Riedler, P. University of Vienna, Dept. of Hydrobotany, pati@pflaphy.pph.univie.ac.at
Schagerl, M. University of Vienna, Dept. of Hydrobotany, michael.schagerl@univie.ac.at
Heiler, G. University of Vienna, Dept. of Limnology,
Hein, T. University of Vienna, Dept. of Limnology, thomas.hein@univie.ac.at
Holarek, C. University of Vienna, Dept. of Limnology, holarek@zoo.univie.ac.at
Schrutka, S. University of Vienna, Dept. of Limnology, susanne@zoo.univie.ac.at
Schiemer, F. University of Vienna, Dept. of Limnology, schiemer@zoo.univie.ac.at

 
HYDROLOGICAL CONNECTIVITY: A KEY-FACTOR FOR PHYTOPLANKTON COMMUNITIES IN FLOODPLAINS OF THE RIVER DANUBE, AUSTRIA
 
The floodplain of the Danube near Vienna consists of various sections of different dynamic character corresponding to the grade of hydrological connectivity to the river. Therefore, in more dynamic sections water level fluctuations of the main stream influence physical and chemical parameters as well as the assemblage of the plankton communities. The aim of this study was to investigate the controlling effect of hydrology on biomass and diversity of phytoplankton in two characteristic floodplain sections - an isolated and a dynamic part. In 1997 phytoplankton as well as zooplankton were quantified weekly. In the isolated section of the floodplain algal development was mostly restricted by high grazing pressure resulting in low standing stocks. However phytoplankton of the more dynamic section was controlled by water level fluctuations of the Danube. Algal biomass and diversity were expressed by an optimum curve related to days after flood pulse. Within the first days after flood events biomass was low due to washing out; the algal community of the floodplain consisted mainly of centric diatoms inoculated by the river. One week later favourable environmental conditions caused maxima in biomass and diversity. During the following weeks biomass as well as diversity were reduced by high grazing pressure removing preferentially small algal cells.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS47TU0668S