Factors of biodiversity as criteion for evaluating ecological status of water bodies in Astrakhan

Abstract

The article presents an assessment of the quantitative and qualitative composition 
 of zooplankton in the zoocenosis of the water bodies of Astrakhan. There have been analyzed 
 bioindicators that allow to determine the structure of zooplankton during the research period. 
 A comparative characteristic of the reservoirs has been carried out, according to the indicators 
 of species density (species richness), complexity of the community structure and dominating species. Samples of zooplankton collected in the autumn of 2016 and 2017 in the water bodies within the city limits (the Tsarev river (stations Strelka, Bridge) and the Kutum river (station Strelka opposite the Civil Registry Office and nearby N. Ostrovsky Street) served as the research material. According to the analysis results of biodiversity indices, it has been found that the highest increase in quality indicators (almost doubled in 2017, compared to 2016) was observed in relation to the density of organisms in the Tsarev river. At the same time, the indicator of complexity of the plankton community structure, expressed in quantitative terms, showed an increase by 1.4 times at all stations in 2017, compared to 2016. This is a signal of improvement in the environmental component in urban water bodies. According to the Simpson index values in 2017, plankton species can be assumed to dominate in the zoocenosis. The population of the zoocenosis in the water bodies of Astrakhan is exposed to the anthropogenic impact, which causes changes in the quantitative and qualitative characteristics of communities and their structure. However, increasing values of all three considered biodiversity indices in 2017 indicate a gradual restoration of the biocenosis structure, and an increasing proportion of species in composition of the plankton community.