Aquatic Bioresources & Environment, Vol. 3, No 4, 2020
Current state of the habitat of commercial invertebrates in the hypersaline lakes of CrimeaHydrological and hydrochemical conditions in the hypersaline water bodies of Eupatorian, Tarkhankut, Perekopsk, and Kerch groups of lakes were investigated. Fisheries value of these lakes lies in providing the habitat for such fishing targets as brine shrimps (Artemia) and chironomids. As the main source of primary empirical data, findings of the expeditions conducted in the spring, summer and autumn seasons of 2017–2019 have been used. As a result, it has been found out that, in general, abiotic environmental factors in the majority of the lakes in the spring – autumn season were adequate for development of the aquatic living organisms inhabiting them. It was supported by positive hyrdobiological developmental indices of these species and indicated their high adaptability to the existing state of their habitat, in particular, saline and oxygen regimens. However, the autumn season of 2017 was unfavorable for most of the lakes in terms of development of the aquatic living organisms. Substantial increase in salinity led to the depression of brine shrimp populations and to the death of chironomids. A fairly high content of mercury in some hypersaline water bodies located in the Western and Northern Crimea also comes under notice. In the case of Aygul Lake, it is associated with proximity of chemical enterprises; however, the sources of polluting substances in the other investigated water bodies at present remain unknown and require further investigation.
Hydrological and hydrochemical criteria for typification of the water bodies aimed for development of commercial aquaculture in the southern and south-eastern parts of the Rostov RegionThis paper presents materials on the development of criteria for the typification of water bodies for the purposes of commercial aquaculture on the example of model water bodies in the Rostov Region. Altogether, 24 water bodies located in the southern and south-eastern parts of the Region have been investigated. The development of criteria for the typification of water bodies has been carried out based on hydrological and hydrochemical indicators, which were scored in 4 blocks. The total score established for the main hydrological and hydrochemical parameters can be used as a criterion for a water body being suitable for the purposes of commercial aquaculture. The dependence of suitability of the water body for fish farming on its location, the average annual flow rate of rivers or the annual precipitation–evaporation ratio according to the established scores has not been revealed. However, in the zone of very arid climate, more unusable water bodies have been identified. Since, according to the conditions of water availability, almost all water bodies should be classified as the reservoirs that are insecure for fish farming, the number of water bodies not recommended or recommended with significant restrictions amounted to only 25 % of the total. This indicates a fairly high potential for fish farming even in the arid zone of the Rostov Region. A brief hydrological and hydrochemical characterization of each investigated water body can be used to develop scientifically grounded recommendations for the organization of fish farms for the purposes of commercial aquaculture.
Hydrometeorological conditions of the Kerch Bay in 2017–2019Based on the data from weekly hydrometeorological observations, conducted in the Kerch Bay in 2017–2019, comparative analysis of variability in average monthly values of surface air and water temperatures, wind activity and wave action, water transparency, and salinity of the upper water layer with those recorded in 2007–2009 has been conducted; these two time ranges have been also compared with similar conditions of the second half of the 20th century and the beginning of the 21st century. During the recent decade, a trend of the increase in the amount of hot summer days and the decrease of freezing winter ones was recorded, as well as the raise of water salinity by a significant measure, from 10.7–12.8 to 14.5–17.6 ‰, resulting from the reduction of freshwater river flow into the Azov Sea and increased evaporation due to higher water temperature. Prevailing negative anomalies of wind speed were observed, as well as the change of the negative trend in the first time range to the positive trend in the second one. Due to the limited fetch distance, average monthly wave height in the bay over the course of entire 2017–2019 observations did not exceed 0.9 m. Correspondence between positive trends of wave height and wind speed was recorded. During the same period, the annual maximum of transparency coincided with the summer season, whereas the annual minimum fell on different months of the other seasons.