Open AccessRETROSPECTIVE ANALYSIS OF RESTRUCTURING IN COMPOSITION OF MACROZOOBENTHOS UNDER CASPIAN SEA TRANSGRESSION
Author(s) -
Anna Viktorovna Mikhajlova
Publication year - 2021
Publication title -
vestnik astrahanskogo gosudarstvennogo tehničeskogo universiteta. seriâ: rybnoe hozâjstvo
Language(s) - English
Resource type - Journals
eISSN - 2309-978X
pISSN - 2073-5529
DOI - 10.24143/2073-5529-2021-2-47-54
Subject(s) - fauna , biomass (ecology) , ecosystem , hydrobiology , productivity , salinity , crustacean , ecology , biology , fishery , oceanography , aquatic environment , geology , economics , macroeconomics
The article highlights the processes of lowering and raising the Caspian Sea level and its influence on the quantitative and qualitative characteristics of the aquatic bioresources, including zoobenthos. The development of macrozoobenthos in the Caspian Sea including the Northern Caspian is associated with various processes: chemical, physical and biological. The presence of macrozoobenthos determines the fish productivity in the sea, it is an integral part of the ecosystem of the northern part of the Caspian Sea. In this regard, the assessment of the composition and quantitative characteristics of bottom communities becomes important. One of the urgent tasks of modern hydrobiology is detecting the basic regularities in the biotic processes that affect the qualitative and quantitative changes in the aquatic organisms. This research is of a retrospective nature. On the basis of a long-term analysis of the dynamics of the species structure of bottom zoocenoses there have been revealed the changes in the macrozoobenthos of the western part of the Northern Caspian in the first and second periods of the sea level rise (1978–1988 and 1989–1995). Decreasing water salinity, increasing desalinated zones and areas with oxygen deficiency in the bottom horizon (in the extremely high-water years of 1990 and 1991) contributed to the significant changes in the quantitative and qualitative composition of the bottom fauna. From the first stage to the second there was recorded a decrease in the number and biomass of crustaceans and molluscs. The species Stenogammarus macrurus (G. O. Sars) and Stenogammarus similis (G. O. Sars), which are tolerant to the significant salinity fluctuations, as well as abra, which is resistant to oxygen deficiency were most abundant in the water complex with light salinity. Also, there has been considered the water content of the rivers of the Caspian basin and the type of soil as factors influencing changes in the concentration of macrozoobenthos.