Purpose. Investigation of the effect of higher aquatic vegetation growing on shallow water areas of the Kiev reservoir on conditions of spawning of commercial fish species and growth of their juveniles.
Methodology. Materials for the study were higher aquatic plants, the number of which was counted with the aid of a 1 x 1 m frame. Bottom deposits for determination of the biomass of benthic organisms were collected using dredges of different constructions. Fish juveniles were caught using beach seine. Dissolved oxygen content was measured with the aid of the thermooximeter AZhA-101M.
Findings. It was found that during last years, shallow water areas of the Kiev reservoirs are characterized by rapid colonization with higher aquatic vegetation. The most abundant among them is water chestnut, the number of which reaches 75 %. Its number on some areas of the upper part of the reservoir reaches 75 plants per 1 m2. During summer, with water temperature of 25 – 27 0С, a reduction of dissolved oxygen content to 0,5 – 0,7 mg/L was observed that resulted to fish kills. A dependence of the number of benthic organisms from vegetation type, which grows on these areas, was found. It was found that fish juveniles are absent on areas, where water chestnut predominated.
Originality. Every year, areas covered by water chestnut considerably expand that result in deterioration of hydrological regime of the reservoir. Significant siltation of bays due to slowdown of water current is observed. Reduction of oxygen content in water leads to decrease of both benthic organisms and fish juveniles.
Practical Value. It is recommended to conduct a complex enhancement of shallow water areas of the Kiev reservoir but due to the fact that water chestnut is listed in the Red Book of Ukraine as a protected species, it is prohibited to conduct such enhancement works aimed at reducing areas covered by this species.
Key words: Kyiv reservoir, aquatic vegetation, water chestnut, silt, silted sand, fingerlings, zoobenthos.
Purpose. Study of the ecological state of aquaculture ponds of the Lviv fish farms “Rudnyky” and “Derzhiv” for creation of optimum conditions for fish growing in ponds.
Methodology. Growing of fish in the fish farm “Rudnyky” were conducted in the summer brood fish pond №12 of 4.2 ha area. The pond was stocked with yearlings of Lubin scaled and framed carps with an average weight of 83.3 g and stocking density of 1428 fish/ha. In the fish farm “Derzhiv”, growing of fish was conducted in the pond №1 of 4.2 ha area. The pond was stocked with fish larvae with stocking density of 18000 fish/ha. Determination of hydrochemical parameters was conducted using generally accepted analytical chemical methods. Quantitative determination of heavy metal content in water and bottom sediments was conducted by direct absorption in propane-butane flame with the aid of the absorption spectrophotometer C-115 M1.
Findings. As a result of the conducted studies, we determined the pollution level of aquaculture ponds in the Lviv fish farms. Main hydrochemical indices, which characterize quality of water pond, meet norms for fish farming. All studied heavy metals in pond water of “Rudnyky” fish farm were at higher concentrations compared to those in the fish farm “Derzhiv”. Bottom sediments are characterized by a tendency of increasing nickel concentrations in both examined fish farms, values of which exceeded the maximum acceptable concentration. In the order of an increase of heavy metal content in bottom sediments, they can be ranged as Fe-Mn-Zn-Cd-Pb-Co-Cu-Ni.
Originality. The ecological state of aquaculture ponds of the Lviv fish farms “Rudnyky” and “Derzhiv” has been investigated for the first time.
Practical value. The obtained results of the ecological state of aquaculture ponds allow creating optimum conditions for growing of fish.
Key words: hydrochemical regime, heavy metals, bottom sediments.
Purpose. Determination of the diet spectrum of European grayling (Thymallus thymallus), qualitative and quantitative composition of the gut content of age groups (2+, 1+, 0+) from Teresva and Tereblya Rivers of the Zakarpattia region.
Methodology. The initial material at a quantity of 28 multiple age individuals of European grayling was collected during field works in Zakarpattia rivers. The material was collected with the assistance of Zakarpattia Fish Protection Inspection. Fish were taken from poachers’ fishing nets in a fatal condition, then they were preserved in a 10% formalin solution. Processing of preserved material was conducted in laboratory conditions. The diet of multiple-age groups (2+, 1+, 0+) of European grayling from Teresva and Tereblya rivers of the Zakarpattia region was investigated.
Findings. It was found that European grayling consumed mainly benthic invertebrates, preferring amphibiotic organisms of Insecta class. Diptera, Trichoptera, Plecoptera, Coleoptera, Ephemeroptera, Odonata, and Amphipoda representatives were common in the diet of age-2+, 1+, 0+ fish. Gut fullness content index of young-of-the-year grayling with an average weight of 12,3 ± 0,72 g was in average 384,54 ± 114,01 %оо, age-2+ fish with an average weight of 29,53 ± 2,14 g – 177,75 ± 16,41 %оо, and age-3+ fish with an average weight of 91,4 ± 11,42 g – 168,49 ± 25,44 %оо, respectively.
Originality. Information on European grayling diet in the Zakarpattia rivers in current conditions is insufficient because this species in listed in the Red Book of Ukraine that limits obtaining the materials for its studies.
Practical value. The obtained data allow scientifically justified determining the stocking amounts of European grayling juveniles for increasing its natural populations in the rivers of Zakarpattia.
Key words: European grayling, diet, gut fullness index, Zakarpattia rivers.
Purpose. To investigate the sources of scientific information on biological functions of heavy metals (Fe, Zn, Mn, Cu, Ni, Co, Pb, Cd) and their negative effect on biota of fresh water bodies.
Findings. A review of works of a variety of scientists showed that the majority of the studied heavy metals (Fe, Zn, Mn, Cum and Co) played an important role in vital functions of freshwater organisms. The significance of other studied heavy metals (Ni, Pb, and Cd) is probable or unknown. Besides biological importance, we also know about toxicity of heavy metals – a group of mineral polluting substances, which are the most distributed and dangerous for biota. Their negative effect includes drastic deterioration of conditions for existence of the majority of aquatic organisms, some species disappear, others reduce their number, components of trophic chains are lost, links in ecosystems become broken, and productivity of biocenoses decreases.
Practical value. An array of generalized information will be useful for scientists who investigate freshwater ecosystems and effect of toxicants on them, in particular heavy metals.
Key words: heavy metals, biological role, toxicity, freshwater aquatic organisms.
Purpose. Trying to develop ways to optimize and reasonable prediction of growing planting material.
Methodology. The study based on theoretical, experimental and laboratory methods adopted in the fishery, physico-chemical and hydrobiological studies.
Findings. Studies have shown that we used calculations allow us to determine the optimal threshold stocking density of individual species to grow. The use of regression equations that take into account mineral and organic fertilizers, planting density planting material, makes it possible to predict fish productivity with satisfactory accuracy.
Originality. The analysis of influence of the level of technological components and environmental factors on fish production nursery ponds.
Practical Value. The results can be used to optimize the stocking densities and forecasting fish production nursery ponds for the given soil-climatic zones.
Key words: fish production, rearing ponds, optimization, forecasting, correlation, regression equations.
Purpose. Natural feeds are important in pond fish diet because they contain all nutrients necessary for fish growth and development. The share of natural feeds in fish diet has great effect on fish growth and immunity, assimilation of artificial feeds. The main way of assured procurement of natural feeds for fish feeding at different stages of their development is artificial cultivation of aquatic organisms. However, cultivation of natural feeds is not virtually performed in aquaculture enterprises of Ukraine, therefore an analysis of available data on zooplankton cultivation is important for looking for optimal and economically profitable methods of enrichment of pond fish diet with natural feeds.
Methodology. Methods of cladoceran cultivation were the object of the study, material for the study – literature data on ways and methods of zooplankton cultivation.
Findings. Cultivation of various species of zooplankton is performed for feeding of pond fish on different life stages. Main object of cultivation in aquaculture is Daphnia magna Straus, juvenile forms of which are consumed by fish larvae, while adult organisms are the most valuable for yearlings and older fish. The efficiency of hydrobiont cultivation highly depends on the selected object, containers, where cladocerans are cultivated, optimum conditions, peculiarities of water supply, species, and application of fertilizers and feeds.
Originality. The highest production of zooplankton can be obtained when cultivating D. magna in tanks with continuous flow and in net cages installed in ponds under condition of ensuring requirements of the culture in bacterial and algae feeds (due to application of fertilizers and feeding with feeds and microalgae taking into account their presence in water, which is in the tank-cultivator).
Practical value. Simplicity of the methods and high efficiency of zooplankton cultivation for preparation of pond fish juveniles is the basis of its wide use in current economical conditions. Cladoceran cultivation is especially important during the period of its active consumption by fish in summer months, when a depletion of the natural forage base occur in ponds.
Key words: natural forage base, D. magna cultivation, tanks, cages, daphnia pits.
Purpose. The analysis of nucleotide sequences of the 16S rDNA gene of virulent strains of Yersinia ruckeri and to develop the method of molecular diagnostic of enteric redmouth disease.
Methodology. By the method of CLUSTALW algorithm in MEGA software version 6.0 the nucleotide sequences of the 16S rDNA gene of virulent strains of Yersinia ruckeri were analysed. For development of molecular diagnostic of Y. ruckeri the method of polymerase chain reaction (PCR) was used. Primer selection was carried out in software VectorNTI11 and on-line-service BLAST. The PCR products were investigated by the methods of sequencing and nucleotide analysis.
Findings. Based on PCR assay the method of molecular diagnostic of enteric redmouth disease agent, bacterium Y. ruckeri was developed. It was shown that specific oligonucleotide primers generated PCR products in size of 600 base pairs. PCR products were investigated by the sequencing that showed right targeting of primers in reaction.
Originality. Among high-conservative gene of 16S rDNA of Y. ruckeri the fragment of DNA was determined to which the specific primers for rapid diagnostic of virulent strains were selected.
Practical Value. Rapid diagnostic of yersiniosis will allow to identify an agent of this infectious disease, bacterium Y. ruckeri, and to provide the prophylactic or medical measures in the fish farming of Ukraine.
Key words: Y. ruckeri, rapid diagnostic, PCR.
Purpose. The aim of this work is to clarify the matter of suitability of current Gobioninae systematics, where Rheogobio is used as a synonym of Romanogobio or as a separate taxon by comparing four species of the genera Gobio and Romanogobio on the basis of osteological data and the structure of swimming bladder.
Methodology. Four gudgeon species were examined based on the structure of axial skeleton and cranium. Osteological specimens were prepared after cleaning and staining with alizarin red S. Measurements were performed with ScopePhoto using DCM 500 digital camera. Calculations were performed using Statistica 8.0. For determination differences between species we used Student’s t-test and discriminant analysis. Drawings were made with CorelDRAW X5.
Findings. R. uranoscopus is a specific species, swimming bladder of which reduced and its size is on average 10,6 % of SL, while in other gudgeons it reaches 21,0 to 31,8 % of SL. It may be an adaptation for occupying sites with high velocity, where it concentrates.
Mahalanobis distance clearly demonstrates the difference of R. uranoscopus from other investigated species, the most similar species to R. uranoscopus by a complex of osteological data is R. kesslerii the least similar is G. carpathicus. According to discriminant analysis, R. uranoscopus is distinctly different from the genera Romanogobio and Gobio.
The structure of separate elements of cranium, number of vertebrae and pectoral girdle bones also shows high distinction of R. uranoscopus from other species.
Originality. Originality of this work is a new look on the systematic status of the subgenera Rheogobio based on osteological and other data.
Practical value. Practical value of this work is an clarification of systematic status of the subgenera Rheogobio for agreement of nature protection documentation for avoiding different interpretations of the systematic status of species belonging to these subgenera.
Key words: Osteology, systematics, taxonomy, Romanogobio, Gobio, Rheogobio.