Microplastics in a dam lake in Turkey: type, mesh size effect, and bacterial biofilm communities

The evaluation of microplastic (MP) pollution has been drawing attention for the last decades. MP pollution has been studied widely in marine environments, but limited data exists for freshwater ecosystems on potential source and transport of MPs. The type, shape, plastic components, and the color of the MPs were investigated using various-mesh-sizes (300 and 100 μm) nets in four sampling stations of Süreyyabey Dam Lake in Turkey. The growth of bacterial isolates on the MPs surface and surrounding water was also investigated. The type of the MPs and the interaction between the mesh size and the type of the MPs showed significant differences (p < 0.05). Fibers were found to be the most abundant particle type constituting 45% and 80% of the total MPs found in 330-μm and 100-μm mesh sizes, respectively. In total the observed MP abundance in the dam lake was 5.25 particles m^-3, and 4.09 particles m^-3 was observed for 100-μm and 330-μm mesh sizes, respectively. The color of the identified microplastics showed variations among microplastic types; however, the dominant color was transparent in each net. The main plastic components of the MPs are polyethylene terephthalate, polyvinyl chloride, polystyrene, polyethylene, and polypropylene. The microbial community mainly consists of potentially pathogenic strains such as Escherichia coli, Enterococcus faecalis, and Acinetobacter baumanii complex. The current study could contribute valuable background information both for MP pollution and for biofilm composition in a dam. However, the surface of the MPs and biofilm formation should be investigated urgently to understand the vector potential of MPs.