Rybohospodars'ka nauka Ukrayiny (Fisheries Science of Ukraine)

5-15

Authors: S. Kruzhylina, I. Velykopolsky, O. Didenko

Purpose. To study qualitative and qualitative indices of macrozoobenthos as one of main components of the forage base of benthophagous fishes in mountain river reaches of the Transcarpathian region and determination of their saprobity level. Methodology. Thhj,9.e study was carried out in summer period of 2009 in mountain river reaches of the Tisa river catchment. Zoobenthos samples were collected by a Surber sampler (25 × 25 cm) on the bottoms of different fractions with different water flow rate (riffle, run, pool). Collection, processing and interpretation of the obtained data was carried out according to generally accepted hydrobiological methods developed for mountain river studies. Saprobity was of the studied rivers was calculated by Pantle-Buck formula. The Zelinka-Marvan saprobity index was used for calculations. Findings. Qualitative and quantitative macrozoobenthos indices have been studied. The number of zoobenthos on the investigated river sections ranged from 416 to 7712 ind./m2 with biomasses from 2.96 to 83.84 g/m2. The major portion of the zoobenthic biomass in the majority of rivers was due to caddis fly larvae composing up to 93% of the total biomass. An important role in the total biomass of the zoobenthos also belonged to mayfly (up to 53%) and stonefly (up to 55%) larvae and in lower degree amphipods (up to 39%), chironomid larvae (up to 14%) and aquatic coleopterans (up to 5%). According to the calculated potential fish productivity, the mountain rivers can be apparently separated into three groups: little productive (4.2–12.7 kg/ha), medium productive (13.2–21.6 kg/ha) and high productive (25.3–85.3 kg/ha). Mountain river reaches of the Transcarpathian region were found to belong to pure χ-saprobic, and о- і β-mesosaprobic zones, the saprobity index in which ranged from 0.35 (Rika river) to 1.7 (Shipot river). Originality. For further calculation and assessment of brown trout and European grayling stocking amounts for mountain reaches of the Tisa River basin, we investigated qualitative and quantitative indices of macrozoobenthos as one of major components of the forage base for benthophagous fishes and calculated their potential fish productivity. Practical value. Data on macrozoobenthos biomass and saprobity of mountain river reaches can be used for calculation and assessment of the possibility of stocking the studied river with juvenile brown trout and European grayling as well as for calculation of possible damages resulting from construction of small HPP (a tendency for construction of which on the Transcarpathian rivers lately becomes more significant). Keywords: Tisa river catchment, mountain rivers, macrozoobenthos, saprobity, potential fish productivity.

26-36

Authors: А. Dvoretsky, O. Zaychenko, L. Baydak, А. Кyrylenkо

Purpose. To study the development of the water quality of the Dniprovs’ke reservoir, which is a water of body of complex including fisheries importance and is characterized by an increased anthropogenic pressure as a result of the processes of the toxification and self-purification determined based on toxicity index (Іt). Methodology. We used the methods of bioindication (determination of the number and biomass of phytoplankton and heterotrophic bacterioplankton), biotesting (Іt determinaiton with the aid of Daphnia magna), hydrochemistry (determination of main trophic-saprobiological parameters of water quality) as well as the correlation analysis of these parameters. Findings. According to the 2012 data, tropho-saprobiologic, algological, microbiological parameters and toxicity index as an integral parameter were analyzed concerning to water quality. Regularities of dynamics and relationship of the indexes were studied. The environmental assessment of water quality of the most polluted upper part of the Dniprovs’ke reservoirs was carried out for each of the parameters studied: in areas where agro-industrial wastes enter, water is classified as «moderately polluted» – «very dirty». The data testify to strong local water pollution of the reservoir and a good renewable ability of the ecosystem. It was shown that in conditions of human toxification the adequate response concerning water quality gives the toxicity index as an integral indicator of toxification and self-purification processes. The dual role of phytoplankton and heterotrophic bacterioplankton in formation of water quality of the anthropogenically loaded reservoir was revealed: these components are involved in the processes of self-purification or toxification in accordance with periods of microalgae development during the season. This is displayed in corresponding changes of TI and the correlation coefficient. It was found that the self-cleaning of the reservoir is a major factor of improvement of the reservoir water quality and, consequently, the formation of environmentally safe habitat for fish. This is the main regularity, which affects the formation of self-cleaning processes and is reflected through the relations between hydrochemical, toxicological and hydrobiological indexes, the leading role in which is played by phytoplankton «blooming». Originality. For the fist time we showed that the correlation coefficient of the parameter with It gives an estimate of the contribution of the corresponding component of the reservoir ecosystem to the result of its toxification and self-purification. Practical value. The relationships, which relate It to ecosystem components, are important for the development of models for water quality and fish-productivity management. Keywords: self-purification, ecologically safe habitat, anthropogenic pressure, phytoplankton, bacterіoplankton, bioindication, biotesting.

58-69

Authors: P. Shekk

Purpose. To determine the optimum, critical, and threshold values of water oxygenation for embryos, larvae and fingerlings of mullets and flatfishes under different temperature conditions. Methodology. Oxygen consumption was studied in chronic experiments with «interrupted flow» method with automatic fixation of dissolved oxygen in water with the aid of an oxygen sensor and automatic, continuous recording of the obtained results. «Critical» (Pcrit.), and the «threshold» (Pthr.) oxygen tension in the water have been determined. Findings. Under optimum conditions, the normal embryogenesis of mullets and flatfish to the gastrulation stage, provided 90–130% oxygen saturation. The critical content was 80–85%, the threshold – 65–70% of the saturation. At the stage of «movable embryo» depending on water temperature and fish species, the optimum range of water oxygenation was within 70‒127.1%. The most tolerant to oxygen deficiency was flounder (Pcrit – 25.4–27,5; Pthr. – 20.5–22.5%), the least resistant to hypoxia was striped mullet (Pcrit. – 50–60; Pthr. – 35–40%). The limits of the critical and threshold concentration of dissolved oxygen directly depended on the temperature and salinity, at which embryogenesis occurred. An increase in water temperature and salinity resulted in an increase in critical and threshold values for oxygen tension embryos. Mullet and flatfish fingerlings in all stages of development had a high tolerance to hypoxia, which increased as they grew. They were resistant to the oversaturation of water with oxygen. The most demanding for the oxygen regime are larvae and fingerlings of Mugil серhalus and Liza aurata. Hypoxia tolerance of Psetta maeoticus and Platichthys luscus at all stages of development is very high. The fingerlings of these species can endure reduction of the dissolved oxygen in water to 2.10 and 1.65 mgO2/dm3 respectively for a long time without visible effects. Originality. For the first time, we experimentally established the optimum, critical and threshold values for water oxygenation for embryos, larvae and juveniles of striped mullet, golden mullet, haarder, flounder and Black Sea turbot. Practical value. The obtained data can be used for the optimization of culture conditions and commodity cultivation of mullets and flatfishes. Keywords: oxygen saturation, critical thresholds, embryos, larvae, fingerlings, mullets, flatfish.

78-85

Authors: O. Deren

Purpose. To study the effect of feeding carp with VMA premix in a complex with fodder yeasts and separately on their productivity and some biochemical parameters of blood as well as to analyze the level of provision of the experimental groups of fish with natural feeds. Methodology. The study was based on experimental and laboratory methods adopted in fisheries, hydro-chemical, biochemical and statistical studies. Findings. The study has established that, at early season, the cultured fish was provided with natural feeds to a certain degree that was evidenced by the analysis of the gut content of experimental groups. At the end of the season the percentage of natural feed in the gut content was low, but this time fish received normalized amount of artificial feed. Hydrochemical parameters in experimental ponds were within normal limits, and temperature regime was optimal for carp growth and metabolism. When feeding of 1+ carp was supplemented with to VMA premix, fish productivity increased by 27.4%, mean weight increased by 12.9%, and the feed rate dropped by 14%. A complex introduction of VMA premix with fodder yeasts into main diet of carp resulted in these changes by 15.9, 36.8 and 28%, respectively. The experimental groups of fish showed an improvement in blood biochemical parameters, namely, a significantly increase in the number of red blood cells and hemoglobin content, and a trend for an increase in the protein content of blood serum and its fractions. Hence, this method of the diet adjustment can be useful the most efficiently under condition that all indicated factors are present together, simultaneously and ensure the implementation of the main task of fish farm – optimum fish weight gain and effectiveness of feed use. Originality. For the first time we carried out an analysis of the effect of the introduction of the composition of VMA premix and fodder yeasts to the main diet of 1+ carp on the economic component of their culture and some physiological and biochemical parameters. Practical value. The obtained data will allow scientifically proven optimizing the composition of the diet for commodity carp and applying these developments in industrial conditions in order to improve the profitability of commodity fish farming. Keywords: 1+ carp, VMA premix, fodder yeasts, gut content, fish productivity, cost of feed, biochemical composition of blood.