Two decades of plastic exposure in freshwater fishes from Romania

Freshwater has been polluted with plastics for decades, but only a few scientific papers have described it until now. This is the first study to investigate the presence of meso- and microplastic particles in the digestive tract of fish from an inland river in Romania. Fish specimens representing the ichthyocenosis of the Oituz River were sampled by electrofishing at different sampling sites (upstream to downstream) in 2004, 2008 and 2015, and the results were compared. Plastic particles were classified and counted according to shape as: fibers, films, and fragments (in decreasing order) and their size measured, and according to color (eight groups were recorded, blue being the most numerous, followed by transparent and red). There was no correlation between length and number of plastic particles. There was a positive correlation between weight and number of plastic particles. All fish species investigated are omnivorous, so no differences in feeding habits were observed. Feeding habitats were compared and demersal species accumulated more plastic particles than the benthopelagic ones. Scanning Electron Microscopy (SEM) was used to observe the surface morphology of the found microplastics. The main polymers were identified by FTIR spectroscopy and most common type of polymer was polyamide. Older samples contained a higher number of micro- and mesoplastics (mainly polyamide and polyethylene terephthalate), with the recent lower amounts likely due to pollution control measures through the recycling of both PET bottles and other plastics that previously reached the riverbed.