Gastric Microplastics in Clarias gariepinus of the Upper Vaal River, South Africa

Abstract

Microplastics are defined as plastics smaller than 5 mm down to 0.05 mm. These plastics enter the environment and undergo certain physical changes, most notably density changes and a relative increase of surface size. Microplastics can then release or absorb toxicants from the surrounding environment. These plastics may then enter the food chain from producers to top predators. In this study, microplastics were investigated in four study sites in the upper Vaal River, South Africa. The goal of the study was to determine the levels of plastics in water, sediment and a top predator, the benthic fish Clarias gariepinus. In this study, a 10% KOH digestion of water and fish, and density separation of sediment with NaCl (1.2 g cm3) was used to extract microplastics for identification. Microplastics were detected in water (3, 300 particles m−³), fish (7.47 particles per fish) and sediment (46.7 particles kg−1). Microplastic intake was not attributed to the microplastic shape or size of the fish that ingested it. This highlights the need to understand how niche-specific microplastic concentrations are, which will not only aid in quantifying microplastics accurately in the environment but to better understand how they may influence various ecosystems.

Decadal Assessment of Microplastics, Pharmaceuticals, and Pesticides as Contaminants of Emerging Concern in Kenya's Surface Waters: A Review

“…Also, a total of 129 filamentous microplastic particles were found ingested by the zooplankton groups along the Kenyan coastline (Kosore et al, 2018). The results from Kenyan studies concur with other similar studies, whereby microplastics have been detected in the gastrointestinal tract of Nile perch (Lates niloticus) and Nile tilapia (Oreochromis niloticus) on the southern shore of Lake Victoria, Tanzania (Biginagwa et al, 2016); in cockles (Anadara antiquata) from coastal Tanzania (Mayoma et al, 2020); and in the African mud fish (Clarias gariepinus) from the Vaal River, South Africa (Dahms et al, 2022). Apart from drinking water, consumption of these seafood forms one of the major ways in which humans are exposed to microplastics via gastrointestinal ingestion; other pathways include pulmonary inhalation and dermal infiltration (Yuan et al, 2022).…”

Overviewing the Ground Reality of Microplastic Effects on Seafoods, Including Fish, Shrimps and Crabs: Future Research Directions

“…Furthermore, MPs were also assessed from the stomach of the benthic fish Clarias gariepinus , which is the top predator of the Vall River, South Africa. The authors reported that each fish contained 7.47 particles/fish; however, the content of MPs in the sediments and water was 46.7 particles/kg and 3300 particles/m 3 , respectively, indicating that the river is heavily loaded with MPs [ 63 ].…”