Bacterial activities in newly deposited sediments of the River Danube in Lower Austria
Farnleitner, A.; Kasimir, D. G.
After a particular high-water event in the River Danube, in April 1994, physicochemical parameters (pH, pE, temperature, sediment water content, specific mass of sediment, grain size distribution) and microbial parameters (direct counts of bacteria, bacterial biomass, MUF-ß-D-glucopyranoside hydrolysis rate) were determined in newly-formed deposits in the Rosskopfarm, a backwater near Hainburg, Lower Austria. The investigations were carried out during a period of 4 months. Bacterial numbers, biomass, pH and pE changed significantly within the first 3 to 5 weeks after sediment deposition and, with a reduction in pH, aerobic sediments became subaerobic or anaerobic. Bacterial production was estimated to reach 0.8-2.5 g C/m2 sediment and day. Floods appear able to provide significant amounts of high quality material for consumption by higher trophic levels, mediated by the metabolic activities of bacteria.