Phytoplankton of the Balkhash Lake was represented by 91 species with average abundance of 1,002.4 mln. ind. m -3 and average biomass of 0.853 g m -3 in summer 2004. Maps of spatial distribution revealed that phytoplankton abundance was confined within the nearestuary sections of the rivers. Correlation analysis and 3D Surface Plots showed that the average mass of the algal cell decreased with increased phytoplankton abundance, species richness, and Shannon Bi index values. Synchronicity of the spatial dynamics of W-Clarke and ∆-Shannon values evidenced the possibility of obtaining information on the structure of communities by both calculated and graphical methods. REZUMAT: Cartografiere și parcelare de suprafață 3D statistice în analiza fitoplanctonului lacului Balkhash, Kazahstan.Fitoplanctonul lacului Balkhash a fost reprezentat de 91 de specii cu abundența medie 1.002,4 mln. ind. m -3 și o biomasă medie de 0,853 g m -3 , în vara anului 2004. Hărți de distribuție spațială au arătat că abundența fitoplanctonului a fost limitată în cadrul secțiunilor în apropierea estuarului râurilor. Analiza corelațiilor și parcelarea de suprafață 3D au arătat că masa medie a celulelor algale a scăzut atunci când a crescut abundența fitoplanctonului, bogăția de specii, și valorile indicelui Shannon Bi. Sincronicitatea dinamică spațială a valorilor Δ-Shannon și W-Clarke a evidențiat posibilitatea de a obține informații cu privire la structura comunităților prin metode calculate și grafice.

The water level variations of the Lake Balkhash, the Kapshagay Reservoir and the Ili River and the linkage with salinity and biological conditions are investigated in this work using different techniques: satellite radar altimetry, in situ gauges, historical archives of fish population counting and field works. We show that it is possible now to monitor, over decades, in near real time, with high precision, the water level changes in the Lake Balkhash from satellite altimetry, over the reservoir and also along the Ili River. The vulnerability of the lake fauna and flora populations is enhanced by the morphometry of the lake: shallow and separation of the eastern basin from the western basin through the narrow Uzun‐Aral strait. Water policy of the Ili River also plays a fundamental role in the evolution of the Balkhash Lake. The Ili River that provides 80% of the surface water of the lake is a transboundary river. Development of intense irrigated agriculture in the upstream part of this river, located in the Chinese territory, could lead in the future to high hydrological stress in the downstream regions with potentially high damage in the delta and for fishery production. We show here the recent evolution of the Lake Balkhash basin from satellite data. Some interannual oscillation of 6–8 years over the last decade has been highlighted, with a water level of the lake still at a high value, but prediction on increasing irrigation is also highlighting the vulnerability of this lake. Linkage between water level change along the river and the downstream waters is also investigated. It shows that the role of the reservoir is not fundamental in the understanding of the Lake Balkhash water level changes which is in contrast highly correlated to upstream river level changes.

The Balkhash Lake is a unique natural water body with a gradient of the total content of dissolved salts along its longitudinal axis and the increased level of toxic pollutions. To assess the spatial distribution of environmental factors along the Balkhash Lake surface, methods of bioindication and statistical mapping were used. An assessment of the overall level of toxic pollution was carried out using the Water Ecosystem State Index (WESI). Phytoplankton has been used to assess the ecological state of the Balkhash Lake in the summer of 2004. A total of 92 species were found in the algal communities, with prevalence of Chlorophyta in the western, fresher water part, and Bacillariophyta in the eastern, brackish part. Mapping showed a positive relationship between the species richness in algal Divisions and macrophytes. Changes in the proportion of indicator species within the composition of phytoplankton reflected the spatial gradient of depth, TDS, pH-values, organic pollution. According to bioindication data, the waters of the Balkhash Lake are moderately polluted, water quality class III. The WESI index calculation revealed the effect of the total toxic pollution on the phytoplankton of the Western Balkhash. The spatial distribution of the WESI index showed that in the zone the influence of river flow has stimulating effect of biogenic elements on phytoplankton but was partially leveled by the increased level of toxic pollution.

This article presents materials on the current state of the native ichthyofauna of the Ile-Balkhash basin, affected by large-scale acclimatization works. Four species of the ichthyofauna composition are listed in the Red Book of Kazakhstan: spike ( Acipenser nudiventris Lovetsky, 1828), Aral barbel ( Barbus brachycephalus brachycephalus Kessler, 1872), Balkhash marinka ( Schizothorax argentatus argentatus Kessler, 1874), Balkhash perch ( Perca schrenkii Kessler, 1874). Due to the ineffectiveness of fish conservation measures, including the prohibition for catching of these fish species, which are not found anywhere except in the Ile-Balkhash basin, it is necessary to impose artificial reproduction, changes in the Fishery Rules and organization of commercial rearing. The work is based on research materials of 2001-2018 conducted in Lake Balkhash, the delta and the lower reaches of the Ile and the Tokraun. The status of spike populations ( Acipenser nudiventris Lovetsky, 1828), Aral barbel ( Barbus brachycephalus brachycephalus Kessler, 1872), Balkhash marinka ( Schizothorax argentatus argentatus Kessler, 1874) and Balkhash perch ( Perca schrenkii Kessler, 1874). The main reasons preventing the maintenance of a high number of endangered species have been established: small area of natural spawning grounds, death of fry in linmeshing fishing gear, large-scale poaching (spike); deterioration of conditions for the natural reproduction, mass mortality of young fishes in the irrigation system (Aral barbel); total elimination and food competition with pike perch (Balkhash marinka, Balkhash perch). The prospects for preservation of rare and endangered fish species have been considered, recommendations for breeding and replenishing populations of species listed in the Red Book have been given: measures for artificial reproduction and prevention of juvenile death, creating favorable conditions for fattening and reducing the pressure of trophic competition. Without taking adequate measures for reducing the anthropogenic impact on natural resources, including ichthyofauna, the number of main commercial fish species will decrease, rare species of fish will die out.

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