INFLUENCE OF ENVIRONMENTAL FACTORS ON EMERGENCE AND SPREAD OF HELMINTHOSES IN PERCH (PERCA FLUVIATILIS L.)
The article presents the results of the sanitary and parasitological studying fish in case of perch (Perca fluviatilis L.), one of the most abundant representatives of predatory fish species in the Astrakhan region. Only two types of parasites were found in all the studied samples: Eustrongylides (nematode larvae) and Rossicotrema donicum (trematode metacercariae). More often, perch species were affected by the metacercariae of Rossicotrema donicum. The relationship between the quantitative and qualitative composition of the detected helminths has been stated. The number of eustrongylids extracted from perch is greater in the samples from the Kigach River, while the number of metacercariae was minimal. The largest amount of Rossicotrema donicum was found in samples from the Volga River, eustrongylids in perches from the selected area were not found. There was carried out the analysis of hydrochemical indicators of the selected reservoirs (in the Narimanov region - the Volga river, in the Krasnoyarsky region - the Kigach river, in the Privolzhsky region - the Krivaya Bolda river), and the comparison of the above data revealed a positive and an inverse correlation between the indicators of combinatorial water impurity index (CWII), specific combinatorial water impurity index (SCWII) and the detected parasites. The correlation coefficient between CWII and the amount of Rossicotrema donicum was 0.97, between SCWII and Rossicotrema donicum - 0.97, between CWII and the amount of eustrongilids it made -0.98, between SCWII and the amount of eustrongilids it was -0.98. The amount of Rossicotrema donicum was supposed to increase with water contamnination, and the amount of Eustrongylides, on the contrary, decreased. Depending on the found relationship, it can be assumed that the Kigach channel is the cleanest water body (maximum found number of eustrongylids - 20), and the dirtiest is the Volga river (no eustrongylids have been found, the number of Rossicotrema donicum - 369).