The state of hydrobionts in the Tyub‐Karagan Bay structure, Kazakhstan

Abstract

Aim. The purpose of the research was to study the state of hydrobionts in the Tyub‐Karagan Bay structure by season for a comparative analysis of their state with previous studies by the authors.Material and Methods. The conditions of hydrobionts (phyto, zoo‐plankton and macrozoobenthos) of the Tyub‐Karagan Bay structure have been studied for three seasons. Studies were carried out by traditional methodology.Results. The species composition of phytoplankton communities in spring was found to be less constant than in autumn; this is associated with heterogeneity in external conditions at the beginning of the growing season. The seasonal dynamics of zooplankton conformed to certain patterns. As a rule, from the beginning to the end of the growing season there was an enrichment of species composition and an increase in the quantitative indicators of zooplankton communities. The highest biomass was formed by bottom cenoses, where large mollusks play a leading role.Conclusion. During the 2018 research period, species richness and species diversity of phytoplankton were at a high level. Representatives of two categories were observed most often. Blue‐green dominated in number, while diatoms formed the basis of biomass. Species richness and species diversity of zooplankton was at a low or moderate level and most often constant. The seasonal dynamics of macrozoobenthos had common and specific features, depending on the research station location. Disproportionate changes in the quantitative indicators of bentonites are associated with a decrease in the average weight of individuals by autumn. This happened both through the strengthening of the role of small species and by an increase in the proportion of younger age stages in populations of bottom invertebrates.