The European Perch as the Bioindicator of the Nitrogen Load on the Anthropogenic Reservoirs: Toxicology and Trophology

In ten small anthropogenic reservoirs located in the Cis-Urals, fish were caught and water samples were taken to analyze the content of dissolved mineral forms of the nitrogen. Fluctuating asymmetry indicators of the seismosensory canals pores number in four paired dermal head bones of European perch individuals were determined. It was found that these indicators are positively and statistically significantly related to the average nitrate content in the studied reservoirs in late spring. It was also noted that the relative abundance of the European perch in fish communities of these reservoirs decreases with an increase in the content of dissolved mineral nitrogen. The identified trends are discussed in two aspects of the possible effect of nitrates on individuals of this fish species: toxicological and trophological.