First biomonitoring of microplastic pollution in the Vaal river using Carp fish (Cyprinus carpio) as a bio-indicator

Fish inhabiting freshwater environments are susceptible to the ingestion of microplastics (MPs). Knowledge regarding MPs in freshwater fish in South Africa is very limited. In this study, the uptake of MPs by common carp (Cyprinus carpio) in the Vaal River in South Africa was assessed. MPs were detected in all of the twenty-six fish examined, 682 particles of MPs were recovered from the gastrointestinal tracts of the fish with an average of 26.23 +/- 12.57 particles/fish, and an average abundance of 41.18 +/- 52.81 particles/kg. The examination of the physical properties of MPs revealed a predominance on fibers (69%), small-sized particles of less than 0.5 mm (48%), as well as prevelance of coloured MPs (94%), mostly green, blue, and black. Using Raman Spectroscopy, the following plastic polymers were identified: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE). To the best of our knowledge, this study, is the first to report MPs uptake by freshwater biota in the Vaal River using common carp as a target organism. It provided evidence of MP contamination in the Vaal.

Automated summary

This study is the first to report the ingestion of microplastics by freshwater fish in the Vaal River in South Africa. It found that microplastics were detected in all of the examined fish, predominantly in the form of fibers and colored particles.