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In current paper we presented the dynamics of the macrozoobenthos in Eastern Sivash depending on temporal and spatial salinity fluctuations from pleiomesohaline to polyhaline and hyperhaline. We shown that the highest species richness and biomass were observed in polyhaline conditions at the lowest salinity values, and the maximum density was in pleiomesohaline conditions. The lowest species riches and biomass were observed in hyperhaline conditions. Keywords: Eastern Sivash; macrozoobenthos; distribution; abundance; biomass References Almazov, O.M. (1960). Hydrochemical characteristic of eastern Sivash: Biological substantiation of the development of the mullet farming of Eastern Sivash and Molochnyi Estuary. Proceedings of the Institute of Hydrobiology Academy of Sciences of the USSR, 35, 10-18. (In Russian) Anistratenko, V.V., Anistratenko, O.Yu., Khaliman, I.A. (2007). Composition of the molluscs fauna of the Sea of Azov as a function of its salinity regime. Dopovidi NANU, 4, 161-166. (In Russian) Anistratenko, V.V., Khaliman, I.A., Anistratenko, O.Yu. (2011). The Molluscs of the Sea of Azov. Kiev: Naukova dumka. (In Russian) Antonovskiy, O.G., Degtyarenko, O.V. (2009). Comparative description of fresh and saline water mollusks of North Azov region. Recent questions biology, ecology and chemistry: electric. science. profession. kind., 2, 33-45. Available at: http://sites.znu.edu.ua/bio-eco-chem-sci. (In Ukrainian) Antonovskiy, O.G., Gaponova, V.V. (2008). Sivash macrozoobenthos on the present state of ecosystem development. Science and Practice: Procedd. Int. Sc. Conf. (Poltava, March 3-7, 2008). Poltava: Poltava National Agrarian University (In Ukrainian) Antonovskiy, O.G., Krutikova, O.O. (2012). Dynamics of macrozoobenthos of Eastern Sivash in conditions of hydroecological changes. Bulletin of the Zaporizhzhya National University. Series Biological sciences, 3, 96-103. (In Ukrainian) Grintsov, V., Sezgin, M. (2011). Manual for the identification of Amphipoda from the Black Sea. Sevastopol. Khaliman, I.A., Anistratenko, V.V., Degtyarenko, E.V. (2015). Regional peculiarities of malacofauna in waterbodies of different types of the North-West Azov Sea Coast. Dopovidi NANU, 11, 98-105. doi.org/10.15407/dopovidi2015.11. (In Russian) Kiseleva, M.I. (2004). Polychaete worms (Polychaeta) of the Black and Azov seas. Apatity: A publication of the Kolskiy Scientific Center of the Russian Academy of Sciences. (In Russian) Marushkina, O.O. (2013). Features of distribution and ecology of macrozoobenthos of Eastern Sivash. Proceedings of the Zoological Museum, 44, 10-41. (In Ukrainian) Methods of hydroecological researches of surface waters. (2006). Romanenko, V.D. (Ed.). Kyiv: Logos. (In Ukrainian) North-western part of the Black Sea: biology and ecology: monograph. (2006). Zaitsev, Yu.P., Aleksandrov, B.G., Minichev, G.G. (Eds.). Kyiv: Naukova Dumka. (In Russian) Pauli, V.L. (1936). To the biology of Sivash. Proceedings of Kharkiv A. M. Gorky State University. 6-7, 273-276. (In Ukrainian) Stocker, G., Bergmann, A. (1977). Ein Modell der Dominanzstruktur und seine Anwendung. 1 Modelbildung. Modellrealisierung. Dominanzklassen . Arch. Naturchutz. und Landschaftsforschung, 17 (1), 1-26 (in German). Stolyarov, A.P. (2013). Features of the structural organization of the macrobenthos community in estuarine ecosystems (Kandalaksha Bay, the White Sea). Succeeding in modern biology, 133 (2), 191-208. (In Russian) Tarasov, N.I. (1927). To Syvash hydrobiology. News of State Hydrobiological Institut., 19, 59-68. (In Russian) Vinogradova, Z.A., Vinogradov, K.O. (1960). Zoobentos of the Eastern Sivash. Proceedings of the Institute of Hydrobiology, Academy of Sciences of the USSR., 35, 50-71. (In Ukrainian) Vorobiev, V.P. (1940). Hydrobiological essay of Eastern Sivash and the possibility of its fishery use. Proceedings of Azov-Black Sea Research Institute of Marine Fisheries and Oceanography, 12, 69-164. (In Russian) Vorovka, V.P. (2013). Features of the hydrological connection of Sivash with the Sea of Azov. Hydrology, hydrochemistry and hydroecology, 2 (29), 84-89. (In Ukrainian) Zhadin, V.I. (1960). The Methods of hydrobiological study. Moscow: Vysshaya shkola. (In Russian)

A method of modeling the phenomenon of bursting behavior in neural systems based on delay equations is proposed. A singularly perturbed scalar nonlinear differentialdifference equation of Volterra type is a mathematical model of a neuron and a separate pulse containing one function without delay and two functions with different lags. It is established that this equation, for a suitable choice of parameters, has a stable periodic motion with any preassigned number of bursts in the time interval of the period length. To prove this assertion we first go to a relay-type equation and then determine the asymptotic solutions of a singularly perturbed equation. On the basis of this asymptotics the Poincare operator is constructed. The resulting operator carries a closed bounded convex set of initial conditions into itself, which suggests that it has at least one fixed point. The Frechet derivative evaluation of the succession operator, made in the paper, allows us to prove the uniqueness and stability of the resulting relax of the periodic solution.

A pair of diffusion connected FitzHugh–Nagumo oscillators with an asymmetric interaction are considered. The problem is investigated in the close to critical case, where the matrix of the linear part of the system has a pair of purely imaginary eigenvalues. The normal form is constructed and its coefficients are determined depending on the initial parameters. The source system may be in two different situations: stable singlefrequency oscillations with two different frequencies coexist or a single-frequency mode branches from the equilibrium. The obtained asymptotic results are supplemented by the numerical analysis.