engleski

Assessment of microplastics presence in the water and impact on fish near wastewater discharges in the riverine ecosystem

Pollution of rivers by microplastic (MP) is a growing problem, especially near wastewater discharges. When ingested by aquatic organisms, MP fragments can cause various toxic effects, especially oxidative stress. The present study was conducted in the Krka River in Croatia, the lower part of which is a national park, but the upper part is affected by wastewaters. The aim of the study was to determine the presence of MP in river water and its uptake and effects on native fish brown trout (Salmo trutta Linnaeus, 1758). Samples were collected in the spring of 2021 at the Krka River source as an unpolluted reference site and downstream of the wastewater discharge. All water samples (after filtering) and fish gut contents(after digestion with HNO3 and HF) were examined under a stereomicroscope for the presence of MP. Assessment of oxidative stress involved measurement of biomarkers of antioxidant protection (glutathione and activities of the enzymes glutathione S-transferase and catalase) and of oxidative damage (malondialdehyde) in fish intestines. MP was found in water samples and gut contents of fish from both sites, confirming its presence and dietary uptake in fish even in locations without direct anthropogenic influence. All biomarkers indicated an increased antioxidant response downstream of the wastewater outlet, suggesting a possible influence of pollutants, including MP, on oxidative stress in fish. Therefore, our results confirmed the presence and effect of MP on organisms and highlighted the need for further investigation of the impact of MP on the sensitive karst ecosystem.

Krka River ; karst ; biomarkers ; plastics

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