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 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.