Azov Sea Basin Research Articles

Extension of the spawning area of the far eastern mullet Liza haematocheilus (Temminck et Schlegel, 1845) acclimated in the Sea of Azov and Black Sea Basin: Recent data on reproduction ecology

Extension of the spawning area of the far eastern mullet Liza haematocheilus (Temminck et Schlegel, 1845) acclimated in the Sea of Azov and Black Sea Basin: Recent data on reproduction ecology

Far Eastern Mullet Mugil soiuy Basilewsky (Mugilidae, Mugiliformes): The Genetic Structure of Populations and Its Change under Acclimatization

The introduction of Far Eastern mullet (pilengas) in the Azov Sea in the 1970s-1980s has resulted in the formation of a self-reproducing commercial population. We have carried out a comparative population-genetic analysis of the mullet from the native (Primorye, the Sea of Japan basin) and the new (The Azov Sea basin) ranges. Genetic characteristics of three Primorye and three Azov local samples were studied using electrophoretic analysis of 15 enzymes encoded by 21 gene loci. In the Azov mullet, the initial heterozygosity characteristic of the donor population was preserved while the genotype and the allele compositions changed; the changes included a 1.9-fold reduction in the percentage of polymorphic loci and 1.5-fold reduction in the mean number of alleles per locus. The genetic differences between the Azov and the Primorye sample groups were highly significant. In the native range, no genetic differentiation among the mullet samples from different areas was found (Gst = 0.42%), whereas in the Azov Sea basin, the samples from spatially isolated populations (ecological groups) exhibited genetic differences (Gst = 1.38). The genetic divergence of the subpopulations and the excess of heterozygotes at some loci in the Azov mullet suggest selection processes that formed genetically divergent groups associated with the areas of different salinity in the new range. The salinity level is assumed to be the most probable factor of local differentiating selection during fast adaptation and naturalization of the introduced mullet.

Water resources management of the southern rivers of Russia with reference to fisheries requirements

Water consumption from Russia's southern rivers has increased substantially in recent years as a consequence of intensified economic activity. The volume of irreversible river‐flow withdrawal from the Azov Sea basin varies between 11 and 13 km3 year−1. The majority of the abstracted water is used for irrigation. By 1990, the decrease in discharge into the Caspian Sea was 41 km3 year−1. Withdrawals of water from the Kura, Terek, Ural and other rivers have so far exceeded the ecologically admissible limits and become critical. The paper discusses methodological approaches for the elaboration of standards for water withdrawal and ecologically safe discharges into the southern seas. New data are presented on the dynamics of fish abundance as a function of the hydrological characteristics of rivers and water salinity. The results of the system analysis and regressive modelling formed the basis of a programme to develop policies for water management for fisheries in the lower Don. The principles and criteria for water withdrawal under variable hydrological regimes for the rivers entering the Azov and the Caspian Seas should be tested for their applicability for other water bodies (e.g. rivers, water reservoirs and lakes).

The Effects of Environmental Changes Caused by Human Activities on the Biological Communities of the River Don (Azov Sea Basin)

The Don River is the main river system in the Azov Sea Basin. The average water flow is about 28 km3 per year. The biota of the river system is characterized by a rich vegetation and animal life including aquatic organisms. Great changes in the environment of the River Don have been observed since the period 1930 - 1960, when large numbers of dams were constructed, diverting water flow for heavy industry, energy production, agriculture and other uses. Simultaneously, water pollution increased. As a consequence, the biota of the region has been impacted negatively. Some of the detrimental effects are the decreased reproduction of commercially important fish species, and the much reduced catches of these fish. This report reviews the changes that have occurred in the ecosystem of the River Don Basin.