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Floodplain mollusc fauna of the lower Elbe and its tributaries -its history, ecology and changes induced by invasion plant species
Horáčková, Jitka ; Juřičková, Lucie (advisor) ; Pokorný, Petr (referee) ; Čejka, Tomáš (referee)
The molluscs are very suitable model of invertebrate group for ecological and palaeoecological studies for their specific traits. In the first part of the thesis, we showed based on available fossil mollusc successions that development of the floodplain mollusc fauna took place quite different way in various river floodplains, depending on their specifics and geographical location, because especially the ones situated in the chernozem area of the Czech Republic had very different history. Detailed processing of five fossil mollusc successions in the lower Ohře River floodplain confirmed the impoverishment of recent forest malacofauna does not relate to natural processes only (chapters 3 and 10), but it arises from historical development of this area which was under permanent stress of the human settlement and agricultural utilization (chapter 1) since the coming of the Neolithic people. We made similar conclusions in case of another 11 fossil mollusc successions in the neighbouring České Středohoří Mts. (chapter 2). In the second part of the thesis (chapter 3), we investigated the ecological patterns responsible for species richness and composition of the floodplain mollusc fauna are especially the elevation and humidity gradient, and then vegetation type and its biomass, light conditions of the...
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Floodplain mollusc fauna of the lower Elbe and its tributaries -its history, ecology and changes induced by invasion plant species
Horáčková, Jitka
The molluscs are very suitable model of invertebrate group for ecological and palaeoecological studies for their specific traits. In the first part of the thesis, we showed based on available fossil mollusc successions that development of the floodplain mollusc fauna took place quite different way in various river floodplains, depending on their specifics and geographical location, because especially the ones situated in the chernozem area of the Czech Republic had very different history. Detailed processing of five fossil mollusc successions in the lower Ohře River floodplain confirmed the impoverishment of recent forest malacofauna does not relate to natural processes only (chapters 3 and 10), but it arises from historical development of this area which was under permanent stress of the human settlement and agricultural utilization (chapter 1) since the coming of the Neolithic people. We made similar conclusions in case of another 11 fossil mollusc successions in the neighbouring České Středohoří Mts. (chapter 2). In the second part of the thesis (chapter 3), we investigated the ecological patterns responsible for species richness and composition of the floodplain mollusc fauna are especially the elevation and humidity gradient, and then vegetation type and its biomass, light conditions of the...
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Evaluation of proposed revitalization of the river Ploučnice close to Mimoň in terms of remobilization of historical contamination
Slabá, Eva ; Matys Grygar, Tomáš ; Elznicová, J.
The aim of the study was to estimate the uranium contamination in the alluvial sediments of original river beds of the Ploučnice river between 72-73 river kilometer on a left bank, near Mimoň town, and evaluate if the contamination should be included into preparation of revitalization projects. The study of contamination was started by mapping the gamma activity of the surface of the floodplain. Based on the resulting map the sediment samples were taken by hand earth drill from the former floodplain and channels abandoned in the 1980s by regulations. The samples were analysed by laboratory X-ray fluorescence (XRF). This step was followed by subsequent mapping by handheld XRF to specify the contamination pattern in the floodplain in more details. The evolution of watershed as well as the exact terrain model were processed by GIS program. Two major contaminated areas have been found, and further sampling was conducted. This enabled us to reconstruct the historical development of contamination at exceptional time scale resolution and describe precisely the evolution from the 19th century to the time of the regulation of that river reach. It has also been shown, that any revitalization in the near future would be probably thwarted due to extremely fast river changes which would cause an immediate re-introduction of the historical contamination into the fluvial system.
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Development of the fish assemblage in a restored river backwater
Hohausová, Eva
The restoration of the Kurfürst backwater was undertaken between December 1993 and November 1994. Already during the restoration, the number of fish species (>1+ fish) increased to 12, compared to 9 recorded before it. The following monitoring programme (1995-99) revealed further increases, up to 17 species. The structure of the fish assemblage, in terms of main species, reproductive and ecological groups, did not differ substantially between years, regardless of seasonal changes. Six species were newly recorded after restoration. Most species were found as both, 0+ and older fish, as many species probably spawned in or used the backwater as a nursery. The structure of the 0+ fish assemblage was also similar both before and after the restoration. After the 6-year monitoring, the restoration of the backwater can be considered as of benefit for the fish assemblage. Now, much will depend on the following development of the backwater, if it can further serve for local fish populations.
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