BIOTESTING OF THE ANTHROPOGENIC IMPACT ON AREAS OF THE R. ROS AND R. PROTOKA ON THE VIABILITY OF CARP FISH EGGS AND LARVAE
Authors: Khudiiash Yu. , Potrokhov O. , Zinkovskyi O. , Vodianitskyi O. , Kofonov K. , Krasiuk Yu. M. 
Published: December 2023

Due to the increasing anthropogenic load, almost all water bodies are intensively polluted. Excessive intensity of natural resource use, siltation, pollution and overgrowth of rivers, and non-compliance with the restricted management regime in coastal protection zones lead to a general deterioration in the ecological state of aquatic ecosystems.

Water pollution is caused by discharges of harmful substances by industrial enterprises, intensive fertilization and the use of plant protection products by agriculture. Municipal and household wastewater also plays a significant role in shaping the quality and quantity of surface water.

Identifying the problem of increasing anthropogenic pressure on aquatic ecosystems through the study of environmental indicators is particularly relevant.

Typically, monitoring is carried out to establish the ecological status of water bodies. The main objectives of monitoring are to assess and forecast the state of the environment, identify negative changes and provide recommendations for their elimination or minimization.

In particular, on 1 January 2019, a new procedure for state water monitoring came into force, which meets the requirements of European legislation, primarily the Water Framework Directive. It is based on diagnostic monitoring to identify the most vulnerable and problematic areas of a water body.

One of the monitoring methods is biotesting. This involves the experimental determination and assessment of the impact of factors on living organisms. The level of pollution of the studied water areas is determined based on the study of changes in the indicators (physiological, biochemical, cytogenetic) of the test objects.

The aim of the study was to determine the degree of toxicity of water from some parts of the Ros River and the Protоka River by the survival of eggs and larvae of Cyprinus carpio (Linnaeus, 1758) and Hypophthalmichthys molitrix (Valenciennes, 1844) as an indicator of environmental toxicity.

The object of the study was the channel part of the Ros River and the Protоka River with varying degrees of anthropogenic load. These are the sections of the Ros River near the village of Horodyshche, where pollution occurs due to municipal water and agricultural runoff, and the village of Pylypcha, where water is polluted from agricultural land. In addition, a site on the Protоka River near Pishchana village was investigated, namely the area with agricultural fields directly adjacent to the river. The control site was the area near the Oleksandriia arboretum (Ros River, upstream of the town of Bila Tserkva).

The test objects (indicators) were caviar and larvae of carp and white silver carp, which were produced by the factory method at the Bila Tserkva Experimental Hydrobiological Station of the Institute of Hydrobiology of the National Academy of Sciences of Ukraine.

Biotesting was carried out in 50 ml Petri dishes. During the testing, 50 carp eggs, 30 white carp eggs and 30 carp larvae were placed in each cup. A total of 6 series of experiments on eggs and larvae fish were conducted for each test water from all sampling points. To reduce the impact of fish metabolites, water in Petri dishes was replaced three times a day with water from the experimental sites.

The data obtained were statistically processed using Statistica 10.0.

The results of the study of hydrochemical parameters of biogenic compounds in the experimental reservoirs fully correspond to the nature of pollution.

Higher concentrations of ammonium nitrogen were observed in the water of the Ros River near the villages of Horodyshche, Pylypcha, and Protоka in the water of the Protоka River near Pishchana village compared to the water of the Ros River near the Oleksandriia Arboretum. A higher content of nitrite ions was detected in the water near Pishchana village, Protоka River, compared to other research sites, indicating fresh pollution of the water body. It was found that in the area of Horodyshche village, Pylypcha village and in the area of Pishchana village the content of nitrate ions was higher compared to the Ros River (near the Alexandria arboretum).This is the result of constant runoff from agricultural land adjacent to these sites.

The level of pollution in some areas of the Ros River and the Protyka River was studied by the viability of eggs and larvae of Cyprinus carpio and Hypophthalmichthys molitrix. The analysis of the results of biotesting the degree of toxicity of water from these reservoirs showed that the viability of eggs in water from the areas near the villages of Pylypcha and Pishchana was slightly higher than that of eggs incubated in water from the area near the village of Horodyshche and the Alexandria Arboretum.

The decrease in the survival rate of fish embryos (Horodyshche village and Alexandria arboretum) is indirectly related to the higher content of phosphate ions in the water sampled in these areas. Under such conditions, the number of bacterioplankton may increase, which disrupts the oxygen regime in the aquatic environment and leads to negative consequences. It was found that in the most polluted water near Pishchana and Horodyshche villages, the survival rate of carp larvae was lower than in the water near the Alexandria Arboretum and Pylypcha village. This indicates that fish are most vulnerable to toxic environments during the larval stages of development. It was noted that the concentration of phosphate phosphorus in the section of the Protоka River near the village of Pishchana was minimal compared to other experimental sampling points. Under such conditions, the presence of inorganic nitrogen in the water plays an important role in the toxic effect on the viability of fish larvae. Excessive intake of nitrogen compounds, especially ammonium and nitrite, significantly reduces the viability of carp larvae.

According to the results of the studies, it was found that carp and white carp eggs are not adversely affected by municipal and household wastewater and agricultural field runoff at a concentration of phosphorus of up to 0,67 mg P/dm3, ammonium ions of up to 0,85 mg N/dm3 and nitrite of up to 0,06 mg N/dm3.

An indirect effect of phosphorus phosphate was observed - an increase in its concentration to 0,60-0,67 mg P/dm3 negatively affects the viability of developing eggs. This is due to the excessive development of bacterioplankton and deterioration of the oxygen regime.

Excessive intake of nitrogen compounds, especially ammonium and nitrite, above 0,85 mg N/dm3 and 0,06 mg N/dm3, respectively, significantly reduces the viability of carp larvae that have left the shell. In the most polluted section of the Protoka River, their viability decreased by 55.9%.

It has been established that a more effective indicator of environmental toxicity is the survival rate of both species of fish at the early postembryonic stage of development.

Based on the data obtained, it can be argued that washouts from agricultural fields and municipal wastewater cause significant damage to the fish population. The reproduction of fish is significantly affected by anthropogenic pollution.