Seasonal succession of Trachelomonas (Euglenophyceae) in a shallow eutrophic lake
W.-H. Kusber
Freie Universität Berlin, Institut für Systematische Botanik und Pflanzengeographie
Altensteinstr. 6, D-14195 Berlin
The temporal distribution of Euglenophyceae was determined throughout one year using Utermöhl's method. Cell numbers and volumes were calculated for each Trachelomonas species. Size, shape, and protoplast morphology were documented for each taxon. The volumes of the protoplast and of the envelope were measured separately.
Trachelomonas (T. volvocina > 700 cells ml-1) dominated in the Euglenophyceae by cell numbers after ice break in spring. This peak was followed by high cell numbers of euglenoid genera without envelope (e.g. Euglena, Phacus). In summer the genus Trachelomonas occurs with more species but low relative abundances. Almost all Trachelomonas species show a temporal distribution with two peaks, one in spring and one in autumn. In winter T. volvocina survives under ice cover with very low cell numbers (minimum 0,3 cells ml-1).