Seite - 184 - in Freshwater Microplastics - Emerging Environmental Contaminants?

and activities of plastic-associated biofilms (Fig. 1).Only someof the parameters shown inFig. 1 have been investigatedwith reference tomicroplastics.However, efforts to identify factors driving the formation of these assemblages in marine habitats have recently been reviewed [12, 13, 20]. Microplastics are rapidly colonized by environmental microorganisms (within hours; [21]).Manyfactorsdrivingthedevelopmentofplastispherecommunitiesare likely to be similar between freshwater and marine habitats. For example, in agreement with research into biofilm formation on other artificial substrata [19, 22], there is evidence for the importance of surface properties (including roughness and hydrophobicity) during early colonization of microplastics [12, 23].Exposure to ultraviolet (UV) radiation andwaves canmodify the surface chemistry and structure of plastics (e.g., via the formation of cracks and pits, a reduction inmolecular weight, and an increase in surface oxidation), whichmay Fig.1 Physical,chemical,andbiological factors likely toaffect theformationandcompositionof plastispheremicrobial assemblages.Only a limited selection of these parameters has been inves- tigatedwith specific reference tomicroplastics 184 J.P.Harrison et al.