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The dynamics of the state of the Sea of Azov during the 20th and early 21st centuries is described. The basic factors that form the hydrological regime of the sea are presented. It was revealed that the current state of the Sea of Azov, characterized by a significant positive anomaly of water temperature and salinity, has not previously been noted in the history of the study of the sea. It has been noted that the standard deviation of series of the mean annual values of water salinity and temperature increases, which may indicate an increase in variability of these characteristics in the modern period. [ABSTRACT FROM AUTHOR]

This work reports on the cyclicity of the climate in the Sea of Azov Region studied on the basis of paleogeographic methods. The results of drilling on Dolgaya Spit of the Sea of Azov are presented. The diatoms and palynological analyses, as well as the soil column dating, indicate the cyclical pattern of climatic variability and accelerated silting of the Don delta under regulated runoff. The rate of sedimentation in the Sea of Azov during the Ancient Azov and New Azov stages varied from 0.2 to 2.0 mm/year. In the current period, under conditions of water scarcity and lack of floods, the sedimentation rate of clayey silts was 10–30 mm/year at the avandelta. Based on the analysis of hydrometeorological information, the period of time from 1884 to 2020 can be divided into three periods: I, cold; II, transitional; and III, warm. The study of the indicated specific features of the development of natural processes gives grounds to expect the next transitional period with dramatical interannual fluctuations of temperatures and alternation of warm and severe winters in the coming decade. [ABSTRACT FROM AUTHOR]

On the basis of theoretic-probability analogies, a quantitative characteristic of diversity of the river delta, the variance, is proposed. The series of computer experiments with a hydrological model demonstrate that an increase in the variance of the delta structure reduces the intraannual amplitude of fluctuations in salinity of the closing reservoir. The simulations for the Don River and Taganrog Bay (the Sea of Azov) used as the closing reservoir show that modern climatic change and anthropogenic factors reduce the proper functioning of the River Don arms. Therefore, there is a prospect of decrease in the variance of river runoff and, hence, destabilization and increase in the variability of salinity in the closing reservoir. [ABSTRACT FROM AUTHOR]

An integrated mathematical model of the Barents Sea and White Sea Large Marine Ecosystem proposed as a tool for assessing natural risks and efficient use of the biological resources is considered. The model includes the following main blocks (modules) of (а) oceanographic variation and biological productivity; (b) trophodynamics and fishery management; (c) environmental and biota pollution; (d) social and economic development; and (e) assessment of ecological risks from marine activities. The results of using the integrated model for assessing hydrological variability, long-term dynamics of ecosystem productivity, and assessment of fishing pressure on the most important fishery species of the Barents Sea are presented. A new scheme of zoning of the Barents Sea area performed under the supervision of Academician G.G. Matishov with respect to geomorphological and hydrological factors is proposed. A comparative scheme of distribution of the estimated gross primary production in the Barents Sea area in the second half of the twentieth century and in the 2010s is presented. The energy balance of the Barents Sea ecosystem in the late 1900s and early 2000s is calculated by the model of trophodynamics. The necessity of using mathematical models of the ecosystem instead of single-species models during the calculation of fishing pressure on the populations is suggested. To estimate fishing mortality, it is necessary to take into account not only spatial effects related to the features of a fish life cycle and distribution of fishing pressure, but also the impact of climate factors and ecosystem interactions. The use of recent information technologies both in the field of accumulation and analysis of the primary data and in the area of their subsequent generalization for the diagnosis of past changes makes it possible to understand better the possible consequences of the existing plans for developing and use of available natural resources for the Barents Sea and White Sea LME based on the experience (sometimes negative) of recent years and expected climate changes. [ABSTRACT FROM AUTHOR]

The chlorophyll a concentration (Cchl a) in the Sea of Azov is estimated by the two-band NIR-red algorithm [34] from MERIS images for 2002-2012. The sea-truth spectrophotometric measurements and MERIS remote estimates of Cchl a are compared. The monthly average Cchl a values are mapped from MERIS data for its lifetime for the first time. The features of the spatiotemporal distribution of Cchl a are ascertained. Differences between the seasonal dynamics of Cchl a in the Sea of Azov according to the literature data and the dynamics derived from MERIS data are found, namely: the summer-autumn phytoplankton growth period is longer than the spring period and is characterized by higher Cchl a values throughout the water area. [ABSTRACT FROM AUTHOR]