SCIENTIFIC AND PRACTICAL ANALYSIS OF THE STATE OF THE NATURAL FEED BASE IN PONDS OF SOUTHERN UKRAINE UNDER CONDITIONS OF TRANSFORMATION OF ABIOTIC AND BIOTIC FACTORS

Abstract

Conducted research on the basis of the breeding ponds of the Kherson production and experimental plant for breeding of the ordinary fish indicate atypical dynamics of the development of the components of the natural feed base. Such aspects form a low fodder potential, as a result of which they create a threat to ensure obtaining high quality fish planting material for introduction into the lower Dnipro, which is the main criterion for the adaptation period in new living conditions. Analysis of the results of the level of development of fodder resources during the growing season indicates low biomass of phytoplankton in ponds in the spring-summer period, respectively 0.517– 2.257 g/m3 , 4.14 – 14.43 g/m3 . In autumn, excessive values of more than 60 g/m3 were noted, reaching maximum values 102.54 g/m3 . The results of practical studies show that the biomass of zooplankton in breeding ponds varied greatly, in the spring period of intensive vegetation, the biomass of zooplankton ranged from 7.83 to 96.37 g/m3 . At the end of the growing season, the level of zooplankton development had the lowest biomass indicators compared to the spring-summer period, decreasing to 1.23 – 14.08 g/m3 . The average seasonal biomass of zoobenthos varied from 1.9 g/m2 to 5.0 g/m2 , characterizing the uniform dynamics of benthic organisms, in contrast to planktonic ones, which had atypical indicators of biomass dynamics both during the growing season and after ponds.The results of the conducted research indicate the need to stimulate the natural fodder base by adding organic-mineral fertilizers to low-productivity ponds in the spring-summer period, changing the strategy of forming the composition of the polyculture in accordance with the productivity of the breeding ponds according to the level of development of fodder hydrobionts. Macrophytes, phytoplankton, zooplankton and zoobenthos are the main feed objects in fish breeding ponds. They are the main food objects for herbivorous carp species of fish. The viability of larvae and younger age groups is determined by the level of metabolism, which reflects the living conditions and the level of provisioning of the food base of fish. The natural fodder base of ponds is a part of fodder resources and is a collection of hydrobionts, products of their decay (detritus), which are in the reservoir and are used directly as food for hydrobionts. Taking into account the obtained results, it was noted that the main task of specialists of fish farming enterprises is to optimally and tirelessly use feed resources with the aim of transforming them into a fodder base of ponds by simultaneously growing different types of fish − polyculture, using compacted plantings, intensification measures