Hydrology as a major factor determining plankton development in two floodplain segments and the River Danube, Austria

Hydrological connectivity is central to the understanding of ecological processes in large river-floodplain systems. Effects of hydrological connectivity were investigated in context with the restoration of ecological integrity. In Austria, downstream of Vienna, the River Danube and two floodplain segments were compared, based on their hydrological and physico-chemical conditions. The biomass of bacterio-, phyto-, proto- and metazooplankton was studied along with the controlling environmental factors influenced by hydrological processes. Lotic conditions led to higher phytoplankton biomass, whereas under lentic conditions the heterotrophic compartments dominated the plankton. The biomass ratio of phyto- to bacterioplankton declined as hydrological connectivity decreased.