Bacterial production, protozoan grazing, and mineralization in stratified Lake Vechten

The role of heterotrophic nanoflagellates (HNAN, size 2-20 μm) in grazing on bacteria and mineralization of organic matter in stratified Lake Vechten was studied.Quantitative effects of manipulation and fixation on HNAN were checked. Considerable losses were caused by centrifugation, even at low speed, and by filtration if the vacuum exceeded 3 kPa. HNAN were well preserved for several weeks with unbuffered 5% formaldehyde as well as with 0.3 to 1% glutaraldehyde (final concentrations). However, the chlorophyll autofluorescence of phototrophic nanoflagellates was strongly decreased by formalde... Mehr ...