AGE AND SEASONAL DYNAMICS OF THE SYMBIOCENOSES OF GRASS CARP AND SILVER CARP IN FISH PONDS

Purpose. Identification and analysis of age and seasonal dynamics of the symbiocenoses of grass carp and silver carp in fish ponds. Methodology. The work was performed at Belotserkovskoy hydrobiological station, located on the river Ros within Belaja Cerkov. The objects of the study were symbiotic communities of grass carp and silver carp of different age groups (from yearlings to age-5 fish). Fish underwent partial parasitological dissection using generally accepted methods. Findings. The age and seasonal dynamics of the symbiotic communitues of grass carp and silver carp were investigated during different seasons of one year. The effect of different factors on the formation of symbiotic communities have been analyzed. Different species of symbiotic organisms were characterized by different temperature preferences (Peritrcha have the highest rates of invasion in the summer). The distribution of symbionts depend on the way of their transmission. Some species of protista, monogenea and parasitic crustaceans infect the host during their high density (wintering or spawning). Other species of symbiotic organisms infect the host by nutritional way, therefore the invasion rates increase with the intensity of feeding. The differences in symbiotic community structure of fish of different age group are related to the differences in species biology. The composition of symbiotic communities of fish of different age groups contain symbiotic organisms that do not depend on the host age (metacercaria of Diplostomum, some Protista); species that more rapidly infect fish juveniles (some species of ciliates, cestoda ? B. acheilognathi) and species that predominantly infect older age group (monogenea, parasitic crustaceans). Originality. For the first time, we performed complex investigations of symbiotic communities of grass carp and silver carp in view of the specificity of their biology and during different seasons. Practical value. The results of the work can be used for the development of optimum periods for pest control and prevention of epizooties as well as for controlling some species of parasites.