ASSESSMENT OF ENVIRONMENTAL STATE OF WATERCOURSES OF DELTA OF THE VOLGA RIVER BY THE STRUCTURE OF BOTTOM COMMUNITIES

Aim. The assessment of the ecological status of watercourses of Delta of the Volga River on the structure of benthic communities. The main objective of our researches was the assess the ecological status of watercourses of Delta of the Volga River on the basis of the analyzes of the structural-functional characteristics of benthic communities.

Location. Delta of the Volga River was the area of researches.

Methods. Processing samples of zoobenthos of the studied watercourses of Delta of the Volga River was produced according to standard techniques. (Zhadan V.I.,1960, Vinberg G.G., 1984, Abakumov V.A., 1992). Altogether were selected and processed 516 samples of zoobenthos. Species identification was done using the "Atlas of invertebrates of the Caspian Sea" (Birshtein A.Ya., 1968)
and “The determinant to freshwater invertebrates…” (Kutikova L.A., 1977). Next, based on the obtained data, we determined the abundance and biomass of species per m2 surface area of the bottom. To the assessment of the ecological status of watercourses of Delta of the Volga River by the structure of microzoobenthos we used the following indicators: number of species, abundance (N, specimens/m2), biomass (B, g/m2), percentage of principal taxonomic groups, oligogenic index of Parele (D1) (Parele E. A., 1974), biotic index of Wudiwiss in the modification of Nasibulina (B) (Nasibulina B. M., 1995), the index of species diversity of Shannon-Uiver (H, bit/copy) (Shitikov V. K., 2003).

Results. The obtained results of the assessment of the ecological status of watercourses in the Delta of the Volga River by the structure of benthic communities show that the same species having in different water bodies their different representation and structural-functional characteristics were the kernel of bottom fauna. According to the values of the modified biotic index of Wudiwiss and oligochaetae index of Parele calculated for the whole period of studies, the water quality in the Volga River (from Barbasi to water-post, Astrakhan), and the sleeves Buzan and Akhtuba was characterized as "slightly contaminated"with the dominance of β-mesosaprobic organisms. n the sleeveless Bushma, Kizan', Bakhtemir characterised as "polluted" with a predominance of β-α-mesosaprobic. The picture of the distribution of quantitative indicators of zoobenthos in the Delta of the Volga River in average perennial aspect had uneven character, with the manifestation of a clear trend to decreasing their values from the Eastern part of the Delta (the Volga River) to the West (the sleeve Bakhtemir).

Main conclusions. Thereby, on the basis of qualitative and quantitative characteristics of zoobenthos and calculated biological indices it was noted that the water quality of watercourses in the Delta of the Volga River can be characterized as "Slightly contaminated and "Polluted". In the average perennial aspect in the watercourses of Delta of the Volga River was observed uneven distribution of quantitative indicators of zoobenthos with the manifestation of a clear trend to decreasing their values from the Eastern part of the Delta to the West.

1. Abakumov V.A. 1992. Guidebook for hydro-biological monitoring of freshwater ecosystems. St. Petersburg, Hydrometeo Press, [Rukovodstvo po gidrobiologicheskimu monitoring presnovodnykh ekosistem, Spb.: Gidrometeoizdat]. 319 p. (in Russian).

2. Bakanov A.I. 2000 The use of zoobentos for monitoring of limnetic reservoirs Collected papers. Biology of inland waters. Moscow: The Science Press (№1), [Ispol’zovanie zoobentosa dlya monitoring presnovodnykh vodoyemov Sb. trudov. Biologiya vnutrennikh vod. M.: Nauka]: 68-83 (in Russian).

3. Birshtein A.Ya. 1968. The Atlas of invertebrates of the Caspian Sea. Moscow, Food industry, [Atlas bespozvonochnykh Kaspiiskogo morya. M.: Pishchevaya prom-st’] . 415 p. (in Russian).

4. Vinberg G.G. 1984. Methodical guidelines for materials processing by the hydro-biological researches on limnetic reservoirs Zoobenthos and its products. Leningrad, USSR academy of sciences proceedings of the zoological institute [Methodicheskie rekomendatcii po obrabotke materialov pri idrobiologicheskikh issledovaniyakh na presnovodnykh vodoemakh zoobentos I ego produktciya. L.: Zool. In-t AN SSSR]. 52 p. (in Russian).

5. Zhadin V.I. 1960. Methods of hydro-biological research. M, The higher school, [Metody gidrobiologicheskogo issledovaniya. M. Vysshaya shkola]. 190 p. (in Russian).

6. Kutikova L.A. 1977. The qualifier of freshwater invertebrates of the European part of the USSR (plankton and benthos). Leningrad, Hydrometeo Press, [Opredelitel’ presnovodnykh bespozvonochnykh evropeiskoi chaste SSSR (plankton I bentos]. L.: Gidrometeoizdat]. 510 p. (in Russian).

7. Nasibulina B.M. 2004. Bioindication of water quality in the Lower Volga River (Bioindikatciya rfchestva vod Nizhney Volgi) B.M. Nasibulina, U. M. Dedkov. The materials of the Congress. Part 1. ECWATECH. Moscow.: 261-263 (in Russian).

8. Parele E.A. 1974. Oligochaetofauna of mouth of the Daugava River in pollution conditions.The factors of natural purification of the mouth of the Daugava River. Riga, 106-121. [Oligochaetofauna ust’evogo raiona reki Daugavy v usloviyakh zagryazneniya. Faktory samoochishsceniya ust’evogo raiona reki Daugava. Riga]: 106-121 (in Riga).

9. Finogenova N.P. 1976. Estimate of contamination level of waters on a composition of bottom animals//Methods of the biological analyze of fresh waters. Leningrad, USSR academy of sciences proceedings of the zoological institute, [Otcenka stepeni zagryazneniya vod po sostavu donnykh zhivotnykh]. Metody biologicheskogo analiza presnykh vod. L. Izd-vo ZIN AN SSSR): 95-106. (in Russian).

10. Chuikov Yu.S. 1996. Hydrochemical regime of the Lower Volga, Astrakhan, (4), [Gidro-gidrokhemicheskii rezhim Nizhnei Volgi. Astrakhan]. 225 p. (in Russian).

11. Shitikov B.K. 2003. Quantitative Hydroecology: methods of the system identification. Tolyatti, Institute of ecology of Volga basin RAS, [Kolichestvennaya gidroecologiya: metody sistemnoi identifikatcii]. 463 p. (in Russian).