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Aim. We present the findings of studies of the current state of benthic fauna of the Volga delta channels by the structure of benthic communities. The study has been carried out in the framework of researches by FSBSI "Caspian Fisheries Research Institute" conducted in the period from 2010 to 2014. The main goal was to assess the current state of benthic fauna of output channels of the Volga delta areas against the backdrop of changing water availability of the Volga river.Methods. We have conducted sample processing of zoobenthos within investigated watercourses of the Volga River according to conventional methods of Zhadin V.I. (1960), Winberg G.G. (1984) and Abakumov V.A. (1992).Results. The results of the work on the study of the modern state of the benthic fauna of the Volga delta channels show that the species composition of macrozoobenthos in these sections of the river in dry years was characterized by mass development of oligochaetes. With the increase of water content (between the years 2012 and 2013) in all studied water streams there is a change of the dominant group. With the decrease in the annual runoff (in 2014) the qualitative characteristics of zoobenthos have changed. In the average long-term aspect, the distribution pattern of quantitative indicators of benthic invertebrates in the delta of Volga river was uneven, and their greatest density has been marked in the wet year.Main conclusions. Thus, the research found that increase of the water content of the Volga River positively influences the hydrobiological picture in the output channels of the delta of the Volga River.

Abstract. Aim. Industrialization of Caspian oil and gas supplies requires a serious approach to the problem of protecting and preserving the region’s unique environment that, in fact, represents a property of international commons. The article studies into the impact of the Caspian modified waters on the benthos faunistic composition.Methods. Zooplancton and zoobenthos hydrobiology material was collected in the Central Caspian survey loop. Samples were collected in spring and summer in 2002 – 2007 in the western part of the Caspian Sea (Dagestan offshore location of the Caspian Sea from Smirnovsky Midstream Sandbank and Pearl Bank till Derbent latitude) on “Tsada” vessel. They were collected from 25 stations located on ten standard parallel latitude logs with depth scope of 8–100 m from 0, 10, 25, 100 m horizons. These samples were used as a material for characterizing phyto- and zooplankton.Results. The benthic can be considered the most stable communities of the marine environment as they are the most resilient to quantity and modifications. Heterogeneous and variable ecosystem (biotope) is typical of the areas with strong currents as the organic quality, quantity and physic-chemical properties are marked by variability.Location. The Caspian zoobenthos state as well as the features of the Caspian Sea benthos communities characterize the ecology of the Caspian Sea and give a true view of the situation in the drilling sites. This will help predict and avert negative effect of hydrocarbon production on the Caspian Sea ecosystem. Main conclusions. Water modification must be intensive, long-lasting and frequent for it to have an impact on benthos.