Geology, geography and global energy

Scientific and Technical Journal

Transformation bio-resources in freshwater hydrological objects

2018. №4, pp. 198-202

Nasibulina B.M. - D.Sc. (Biology), Professor, Astrakhan State University, 1 Shaumyan Sq., Astrakhan, 414000, Russian Federation,

Kurochkina T.F. - D.Sc. (Biology), Professor, Astrakhan State University, 1 Shaumyan Sq., Astrakhan, 414000, Russian Federation,

This article presents the observational data on quantitative and qualitative changes in benthic community in respect of the seasonal aspect in the waters of Volga River delta. It shows that groups of mollusks, crustaceans, oligochaetes and larvae have a crucial role in the formation of zoobenthos. It is noted that the spring period comes amid poor biodiversity in the communities. The high quantitative indicators, which are usual in context of organic pollution, were identified for oligochaetes species. The large biomasses for huge filter-feeding bivalves are also highlighted: Unio pictorum, U. longirostris, Dreissena polymorpha, adapted to high-suspended sediment concentration levels. It demonstrates that the summer period is rich in biodiversity of malacofauna (Lithoglyphus naticoides, Dreissena polymorpha, Viviparus viviparus, Bithynia tentaculata, Valvata piscinalis, Theodoxus pallasi, Unio pictorum, U. Longirostris), crustaceans (Dikerogammarus caspius, D. haemobaphes, N. robustoides, P. obesus, corophiidae: Corophium curvispinum, C. Nobile) and larvae - chironomids: Chironomus gr. plumosus, C. dorsalis, Polypedilum nubeculosum, Cryptochironomus gr. Defectus. The quantitative dominance of oligochaetes was identified in all the monitored watercourses (66 % of the total population). We determined the reduction of zoobenthos species in autumn period, which is probably caused by a drop of water temperature, the end of a larva’s development cycle and the adult’s flight, as well as by grazing of these species by other organisms. All in all, the percentage shows the dominance of the pollution tolerant zoobenthos species in the waters of Volga River delta. These include oligochaetes: Tubifex tubifex, Limnodrilus hoffmeisteri, mollusks - Dreissena polymorpha, Viviparus viviparus, Lithoglyphus naticoides, crustaceans - - Dikerogammarus caspius, Corophium curvispinum and among larvae - chironomids.

Key words: донные сообщества, сезонные изменения, биомасса, численность, зообентос, биоразнообразие, моллюски, ракообразные, олигохеты, хирономиды, benthic communities, seasonal changes, biomass, population, zoobenthos, biodiversity, mollusks, crustaceans, oligochae