The Current State of Zooplankton Diversity in the Middle Caspian Sea during Spring

The study of planktonic animals the Caspian Sea is topical and, during last centuries, has brought and continues to bring new results. This an inevitable process attributed introduction non-indigenous predatory representatives zooplankton by ballast water ships. During period, Middle was represented 13 taxa consisted mainly species typical Palearctic region. Native fauna three species—cladoceran Evadne anonyx, Podonevadne camptonyx, copepod Halicyclops sarsi period. quantitative variables did not reach a high level in May 2020 2021 compared data previous years. Cladocerans copepods Acartia tonsa, larvae Cirripedia dominated 2020. By 2021, dominant year had been replaced cladoceran nordmanni. One-way ANOVA analysis detected significant differences cladocerans between different years study. decreasing abundance, biomass, alteration period may be associated with feeding type predator slight elevation salinity.