Effect of water temperature on egg incubation time and quality of newly hatched larvae of northern pike (Esox lucius L., 1758) Summary This study examined the effect of temperature on egg incubation, survival of eggs during embryonic development and quality of newly hatched larvae of northern pike (Esox lucius L.) under laboratory conditions. Eggs of similar size (diameter 2.7 AE 0.16 mm and weight 6.11 AE 0.35 mg) from five females were incubated at 3, 6, 10, 14, and 18°C (groups A, B, C, D, and E, respectively). The lowest fertilization (FR) and hatching rates (HR) were observed in larvae incubated in group A, 44.6 AE 3.2% and 18.26 AE 2.25%, respectively. The highest FR and HR were found in group B (FR, 71.3 AE 4.3%; HR, 56.2 AE 3.21%) and C (FR, 65.6 AE 3.1%; HR, 65.5 AE 5.41%). Time of incubation period varied from 38 AE 0.33 days (120 AE 1.03°d) when 5% larvae were hatched to 46 AE 0.42 days (144 AE 1.31°d) when 95% larvae were hatched in group A and 2.5 AE 0.08 days (44.67 AE 1.42°d) when 5% larvae were hatched to 3.42 AE 0.06 days (61.11 AE 1.07°d) when 95% larvae were hatched in group E. Larvae from groups A, D, and E were characterized by the lowest values of variables such as resistance to osmotic stress after 90 min of exposure of saline solution (OS = 54 AE 3-76 AE 3%), frequency of normally developed larvae (FNL = 23.8 AE 4.14-87. 1 AE 2.42%), and yolk sac volume (YsV = 3.41 AE 0.44-3.89 AE 0.45 ll 3 ). The highest quality larvae were recorded in groups B and C: OS = 92 AE 3% and 80 AE 4%, FNL = 89.7 AE 3.62% and 93.8 AE 3.17, YsV = 3.3 AE 0.66 ll 3 and 3.04 AE 0.42 ll 3 ). Fertilization and hatching rates and quality of larvae showed optimal temperature for successful egg incubation and production of high quality larvae to be 6 to 10°C. Relationship of ontogenic rate to temperature showed development of the pike embryo to be hypothetically stopped at 3.3°C.U.S.

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PRoCeSS PATTeRN of heTeRogeNeouS gAS hyDRATe DePoSiTS DiSSoCiATioNPurpose. Justification of the effective dissociation process parameters of heterogeneous gas hydrate deposits and elaboration of their classification according to the thermal energy consumption.methodology. The methodological basis of the conducted complex research is the analysis and synthesis of literary sources, devoted to studying the peculiarities and thermobaric properties of gas hydrates, analytical calculations and laboratory experiments on the thermal energy consumption for the efficient decomposition of gas hydrates, experimental studies of the hydrate formation process and gas hydrate deposits of the mottled structure dissociation.findings. The parameters of formation and stable gas hydrate occurrence in natural environment, which should be taken into account when developing gas hydrate deposits, are substantiated. The existing classification of gas hydrate deposits in sedimentary rocks is analyzed. The regularities of the gas hydrate deposits dissociation process and methane gas production, depending on the percentage of rock intercalations content, are established. The volumes of analysis zones and gas output from heterogeneous gas hydrate deposits are determined. The amount of thermal energy that is necessary to be consumed to produce 1000 m 3 of hydrated gas during the gas hydrate deposits development, is calculated.originality. It is established that the thermal energy consumption on the dissociation process in order to obtain methane gas varies with a parabolic dependency with an increase in the rock intercalations proportion in the gas hydrate deposit. A new classification of gas hydrate deposits, based on the content of rock intercalations and the amount of spent thermal energy for gas hydrate dissociation, has been developed.Practical value. The results of studies with sufficient accuracy for practical application may be used in the development of the Black Sea gas hydrate deposits in order to obtain natural gas. The revealed dependencies of the methane gas output on the rock intercalation share are a tool for determining the effective application of technologies for the gas hydrate deposit development.