View of the territory of the Damchik section of the reserve and the bed of the Old Volga river

Chief Specialist Viktor Zubarevich prepares the DSS Pro multi-parameter probe (YSI, USA) for operation

Sampling at sea and in the delta

Expedition leader Pavel Khlebopashev analyzes samples in the laboratory

From May 25 to June 2, 2022, employees of the IO RAS (researcher Khlebopashev P.V. (head of the expedition), junior researcher Borisenko G.V., chief specialist Zubarevich V.L., Laboratory of Biohydrochemistry, and Senior Researcher Sapozhnikov F.V., Laboratory of Ecology of Coastal and Bottom Communities) conducted research in the waters of the northern part of the Caspian Sea and the Volga River delta. The expedition camped at the Damchik site of the Astrakhan State Biosphere Reserve.

Biological and hydrochemical studies covered the water area of the fore-delta and the channel (erik) of the Volga River delta, 29 stations were made, 150 measurements of hydrochemical, hydrophysical and hydrobiological parameters were made.

This year’s expedition was a continuation of the research of 2021 during the flood period, during which data were obtained on the spatial variability of temperature, the main hydrochemical (biogenic elements, dissolved oxygen, parameters of the carbonate system) and hydrobiological (content of chlorophyll "a" and phytoplankton species composition) parameters , as well as the main salt composition and pollutants in the water area of the foredelta and the adjacent shelf.

The main difference from the work of the previous year was the achievement of the zone of mixing of river and sea waters (salinity of 4 psu was found) on the beam of Zhemchuzhny Island and the selection of hydrochemical samples in this area. Last year's expedition showed a frontal zone in this region of the Caspian Sea, expressed in a high content of chlorophyll "a" against the background of a low content of the main nutrients and high oxygen saturation. To assess the degree of river runoff transformation in Phragmites latissimus reed beds, samples were taken for biological and hydrochemical parameters and hydrological parameters were measured.

At the moment, the processing of the obtained water samples and biological samples continues in the Laboratory of Biohydrochemistry. The obtained data will expand the understanding of river runoff transformation both in the Volga River delta itself and in the mixing zone of the Caspian and Volga waters.

The study was carried out within the framework of the state task of the IO RAS (FMWE-2021-0007) "Marine and ocean ecosystems in a changing climate and anthropogenic impact: the structure and biological productivity of the ecosystem of the Arctic Basin and the seas of Russia, ecosystems and potential biological resources of the open ocean" (head - Academician M.V. Flint). We thank the Deputy Director for Science of the Astrakhan Reserve Ph.D. Kirill Litvinov for help in organizing the research.