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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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Seasonal dynamics of mats composed by green alga Zygnema (Zygnematophyceae)
Trumhová, Kateřina ; Pichrtová, Martina (advisor) ; Remias, Daniel (referee) ; Žárský, Jakub (referee)
The mats formed by Zygnema spp. are well known and frequently found in streams, puddles, seepages, and ponds. Owing to the low and inconsistent water quantity of these biotopes, algae are periodically subjected to stresses like desiccation, freezing, or strong solar radiation. Recent studies have revealed that Zygnema survives various stresses in pre-akinetes, modified resistant vegetative cells. However, earlier experiments mostly aimed at osmotic stress and desiccation. Moreover, the mats formed by these algae have seasonal dynamics that have been observed several times, not only in temperate conditions but also in the Arctic. Field observations revealed that most of the biomass is periodically lost, and new mats are formed every year. Simultaneously, we know little about the genetic composition of the mats and how it changes over time; previous work has focused mainly on the mats as an entirety. Therefore, this work mainly aimed to subject the mats formed by the algae Zygnema spp. to long-term observation and subsequent experiments. We selected a region in the Austrian Alps, which we visited several times a year, and sampled two sites with different water regimes. Further research in collaboration with colleagues occurred in the Arctic. Zygnema spp. strains were subsequently isolated from the...
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Separation and Elemental Composition of Tardigrades and Rotifers from Cryoconite in Svalbard
Jaroměřská, Tereza ; Žárský, Jakub (advisor) ; Šabacká, Marie (referee)
For years considered pristine, glacial ecosystems are attracting more attention of biologists from various branches in last decades. Moreover, they are currently considered to be ecosystems forming the coldest biome on the Earth. The life on glaciers ranges from viruses and bacteria to highest consumers such as few groups of microinvertebrates. The most common are tardigrades (phylum Tardigrada) and rotifers (phylum Rotifera) which inhabit cryoconite holes on the glacial surface. Several studies highlight the importance of the role of these consumers. However, due to the dominance of prokaryotes on the glacial surface, these microinvertebrates are usually out of the major scope of most studies aiming at biological processes. The present study shows pioneering results on the isotopic composition of tardigrades and rotifers, which are the top consumers in cryoconite ecosystems, and is a foundation for the exploration of trophic pathways and interactions within cryoconite holes using elemental and stable isotopic analyses. It also presents information about the species composition of tardigrades and rotifers on different glaciers and in different parts of the ablation zone. We identified 5 species of tardigrades (Hypsibius sp., Hypsibius cf. dujardini, Pilatobius sp., Isohypsibius sp. and Cryoconicus...
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Separation and Elemental Composition of Tardigrades and Rotifers from Cryoconite in Svalbard
Jaroměřská, Tereza ; Žárský, Jakub (advisor) ; Šabacká, Marie (referee)
For years considered pristine, glacial ecosystems are attracting more attention of biologists from various branches in last decades. Moreover, they are currently considered to be ecosystems forming the coldest biome on the Earth. The life on glaciers ranges from viruses and bacteria to highest consumers such as few groups of microinvertebrates. The most common are tardigrades (phylum Tardigrada) and rotifers (phylum Rotifera) which inhabit cryoconite holes on the glacial surface. Several studies highlight the importance of the role of these consumers. However, due to the dominance of prokaryotes on the glacial surface, these microinvertebrates are usually out of the major scope of most studies aiming at biological processes. The present study shows pioneering results on the isotopic composition of tardigrades and rotifers, which are the top consumers in cryoconite ecosystems, and is a foundation for the exploration of trophic pathways and interactions within cryoconite holes using elemental and stable isotopic analyses. It also presents information about the species composition of tardigrades and rotifers on different glaciers and in different parts of the ablation zone. We identified 5 species of tardigrades (Hypsibius sp., Hypsibius cf. dujardini, Pilatobius sp., Isohypsibius sp. and Cryoconicus...
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Stoichiometric patterns in cold oligotrophic aquatic systems
Jaroměřská, Tereza ; Žárský, Jakub (advisor) ; Vymazal, Jan (referee)
Ecological stoichiometry is a conceptual framework which helps us to describe an ecosystem through its elemental composition, fluxes of matter and balance of energy. In glacier habitats, ecological patterns are different than in the terrestrial environment, and the research has been done mostly in the last decade. The result is that stoichiometric data only exists in small amounts, and are influenced by searching area and preference of the researcher. Stoichiometry of glacial hydrological systems has patterns which are specific for these habitats, and the knowledge about invertebrate stoichiometry living in those waters is still in its early days. Powered by TCPDF (www.tcpdf.org)
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Biogeographical position of the Tristan da Cunha archipelago based on floristic records.
Vinšová, Petra ; Kopalová, Kateřina (advisor) ; Žárský, Jakub (referee)
The archipelago Tristan da Cunha is situated in the South Atlantic Ocean, about midway between South America and southern tip of Africa. It represents one of the least disturbed temperate island systems in the world, supports many endemic plant and animal species. Although the locality is interesting by many aspects, many fields still remain under-studied. This bachelor thesis presents a synthesis of available literature about the archipelagos non-marine non-vascular floras, which are of a great diversity, but mostly still overlooked by scientist. For some of them were made lists of taxa present. Further, the distributional ability and patterns of this plant groups are discussed. KEYWORDS: Tristan da Cunha; Oceanic islands; Botanic; Distribution; Island Biogeography; Lichens; Mosses; Liverworts and Hornworts; Diatoms;
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