Therefore, a special role in the toxic effect on the viability of fish larvae is assigned to the presence of inorganic nitrogen in the water. An excessive intake of nitrogen compounds, especially ammonium and nitrite, significantly reduces the viability of carp larvae that have left the shell. It was established that a clearer indicator of the toxicity of the environment is the survival rate of both species of fish, which are at the early post-embryonic stage of development The results of research into the hydrochemical state of experimental reservoirs, which fully correspond to the nature of pollution, are presented. A significant increase in the concentration of ammonium nitrogen in the water of the Ros River in the area of the villages Horodishche, Pylypcha and of the Protoka River near the village of Pishchana was noted by compared to the Ros River near the Oleksandria Arboretum. There is also an excess of the concentration of nitrite ions in the water in the Protoka river near the village Pishchana compared to other experimental sites, which indicates fresh pollution of the reservoir. In the water of the Ros river in the area of the villages Horodishche, Pylypcha and in the water of the Protoka River near the village Pishchana content of nitrate ions was higher compared to the Ros River (near the Oleksandria Arboretum), which is a consequence of the constant inflow of leachate from agricultural lands, which are adjacent territories to these areas. The level of pollution of some areas of the Ros River and the Protoka River was studied in terms of survival (viability) of developing eggs and larvae of carp and white carp. The analysis of the results of biotesting of the degree of toxicity of water from these reservoirs showed that the viability of eggs in water from areas located near the villages Pylypcha and Pishchana was slightly larger than that of the eggs, which was incubated in water from the area near the village Horodishche and Arboretum of Oleksandria. The decrease in the survival rate of fish embryos (the village of Gorodishche and Oleksandria Arboretum) is indirectly related to the higher concentration of phosphate ions in the water sampled at these sites. Under such conditions, an increase in the number of bacterioplankton is possible, which disrupts the oxygen regime in the environment and leads to negative consequences. In the most polluted water near the villages Pishchana and Horodishche, the survival rate of carp larvae was lower than in the water near the Oleksandria Arboretum and the village Pylypcha. This indicates that in the larval stages of development, fish are most vulnerable to a toxic environment. It was noted that the concentration of phosphorus and phosphates in the section of the Protoka River near the village Pishchana was minimal compared to other experimental sampling points.
biotesting, survival, fish eggs and larvae, ammonium nitrogen, nitrites, nitrates, phosphates, environmental toxicity
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