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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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The diversity of filamentous freshwater algae and factors affecting the dynamics of their communities
Hadravová, Anna-Marie ; Šťastný, Jan (advisor) ; Woodard, Kateřina (referee)
This bachelors thesis is summing up the knowleadge from published papers which are dealing with the ecology of filamentous algae communities. It is focused on how the seasonal dynamics and biotic and abiotic factors do affect the communities of filamentous algae. The first part of the thesis contains a taxonomical overview of genera of the concern. In the second part there are different types of water habitats divided by their morphology and other characteristics (depth, temperature etc.). I am dealing with the factors affecting the composition of filamentous algae communities in stagnant waters of the temperate zone. No comprehensive works focusing on this field have been published so far. My thesis presents a synthesis of knowledge from avaliable sources. The species concepts of many filamentous algae are quite confusing, that is why their species determination is so difficult. That is the reason why there are not many journal articles dealing with such ecological issues. Key words: filamentous algae, ecology, freshwater habitats, diversity
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The role of microhabitats in spatio-temporal differentiation of phytoplankton flagellates
Pusztai, Martin ; Němcová, Yvonne (advisor) ; Bílý, Michal (referee)
This thesis deals with factors structuring phytoplankton flagellates. The aim of the thesis was to investigate the role of microhabitats in spatio-temporal differentiation of lentic communities of these flagellates, which has not been rigorously examined to date. The study was conducted during 2010-2013 in the shallow littoral sites of Horní rybník, Rybníčky u Podbořánek Nature Reserve. Phytoplankton flagellates showed cyclic seasonal dynamics, which was reflected by significantly different community structure and species richness during the season. In contrast, silica-scaled chrysophytes showed a non- cyclic seasonal dynamics. The impact of the season was strongly correlated with the impact of fluctuating environmental factors - pH, conductivity and temperature. Gradient of interrelated environmental factors between the northern and southern shore together with microhabitat - substrate type played the major role and accounted for 64.4 - 75.8 % variability in the data. Microhabitat type (plankton, metaphyton, epipelon) significantly affected species richness and community structure also in the course of the season. A large number of species was assessed to prefer a certain type of microhabitat. These preferences were observed at both species and generic levels, and even at the level of the main taxonomic...
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Distribution, diversity and ecology of benthic desmids along local spatial scale
Svoboda, Pavel ; Šťastný, Jan (advisor) ; Řeháková, Klára (referee)
Besides spatial heterogeneity, an important component of diversity of the protist communities is also the variation in species assemblages through time (temporal turnover). Spatial and temporal variation in patterns of distribution and abundance of lentic microphytobenthos assemblages is often large and occurs at relatively small spatial scale. Desmids (Zygnematophyceae) often constitute a characteristic part of the microphytobenthos of peat bogs. Despite their important role in primary production and fact that they are useful indicators of ecosystem uniqueness, investigations of their seasonality and spatial distribution are scarce. In my thesis I have investigated if desmid epipelic communities are driven rather by neutral or niche-based processes, and I also focused on the factors affecting their diversity, seasonal dynamics and spatial patterns at the local spatial scale. The study was conducted at the two different types of biotopes - minerotrophic lowland peat bogs (Doksy region) and ombrotrophic raised bogs (Jizera Mountains region). Seasonal changes in species composition and diversity of assemblages were not evident. This may be affected by a monopolization effect and also that local abundance of species was positively correlated with population persistence, which suggests that high local...
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Spatial heterogeneity and seasonal succession of phytoplankton along the longitudinal gradient in a eutrophic reservoir
RYCHTECKÝ, Pavel
Spatial distribution and seasonal succesion of phytoplankton along the longitudinal axis of a eutrophic Římov reservoir (Czech Republic) was investigated from April to October 2007, at 1?2 week intervals. Phytoplankton spatial heterogeneity was the most apparent during the summer reflecting a pronounced gradient of environmental parameters from the river inflow to the dam. The riverine zone differed markedly from downstream parts of the reservoir, being dominated by functional groups D and J (large cryptophytes and colonial diatoms). While a dense cyanobacterial bloom (groups H1 and M) occurred in the transition zone, considerably lower biomass of desmids (Group N) was found at lacustrine zone at the same time. A sudden flood event considerably altered nutrient and light availability, and later even resulted in cyanobacterial dominance in the whole reservoir.
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Spatial heterogeneity of soil CO2 efflux in four different ecosystems
Dařenová, Eva
Manual measurements of soil CO2 effl ux on a larger number of positions can give precise estimation of CO2 effl ux from the investigated area and together with temporal dynamics, observed in continuous measurements, can provide a good view on the ecosystem carbon balance. In this study we investigated the spatial heterogeneity of soil CO2 effl ux in four diff erent ecosystems (spruce forest, beech forest, wetland, grassland). Soil CO2 was measured on a net of 25–65 positions using a manual measurement system. We tried to fi nd responsible factors for the heterogeneity and to determine a measurement protocol for the most precise estimation of soil CO2 effl ux. Th e highest respiration activity was observed in the spruce forest, the lowest in the wetland ecosystem, where it was caused by a high water table. In the wetland ecosystem, there was the highest spatial heterogeneity of respiration activity, which reached almost 60 %. Th is high heterogeneity was caused by the gradient of the water table depth. Contrary to this, the lowest heterogeneity was found in the grassland where it was only about 15 %. In the spruce and beech forest the heterogeneity ranged between 35 and 45 %. As infl uencing factors we investigated e.g. soil moisture, tree distance and amount of the above ground biomass.
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Spatial heterogeneity of physico chemical parameters and phytoplankton along the longitudinal profile of the Římov Reservoir
NOVOTNÁ, Jitka
In 2011, vertical and longitudinal gradients of temperature, oxygen, pH, conductivity and chlorophyll were measured in the Římov Reservoir. Relative distance model was employed to evaluate spatial heterogeneity of parameters measured along the longitudinal axis of the reservoir. The inflow part comprised 15 % of the overall reservoir length and was characterized with temperature, pH and chlorophyll values lower than the rest of the reservoir. Highest chlorophyll and dissolved oxygen concentrations along with pH were measured in the transition zone constituting 40 % of the reservoir length. Lacustrine zone with low chlorophyll concentration accounted for 45 % of the reservoir. It was characterized with pronounced metalimnetic and hypolimnetic oxygen minima during summer as well as the marked increase in conductivity towards bottom.
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The morphological and genetic differentiation of \kur{Daphnia} in canyon-shaped reservoirs
HOROVÁ, Barbora
We analysed the pattern of spatial heterogeneity of Daphnia longispina species complex in 11 canyon-shaped reservoirs. We found for the first time that the spatial pattern is not random. Daphnia cucullata shows strong preference for upstream regions while Daphnia longispina and D. galeata x longispina are preferring the deep downstream parts of reservoirs. These not random pattern is probably driven by longitudinal and vertical ecological gradients (fish predation pressure, nutrient concentration, phytoplankton biomass etc.)
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