Original paper

A microscopical study of diatom phytoplankton in deep crater Lake El'gygytgyn, Northeast Siberia

Cremer, Holger; Wagner, Bernd; Juschus, Olaf; Melles, Martin


A survey of the planktonic diatom community was carried out during summer 2003 in Lake El'gygytgyn, a deep, cold, low conductive and oligotrophic crater lake in the Northeast Siberian Arctic. Five planktonic diatom species were identified: Cyclostephanos dubius, Cyclotella ocellata, Cyclotella tripartita, Pliocaenicus costatus, and Stephanocostis chantaicus. The morphological details of the five taxa are documented by light and partly also scanning electron micrographs. Additionally, ecological and biogeographic data are provided. This is the first evidence of S. chantaicus in a north-east Siberian lake and one of the first findings of P. costatus outside the Baikal Lake region. The diatom community in summer 2003 was almost monospecificly dominated by Cyclotella ocellata (>96%), a species that displays a tremendous morphological variability. High concentrations and accumulation rates of diatom frustules during the ice-covered period (May-June 2003) indicated considerable under-ice phytoplankton growth.