The aim of this study was to investigate the effects of subchronic exposure to atrazine on fish growth and the development of histopathological changes in selected organs (gill, kidney, liver) in Danio rerio. Juvenile growth tests were performed on D. rerio according to OECD method No. 215. For 28 days, fish at an initial age of 30 days were exposed to the environmental atrazine concentration commonly detected in Czech rivers (0.3 μg/L) and a range of sublethal concentrations of atrazine (3.0, 30.0 and 90.0 μg/L). The results showed decreasing growth rates and morphological changes in the liver (dystrophic lesions of hepatocytes) at 90.0 μg/L of atrazine. The environmental concentration of atrazine in Czech rivers did not have any effect on fish growth and development of histopathological changes in D. rerio. The value of NOEC was 30.0 μg/L and the value of LOEC was 90.0 μg/L.
In the Upper Vistula River course three sections were distinguished: first, at 11 km of the river course, with low trophic level of water (mean yearly yield <30% of Chlorella pyrenoidosa Chick. control cultures), second, up to 66.2 km of the river course, with the moderate trophic level (between 30-50% yield of control), third below 115.6 km of the river course, with the high trophic level (between 50-80% of control yield). The highest water trophic level (80% of control cultures yield) was evidenced at 115.6 km of the river course, due to the input of industrial and municipal sewage. The yield of Chlorella cultures was highly significantly positively correlated with the content of organic matter, electrolytic conductivity, P-PO₄, N (as N-NH₄+N-NO₃), S-SO₄, Ca and Mg concentration in the water. In case of Cd, Cu, Pb, Mn, Zn no correlation was found.