Anthropogenic pressure and specifically metallic pollutants may disrupt microbial ecosystems in coastal areas, including planktonic or biofilm communities. This study aimed at determining the poorly studied impacts of chemical pollutants on marine microbial biofilm community. We compared such influence to the contribution of planktonic microorganisms to the biofilm community composition combining taxonomic biomarker and network analysis. Inert PC plates were immersed for one month at five sites in Toulon Bay (North-Western Mediterranean Sea) along multi-elemental chemical gradients, at both the surface and bottom of the water column. Seawater was sampled weekly during one month for both chemical and Illumina sequencing of 16S rRNA gene amplicons. Biofilms were sampled after one month of immersion.