|
|
Biodiversity of standing floodplain waters and processes of its formation and preservation
Pithart, David
Water chemistry and planktic communities in the naturally eutrophic alluvial waters in the Lužnice floodplain have been studied. The floofplain waters are naturally eutrophic, with strong vertical physico-chemical gradients and oxygen depletions at the botom. Small pools and backwaters of this type have unique phytoplankton structure. Prevailing dominance of flegellates, namely Cryptophyceae, and low proportion of green chlorococcal algae and Diatoms, and almost absence of Cyanophyceae are very unusual for such eutrophic waters. Flagellate dominate thanks their ability to keep the vertical position in a permanently light limited conditions (resulted from poorly mixed water columns and intensive shading of water surface by vegetation). Floodplain geodiversity play crucial role, determining morphology and location of pools and backwaters, their exposition to flooding and inflows of underground water. Terrestial vegetation effects light exposition, leaf litter.
|
|
|
The effect of a high through-flow on the plankton of the reservoir Slapy?
Hrbáček, Jaroslav
In August 2003 an extraordinary intensive trough-flow has replaced the volume of water in the Slapy Reservoir in few days. Immediately a decrease of the transparency pH, frequency of planktonic crustaceans and an increase. In comparison with the previous years in the weeks following the flood an unusual increase of the frequency of blue greens mainly Microcystis and the diatoms Melosira a decrease of the diatom Fragillaria, and desmid Staurastrum was observed. As a possible cause decrease of pH and increase of total phosphorus has to be considered. As a possible cause of the decrease of the cladoceran Diaphanosoma and increase of species of Daphnia and Bosmina either the decrease of predation pressure by the export of fry due to the flood or the increase of food basis due to more intensive development of phytoplankton has to be considered. The effect of an exceptionally high through-flow on plankton is far from a dramatic one.
|
|
| |
|
| |
|
|
Fytoplankton aluviálních tůní
Pithart, David ; Kylbergerová, Magdalena ; Pechar, Libor ; Hrbáček, Jaroslav ; Fiala, Dan ; Bílý, Michal ; Rulík, M.
Phytoplankton of alluvial pools at Lužnice alluvium have been investigated by following methodological approaches: seasonal course of phytoplankton in two pools, extensive sampling (quarterly) of 30 pools, and phytoplankton diurnal vertical migration studies in several pools. Prevailing dominance of phytoflagellates, especially Cryptophyceae and Euglenophyceae and low contribution of coccal forms as Chlorococcales and Cyanophyte has been found as a main feature of phytoplankton community. This is caused by poor mixing of water column (large relative depth, wind protectio), where th ecoccal forms sediment out and are outcompeted by motile forms, able to determinate the position within the water column.
|
guest ::
