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Dynamics and structure of diatom communities in glacier and/or groundwater-fed streams.
Prüherová, Alžběta ; Kulichová, Jana (advisor) ; Žárský, Jakub (referee)
Alpine streams and their algal communities have been increasingly challenged in recent years by the effects of climate change, particularly associated with glacier retreat and their melting. Glaciers in particular are an important hydrological source for alpine ecosystems, which are threatened by rising temperatures, that are more influential in these areas than at lower altitudes. Due to the ongoing retreat of glaciers, glacier meltwater is increasingly being added to tributary streams. This glacier water has significantly different characteristics and may thus be a significant contributor to changes in the diatom biodiversity of alpine aquatic ecosystems. The manipulated experiment of this thesis took place from July to September 2020 in the Swiss Alps. Using permanent diatom slides created out of samples taken from the experimental channels, changes occurring when glacier meltwater was added to ground water-fed tributary streams and changes occurring when ground water was added to glacier-fed streams were analysed. Changes in diatom abundances were compared with environmental factors such as temperature, pH, turbidity or conductivity. Glacial streams were characterised by significantly lower temperature, higher values of conductivity and turbidity, higher oxygen saturation and also higher pH...
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The influence of glacial meltwater on benthic algal communities in alpine streams.
Prüherová, Alžběta ; Kulichová, Jana (advisor) ; Vinšová, Petra (referee)
The specifics of glacial streams, as streams fed and influenced by mountain glacier are very tough conditions which, in these alpine habitats, last all year long. Typical features of a glacial stream are cold temperatures, oligotrophic water, high flow rate which is connected to a very good oxygen saturation and the stream level fluctuations, not only visible during the whole year, but also in a scope of a few hours during one day. Therefore populations of organisms living in these habitats have to be sufficiently adapted to such harsh environment, in order to not just survive local harsh conditions, but effectively use them to reproduce and inhabit the limited space. This thesis is focused on benthic communities of these water bodies and is a summary of knowledge from studies done mainly in Italian, Austrian and Swiss Alps. Seasonal influence of the glacier and the influence of climate change on the fragile communities inhabiting glacial streams in higher altitudes is then discussed as well as the types of streams in the alpine zone dividing said streams into several types, first into three main types according to their water source and later on into more specific types of the Alps streams according to their bed rock and other geographic variables. Glacial streams are nowadays the subject of...
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