Zooplankton species diversity dynamics of thermokarst lake from lena delta river

Abstract

© 2020 International Multidisciplinary Scientific Geoconference. All rights reserved. The article describes a long-term and seasonal dynamics of zooplankton species diversity and its relationships with hydrologic factors were investigated on Lake Fish located in Samoylov Island on the northeast of the Republic of Sakha (Yakutia), Russia. This lake was chosen as a research object due to its mixed type of origin: thermokarst-polygonal. Zooplankton was sampled at three locations: on the pelagic and littoral zones of the thermokarst part and polygonal part of the lake. In total, 90 taxa (80 species) of zooplankton, including 46 species Rotifera, 14 species Cladocera (Crustaceae), and 22 species Copepoda (Crustaceae) have been identified. A gradual increase in the number and diversity of species was observed from April to June. Several peaks in zooplankton species diversity were repeated during the summer months. A gradual decline in taxonomic diversity of zooplankton was notable from late August to September. The maximum species diversity was recorded in the pelagic zone of the lake. Mass species Conochilus unicornis, Kellicottia longispina, Keratella cochlearis, Keratella quadrata from Rotifera, Bosmina (Eubosmina) longispina from Cladocera, and Eudiaptomus graciloides from Copepoda forming the basis of the lake's zooplankton had Holarctic or Palearctic distribution despite the predominance of widespread species in the zooplankton communities. The predominance of littoral species in the zooplankton of the lake due to the overgrown polygonal part and shallow shores of the thermokarst part of the lake. This work was supported by the subsidy allocated to Kazan Federal University for the state assignment #671-2020-0049 in the sphere of scientific activities and by the Russian Foundation for Basic Research (project no. 18-05-00406). The part of this work concerning microscopy of zooplankton was supported by grant from Russian Scientific Foundation (project no. project no. 20-17-00135).