INCREASING THE PRODUCTIVITY OF ZOOPLANKTON COMMUNITIES WITH THE USE OF EKOVITAL AND VETCH-OAT GRASS
Purpose. To investigate the potential of zooplankton productivity in aquatic ecosystems under experimental conditions of the microcosms with the use of the green fertilizer (vetch-oat grass) and Ekovital. Methodology. The study was conducted under the conditions of model ecosystems (microcosms) installed in fish-breeding ponds. We used a complex of intensification measures (enhancement, inoculation of vetch-oat seed mixture (1:1) with Ekovital at quantities of 1.4; 2.9; 4.3 ml/kg (variants D1, D2, D3), followed by sowing the pond beds with the vetch-oat mixture (1:1), growing of vetch-oat grass for the green fertilizer). The seeds were sown at a ratio of 70 kg of grains for 1 ha of ponds area. The first control variant (K1) - without green fertilizer and without preparation. The second control version (K2) vetch-oat seeds were soaked in the corresponding quantity of water without preparation and after they were sown on the pond bed. The preparation Ekovital contains specific nitrogen-fixing nodule Rhizobium leguminosarum and phosphorus mobilizing Bacillus megaterium-6 bacteria. Hydrochemical, hydrobiological, fisheries, and statistical studies were conducted according to standard methods. Findings. It was found that the application of Ekovital in a combination with enhancement activities gives an opportunity to obtain a green fertilizer of up to 1.03 ± 0.08 t/ha during 40 days for increasing pond ecosystem productivity. The stimulation of zooplankton development gave an opportunity to obtain the maximum biomass of 9.85-31.78 g/m <sup>3</sup> that was 4-16 times higher than in that in the control - 2.54-3.30 g/m <sup>3</sup>. The mean values of zooplankton biomass in the experiments were 4.30-9.17 g/m <sup>3</sup>, that was 3-9 times higher than those in the control - 1.06-1.40 g/m <sup>3</sup>. The experimental variants showed a tendency for increasing the share of cladoceran crustaceans. The production of zooplankton organisms was increased to 1834.8 kg/ha - the level of the most productive breeding ponds of the forest-steppe zone of Ukraine. The potential of natural fish productivity of an aquatic ecosystem based on zooplankton when applying the green fertilizer (vetch-oat grass) and Ekovital showed a 3-7 time increase compared to the control. The maximum potential natural fish productivity based on zooplankton was achieved at the level of 152.90 ± 85.25 kg/ha in the variant D2. Originality. For the first time we presented the results of the studies of zooplankton community productivity in fish-breeding ponds with the use of the green fertilizer of vetch-oat grass and bacterial preparation Ekovital under the conditions of model ponds ecosystems (microcosms). Practical value. The received results are the basis for further studies on the use of a method for increasing natural fish productivity in fish-breeding ponds with the use of a green fertilizer such as vetch-oat grass and Ekovital.