Two complete mitochondrial genome sequences of ship sturgeon Acipenser nudiventris from the Caspian Sea and from Balkhash Lake (introduced from the Aral Sea during the last century) were determined by PCR-based sequencing method. The whole mitogenome sequences have been deposited in GenBank under accession numbers KU321568 and KU321569.

The variability of hydrochemical parameters, the heterogeneity of the habitat, and a low level of anthropogenic impact, create the premises for conserving the high biodiversity of aquatic communities of small water bodies. The study of small water bodies contributes to understanding aquatic organisms’ adaptation to sharp fluctuations in external factors. Studies of biological communities’ response to fluctuations in external factors can be used for bioindication of the ecological state of small water bodies. In this regard, the purpose of the research is to study the structure of zooplankton of small lakes in South-East Kazakhstan in connection with various physicochemical parameters to understand the role of biological variables in assessing the ecological state of aquatic ecosystems. According to hydrochemical data in summer 2019, the nutrient content was relatively high in all studied lakes. A total of 74 species were recorded in phytoplankton. The phytoplankton abundance varied significantly, from 8.5 × 10⁷ to 2.71667 × 10⁹ cells/m³, with a biomass from 0.4 to 15.81 g/m³. Shannon diversity index of phytoplankton in the lakes at high altitude varied from 1.33 to 2.39 and from 0.46 to 3.65 in the lakes at lower altitudes. The average weight of the cells of algae species varied from 0.2079 to 1.5076 × 10⁻⁶ mg in the lakes at lower altitudes, the average weight of the cells of algae species changed from 0.6682 to 1.2963 × 10⁻⁶ mg in the lakes at higher altitudes. Zooplankton was represented by 58 taxa. The total abundance of zooplankton varied from 0.05 to 169.00 thousand ind./m³ with biomass of 0.51–349.01 mg/m³. Shannon diversity of zooplankton in the lakes at lower altitude fluctuated from 0.42 to 2.32 and it was 0.66–1.77 in the lakes at higher altitudes. The average individual mass of specimens in zooplankton in mountain lakes ranged from 0.021 to 0.037 mg and varied from 0.002 to 0.007 mg in other lakes. The main factors in the development of the structure of zooplankton communities in small lakes were temperature, TDS, the content of nitrates, phosphates, and the composition and biomass of planktonic algae. The hydrochemical and biological data of the investigated lakes indicated their organic pollution. Our results once again confirmed the applicability of structural variables of zooplankton in assessing water quality.

Purpose: Review the experience, principles and parameters of the sturgeon assessment quality by anomalies in early ontogeny. Results: Maintaining the number of sturgeon fish in the transboundary Caspian Sea is provided by five states (Russia, Iran, Azerbaijan, Turkmenistan, Kazakhstan) at 16 Sturgeon hatcheries, where their artificial reproduction is carried out. FAO recognizes Russia’s leadership in creating the basic technology for the sturgeon artificial reproduction, but the other four Caspian states also make a significant contribution to its modern optimizations. There is almost a century of tradition behind the technological development of artificial reproduction in sturgeons. During the artificial reproduction of sturgeons, anomalies in the structure and functions may occur, such as deformities, defects in organs and tissues, edema, hematomas, etc. The sturgeon anomalies classification is based on structural and functional principles. Identification of anomalies is carried out on the basis of a previously created classification, divided into nine large classes. Identification of sturgeon anomalies during the period of their artificial reproduction makes it possible to clarify the real value of replenishment of their stock. Methods: Analysis of professional scientific literature and practical guides. Conclusions: The presence and number of Sturgeon anomalies make it possible to determine their death percentage to calculate the real number of replenishment of the Caspian Sturgeon stock.

The study of planktonic animals of the Caspian Sea is topical and, during the last centuries, has brought and continues to bring new results. This is an inevitable process attributed to the introduction of non-indigenous predatory representatives of zooplankton by ballast water of ships. During the study period, the zooplankton of the Middle Caspian Sea was represented by 13 taxa and consisted mainly of non-indigenous species typical of the Palearctic region. Native fauna was represented by three species—cladoceran Evadne anonyx, Podonevadne camptonyx, and copepod Halicyclops sarsi during the study period. The quantitative variables of zooplankton did not reach a high level in May 2020 and 2021 compared to the data of previous years. Cladocerans Podonevadne camptonyx, copepods Acartia tonsa, and larvae of Cirripedia dominated in 2020. By 2021, the dominant species of last year had been replaced by the cladoceran Evadne nordmanni. One-way ANOVA analysis detected significant differences in the quantitative variables of cladocerans and copepods between different years of zooplankton study. The decreasing abundance, biomass, and alteration of the dominant zooplankton species in the Middle Caspian Sea during the study period may be associated with the feeding type of predator species and a slight elevation of water salinity.