Microplastics collected at sea harbour a high diversity of microorganisms including some Vibrio genus members, raising questions about the role of microplastics as a novel ecological niche for potentially pathogenic microorganisms. In the present study we investigated the adhesion dynamics of Vibrio crassostreae on polystyrene microparticles (micro-PS) using electronic and fluorescence microscopy techniques. Micro-PS were incubated with bacteria in different media (Zobell culture medium and artificial seawater) with or without natural marine aggregates. The highest percentage of colonised particles (38-100%) was observed in Zobell culture medium, which may be related to nutrient availability for production of pili and exopolysaccharide adhesion structures. A longer bacterial attachment (6 days) was observed on irregular micro-PS compared to smooth particles (<10h) but complete decolonisation of all particles eventually occurred. The presence of natural marine agreggates around micro-PS led to substantial and perennial colonisation featuring monospecific biofilms at the surface of the aggregates. These exploratory results suggest that V. crassostreae may be a secondary coloniser of micro-PS, requiring a multi-species community to form a durable adhesion phenotype. Temporal assessment of microbial colonisation on microplastics at sea using imaging and omics approaches are further indicated to better understand the microplastics colonisation dynamics and species assemblages.