieces/m 2 ) This variation in sampling and analytical techniques affect the overall results of each study, leading to a problem of incomparability. This highlights the need for the use of standardized protocols that allow harmonization between studies, and while there has been a certain effort in this direction for surface water studies, harmonization of the methods used for sediment is still lacking.