Cestode species Khawia sinensis as indicator of epizootic state of rivers of Dagestan and test of microelement composition in fish meat

Abstract

Caviosis in the waters of the south of the Russian Federation is a poorly studied problem. Indicators of the extent of invasion were in the range of slightly moderate registration with extent of invasion (9.00-15.00%) with an abundance index of cestodes Khawia sinensis (1.40-2.18 ind./piece) in fish of different species (bighead carp, grass carp, black carp (black Chinese roach), spirlin, Sabanejewia caucasica, Krinitsky char, Tersk nase, Tersk barbel, silver Prussian carp, rutilus, Tersky gudgeon) in the basin of the Terek river, and a high level of detection of cestodes in the intestine of fish of 6 species (common carp, European carp, Tersk barbel, crucian carp, rutilus, Tersky gudgeon) was registered with extent of invasion criteria (21.00-37.00%) and an epizootic degree of abundance index of the cestode species Khawia sinensis (4.16-6.13 ind./piece). As a result of biochemical studies of 20-30 fish muscle samples within the boundaries of Dagestan authors found that the intensity of infection of fish of 14 species in Terek river basin with intestinal cestodes Khawia sinensis reduces the content of iodine, cobalt and iron in the muscles, that affect the nutritional value of fish. The content of biogenic microelements in the muscles of fish infected with cestodes Khawia sinensis was 2-5.9 times less than in fish free from helminths, which confirms the fact that the biological qualities of fish decrease with intensive cestode invasion. The most intensive infection with intestinal cestodes Khawia sinensis in comparison with fish populations free from helminths caused the marked reduction in the content of biogenic micronutrients in the muscles of trout, common carp, European carp, grass carp, black Chinese roach.